# Tight Arse Stir Plate



## sosman

Ok so I haven't used it in anger yet but here is my latest project, inspired by the many already out there on the web.

http://brewiki.org/StirPlate


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## vlbaby

thats an interesting website. I wonder if a stirrer could be added to the fermeter to speed things up a bit, particularly in lagers.

vlbaby.


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## Hoops

Top stuff SOS

Simple but effective. Looks like another project on the list for later  <_<


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## dicko

Hi Sosman,

Looks like a good project.
Can you tell me where you got the stir bar?

Cheers


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## Gulf Brewery

dicko said:


> Hi Sosman,
> 
> Looks like a good project.
> Can you tell me where you got the stir bar?
> 
> Cheers
> [post="54754"][/post]​



The stir bars are available from lab supply places. They vary in price from $4 for a 4mm long one to about $9 for a 70mm long one. 

I have an article showing exactly how to build a magnetic stirrer. All I need is for the gallery to come up and I can post the article.

Cheers
Pedro


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## Gulf Brewery

Finally got organised. You can see the article on how to build a stirrer here


Cheers
Pedro


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## Hoops

Damn you guys, you just make me want more stuff :excl: 

Just got back from Jaycar with some rare earth magnets  

Great posts with good info and pics. Keep it up guys.

Hoops


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## Boots

Great document Gulf brewery.

Another thing to go on the list h34r:


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## jgriffin

I know what i'm doing on the workbench at work on monday.

Cheers Sos, what a great and cheap idea.


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## sosman

Yes it is a good idea - I have no idea who first came up with it.

The stir bar (40mm) came from science supplies aust. IIRC http://www.ssapl.com.au in Mitcham (opposite Ellerslie Hops).

The magnets came from Alpha Magnetics in Boronia.


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## nonicman

Thanks Sosman and GulfBrewery, I may have the bits for this project (minus the stirrer) around the house


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## sosman

I updated the wiki page with the 'final' details. I am waiting for the acid wash to settle before I crank up the starter so it will be brewing a SFA this weekend but I will report back on how well the yeast starter comes up (assuming I don't kill all the yeast at pH 2 overnight).

http://brewiki.org/StirPlate






cheers


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## Kai

Sexy. I've occasionally dreamed about a stir plate for my starters.

(edit) digressing a little, what was the shutter speed on your camera? You did well to capture that flea in action.


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## sosman

Kai said:


> Sexy. I've occasionally dreamed about a stir plate for my starters.
> 
> (edit) digressing a little, what was the shutter speed on your camera? You did well to capture that flea in action.
> [post="54806"][/post]​


Wouldn't have the foggiest. The stir bar doesn't go real fast though.


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## Plastic Man

I bought some cheap rare earth magnets last year from Oatley Electronics

http://www.oatleyelectronics.com/items.html

A few of the 7mm OD ones for $0.55 may work for the stirrer. They are amazingly strong.

Also had another browse of their web site today. Some interesting stuff. Check out the Bargain Corners 1 to 5 for some interesting temperature control gear.

Also do a search on:

GH1 maybe a good 24V small fan
MF3 12V fans for $4
TC001 interesting sounding temp controller.


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## dicko

> Also had another browse of their web site today. Some interesting stuff.



Hi Plastic Man,

Interesting site, that 24v 320 rpm geared motor might be good for a grain mill and for $79.00 it would be pretty cheap.

Cheers


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## Gulf Brewery

Plastic Man said:


> I bought some cheap rare earth magnets last year from Oatley Electronics
> 
> http://www.oatleyelectronics.com/items.html
> 
> 
> TC001 interesting sounding temp controller.
> [post="54822"][/post]​



Dicko

I have 2 of the TC001 controllers which I was going to use them for spare parts. I don't think it is going to be easy to use them as a temperature controller. If someone has worked out a way of using them, then please tell us.

Cheers
Pedro


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## Hoops

What size flasks do you guys use?
I was thinking maybe getting a 500ml, 1L and 2L.
Also what size stir bars would you use with the coresponding flasks?

Anyone else in Brisbane know a Lab supply place with good prices?
Anyone else in Brisbane want to buy some of this stuff together? (erlenmeyers & stir bars)

Hoops


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## vlbaby

That temperature controller looks like it could be ok for controlling a HLT or mash tun etc. I dont see any mention of the type of temp probe it uses or if there is a readout etc. Doesnt seem to much info on that website, not enough to decide if it can be used or not.

vlbaby.


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## Goat

Hoops - I started with a 1L , but its really too small, so I've got 2 3L ones which are perfect. 

Because of the shape, boil-overs are really easy, so you wont be able to fill it to the volume - I usually go 2.5L in my 3L flask to allow plenty of head space in the top of the flask.


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## jgriffin

Hoops said:


> What size flasks do you guys use?
> I was thinking maybe getting a 500ml, 1L and 2L.
> Also what size stir bars would you use with the coresponding flasks?
> 
> Anyone else in Brisbane know a Lab supply place with good prices?
> Anyone else in Brisbane want to buy some of this stuff together? (erlenmeyers & stir bars)
> 
> Hoops
> [post="54857"][/post]​



I'm up Hoops. Just did a yellow pages, and it looks like there is a good dozen supply places that would fit the bill.


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## Hoops

> Hoops - I started with a 1L , but its really too small, so I've got 2 3L ones which are perfect.
> 
> Because of the shape, boil-overs are really easy, so you wont be able to fill it to the volume - I usually go 2.5L in my 3L flask to allow plenty of head space in the top of the flask.



So probably a 1L & 3L then?
What about those that use slants? would a 500ml/250ml be good then?



> I'm up Hoops. Just did a yellow pages, and it looks like there is a good dozen supply places that would fit the bill.


I've used 2 in Brisbane so far. Will have to get prices this week, just need to decide on sizes and qty.

Hoops


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## sosman

Hoops said:


> What size flasks do you guys use?
> I was thinking maybe getting a 500ml, 1L and 2L.
> Also what size stir bars would you use with the coresponding flasks?
> [post="54857"][/post]​



I have a 250ml, 1L and 2L. The 250 fits in my pressure cooker. The 2L won't fit in my dishwasher. At this stage I have no real reason to go to 3L, I previously made starters in 1.25L PET bottles and if the gain in yeast production claimed for a stirplate is fair dinkum, the 2L should be more than adequate.

I don't boil my wort in the flask generally (sometimes). I sterilise it in a pressure cooker the night before and I use other methods to sanitise/sterilise the flasks.

I have a 40mm stir bar which works ok in all of my flasks. I think the length is more a factor of the magnet spacing than the flask size (assuming it will fit).

I will be going back and buying a longer stir bar (my magnets are quite far apart) and also *won't be bothering with the ring/pivot* style. The only reason I can see for these is to drive you mad with the clunking that goes on every revolution.


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## sosman

Less than a day since I said _"I have no need for anything bigger than 2L"_ I am looking for something bigger 







http://brewiki.org/StirPlate


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## jgriffin

Holy Sheet! Is that all krausen, or is it a combo of krausen and foam?


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## Batz

sosman
What about these bottles , I use them for my lager staters , 5lt
And they are only around $15.00
The bottom is slightly concave , this maybe a problem?

Batz


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## Hoops

Holy shit that's impressive SOS!

I was thinking the same thing today Batz, I have a few of those bottles.
Will have to make the mag stirrer and give it a try I think.

Hoops


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## Gulf Brewery

Batz said:


> sosman
> What about these bottles , I use them for my lager staters , 5lt
> And they are only around $15.00
> The bottom is slightly concave , this maybe a problem?
> 
> Batz
> [post="54886"][/post]​



Batz

The bottles need to be flat bottom. I have tried using ones with a slight curve and they don't work. If you had strong enough magnets, you may get it to work.

That sight of overflowing flasks is common. Dunno what to use after a 2 litre flask. If anyone knows of some 3 or 4 litre flat bottom flasks, it would be appreciated.

Cheers
Pedro


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## sosman

Gulf Brewery said:


> That sight of overflowing flasks is common. Dunno what to use after a 2 litre flask. If anyone knows of some 3 or 4 litre flat bottom flasks, it would be appreciated.
> [post="54890"][/post]​



Pedro, Science Supply Australia have 3L jobbies. I figure, 3L is not going to make much difference. The conical shape almost ensures that once the foam starts, the moment you look away it has blown out. I am more inclined to fit a blow off tube into a sanitised flask.

As for the 4.5L demijons, I have a couple but as Pedro said, I think the concave inner surface is not your friend.

Big, expensive, thin-walled, glass vessels and a pissed bloke don't mix. Think of it as a really big hydrometer.


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## Kai

Another option is using a shaker plate or whatever they're called, and sticking a couple of marbles in it. As the plate shakes the marbles will keep the starter agitated, but in a gentler fashion than a stirrer. And it means you can use a concave-bottomed vessel too.


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## pint of lager

Hoops asked what size flasks do we all have.

I use a 100ml erlenmeyer for the first step from the petri dish. This fits in the pressure cooker. I also have a couple of 250ml which fit in the pressure cooker.

There are a couple of 1 litre flasks but they have sat in the cupboard for the last two years unused. There is also a 2 litre flask in there, waiting for the day the stir plate happens.

To make up a starter, I make 600ml of 1.040sg wort from water, DME and some Wyeast nutrient. 50ml of this goes into the 100ml flask, the rest is divided up between two 250ml flasks, cover the three flask openings with squares of foil and pressure cook for 25 minutes. Put the 250ml flasks somewhere safe. Add yeast to the 50ml wort, fit bung and airlock, when this is fermenting, transfer to 5litre demijohn with the contents of the other two flasks. This means the wort for the first two steps is sterile.

Most of my gear came from Livingstone.


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## Hoops

So really you only need a 100ml erlenmeyer and a 5L demijon (250ml ones only used to sterilise wort)

Hmmm which ones to get then.......


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## sosman

jgriffin said:


> Holy Sheet! Is that all krausen, or is it a combo of krausen and foam?
> [post="54885"][/post]​


I am not sure of the distinction. It is very thick, creamy foam. There is no aeration going on as such, the stirrer is on quite slow.


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## Doc

I've refreshed your page this morning to catch the updates to the neat project. I'm really interested to see how much slurry you have generated when it all settles out.
I'm thinking this is a great way to make a larger quantity of yeast for my lagers, and allow me to just pitch the slurry.
I think I have an old PC fan in the shed and most of the other bits except for the magnets and a flat bottom flask. I think I'll be up to give it a go.
Thanks for the inspiration.

Doc


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## sosman

Doc said:


> I've refreshed your page this morning to catch the updates to the neat project. I'm really interested to see how much slurry you have generated when it all settles out.
> I'm thinking this is a great way to make a larger quantity of yeast for my lagers, and allow me to just pitch the slurry.
> I think I have an old PC fan in the shed and most of the other bits except for the magnets and a flat bottom flask. I think I'll be up to give it a go.
> Thanks for the inspiration.
> [post="54963"][/post]​



I added a pic of the settled yeast just now. I want to check the pH and gravity of the wort to follow up on my misgivings about non-ideal starting conditions. 

Give it a go - one of the easier projects you could take on.


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## Doc

sosman said:


> I added a pic of the settled yeast just now. I want to check the pH and gravity of the wort to follow up on my misgivings about non-ideal starting conditions.



Wow that looks like a decent amount of slurry for 24 hours.
I think this will be a must for my lager starters.

Off to find magnets :lol:

Beers,
Doc


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## pint of lager

Maybe a coffee plunger pot would be suitable as a flat bottomed flask. So long as you are happy with the covering of some aluminium foil.


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## Batz

Has anyone found a good place to buy the rare earth magnets?

Batz


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## ausdb

Batz, Jaycar in Perth have them and there is a place in Perth taht just sells magnets. I cant remember their name off hand but will look it up today and post it when I do

Cheers Ausdb


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## Batz

Thanks ausdb
I saw them on the JayCar website , a bit expensive I think....someone quoted a price way under that.

Am I correct here or should I expect to pay this?

http://www1.jaycar.com.au/productView.asp?...eMax=&SUBCATID=

Batz


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## Gulf Brewery

Batz said:


> Thanks ausdb
> I saw them on the JayCar website , a bit expensive I think....someone quoted a price way under that.
> 
> Am I correct here or should I expect to pay this?
> 
> http://www1.jaycar.com.au/productView.asp?...eMax=&SUBCATID=
> 
> Batz
> [post="54992"][/post]​



Batz

Look at the one I made (link in this thread somewhere) and I used 2 x bar magnets and glued them together. They work OK, but I haven't tried rare earth ones to see if they are better.

Cheers
Pedro


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## Batz

OK
Checkout Aussiemagnets


http://www.aussiemagnets.com.au/Merchant2/..._Code=RareEarth

Batz


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## PostModern

Old Hard Disk Drives have rare earth magnets. If you've got one sitting around in your spares cupboard they're a great source.


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## Plastic Man

These guys are selling out some rare earth magnets. 55c for the 7mm a 3mm. 

http://www.oatleyelectronics.com/items.html


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## Hoops

Batz said:


> OK
> Checkout Aussiemagnets
> 
> 
> http://www.aussiemagnets.com.au/Merchant2/..._Code=RareEarth
> 
> Batz
> [post="54994"][/post]​


I reckon the 10mm x 5mm would be the go.
If anyone else in Brisbane wants some maybe do a order together?

Hoops


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## quincy

I am just about to start yeast farming. The other challenge for me will be starters as up until now I have not used them or just dumped the next brew straight in on top of a previous trub.

Up until this morning I didn't even know that a "stir plate" existed.  

Now I have read through all this and the related links I have concluded that I need one!!  

Could I start out with a 100ml starter in say a 2litre flask, set up on a stir plate and continue to step it up (over the next 24-48 hrs) to a final volume of say 1 litre while it continues to stir?

Cheers


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## JasonY

Hey Sosman, any plans to bung the stirer in a fermenter! h34r: would be interesting to see what 20L of wort would get up to with a couple of days help from this. I am sure you wouldn't get anywhere near the turbulence you get in the flask but perhaps some potential?


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## jgriffin

JasonY said:


> Hey Sosman, any plans to bung the stirer in a fermenter! h34r: would be interesting to see what 20L of wort would get up to with a couple of days help from this. I am sure you wouldn't get anywhere near the turbulence you get in the flask but perhaps some potential?
> [post="55036"][/post]​




I was thinking the same thing but wasn't game to ask


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## Gulf Brewery

jgriffin said:


> JasonY said:
> 
> 
> 
> Hey Sosman, any plans to bung the stirer in a fermenter! h34r: would be interesting to see what 20L of wort would get up to with a couple of days help from this. I am sure you wouldn't get anywhere near the turbulence you get in the flask but perhaps some potential?
> [post="55036"][/post]​
> 
> 
> 
> 
> 
> I was thinking the same thing but wasn't game to ask
> [post="55037"][/post]​
Click to expand...


I was thinking the same thing but I'm not game to try it 
The loss from foaming would be quite high 

Cheers
Pedro


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## dicko

How about a 25litre brew in a 60litre fermenter?

or

Only turn it on for a short time?

Cheers


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## Batz

On a timer

Mix every hour for 5-10 min. ??


Batz


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## Gulf Brewery

quincy said:


> Could I start out with a 100ml starter in say a 2litre flask, set up on a stir plate and continue to step it up (over the next 24-48 hrs) to a final volume of say 1 litre while it continues to stir?
> [post="55031"][/post]​



Quincy - the only hassle with this is that 100ml doesn't give a lot of depth in a 2 litre flask. Mine is full at the moment, so I can't try it. I think it is better with at least 250ml in the 2 litre flask.



dicko said:


> How about a 25litre brew in a 60litre fermenter?
> or
> Only turn it on for a short time?
> Cheers
> [post="55086"][/post]​






Batz said:


> On a timer
> Mix every hour for 5-10 min. ??
> Batz
> [post="55088"][/post]​



Yep, both possible. The hassle with 25 litres in a 60 litre fermenter is that you won't be able to see the stir bar at the bottom. If it gets off centre, it would be a pain trying to get it back again. Also, the fermenter would need a dead flat spot in the middle.

Once the trub and yeast starts to floc as well, you won't be able to turn it with a fan motor / magnet combo. I know with mine, the fan goes a lot faster without a stir bar to move. I have had the yeast that thick at the bottom of a flask, that the motor could not turn the stir bar.

Cheers
Pedro


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## sosman

JasonY said:


> Hey Sosman, any plans to bung the stirer in a fermenter! h34r: would be interesting to see what 20L of wort would get up to with a couple of days help from this. I am sure you wouldn't get anywhere near the turbulence you get in the flask but perhaps some potential?
> [post="55036"][/post]​


Well not unless I use one of these:


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## sosman

Guys I have no doubt that the stir plate will improve yeast yield but please don't get too carried away with yeast that this trial yielded. Quite a bit of yeast went into the mix at the start, even though it was of quesionable viability. It had been in the fridge under beer for about 6 weeks.


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## JasonY

Gulf Brewery said:


> Once the trub and yeast starts to floc as well, you won't be able to turn it with a fan motor / magnet combo. I know with mine, the fan goes a lot faster without a stir bar to move. I have had the yeast that thick at the bottom of a flask, that the motor could not turn the stir bar.




Holy [email protected] sosman, you wont have any torque problems with that baby. Just watch the yeast don't crawl out and murder you in the night. Look forward to seeing the inevitable explosion. Just make sure it doesn't burn a hole in the fermenter! h34r: h34r: h34r: :beerbang:


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## sosman

pint of lager said:


> Maybe a coffee plunger pot would be suitable as a flat bottomed flask. So long as you are happy with the covering of some aluminium foil.
> [post="54988"][/post]​


The vessel doesn't *have* to be glass. The thin SS such as found in cheap stock pots will work ok (I tried it). You just have to manage sanitation as the wider the mouth, the more chance you have of contaminants blowing in.


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## sosman

Batz said:


> Has anyone found a good place to buy the rare earth magnets?
> [post="54989"][/post]​


Batz I bought my 12x5mm from Alpha Magnetics for 75c each.


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## Hoops

Great stuff Sos.
Just spoke to the guy from Alpha Magnets and he said that they are not supposed to send the rare earth magnets through the mail, and normally courier bag them.

The 12x5mm are 75cea + GST
The 12x10mm are $2ea + GST

Courier bag is $12+ GST and will fit about 50 magnets.

Who in Brisbane is interested in getting a few?

Got a few quotes for erlenmeyers, will get a few more and post them tonight.

Hoops


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## ausdb

Hi Batz

Here are the details of the magnet place in Perth, I said I would post the other day

MAGIC FORCE 
U 25/ 70 Roberts St Osborne Park 6017 (08) 9201 1655


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## Doc

What a shame these guys aren't in Australia. Min order $100 though.
Talk about being specialised :lol:

Doc


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## mobrien

mmm - those glass govered ones look neat!

M


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## sosman

Doc said:


> What a shame these guys aren't in Australia. Min order $100 though.
> [post="55310"][/post]​


Doc - www.ssapl.com.au has stir bars from these guys (or at least the guy showed me the catalog). Today I bought a 60mm plain round one. Easy to clean, no pivot to drive you mad.


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## sosman

Hoops said:


> Great stuff Sos.
> Just spoke to the guy from Alpha Magnets and he said that they are not supposed to send the rare earth magnets through the mail, and normally courier bag them.
> [post="55296"][/post]​


That makes sense. I reckon once the envelope stuck to the inside of the truck or mail box it would be tricky to get it off in once piece.

The price on the courier bag sounds a bit rich, I guess if you can arrange a group buy you'll be right.


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## sosman

Just a followup - after being in the fridge for 24 hours, the starter (slurry only) got pitched into a stout. Fired up in under 2 hours. Oh yes, I also cold pitched.


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## Doc

Just ordered the bits for my build. Scored a 120mm fan from work and have an old power supply at home. 
Ordered some magnets, pot, switch and enclosure that I'll pickup tomorrow.
Ordered a couple of stir-bars from the place you recommended sosman. But jeez they kill you on the courier fee. $14.95 postage/courier fee from Melb to Sydney. They are also out of stock on the 50mm and 70mm stir bars. The lady I ordered with checked with their supplier and they had them in stock so should have mine in my hand probably mid week ( as it is a long brew weekend this weekend).
I checked my two growlers I got from the US on my last trip and they have flat bottoms. They are 1/2 gallon growlers so should be a good size for this application. 

Doc


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## Gout

Doc you think thats bad ($15) i work live within 20min drive and its the same cost for me hence i just take a lunch time to go and grab bits.

hard to hand over $15 delivery when you are buying so little


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## Borret

I have another idea on this project.

I have used the 1.125litre Johnnie Walker bottles as a starter vessel in the past and have noticed that when you want to rouse the yeast you can do so easily by just spinning the bottle back and forth. 
This is because these bottles are square and so you get heaps of turbulence in them just by rotation. 

So I have just acquired (yet to be delivered though) a couple of those glass 5 litre whisky bottles that they dispense from at some bars. (they just throw them out!) I was going to use them for building up cultures to split and store but this thread got me thinking. You are all wanting more capacity and are worried about other vessels not having a flat bottom for the stir bar. 

My thoughts are that these square 5 litre bottles could be used in the same way as the stir-plate but without the need for a piece of stuff in the vessel that you might tip into your fermentor. Why not just make a turn table for the bottle to sit on and either set it up to oscillate back and forward or even just put it on a timer to switch it on and off in the one direction every 30 seconds or so. Result would be constantly agitated starter wort. You can easy get a bung to fit these so I reckon it could work.

Once I get them I might gadget up my idea and report back. Ahh more gadgets.

Borret


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## Borret

I might just add, you can get stirring versions of erlenmyer flasks with 4 vertical ribs/dimples in the side that work the same way. So it's obviously not a new concept.

Borret


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## sosman

Borret said:


> I have used the 1.125litre Johnnie Walker bottles as a starter vessel in the past and have noticed that when you want to rouse the yeast you can do so easily by just spinning the bottle back and forth.
> [post="55451"][/post]​



Spin the bottle is probably nearly as old as beer itself.


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## Borret

If you span the bottle on it's end and tried to get it to stay upright I think you were missing the point of the game.


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## sosman

Here is the overclocked version:


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## Boots

I knew someone would come up with a use for the cheap acrylic sheets I saw today. Nice work Sosman.


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## Gulf Brewery

Boots

Where are the cheap acrylic sheets? I could use them for a few breing tasks.

Cheers
Pedro


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## sosman

Gulf Brewery said:


> Where are the cheap acrylic sheets? I could use them for a few breing tasks.
> [post="55506"][/post]​


I just picked mine up for nicks from the scrap bin at a local "point of sale" joint.


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## Dazzling

G'day all,

just wondering if i didn't have a fan and power supply lying around the place to use, what would be the cheapest option to get one?

Cheers

Dazzling


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## Boots

Gulfbrewery,

They were $4.95 for sheets about 30cm x 30cm roughly. (let me guess, I'm about to find out that that's not cheap?)

They were at Menzel Plastics just down the road from work.


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## Doc

Dazzling said:


> G'day all,
> 
> just wondering if i didn't have a fan and power supply lying around the place to use, what would be the cheapest option to get one?
> 
> Cheers
> 
> Dazzling
> [post="55642"][/post]​



The cheapest option would be to get a fan out of an old PC. See your IT department at work. They would probably have an old power supply kicking around off an external modem or similar device too.

Beers,
Doc


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## vlbaby

You've been a busy bee Sos. That looks really good.  

vlbaby.


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## sosman

Dazzling said:


> just wondering if i didn't have a fan and power supply lying around the place to use, what would be the cheapest option to get one?
> [post="55642"][/post]​


For the fan, rat an old PC power supply. You friendly local PC store probably chucks them out and quite often the fan is still ok.

For a power supply you will need to rig up some variable voltage - a simple circuit with a pot and 3 legged voltage reg powered from a plug pack should do it.


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## Gulf Brewery

sosman said:


> For a power supply you will need to rig up some variable voltage - a simple circuit with a pot and 3 legged voltage reg powered from a plug pack should do it.
> [post="55798"][/post]​



I just used a plugpack and wired a 500 ohm pot in series. It saves all of the hassles trying to regulate power as it doesn't really need to be for the stirrer. I have checked all the maths and it is well within the rating for the pot for plugpacks up to 12 volt.

Cheers
Pedro


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## Doc

Based on Pedro's and SOSMans posts I got my prototype built today.
I scored a couple of 240v fans from work, so one of those formed the basis of my implementation.
A scout through the shed and I found an old light switch. A trip to the electrical store for a fan controller, power plug and some flex and I was in business. I trip to Jaycar and I got a jiffy box.
Here is the unit from the outside.





Here is the inside showing the fan controller closest and the switch at the other end.
For now I've just positioned the magnets on a washer on top of the fan as I'm not sure how high I may have to mount them until my magnetic stir bars arrive this week.
With an old small drill bit on top of the case I got a bit of movement. If I raised the magnets almost to the lid I got a lot of movement.




Beers,
Doc


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## sosman

Doc said:


> Based on Pedro's and SOSMans posts I got my prototype built today.
> I scored a couple of 240v fans from work, so one of those formed the basis of my implementation.
> ...
> With an old small drill bit on top of the case I got a bit of movement. If I raised the magnets almost to the lid I got a lot of movement.
> [post="56180"][/post]​


Doc - looking the goods. Might pay to allow some airflow through the box, depending on how warm the fan runs.

The stir bars I have are magnetic themselves so might "stick" a bit more than a drill bit (which is presumably HSS).


----------



## Hoops

Good stuff Doc. Have you got a part No for that box?
Hopefully pick up the magnets and box this week and have all my quotes back for the erlenmeyers & stir bars.

Hoops


----------



## Doc

Hoops said:


> Good stuff Doc. Have you got a part No for that box?
> Hopefully pick up the magnets and box this week and have all my quotes back for the erlenmeyers & stir bars.



The part number for the box is HB6134
The dimensions are 240 x 160 x 90 and the fan I used is a 120mm one to put it all into perspective.

Beers,
Doc


----------



## Hoops

OK looks like it may be cheapest to get the stuff couriered from Livingstone.
Rough prices are:

50mm stir bars - $6
70mm stir bars - $10

250ml erlenmeyer - $4
500ml erlenmeyer - $4
1000ml erlenmeyer -$6 
2000ml erlenmeyer - $16
3000ml erlenmeyer - $30
5000ml erlenmeyer - $50

From Brisbane (XLmag)
Rare earth magnets - 12mm x 5mm - $5.50 pair ($4.50 pair for 5+ pairs)
Rare earth magnets - 12mm x 10mm - $11 pair ($8 pair for 5+ pairs)

Batz, GMK & JGriffin can you guys confirm exactly what you guys want and Qty.
Once I have an order together I will get a firm quote.

Those that have used them do you think stir bars with pivots are better, or without a pivot??

Hoops


----------



## sosman

I added an internal power supply to the stir plate:





http://brewiki.org/StirPlate


----------



## Doc

Looks slick sosman.

Got my prototype up and running today.
Here it is working on a growler that I had handy.



Here it is doing the business on a 2 litre coffe plunger vessel.



Next to do is fix everything into permanent place and give a test run on a yeast starter.

Beers,
Doc


----------



## sosman

Doc - looks the goods. Did you have any trouble with the stir bar staying in the middle of the growler?

I just ordered some slants from the USA and hopefully the stirplate will help with the propagation.


----------



## Doc

sosman said:


> Doc - looks the goods. Did you have any trouble with the stir bar staying in the middle of the growler?



No, the growler is pretty much flat bottomed. Just a small drop off at the sides.
Also the magnets I'm using a big and strong.

Beers,
Doc


----------



## sosman

I am just firing up a second lot with the stirrer now. This is more of a test, only about 5g of quite old yeast from the bottom of a test tube.


----------



## Doc

I'm thinking about adding a timer onto mine so I can run it for say an hour then stop for an hour, then run for another hourt etc.
I've got it running an extended test run right now on just water to make sure it doesn't throw the stir bar, and doesn't heat up too much.

Beers,
Doc


----------



## sosman

Doc said:


> I'm thinking about adding a timer onto mine so I can run it for say an hour then stop for an hour, then run for another hourt etc.
> I've got it running an extended test run right now on just water to make sure it doesn't throw the stir bar, and doesn't heat up too much.
> [post="57193"][/post]​


Mine (LM317) only gets slightly warm now that I added the heatsink. However bigger stir bars in bigger volumes load the fan quite a bit more.


----------



## Doc

sosman said:


> Mine (LM317) only gets slightly warm now that I added the heatsink. However bigger stir bars in bigger volumes load the fan quite a bit more.
> [post="57199"][/post]​



I've found mine works best in the growler with just under a litre of water and the 50mm stir bar.
Anymore volume, or the bigger stir bar (70mm) and it seems to struggle a bit more.
I'm using a 240VAC fan, so the only thing that can really get warm is the fan controller, but that is rated for more than the load that should be on it.

Beers,
Doc


----------



## sosman

I have 6 slants on the way from the US so the stirrer will be running red hot for a while.

Looks like we are going to have a stir plate and jagmatic coil making day at the melbourne brewers soon. The demo had everyone fascinated (yeast breeding was a secondary issue).


----------



## ausdb

sosman said:


> I have 6 slants on the way from the US so the stirrer will be running red hot for a while.
> [post="57225"][/post]​



Where are you buying the slants from Sosman?


----------



## sosman

ausdb said:


> sosman said:
> 
> 
> 
> I have 6 slants on the way from the US so the stirrer will be running red hot for a while.
> [post="57225"][/post]​
> 
> 
> 
> 
> Where are you buying the slants from Sosman?
> [post="57249"][/post]​
Click to expand...

http://www.brewstersyeast.com/YeastList.asp

I have had a few phone calls with Vivian, if you get in touch, mention my name (paul sorenson).


----------



## kungy

In a good natured way and in all seriousness what is the value of culturing via slants.

Is it just the challenge of culturing yeast, cost .........................

Will

PS i'm just to identify whether i should head this route sometime in the future. I enjoy the challenge and making beer more so than drinking it.


----------



## Gout

Basicly you are starting with a pure yeast, and you are able to get some yeasts that are not availble otherwise

also slants are used for storage etc


----------



## sosman

kungy said:


> In a good natured way and in all seriousness what is the value of culturing via slants.
> 
> Is it just the challenge of culturing yeast, cost .........................
> 
> PS i'm just to identify whether i should head this route sometime in the future. I enjoy the challenge and making beer more so than drinking it.
> [post="57308"][/post]​


Challenge, of course. Never too old to learn new tricks.

Cost, probably not.

Variety, for example, I don't think you can get CL-50 except in slants.

Storage in a small package. Yeast on slants is supposedly good for a year or more so you can keep a variety in the fridge.


----------



## Hoops

kungy said:


> In a good natured way and in all seriousness what is the value of culturing via slants.
> 
> Is it just the challenge of culturing yeast, cost .........................
> 
> Will
> 
> PS i'm just to identify whether i should head this route sometime in the future. I enjoy the challenge and making beer more so than drinking it.
> [post="57308"][/post]​


Kungy

this is something I am looking into now, for me there are 2 main reasons:
1. The challenge
2. Having lots of different yeasts on hand for whenever you need them.

I think it could be cost effective if you had a few people doing it swapping slants ie a yeast bank in a club, but I feel it's more the convenience of having heaps of different yeasts on hand that doesn't take up too much room.

For those doing this already how much does your Agar cost? I saw a pack this arvo for $8 for 50g which seems pretty $$$

Hoops


----------



## pint of lager

75 gms cost $12.95 last year from the health food store. The smaller 25gm bags from Asian supply stores are about $3.

A little goes a long way. You use it at 15 gms per litre. A petri dish uses about 8-10mls of agar solution, so a litre would do around 100 petri dishes.


----------



## Hoops

Cool, thanks for that POL, not such an exorbortant price after all then.


----------



## sosman

Hoops said:


> For those doing this already how much does your Agar cost? I saw a pack this arvo for $8 for 50g which seems pretty $$$
> [post="57329"][/post]​


I paid $1.05 for 25g and I just used 1.5g to make 6 slants and 3 petri dishes. It just so happens that it is the same stuff pictured on the Cagney and Lacey page at OCB re yeast culturing. It is made in Thailand - avoid the flavoured stuff unless you plan on making a wit


----------



## sosman

My first slants:






Hopefully some will survive until my yeast arrives (got shipped overnight).

http://brewiki.org/Yeast/Culturing


----------



## warrenlw63

Mmmmmm.... Sos just shows the brewing community his urine samples. :lol: 

Warren -


----------



## RobW

Don't start taking the pi$$ Warren


----------



## Gough

Reminds me of when I had hepatitis...  

Shawn.


----------



## Weizguy

Gough said:


> Reminds me of when I had hepatitis...
> 
> Shawn.
> [post="57400"][/post]​



Yep, we're all class in Newcastle...


----------



## Gough

:lol:


----------



## warrenlw63

Tends to happen when frequent a shoebox in the middle of the road. 

Throw in a cigarette packet and you've got a nice garage. :chug: 

Warren -


----------



## Gough

Cigarette packet!! Luxury!

Shawn.


----------



## warrenlw63

I'm curtail'n the urge to go Python 'ere. :lol: 

Warren -


----------



## sosman

warrenlw63 said:


> Mmmmmm.... Sos just shows the brewing community his urine samples. :lol:
> [post="57396"][/post]​


These days it comes out that thick too.


----------



## sosman

I have been asked re costs (US dollars):

$5 per slant
$24 priority post (don't know quite how many you could get in for that, I ordered 6 slants and some other stuff).

No idea yet whether they will survive the trip.


----------



## Hoops

OK got some Agar this arvo - $2 for a 25g pack.
Got all the bits for the magnetic stirrer and hopefully put an order in Friday or Monday through Livingstone for the stir bars and erlenmeyers (maybe a few culture tubes for slants) and I'm away


----------



## Doc

My magnetic stir plate has been going just over 24 hours and you can see lots of yeasties spiralling around in the growler. Didn't have a problem with foaming which is good as I left Grandma in charge of my son and house today :lol:
Will let it run until the morning at least then chill to see how much beautiful WLP005 British Ale slurry I have.

Beers,
Doc


----------



## Doc

First test run with yeast is complete. It works a treat.
Here is the unit at the start of the test.




And here it is 35 hours later. Quite an amount of slurry for 1 litre of wort, with minimal yeast to start with. Also I only stopped it about 10mins before taking the picture. There is still an amount of suspended yeast to drop out.




Beers,
Doc


----------



## roach

Doc said:


> First test run with yeast is complete. It works a treat.
> Here is the unit at the start of the test.
> 
> View attachment 2581
> 
> 
> And here it is 35 hours later. Quite an amount of slurry for 1 litre of wort, with minimal yeast to start with. Also I only stopped it about 10mins before taking the picture. There is still an amount of suspended yeast to drop out.
> 
> View attachment 2582
> 
> 
> Beers,
> Doc
> [post="57577"][/post]​


Doc,
Looks the goods Doc - another brew toy to build.

I notice the towel under the stirrer in the second picture. Is that to deaden the noise(do these things run quiet??), or a preventative measure to protect the kitchen bench if the starter erupts?

Roach


----------



## Gout

doc keep us up to date re: lag time, fermentation drop V time and final gravity.

mine took off within 3 hrs in the wort, and finished in 3 days 

roach: i have a container under my flask (ontop of the stirer) to catch any overflow.

it should run quiet, unless the stirbar rattles, then its a pest


----------



## Doc

roach said:


> Doc,
> Looks the goods Doc - another brew toy to build.
> 
> I notice the towel under the stirrer in the second picture. Is that to deaden the noise(do these things run quiet??), or a preventative measure to protect the kitchen bench if the starter erupts?
> 
> Roach
> [post="57607"][/post]​



It was there as a preventative measure in case it had a blow out like sosman's did. I wrapped the towel around it over night to keep a bit of heat in it also.
The unit is quite quiet. The stir bar only makes a bit of noise if it is going to fast.
I probably won't be pitching this yeast in the near future unless I get a chance to brew over the weekend, but I'm travelling between work, clients and the hospital at the moment so brewing is down on the priority list.

Beers,
Doc


----------



## sosman

Doc said:


> ... so brewing is down on the priority list.
> [post="57671"][/post]​


Is there a doctor in the house? Someone take doc's temperature, I think he is running a fever.


----------



## Doc

sosman said:


> Doc said:
> 
> 
> 
> ... so brewing is down on the priority list.
> [post="57671"][/post]​
> 
> 
> 
> Is there a doctor in the house? Someone take doc's temperature, I think he is running a fever.
> [post="57679"][/post]​
Click to expand...


hahhahah, down the list, NOT bottom of the list :lol:
I'm sure I'll squeeze a partial mash brew in on Saturday 

Doc


----------



## sosman

My order arrived from brewsters yeast today :wub: 







Not only that, my first crack at plating seems to have been successful. 





Full update at http://brewiki.org/Yeast/Culturing

Now comes the serious bit - getting my brewsters yeast from one slant and innoculating my "backup copies". I am going to have to drink some serious quantities of beer to stop the shakes


----------



## BrissyBrew

I can see the streaks in the photos, what about the field? do you have single cell colonies isolated in the field ofyour plate?


----------



## Dazzling

So those of you who are successfully using these stir plates, how do you operate them? What I mean is do you run them continuously or in cycles?

Cheers

Dazzling


----------



## Gulf Brewery

Dazzling said:


> So those of you who are successfully using these stir plates, how do you operate them? What I mean is do you run them continuously or in cycles?
> [post="59460"][/post]​



Dazzling

Two hours at a time is usually enough. The noise of the rattling stir bar gets to you after a while and it does foam out when the yeast is really active.

Cheers
Pedro


----------



## sosman

BrissyBrew said:


> I can see the streaks in the photos, what about the field? do you have single cell colonies isolated in the field ofyour plate?
> [post="58299"][/post]​







There are some isolated colonies at the top of this packet. Yeah I know - some isolated mold colonies too. Which BTW present no real impediment to harvesting the yeast from elsewhere on the plate.


----------



## sosman

Dazzling said:


> So those of you who are successfully using these stir plates, how do you operate them? What I mean is do you run them continuously or in cycles?
> [post="59460"][/post]​


Dazzler I run mine as much as I can. The starter I have cookin' now has some antifoam added. Foam is the only thing which forced me to turn off the stirplate last time round.

If you check out the wiki page at http://brewiki.org/StirPlate you will get my drift.


----------



## sosman

I have successfully stepped up some CL50 from a slant to my first starter, hope to brew an APA tomorrow. There are various opinions as to what the size of the first step should be (I have seen suggestions ranging from 10 ml to 200 ml).

Being the lazy bugger I am, I went from loop to 200 ml, then 2 L (I might try some different step sizes next time). The weather has been quite cool and it has taken almost a week. I now have a nice slurry of yeast ready to go in the fridge (which I will cold pitch).

An incubator is on the short list of projects - I can use this for slants/dishes and starters.


----------



## Darren

There are some isolated colonies at the top of this packet. Yeah I know - some isolated mold colonies too. Which BTW present no real impediment to harvesting the yeast from elsewhere on the plate.
[post="59543"][/post]​[/quote]

Sos.
That is Bullshit! If your plate has mould, spores will spread all over your plate as soon as you open it. Sure, if you want to make "penicillin beer" go ahead and use a plate CONTAMINATED with mould.
Anyone who sees mould on their plates should discard them and go back to an original back-up culture.
Darren (who has worked in microbiology for 20 years)


----------



## Gout

I think sos threw that plate out and is working again from the backup slant he has...

cheers for info though, hmmm penicillin beer - yeeek "Doc ale"


----------



## kungy

Ok i've got an order for a stir bar and magnets now i've got a question concerning the assembly of a stirrer. 

I was thinking instead of forking the full price for a polycarb box which to mount the fan in could anyone possibly suggest why a quality plastic box ie decor ones you store foods in, would not work as a substitute. They are strong, water proof, easily cut and drilled and cheap.

Apart from looking cool as it would be clear, i'm at Uni. and don't brew enough to justify forking stacks for the assembly box.

Cheers

Will


----------



## redbeard

kungy said:


> I was thinking instead of forking the full price for a polycarb box which to mount the fan in could anyone possibly suggest why a quality plastic box ie decor ones you store foods in, would not work as a substitute. They are strong, water proof, easily cut and drilled and cheap.
> 
> Apart from looking cool as it would be clear, i'm at Uni. and don't brew enough to justify forking stacks for the assembly box.
> [post="60277"][/post]​



i think it would be ok, thou might be lacking in weight. probably need some ventilation holes in side so air can circulate.

being at uni, i would have thought brewing would be a good money saver ?


----------



## kungy

[/quote]

i think it would be ok, thou might be lacking in weight. probably need some ventilation holes in side so air can circulate.

being at uni, i would have thought brewing would be a good money saver ? 
[post="60360"][/post]​[/quote]

Not quite. I spend money on brewing equipment, and don't brew enough to gain any savings. I made a AG setup for $250 two months ago, plan to make a stirplate and plan to brew in a months time. Thats three months when i haven't brewed, talk about inefficent use of equipment. As they say "time is money"

Will


----------



## sosman

Darren said:


> There are some isolated colonies at the top of this packet. Yeah I know - some isolated mold colonies too. Which BTW present no real impediment to harvesting the yeast from elsewhere on the plate.
> [post="59543"][/post]​
> 
> 
> 
> 
> Sos.
> That is Bullshit! If your plate has mould, spores will spread all over your plate as soon as you open it. Sure, if you want to make "penicillin beer" go ahead and use a plate CONTAMINATED with mould.
> Anyone who sees mould on their plates should discard them and go back to an original back-up culture.
> Darren (who has worked in microbiology for 20 years)
> [post="60058"][/post]​
Click to expand...

If that is bullshit then the lab boys and girls at work are full of it. Make no mistake, if this was the last source of that yeast I had, I would not hestitate an attempt to replate it. When given the choice between a mouldy one and a clean one, of course I would opt for the clean.


----------



## sosman

kungy said:


> I was thinking instead of forking the full price for a polycarb box which to mount the fan in could anyone possibly suggest why a quality plastic box ie decor ones you store foods in, would not work as a substitute. They are strong, water proof, easily cut and drilled and cheap.
> [post="60277"][/post]​


If you are desperate, I am sure you could use almost anything. The kind of Decor containers the missus has are flexible but crack quite easily. It would be a shame to lose a starter and miss out on a brewday because your stir plate croaked.


----------



## kungy

Thanks for the feedback. If I was to rig a wooden stir plate like you have on your site (http://brewiki.org/wiki/homebrew/attachments/StirPlate/attachments/StirrerTestDrive.jpg?ts=1113641842) are there any real negatives apart from the coolness factor and the relative water tightness from a plywood setup??

Will


----------



## sosman

kungy said:


> Thanks for the feedback. If I was to rig a wooden stir plate like you have on your site (http://brewiki.org/wiki/homebrew/attachments/StirPlate/attachments/StirrerTestDrive.jpg?ts=1113641842) are there any real negatives apart from the coolness factor and the relative water tightness from a plywood setup??
> [post="60381"][/post]​


Well the cool factor is the most important one to worry about. As for getting it wet, either water proof it or rig up some blow off arrangement. BTW my second full starter with the stir plate didn't foam over. I did cheat a bit and use a drop of anti-foam.


----------



## kungy

This relates to large rare earth magnets, ie the one Doc got as a group order

Ok i got the magnets (thanks Doc). Gee there fun, within 5 minutes i had hurt myself with them, and within 2 hours i had a couple of small chips on the magnets. I need more self control. 

Anyway, i have seen how people like Sosman have mounted the magnets on the fan on a metal washer. Can this technique be used with magnets like this one, or are they two strong. I would try it myself but i have used my washers on my kettle and mashtun. 

Failing that i was thinking a metal strip placed as a central spoke, with the magnets at the end (not glued down, as i would like to use them for other things in the future), with a light but strong seperater preventing the magnets from sticking to each other. Is the washer a goer, or is the spoke idea better. 

The strength of these magnets are insane. I don't believe a concave flask (sherry flagon) will be a problem at all with a stir bar.

Will


----------



## Doc

Kungy,

I use the bigger magnets on a washer. Same as this pic of mine with the smaller ones.

Beers,
Doc


----------



## sosman

kungy said:


> Ok i got the magnets (thanks Doc). Gee there fun, within 5 minutes i had hurt myself with them, and within 2 hours i had a couple of small chips on the magnets. I need more self control.


If magnets were my only vice then I would have nothing to worry about.


kungy said:


> Anyway, i have seen how people like Sosman have mounted the magnets on the fan on a metal washer. Can this technique be used with magnets like this one, or are they two strong.


In your dreams, the magnets I have are just sitting on the washer held down just by magnetic force. They don't budge at full speed. Anyway, since I have no clue what magnets you are using, it is a bit hard to tell.


kungy said:


> Failing that i was thinking a metal strip placed as a central spoke, with the magnets at the end (not glued down, as i would like to use them for other things in the future), with a light but strong seperater preventing the magnets from sticking to each other. Is the washer a goer, or is the spoke idea better.


The great thing about DIY is that you can just try it. Then some other rainy day try something different. Don't get too dependent on "expert" opinions.


kungy said:


> The strength of these magnets are insane. I don't believe a concave flask (sherry flagon) will be a problem at all with a stir bar.
> [post="60690"][/post]​


Give it a try and let us know.


----------



## pint of lager

Kungy, and anyone else looking for magnets to play with. 

Microwave ovens have very nice circular magnets in the magnetron. These are great for sticking things to the fridge, but very hard to prize back off.

Big old speakers have magnets too. But not as good as the microwave oven magnets.

Keep the magnets away from your wallet with all those nice credit cards in them.


----------



## Hoops

pint of lager said:


> Kungy, and anyone else looking for magnets to play with.
> 
> Microwave ovens have very nice circular magnets in the magnetron. These are great for sticking things to the fridge, but very hard to prize back off.
> 
> Big old speakers have magnets too. But not as good as the microwave oven magnets.
> 
> Keep the magnets away from your wallet with all those nice credit cards in them.
> [post="60729"][/post]​


Careful pulling apart the magnetron from a microwave, from memory they have beryllium in them as an insulator so don't breath in any dust/powder or don't go smashing them up.

Hoops


----------



## kungy

Thanks for the feedback. With some of the questions I ask, I kinda now the answers already. I just like the feedback, particularly from you wise fellows. As a young'n on this forum, and because people think Im crazy making a stir plate its always good for positive reinforcement.

I don't know about microwave ovens, but Im definitely going to crack open some hard drives for their magnets so I can play with them. I'm just a kid at heart.....

Thanks

Will


----------



## Gout

I think i recall there is huge voltages in a microwave, and not sure maybe a high volt cap in there also (eg when its turned off you still are not safe)

i could be wrong, often am  but just dont hurt yourself, look into this further if you are going to pull one apart... or ask someone thats knows about them...as i dont


----------



## Hoops

Spot on Gout, there a high voltage capacitor that has around 2000V across it :excl: 
There should be a discharge path for it but if there's not that will give you one hell of a boot - and probably put your heart into fibrilation and kill you <_< so probably best to leave them unless you know what you're doing.

Hoops


----------



## AndrewQLD

if anyone else is looking for rare earth magnets I have about 12 to spare from an ebay order that I should get within the next couple of days, your welcome to them for cost price plus shipping. From memory they cost me around $2.50 each.

Andrew


----------



## sosman

> It was there as a preventative measure in case it had a blow out like sosman's did.
> [post="57671"][/post]​


I can now report that the antifoam I used in the next starter I made works as advertised (1 drop). Of course then I was getting real paranoid that nothing was happening, especially when you scoop poofteenth of buggerall from a test tube and throw it in 200 ml of wort.

And there is no apparent detriment to the head on the finished beer.


----------



## Hoops

Order from Livingstone arrived today so I now have the stir bars, erlenmeyers, spirit lamps, Schott bottles and SOME petri dishes.
HOWEVER there were no 100mm petri dishes in the order. I have rung them and they were very appolagetic and will send them out ASAP so hopefully everything will be here by he end of the week.

Hoops


----------



## BrissyBrew

sosman if you need to offload another 100 tubes I will take them where abouts are you for pick/delivery/mail etc [email protected] if you want to email me


----------



## sosman

BrissyBrew said:


> sosman if you need to offload another 100 tubes I will take them where abouts are you for pick/delivery/mail etc [email protected] if you want to email me
> [post="62557"][/post]​


BB I want to hang on to the tubes I have. There was another thread where someone was trying organise a bulk buy of the polycarbonate tubes.


----------



## Tony

Just a little story about rare earth magnets

I ordered 4 of them, 2 for me and 2 for a mate. We are both going to build a tight arse stirrer.

I ordered 15mm x 6mm magnets and they cost us anout $8 each. That included postage to the bush so not too bad.

Bloody hell they are strong.

My mate thought it would be funny to stick one on either side of another workmates ear lobe and when they turned his ear white and drew blood he had second thoughts about his actions.

bloody hell they are strong little buggers.

cheers and be carefull with em, they can cause injury :blink: 

will post some pics on mine when its done. Still waiting on the triac to come in to jacar for the speed controller im building

It will cut the AC waveform to limit the speed instead of limiting the voltage . This will help it with torque at low speeds.

cheers


----------



## spog

this thread has generated a lot of replies,discussion i reckon i might just have to have a crack at it too.one more for the mad brewers collection :beerbang:


----------



## sosman

Tony said:


> Just a little story about rare earth magnets
> 
> I ordered 4 of them, 2 for me and 2 for a mate. We are both going to build a tight arse stirrer.
> 
> I ordered 15mm x 6mm magnets and they cost us anout $8 each. That included postage to the bush so not too bad.
> 
> Bloody hell they are strong.
> 
> My mate thought it would be funny to stick one on either side of another workmates ear lobe and when they turned his ear white and drew blood he had second thoughts about his actions.
> [post="62569"][/post]​


I used 12x5mm rare earth from Alpha Magnetics in boronia and they are plenty strong enough and they were only 75 cents each (no postage). As it is, I had to put 18 mm spacers between the fan and the baseplate.

Watchout anyone who walks near your stir plate with a big belt buckle - that could do some damage (but it would be real funny to see).


----------



## sosman

spog said:


> this thread has generated a lot of replies,discussion i reckon i might just have to have a crack at it too.one more for the mad brewers collection :beerbang:
> [post="62575"][/post]​


Go for it.

The Melbourne Brewers had a coil building (see http://www.melbournebrewers.org/wiki/JagMatic) and stir plate building day a week or two ago. Had lots of fun. If you are going to be drinking while building it, buy some spare components - the smoke comes out of them real easy.

As for the stir plate, I am building up my second starter from a slant now, CL-400 yeast which I plan to make an ozzie wheat beer. I just stepped it up to 500 ml. The first beer was from CL-50 using this APA recipe and it has turned out an absolute perler. Shame that because there is no way it is going to last until Pale Ale Mania in August.

I have been thinking of ways to make a "tight arse incubator". In the end I just bunged the fermentation fridge thermostat up to 20 deg and turned on the butter warmer - it has done just the trick.


----------



## spog

thanks sosman, a wheat beer , love wheat beers now i am really keen!


----------



## lou

hi ya all 

few ideas on a tight arse incubator

i put one together many years back for an entirely diferent purpose h34r: 

All you need is a plastic tub - an aquarium heater with temp control and another container to sit in the tub - preferably ceramic - like a vase or something - preferably something with a bit weight to stop it floating - (although you can just weigh it down with a heavy object) 

Place water and aquarium heater and vase in tub - place petri dishes in vase and cover. 

All the insualtion of the water and ceramic container provides near constant temps and you have very accurate control over the temp as well 

might not work that well in summer but it does work 

lou


----------



## sosman

lou said:


> few ideas on a tight arse incubator
> 
> i put one together many years back for an entirely diferent purpose h34r:
> 
> All you need is a plastic tub - an aquarium heater with temp control and another container to sit in the tub - preferably ceramic - like a vase or something - preferably something with a bit weight to stop it floating - (although you can just weigh it down with a heavy object)
> 
> Place water and aquarium heater and vase in tub - place petri dishes in vase and cover.
> 
> All the insualtion of the water and ceramic container provides near constant temps and you have very accurate control over the temp as well
> [post="62599"][/post]​


Lou - thanks for the tip, part of my procrastination is because I want to be able to fit a 2L conical flask on stirplate in there. My fermentation fridge obviously isn't always available. As it turns out, it is holding 20 C quite nicely now, if I turn off the butter warmer it struggles.

I was thinking jaycar digital thermostat, light bulb and cardboard box if I get desparate.


----------



## sosman

Just an update. I have brewed 2 beers now working up from a slant (say a pinhead's worth of yeast) to 2L starter. They have both attenuated well and tast good. I haven't kegged the second one yet, it is at 1.010 and may still drop a point or two. It used CL-400 yeast and the grain bill most mostly wheat.

The first one was an APA and used Cl-50.


----------



## MAH

Hi Sosman

In a related thread you talked about not exceeding 5m/s for stirring. Not sure if I've done my calculations right but would this mean for a 40mm stir bar, you would need to keep the rpms down to 1590 and for a 70mm stir bar 910rpms?

How do you know what rpms the fan is turning at? Is it as simple as if the fan is rated at 3000rpm at 12v, then it would be 1500rpm at 6v? I have no idea but I bet it's not this simple.

Cheers
MAH


----------



## sosman

MAH said:


> In a related thread you talked about not exceeding 5m/s for stirring. Not sure if I've done my calculations right but would this mean for a 40mm stir bar, you would need to keep the rpms down to 1590 and for a 70mm stir bar 910rpms?
> 
> How do you know what rpms the fan is turning at? Is it as simple as if the fan is rated at 3000rpm at 12v, then it would be 1500rpm at 6v? I have no idea but I bet it's not this simple.
> [post="67847"][/post]​


I was just parroting something Pedro mentioned. To be honest, I don't take too much notice of "magic numbers" in brewing, they are ballpark figures, probably dreamed up by some dude in a white lab coat who has never tasted a beer in his life.

Please don't infer that I think Pedro is a wanker, it is just that I have violated many other "rules" in brewing and still managed to make decent beer.

As for calculating it, I believe the 5 m/s was referred to in the context of yeast not liking excessive shear. I imagine that in the bulk of the spinning wort, the shear would be very low since the flow is uniform. I am guessing that at the interface to the stir bar and the flask (presumably at the widest point) would be where the shear is greatest.

For a brief moment of insanity, I pondered the calculations myself and then snapped back to reality as I realised that relating the numbers back to beer quality would probably be tenuous indeed.

I like to stir mine vigorously early, to get air in to the wort. Later on I am more interested in keeping the yeast in suspension and encouraging CO2 out of solution so I turn it down.

Perhaps Pedro could point us at some literature that has done all the hard work for us.

cheers


----------



## Darren

MAH,
I would aim for no more than about 500rpm no matter the size of the stir bar. 8 spins a second is more than is needed. 

Slower is better than faster. Excessive speed will cause foaming of protein and is likely to kill many a yeast cell

Another point is that I have seen many a stir-bar go through the side of a flask when spun at high speed.

cheers
Darren


----------



## PeterS

I managed to follow some very helpful advice and I now I also have a Stir Plate of sorts. Although it does work, I can not yet use it for the purpose it is designed as I have not got a suitable flat bottomed vessel. I thought I make it than find out if what I got that might be suitable. Unfortunately none of my 2l or 5l containers are sufficinetly flat for it to stay in the middle. If I use a flat bottomed ice cream container just to try it, it is fascinating to see the little white flee going round and round. Any helpful hints as to where I might purchase a suitable vessel for this?

Whilst I am at it, I do have another slight problem. The pot that I am using is 500 ohms. I find that it does not give very much leeway as far as controlling the speed. If I change the pot to a smaller value thereby less resistance, would I have greater control of speed or less? (I used two rare earth magnet by the way and a 9v power source)

Thanks for your help in anticipation.

:chug: 
PeterS....


----------



## ozbrewer

i found the same thing Peter, I have a 1k pot here im going to play with and see what happens


Also I have some 250ml flasks spare if you want 1, they are a little small but got to start with. I have been using shcot botles and they seem to work


----------



## PeterS

ozbrewer said:


> i found the same thing Peter, I have a 1k pot here im going to play with and see what happens
> 
> 
> Also I have some 250ml flasks spare if you want 1, they are a little small but got to start with. I have been using shcot botles and they seem to work
> [post="70062"][/post]​



Oh hum. You think that by introducing more resistance, you will slow it down? I guess it makes sence, but I wonder will it allow a wider control over speed? Let me know when you tried it as I have no idea in these matters. (I=E/R)

And thanks for the offer for the 250ml flask but I think it is a wee small for a 1.5 - 2L starter and plating for me is still a ways off..

:beer: 
PeterS....


----------



## Linz

Peter,

A fellow brewer ordered some thick walled beakers from a chap on ebay for a reasonable price. I bought some 2 lt erlenmeyer(sp?) flasks from Livingstone and were as thin as glass could get and cracked first time out.


----------



## pint of lager

I have 10 erlenmeyer flasks of varying sizes from Livingstone, The 100 ml and 250ml sizes get lots of workouts in the pressure cooker, haven't broken one yet.

A couple of the bigger flasks have seen action on the gas top stove, but have changed the starter regime, and they now sit in the cupboard, dusty.

Do be gentle with them as they are glass, and keep thermal shocks to a minimum. That is, don't take it straight off the stove and place on a cold bench.


----------



## PeterS

pint of lager said:


> I have 10 erlenmeyer flasks of varying sizes from Livingstone, The 100 ml and 250ml sizes get lots of workouts in the pressure cooker, haven't broken one yet.
> 
> A couple of the bigger flasks have seen action on the gas top stove, but have changed the starter regime, and they now sit in the cupboard, dusty.
> 
> Do be gentle with them as they are glass, and keep thermal shocks to a minimum. That is, don't take it straight off the stove and place on a cold bench.
> [post="70295"][/post]​



Thank you POL and everybody else who responded. It looks like Livingstone got another customer.

:chug: 
PeterS....


----------



## homebrewworld.com

I done about half a dozen stir plate jobs and resorted to using a s.s. saucepan on my stove for boiling the wort, then cool and transfer while aerating to a beaker (thick glass flat bottom) and yeast then onto the stir plate.
I broke 1 erlenmeyer, & 1 beaker putting them on my stove.......... :angry: 
Anyway, my yeasts go off better than the 'Discovery'
:beerbang:


----------



## Darren

homebrewworld.com said:


> I done about half a dozen stir plate jobs and resorted to using a s.s. saucepan on my stove for boiling the wort, then cool and transfer while aerating to a beaker (thick glass flat bottom) and yeast then onto the stir plate.
> I broke 1 erlenmeyer, & 1 beaker putting them on my stove.......... :angry:
> Anyway, my yeasts go off better than the 'Discovery'
> :beerbang:
> [post="70326"][/post]​





I would recommend that you don't place Erlenmeyer flasks directly onto electric hot plates. Unless the heat is very even they can break. When they do break they make quite a mess and the pieces are very sharp.
cheers
Darren


----------



## GMK

OK

Thanks to Hoops and DOC for getting the parts...

Here is a pic of Magnetic Stir Plate in action for the first time.

Using it to build up a starter of 1026 Cask ale Yeast to pitch in DOC's Strong Ale Recipe.





will post a pic later showing the yeast...


----------



## PeterS

GMK said:


> OK
> 
> Thanks to Hoops and DOC for getting the parts...
> 
> Here is a pic of Magnetic Stir Plate in action for the first time.
> 
> Using it to build up a starter of 1026 Cask ale Yeast to pitch in DOC's Strong Ale Recipe.
> 
> will post a pic later showing the yeast...
> [post="72784"][/post]​



Good one Ken. I am nearly there. Unfortunately, I have not got a suitable flat bottomed flask yet. In the process of evaluating options what and where to get it from. Batz brew day got me into this, now I find myself doing a lot of immitating, March pump, Stir Plate, etc. Sun Dial is next I think...You done it again Batz and thanks..

:beer: 
PeterS....


----------



## sosman

I bung my 250 mL flask with wort and aluminium foil over the top into the pressure cooker for my first step up from a slant.

Then I go straight to a 2 L flask which I just sanitise with my favourite sanitiser.


----------



## Batz

Peter Shane said:


> GMK said:
> 
> 
> 
> OK
> 
> Thanks to Hoops and DOC for getting the parts...
> 
> Here is a pic of Magnetic Stir Plate in action for the first time.
> 
> Using it to build up a starter of 1026 Cask ale Yeast to pitch in DOC's Strong Ale Recipe.
> 
> will post a pic later showing the yeast...
> [post="72784"][/post]​
> 
> 
> 
> 
> Good one Ken. I am nearly there. Unfortunately, I have not got a suitable flat bottomed flask yet. In the process of evaluating options what and where to get it from. Batz brew day got me into this, now I find myself doing a lot of immitating, March pump, Stir Plate, etc. Sun Dial is next I think...You done it again Batz and thanks..
> 
> :beer:
> PeterS....
> [post="72800"][/post]​
Click to expand...



I am glad to help Pete...I think :huh: 

I suppose you want a Banjo dog now as well?

Batz


----------



## ozbrewer

if you cant get a flask cheep enough, try a mason jar/pasta sauce bottle....not ideal but i have used them for the last month or so , and its all working fine


----------



## PeterS

ozbrewer said:


> if you cant get a flask cheep enough, try a mason jar/pasta sauce bottle....not ideal but i have used them for the last month or so , and its all working fine
> [post="73092"][/post]​



How many Pizzas do I need to buy to use the sauce in the bottle?

:beer: 
PeterS....


----------



## Plastic Man

possible cheap heater for a DIY incubator.

http://www.oatleyelectronics.com/kits/k145.html


----------



## Plastic Man

I was having a quick look through the Oatley Electronics Kit listing to see if they also did a temp logging device in ref to Andrews great post, (couldnt see one). Has some interesting cheap temp controllers though.

But one mentioned that it was not suitable for Peltier devices. I didnt know what these were so did a quick google. Interesting devices. These would make great small heaters for a fermentator or incubator. Is anyone using them.

This next post was pretty interesting. A guy used one to keep his beer cold in the sun.

http://www.stud.ntnu.no/~arnesen/peltierbeer/index.html

Also these next two had some good basic info on what Peltiers are.

http://www.electronics-cooling.com/Resourc...96/sep96_04.htm

http://www.peltier-info.com/info.html


----------



## pint of lager

Sunday's job in the shed was to make a stirplate.

An old hard drive was sacrificed for magnets and an old pc power supply was ratted for a fan. There was a decent plastic hobby case lying around doing nothing.

First off, two magnets were glued on. This failed, the stir bar jiggled up and down, but didn't spin, no matter what volts were applied across the fan. So the magnets were ripped off and only one reglued in the centre. Success.

At about 4.2 volts, the stir bar created a nice vortex in 800ml water in an erlenmeyer flask.

Woo hoo.


----------



## redbeard

Good stuff PoL. Nothing like ripping thru old pc parts & re-using them. Perhaps the 1st 2 magnets were 2 close together ?

cheers


----------



## bonk

i built one of these and it seems to work a treat, i need a bigger stir bar however as the bloke at the medical supply shop only had a 20mm bar.

the funny part was, as i was paying for them, he explained that he ordered in some other bars, but the guy went to jail for growing dope.... i wonder what he was up to..


----------



## ausdb

I need to chip in here with my effort, I found an old fashioned industrial strength 5-1/4" floppy disc drive up at the local tip/recycling centre a few weeks back. The lady didn't like my offer of $2 so it cost me $5 but I wasn't complaining.

I went home and took it apart and ended up with two of these!




I just superglued two neodmyium magnets to the little flywheel and sit a piece of plastic on top or if I am worried about overflowing with krausen then I use a tupperware container like this picture.



I originally tried to re use the power supply from the hard drive but it only went for about 1/2 an hour before the smoke decided to escape from one of the capacitors, so now I just use a 12V plugpack.

I made a 2L starter which I pitched into 40L of oxygenated 1.053 wort, it fermented out in about 8 days so I was pretty happy


----------



## Jye

Here is my effort from last night, I used Gulf Brewerys article on how to build one with the exception of a few resistors in series to handle the 20V power supply I am using. The magnets came from jaycar and look like they were made for the job


----------



## Ross

First toy for the new year  

Built it this afternoon, based on Jye's & Sosmans units.






Bought all the parts from Jaycar - cost $75 all up...


cheers Ross


----------



## AndrewQLD

top stuff Ross, You will have starters with 2x the yeast in 2 days. Best thing I ever made, big thanks to Sosman.

Cheers
Andrew


----------



## Zwickel

Hello Brewmates,

this is a manual how to build a magnetic stirrer, unfortunately written in german, but the pictures tells it all:
http://www.experimentalchemie.de/versuch-057.htm

... and here some variations:


















have fun


----------



## ausdb

Zwickel said:


> this is a manual how to build a magnetic stirrer, unfortunately written in german, but the pictures tells it all:
> http://www.experimentalchemie.de/versuch-057.htm
> have fun



Great link Zwickel :beerbang: 

Google is your friend too for translation
http://www.google.com.au/language_tools?hl=en


----------



## Jye

Nice one Ross.

Cheers to better hydrated polyclar


----------



## timmy

Here's my effort.

The fan is from a decommissioned UPS. It's a 240v 45w 180mm. Has no trouble stirring anything!

speed is controlled via a 200va dimmer switch. Just need to be carefull about the speed, it will happily rev to over 2000rpm but not before throwing the stir bar. For this reason i ditched the 15mmx7mm magnets for the 12x5 ones. At about $2 each for the magnets i bought a couple of sizes.


----------



## Trough Lolly

Jye said:


> Here is my effort from last night, I used Gulf Brewerys article on how to build one with the exception of a few resistors in series to handle the 20V power supply I am using. The magnets came from jaycar and look like they were made for the job
> View attachment 4277
> 
> [post="82254"][/post]​



Nice work Jye - I'm about to build my stirrer based on Fitzy's prototype too! I've gotta give my new 2L flask something to do, eh?!  
Regarding the middle piccy (retained in above quote), it looks like you've reverse mounted the fan and magnet (nice fat one too!) in the case or did you flip the fan for the photo???
Correct me if I'm wrong, but your mounting method for the fan means we don't have to mess around with metal brackets and we can just stuff some spacers under the fan to raise the fan in the case so the magnet sits nice and close to the topside when you seal the case?

Cheers,
TL


----------



## Jye

Hey TL, the fan is mounted just like in the pic, I screwed it directly to the bottom of the case with no spacers underneath. IIRC when the lid is on the magnet sits about 10mm away and I found this to be close enough to turn the other magnet easily.

I can take another pic showing the mounting better tonight if that will help.

Cheers
Jye


----------



## Trough Lolly

Thanks Jye,
That's a pretty chunky lookin magnet you have there - and I'm not referring to the image in your signature block! :blink:  
I'm gonna follow your design lead on this version and mount the fan as you have - I'm too lazy to get some metal and cut it into brackets when I can just stuff some scrap strips of timber under the fan if it needs to be raised closer to the underside of the case cover. 
If you're gonna take a pic (and thanks if you do) could you also do a close-up or two of the wiring between the fan / pot and bulkhead power connector - that'd further reduce the chance of me running 12VDC through my body! h34r: I'll use a 12VDC 500mA power supply so I won't bother with any resistors. By the way, did you solder all the connections? I don't have a soldering iron (yet) but if this job can be done without spending extra bucks on a 40W iron, that'd be good...

Cheers,
TL the heavily overspent household budget brewer!! :unsure:


----------



## Jye

I will post some close ups tomorrow. The 12V supply is perfect, I had a 20V hanging around so I needed the resistors to bring the voltage down a bit and I used a few in parallel because I didnt have to correct wattage ones <_< 

You should be able to wire it up the same as in the Peter Fitzsimons article without a soldering iron, just twist the wires tightly onto the jack and potentiometer. These magnets really are perfect for a stir plate and dead easy to centre with some 5 min epoxy, I just turned my fan on low and it centred it self.


----------



## Ross

Trough Lolly said:


> That's a pretty chunky lookin magnet you have there - and I'm not referring to the image in your signature block! :blink:
> [post="127282"][/post]​



TL,

I built mine the same, it works great. I can thoroughly recommend these chunky magnets, they are sold as pairs & are self centering - also being oval shaped they spin really easily even when the flask bottom isn't flat. I mix my polyclar in a kitchen plastic beaker using it, with no worries.

Cheers Ross


----------



## Jye

And they make a cool noise when you use them for their original purpose.


----------



## Doogiechap

So Ross and Jye, am I correct you use the second magnet as the stir bar ? The tight arse im me is coming out bigtime here but it is in mortal combat with the thoughts of the magnet leeching 'nasties into the starter :blink: . Any thoughts ?
Cheers
Doug


----------



## Jye

Doogiechap said:


> So Ross and Jye, am I correct you use the second magnet as the stir bar ? The tight arse im me is coming out bigtime here but it is in mortal combat with the thoughts of the magnet leeching 'nasties into the starter :blink: . Any thoughts ?
> Cheers
> Doug
> [post="127296"][/post]​



Yep the second one is the stir bar and I had the same concern when I first got them so I did a test starter. I couldnt detect anything wrong with the starter using my great sense of smell and taste :blink: and the magnet didnt show any signs of corrosion. The surface isnt like a bar magnet, it has a smooth protective coating which make it easy to clean with napisan or what ever. After a dozen or so starters and using it hydrate polyclar it has no signs of wear and tear.


----------



## Ross

Doogiechap said:


> So Ross and Jye, am I correct you use the second magnet as the stir bar ? The tight arse im me is coming out bigtime here but it is in mortal combat with the thoughts of the magnet leeching 'nasties into the starter :blink: . Any thoughts ?
> Cheers
> Doug
> [post="127296"][/post]​



As Jye say's it's showing no signs of wear & I'm not aware of anything toxic in a magnet, but no doubt someone will enlighten us if there is a potential risk :unsure: .

++

Notice you're using my wit recipe Doggiechap, let me know what you think - My keg ran out a few days ago & it's going straight back on the list of beers to brew...

Cheers Ross


----------



## Pumpy

What sort of stir bars do you use on the heavy concave bottomed jars this type 


Pumpy


----------



## Jye

TL, a few close ups for you.


----------



## crozdog

I recently finished my dual magnetic stir plate after rescuing bits from work which would have been tossed out.

My design uses an incar phone charger to control to fan speed. Details to follow.

i can now make 4l starters for big brews or do 2 different starters simultaneously!

crozdog


----------



## crozdog

The finished insides


----------



## crozdog

details of what I did are in this PDF 

View attachment dual_stir_plate_construction.pdf


----------



## Pumpy

Good work Crozdog .an excellent post 

Pumpy


----------



## Trough Lolly

Jye / Ross and others...
Thanks for the closeups and info - I'm building my stir plate this arvo - I got the parts from Jaycar on the weekend and have the week off so I should have it done by tea tonight! Lashed out and bought the pair of magnets as you guys did - that's one hell of a stirbar for the 2L flask, eh! I ended up getting a bigger case to sit the big flask on - the original one in the specs was too small...Total cost was just over $100 - bigger case, better magnets, soldering iron and stand etc etc
Will post pics in due course..
Cheers,
TL


----------



## Trough Lolly

:excl: Help Please!! :excl:  
I have built the stirrer - exactly the same as Peter and Jye's, but I cannot control the speed of the fan all that well. The power unit is a 12V 300ma unit and I bought the "regulated" version to keep the current under control. I'm finding (as Peter did in his post back in Aug 05 - below) that the 500ohm pot only controls the speed of the fan by a very small degree - and the stir bar seems to behave, but only as the fan is coming to a halt - my assumption is that the 12VDC fan speed is spinning way too high. 


PeterS said:


> ...snip...
> Whilst I am at it, I do have another slight problem. The pot that I am using is 500 ohms. I find that it does not give very much leeway as far as controlling the speed. If I change the pot to a smaller value thereby less resistance, would I have greater control of speed or less? (I used two rare earth magnet by the way and a 9v power source)
> Thanks for your help in anticipation.
> PeterS....


Do I need to get a larger pot from Jaycar to slow down the fan?
Should I use a switchable power supply to drop the voltage to the fan?
I have a very basic circuit - fan, bulkhead power connect and 500ohm pot...all in a large box to stand the 2L flask and I used the big magnets that Jye had in his photo which seems to work a treat...
Any ideas would be much appreciated - I need to spin up some starters pronto!!
Cheers folks,
TL


----------



## Jye

The power supply and 500ohm pot should be fine, if you can post some pics or a diagram of your wiring that would help.


----------



## Ross

I find the speed control very sensitive, you only need the slightest turn to go fron stationary to turbo speed - but I don't find it a problem to control - I turn up high for half a second to get the momentum of the big stirbar going & then back off immediately to the required speed.

cheers Ross


----------



## goatherder

I'm in the middle of building the same setup as you TL.

My speed control is way too sensitive also. I think it's because the pot was of a too low power rating (0.2W). At about the point on the dial where the speed is about right the internals of the pot glow red and some of the smoke comes out. Once this happens, the speed of the fan gets a bit harder to control. I reckon i've toasted the pot around the optimal speed setting. I'm going to run some calcs on it and grab a bigger pot on the weekend - Dick Smith has 3W wire-wound pots. It won't help you much now, but I'll post the results when I've done it.


----------



## Jye

Instead of using a larger pot, which I think will make the sensitivity problem worse, I would try putting a 500ohm resistor in series with the pot. This will lower the supply voltage to the pot and allow it to supply 0-6V to the fan instead of 0-12V *OR* try a lower voltage power pack, maybe a 5V phone charger.


----------



## Trough Lolly

G'day all...
Thanks for the replies - here are some pics of the stirrer.
This is a shot of the wiring - power connect on the left and the pot on the right - wired up as per Pete and Jye's original specs...All soldered!!


Here's a shot of the unit with the magnet fixed to the fan - it's not perfect centre and makes a little bit of noise at full tilt but not enough to make the unit jump around...


Last shot is just from the front...note the larger case to sit a 2L flask on.


I'm beginning to think the pot is too small - you have to wind the pot almost completely clockwise to get any action out of the fan and then its only a few millimeters of play between flat out and nothing - and when I wind the pot clockwise, you get a very high pitched squeal which quickly drops in tone and then the fan starts to turn. Surely this isn't right???
Any ideas/suggestions appreciated - I cannot get the fan to turn slowly enough to allow the stir bar to keep pace with the magnet below - so is it a new pot or should I drop the voltage to the fan??? :unsure: 
And just to make my day even better - I've cracked my brand new Schott 2L Flask so any info can only make this day better!! :blink: :angry: 
Cheers,
TL


----------



## Jye

ah... ignore my last post, I was think you only had to turn a little bit to high speed... when its the other way around.

In that case a larger pot may help. 

You may have a log pot which could explain why the control is sensitive, a linear pot should remove the sensitivity. To check look for an *A* (log) or *B* (linear) printed on the back of the pot somewhere.


----------



## goatherder

Jye said:


> Instead of using a larger pot, which I think will make the sensitivity problem worse, I would try putting a 500ohm resistor in series with the pot. This will lower the supply voltage to the pot and allow it to supply 0-6V to the fan instead of 0-12V *OR* try a lower voltage power pack, maybe a 5V phone charger.
> [post="129304"][/post]​



I was thinking of that - one of the link from sosman's page has some series resistance in before the pot. I'll do the calcs and see what I can work out. I was still going to stick with a 500 ohm pot - just a higher power rating to help keep the smoke on the inside.


----------



## Trough Lolly

Jye said:


> ...snip...
> You may have a log pot which could explain why the control is sensitive, a linear pot should remove the sensitivity. To check look for an *A* (log) or *B* (linear) printed on the back of the pot somewhere.
> [post="129313"][/post]​



I think you're onto something here Jye - stamped onto the back of the pot has a lower case "a" in a circle and beneath it:
ALPHA
B25K
followed by 4L3 in black on the bottom edge of the pot. The 1st pic I attached above shows most of those markings when you click on the image...I might take it to Jaycar and get them to confirm - I can always get a linear pot and some other larger 1K or better pots and experiment (it's easy once you know how to solder!!). I also have some lower voltage power units laying around the house - including one that works between 3 to 12 volts. I need to slow down the fan...
Cheers,
TL


----------



## Jye

Trough Lolly said:


> Jye said:
> 
> 
> 
> ...snip...
> You may have a log pot which could explain why the control is sensitive, a linear pot should remove the sensitivity. To check look for an *A* (log) or *B* (linear) printed on the back of the pot somewhere.
> [post="129313"][/post]​
> 
> 
> 
> 
> I think you're onto something here Jye - stamped onto the back of the pot has a lower case "a" in a circle and beneath it:
> ALPHA
> *B25K*
> [post="129340"][/post]​
Click to expand...


I think the pot you have is linear 25000ohms (B25K), check it with a multimeter or get the guys at jaycar to do it. This is your problem since the resistance is too high until you have turned it all the way to the end. Replace it with a 500ohm and all should be sweet


----------



## Trough Lolly

It's off to Jaycar I go...Thanks Jye.

TL


----------



## DarrylB

TL,

the "squeal" you talk about from the fan is likley the fan trying to start up on too low a voltage/current. Some fans happily start on a wide range of voltages (even down to 40% of their 'rated' voltage) others struggle even at some 75% of their rated voltage. Usually, once spinning, the fan will happily slow down and keep running. The other catch is by introducing the resistor the current to the fan is limited and thus is more likely to stall. 500 ohms would be a much better size resistor as a first attempt.

I usually use a pulse width modulator (PWM) which pulses 12v to the fan so you get enough voltage to start the fan and the speed is then controlled by the pulse on-pulse off ratio. IF you dont mind the fan making a bit of noise, it is possible to have a virtual 0-100% speed range. I haven't looked at the modified phone charger circuit mentioned in this thread in much detail as I already have a circuit to acheive the same thing, but it might be along the same "concept".

Give me a call if you like and I can etch a board for the circuit for you (uses about 8 components so nothing too complicated).

Darryl


----------



## Trough Lolly

G'day all,
Well, Jye, you were right! It was a 25K pot and the Jaycar staff were a tad embarrased...I ended up getting a 500 ohm pot and they wanted to charge me for it until I reminded them that it was their mistake.
Anyways, it's now soldered in and the fan runs a lot slower and is much more controllable - once you get it spinning.
There is one problem left to sort out now - and that's the orientation / centering of the magnet over the fan. Even at low speed, the stirbar is not working as it should - it spins and then flicks off at a tangent and then spins back to the centre and out to a tangent, etc, etc. I'm also getting cavitation from the fan - which I didn't think was a problem, but it's obviously doing that because the large heavy magnet is not centred on the hub. I can see it's slightly off centre so I've carefully cut the magnet off the fan (I used 2 part epoxy and thought I'd be there all night with the stanley knife but it eventually lifted!!). Anyway, I'll draw some lines on the hub of the fan to help centre the magnet, check with the tape measure and refix the magnet to the fan and test before epoxying again.
And who said Friday nights are boring!!!
Cheers,
TL
P.S. Darryl - thanks very much for the kind offer mate - If I can't get this unit to work after re-centering the fan, I might just take you up on the kind offer to etch a board etc. Thanks...


----------



## poppa joe

TL
Has anyone thought about a Train Controller....Would it work...???? if so
Tell the Kiddies Daddy wants to play with it....
Cheers
PJ


----------



## Jye

poppa joe said:


> TL
> Has anyone thought about a Train Controller....Would it work...???? if so
> Tell the Kiddies Daddy wants to play with it....
> Cheers
> PJ
> [post="129528"][/post]​



As long as the voltage is about 12V.


----------



## Trough Lolly

As a result of stuffing around with the voltage all day, I now have all the DC power packs around the house in my possession - and boy, don't we have a decent collection of them?! Every bloody phone charger, answering machine unit, camcorder charger etc - I've got a slew of them on my workbench!!
TL


----------



## Ross

Trough Lolly said:


> As a result of stuffing around with the voltage all day, I now have all the DC power packs around the house in my possession - and boy, don't we have a decent collection of them?! Every bloody phone charger, answering machine unit, camcorder charger etc - I've got a slew of them on my workbench!!
> TL
> [post="129535"][/post]​



I know the feeling TL - i bought one for my stir plate & then realised when I got home, that we have over a dozen redundant transformers i could have used <_< 

cheers Ross


----------



## Trough Lolly

Yup....and when you're trying to measure the gap between the end of the rare earth elliptical magnet and the outer edge of the fan with a ruler - don't use the METAL tape measure! Grab a timber ruler from the kids and you've got a lot less 2 part epoxy to clean up...!!
I think I'll call it quits, grab a beer and watch the footy - and do the centering of the magnet in the morning!!
Cheers,
TL


----------



## Trough Lolly

poppa joe said:


> TL
> Has anyone thought about a Train Controller....Would it work...???? if so
> Tell the Kiddies Daddy wants to play with it....
> Cheers
> PJ
> [post="129528"][/post]​



//Totally unqualified wildassed guess follows//
I suppose it would - it depends on the output voltage and current. My old CB Radio transformer is a regulated 13.8V supply that can push a couple of amps under load - which is way above what the 12VDC 200mA fan needs...

Cheers,
TL


----------



## sosman

Trough Lolly said:


> I'm also getting cavitation from the fan - which I didn't think was a problem


Hmmm, the fan is not supposed to be inside the wort.


----------



## vlbaby

sosman said:


> Trough Lolly said:
> 
> 
> 
> I'm also getting cavitation from the fan - which I didn't think was a problem
> 
> 
> 
> Hmmm, the fan is not supposed to be inside the wort.
> [post="129691"][/post]​
Click to expand...


I think TL means vibration not cavitation.  


vl.


----------



## Trough Lolly

Quite so - apologies for the Red October freudian slip!!

I think my problem may be with the distance between the magnet on the fan, it's centering on the fan and the distance between the magnet in the case and the stir bar - I bought a large case, big enough to comfortably sit a 2L flask and thus, its deeper than the smaller models - I have added some nuts to the bolts holding the fan in place so I can adjust it's height in the case, and thus bring the whole assembly with magnet closer to the underside if the top of the case.
If this cunning plan fails, I'll ditch the elliptical magnets and buy a couple of cheap bar magnets from Jaycar...
Cheers,
TL (who's off to Adelaide for a couple of days tomorrow - will be lurking in the vicinity of the Stamford Plaza bar!!)


----------



## Damon

Not sure what the Motorola motor driver circuit costs but as an option you could use either the top or bottom circuit of the attached to drive a fan up to 3A (3A might be a bit of overkill...). It uses a 555 timer to adjust the PWM applied to the fan and hence the speed for those that are electronically minded. This circuit can adjust from 0% to 100% drive.

Cheers,

Damon 

View attachment stirrer.PDF


----------



## goatherder

I finally made it to dick smith to pick up the pot. I ended up grabbing the 500 ohm 3W wire wound job, I figured it would be pretty hard to burn that fella out. It's just wired up in series with the fan, easy as that. It works a treat.

Here's a pic, thanks to everyone who posted for your ideas and methods.


----------



## Jye

Nice one goatherder  Did you have any problems with the magnet?


----------



## goatherder

Thanks Jye, your photos were a great help.

At first I couldn't work out why the fan wouldn't turn the magnet. The fan would start to spin but would just sit there and quiver. I think the magnet was interfering with the motor, so I stuck a 3/8" washer under it which made it go. I guess my fan didn't have a metal bit under the centre like some pics i've seen.

I was a bit lucky when I glued it all in, I must have got it almost centered. If I keep the speed low enough, the stirrer doesn't develop any precessional movement. I reckon if I want higher speed i'll have to raise the fan up a bit inside the case with some spacers. I should be OK without it though.

I ran it non-stop overnight in the 2l flask and it was still running happily this morning, with no signs of overheating. Now I just need to wait for the wyeast order to come in.


----------



## andreic

Hi all,

just went to Jaycar today to get those "oblique-spheroid hematite magnets". They are on special this month - $6 instead of $15.

Since the thread is titled "tight arse" I thought some others might be interested in a $9 saving...

cheers,

Andrei


----------



## goatherder

dammit, i only got mine two weeks ago


----------



## laurent

goatherder said:


> Thanks Jye, your photos were a great help.
> 
> At first I couldn't work out why the fan wouldn't turn the magnet. The fan would start to spin but would just sit there and quiver. I think the magnet was interfering with the motor, so I stuck a 3/8" washer under it which made it go. I guess my fan didn't have a metal bit under the centre like some pics i've seen.
> 
> I was a bit lucky when I glued it all in, I must have got it almost centered. If I keep the speed low enough, the stirrer doesn't develop any precessional movement. I reckon if I want higher speed i'll have to raise the fan up a bit inside the case with some spacers. I should be OK without it though.
> 
> I ran it non-stop overnight in the 2l flask and it was still running happily this morning, with no signs of overheating. Now I just need to wait for the wyeast order to come in.



Hi,

I did almost the same thing. Only, I glued the magnet to the fan using Blue Tac. Very strong and I can still move the magnet around to reduce vibration. Did you get the vortex up to the bottom of the jar? Sometimes when the speed is too high my stirrer jumps around and might break the jar. I suspect it might be too heavy. I'll try to find some real stirrers. Anybody has one spare for sale?

Cheers,
Laurent


----------



## crozdog

I pulled a few old hard disks apart over the weekend. Each one had 4 rare earth magnets for driving the arm to move heads over the platter.  :beerbang: 

I dunno if they were glued or spot welded onto the mounts, but a few minutes with a grinder (bench or angle) would cut the mounting plate back to the magnet. 

I also reckon they were a good shape to mount on the top of the fans & as they are only a couple of mm thick, spacers might not be required between the fan body & the case.

Here's to tight arse brewing & creative recycling. :beer: 

Crozdog


----------



## goatherder

laurent said:


> Hi,
> 
> I did almost the same thing. Only, I glued the magnet to the fan using Blue Tac. Very strong and I can still move the magnet around to reduce vibration. Did you get the vortex up to the bottom of the jar? Sometimes when the speed is too high my stirrer jumps around and might break the jar. I suspect it might be too heavy. I'll try to find some real stirrers. Anybody has one spare for sale?
> 
> Cheers,
> Laurent



Same thing happens with me when the speed gets too fast. I couldn't get the vortex going to the bottom without the stirrer getting shaky and threatening to break my shiny new flask. From what i've read it doesn't matter, keeping the yeast in suspension is the goal. A slow speed will be enough for that.


----------



## Trough Lolly

goatherder said:


> Same thing happens with me when the speed gets too fast. I couldn't get the vortex going to the bottom without the stirrer getting shaky and threatening to break my shiny new flask. From what i've read it doesn't matter, keeping the yeast in suspension is the goal. A slow speed will be enough for that.



Same here...and this is my problem - I keep blaming the magnet but perhaps it's something else? I find that the fan can only get down to a certain speed and then if I try to slow dow the fan any further, the whole lot comes to complete stop. The stir bar jumps around like I've put some voltage through it and I can't get a vortex. Oh and if you want to trash your 2L flask, let the missus DROP a hermatite oblique magnet into it, when the flask's empty...  :angry: 

Perhaps I need to solder in a couple of resistors in series between the power and the 500ohm trimpot?





TL the electrical numpty...


----------



## Ross

I get a vortex going using these magnets with quite a slow spin, I think being able to control the speed correctly is the most important part. The faster spin showers liquid everywhere, long before becoming unstable.




Cheers Ross


----------



## bindi

I have aquired the gear to make a stir plate  now to build it 



soon I will have enough yeast to take over the world :blink: .


----------



## laurent

Hi Ross,

how much liquid did you have in this flask? Sorry, cannot see very well from the picture B) 

Thanks,
Laurent



Ross said:


> I get a vortex going using these magnets with quite a slow spin, I think being able to control the speed correctly is the most important part. The faster spin showers liquid everywhere, long before becoming unstable.
> 
> View attachment 7606
> 
> 
> Cheers Ross


----------



## Ross

laurent said:


> Hi Ross,
> how much liquid did you have in this flask? Sorry, cannot see very well from the picture B)



Just under 1.5L - It's a 2L flask, or was before I dropped it  

Cheers Ross


----------



## Franko

Dick Smith has some cheap enclosures available on special for $4.92 big enough to house a larger fan 140mm x 140mm
just picked one up



http://www.dse.com.au/cgi-bin/dse.storefro...duct/View/H2508


----------



## Jase

Hi All,

Sorry to bring up an old topic. But I'm in the process of building one of these stir plates. Bought the same case as Franko, and a pair of the oblique-spheroid hematite magnets from Jaycar.

During testing, I placed the fan on the bottom of the case, no spacers, and put the other magnet in a coffee plunger with a flatish bottom, I was getting some vortex, and the unit was working ok. I decided to raise the fan with some 15mm spacers, to create more vortex, but the unit is noisier (vibration etc), and sometimes the magnet in the coffee plunger won't even spin. I've even tried spinning it by hand, but there seems to be too much magnetic force resistance (if there's such a thing). I didn't think that you could have the fan too high. I thought the closer the magnets are together, the better the unit would work.

The reason why I posted, is because I'm ordering a flask from Livingstone today, and am wondering whether I'm better off ordering a stir bar as well (instead of using the magnet in the flask). Any thoughts??? :blink: :huh: 

What size flasks should I be looking at? 2 litre seems to be the go in this topic.

Cheers,
Jase


----------



## Andyd

Grab stir bars as well - they're inexpensive and work well.


----------



## KillerRx4

Stir bars for sure. Forget the oblique thingo magnets. Theyre just begging to break your new flasks.

You will have to find a different magnet to mount on the fan for the stirbar as the oblique magnets poles are different. I have had most success with magnets from old hard drives.


----------



## Ross

I find the oblique magnets work great, they even work in containers where a flat stirbar wont - but they are quite powerfull, so I guess putting them too close together maybe putting undue upward strain on the fan.
The 2L flask is a good choice. So as not to damage the flask, I use a handheld magnet on the outside to slide the oblique magnet down the inside with.

cheers Ross


----------



## goatherder

Ross said:


> So as not to damage the flask, I use a handheld magnet on the outside to slide the oblique magnet down the inside with.
> 
> cheers Ross




You don't even need another magnet - a lump of something steel will do. I used a spanner to hold the magnet while I pitched the yeast.


----------



## crozdog

Jase,

I'd recommend grabbing stirbars as well as a 500ml & 2l erlenmyer flasks from Livingstone's if you're puttin in an order. The freight will be the same & you will get a smaller flask to use to step up your yeasts on the way to 2l.

Beers

Crozdog


----------



## Chilled

I started off with the oblique magnets and tried to use one of the stir bars from Livingstons with it. It failed dismally. 
The stir bars from Livingstons have an North and South pole at each end of the bar as you would imagine with any bar magnet. However the oblique magnets have the North and South poles in the centre of the oblique section with one on top of the other. When used with the stir bar you will find that one end of the stir bar will be attracted to the centre of the oblique magnet and the other will not be attracted to anything. As a result the stir bar does not spin around its centre and goes crazy. Either stick to how Ross does it with the second oblique magnet as your stir bar or purchase rare earth magnets (mine are 15mm diameter and 5mm thick) to use with the stir bars.
Also as Sosman quoted somewhere get the stir bars without the pivot ring. The ones with the pivot ring make a lot of rattling noise. :angry: 

On another note I burnt out a couple of variable resistors in an attempt to adjust the speed of the motor. Then it dawned on me that the power supply plug pack was the sort that had different voltages that you could select. Now all I do is select different voltages on the plug pack to vary the speed of the motor and have got rid of the "pot" altogether.

Chilled


----------



## Trough Lolly

Ross said:


> ...So as not to damage the flask, I use a handheld magnet on the outside to slide the oblique magnet down the inside with.
> 
> cheers Ross



I wish I'd read that utterly logical idea before my wife dropped a spheroid magnet into my new empty 2L flask leaving a bullseye and crack in it! :angry:  

I'm getting frustrated trying to spin ANYTHING with these hermatite magnets - I think I'll give them to the kids and buy a couple of button magnets....  

TL


----------



## Trough Lolly

Chilled said:


> I started off with the oblique magnets and tried to use one of the stir bars from Livingstons with it. It failed dismally.
> The stir bars from Livingstons have an North and South pole at each end of the bar as you would imagine with any bar magnet. However the oblique magnets have the North and South poles in the centre of the oblique section with one on top of the other. When used with the stir bar you will find that one end of the stir bar will be attracted to the centre of the oblique magnet and the other will not be attracted to anything. As a result the stir bar does not spin around its centre and goes crazy. Either stick to how Ross does it with the second oblique magnet as your stir bar or purchase rare earth magnets (mine are 15mm diameter and 5mm thick) to use with the stir bars.
> Also as Sosman quoted somewhere get the stir bars without the pivot ring. The ones with the pivot ring make a lot of rattling noise. :angry:
> 
> On another note I burnt out a couple of variable resistors in an attempt to adjust the speed of the motor. Then it dawned on me that the power supply plug pack was the sort that had different voltages that you could select. Now all I do is select different voltages on the plug pack to vary the speed of the motor and have got rid of the "pot" altogether.
> 
> Chilled



Great post Chilled! :super: 
You just confirmed some of my problems - I'm off to buy some new magnets.


----------



## laurent

Trough Lolly said:


> Chilled said:
> 
> 
> 
> I started off with the oblique magnets and tried to use one of the stir bars from Livingstons with it. It failed dismally.
> The stir bars from Livingstons have an North and South pole at each end of the bar as you would imagine with any bar magnet. However the oblique magnets have the North and South poles in the centre of the oblique section with one on top of the other. When used with the stir bar you will find that one end of the stir bar will be attracted to the centre of the oblique magnet and the other will not be attracted to anything. As a result the stir bar does not spin around its centre and goes crazy. Either stick to how Ross does it with the second oblique magnet as your stir bar or purchase rare earth magnets (mine are 15mm diameter and 5mm thick) to use with the stir bars.
> Also as Sosman quoted somewhere get the stir bars without the pivot ring. The ones with the pivot ring make a lot of rattling noise. :angry:
> 
> On another note I burnt out a couple of variable resistors in an attempt to adjust the speed of the motor. Then it dawned on me that the power supply plug pack was the sort that had different voltages that you could select. Now all I do is select different voltages on the plug pack to vary the speed of the motor and have got rid of the "pot" altogether.
> 
> Chilled
> 
> 
> 
> 
> Great post Chilled! :super:
> You just confirmed some of my problems - I'm off to buy some new magnets.
Click to expand...


Hi,

I mainly agree with this. However, if you keep both oblique magnets together and stick them to the fan, it will help have north/south poles further apart and stabilize the stir bar. Plus it will ensure the poles are on a plane parallel to the stir bar. Now a bit of blue-tac is more than enough to stick the magnets on the fan, helps for repositionning later on. I've been stirring this way twice already 24h straight and it is working great. Maybe the weight on the fan is a bit high and the magnets a bit too strong, but it works.

To vary the speed, I've build a simple voltage regulator as in here:Voltage regulator, first diagram. You'll have to replace R2 with a 1kOhm pot to get voltage from 1,5V to 12V. I think it may be better than a variable resistor, because the fan seems to draw a lot of current and heat up the pot real hot. I use an old laptop power pack to get the 17V input.

I have a 4cm stir bar w/o pivot and a 7cm pivot stir bar. Both works great.

Cheers,
Laurent


----------



## Trough Lolly

Dumb question: are you suggesting that the oblique magnets sit side by side on the fan, or stacked on top of each other!?!?
I'm assuming you mean side by side...yes, bluetack is enough for me too...

TL


----------



## Doc

One of the guys from Brewboard has posted a small video of his stirplate in action.
Wouldn't nornally be that interesting except for the groovy labware he has his starter in.
Video link here

Beers,
Doc


----------



## laurent

Trough Lolly said:


> Dumb question: are you suggesting that the oblique magnets sit side by side on the fan, or stacked on top of each other!?!?
> I'm assuming you mean side by side...yes, bluetack is enough for me too...
> 
> TL



Hi TL,

yes, I meant side by side, laying flat. Easy.

Laurent


----------



## Trough Lolly

Cheers Laurent,
I guess it's worth a try this weekend....


----------



## laurent

Trough Lolly said:


> Cheers Laurent,
> I guess it's worth a try this weekend....



Hi TL,

how did it go last week end? As a final thought, I would not recommend anybody to use the Jaycar oblique magnets.
Pro:
- Strong

Cons:
- Too heavy
- North/South poles are on the side rather than on ends
- Radiation not from the middle, so when adjusted, the weight balance is off and the fan shakes a lot

I would have saved lots of time buying calibrated neodymium magnets for a few more $ ... 

But the final result is still good :lol: 

Cheers,
Laurent


----------



## Jase

Ross said:


> I find the oblique magnets work great, they even work in containers where a flat stirbar wontt
> 
> cheers Ross



I decided to try the oblique magnet in a flat bottom coffee plunger, dropped an old dried yeast in and ran the stir plate for 24 hours. The magnets worked beautifully, whisper quiet and spun perfectly. After turning the stir plate off and letting the yeast drop, I ended up with about 15-20mm of yeast in the bottom of the plunger. Stoked.  

So I decided to order the flasks, without the stir bars. h34r: The flasks arrived today from Livingstone, althought the 2 litre one was a cheapy, not the Simax one I ordered, :angry: Livingstone are fixing that problem. Anyway, I thought I'd test out the new flask, magnet and stir plate. Carefully, placed the magnet into the 2 litre flask, added some water, magnet started to spin, but after 30 seconds, the magnets just stopped, but the fan in the stir plate was still spinning. Can't work out why. I decided to try the 500ml flask instead, carefully placed the magnet in the flask, somewhat harder, and the magnet won't spin at all. I'm at a complete loss as to why the stir plate and magnet were working perfectly using the coffee plunger, but not in the flasks. 

Any advice,

Cheers,
Jase


----------



## The Scientist

Heres an idea for the players;

Managed to pick up a power supply out of an old 386 computer. All I did was turn the fan around in the case and replace the fan cage with a piece of glass from a picture frame. Then attached the magnets and there you have it. The power supply has 4 other 12v power outlets so I can drive another couple of stirrers off this one box.






As Im not really that great at electronics this was easy to set up and works a treat. 

The stir bar is the flat type and in the photo its in a cut down bottle cap. I don't need to use it any more as I have just relanced the fan magnets and its now quite and spins perfectly.

Thanks to all who have given me the inspiration to delve into this project, next up will be the grain mill from a washing machine motors given to me by the neighbours.


----------



## goatherder

nice work the scientist! smart thinking, power supply, fan and mounting box all in the one unit. very neat.


----------



## Tony

I made up a starter with some WLP850 copenhagen lager yeast i had in the fridge an hour ago.

I had it sitting there and remembered i made a tight arse stir plate a year or 2 ago.

I dug deep and found it.

chucked the starter on it and it works bloody great. I have had it there all this time and never used it.

here are some pics

cheers


----------



## TidalPete

Tony said:


> I made up a starter with some WLP850 copenhagen lager yeast i had in the fridge an hour ago.
> 
> I had it sitting there and remembered i made a tight arse stir plate a year or 2 ago.
> 
> I dug deep and found it.
> 
> chucked the starter on it and it works bloody great. I have had it there all this time and never used it.
> 
> here are some pics
> 
> cheers



Tony,

That looks like a 240v jobbie to me? I recently upgraded my stir plate to 240v (Thanks Doc) & am really pleased with the extra oomph that I get. Not that there was anything wrong with my 12v job. 

You've got to keep reminding yourself that you have it.  They are so handy. :beerbang: 

:beer:


----------



## Tony

yep 240v.

the fan inside was an industrial electrical panel ventilation unit fan.

its run by a 240v fan controller...... well thats obvious 

cheers


----------



## TidalPete

Tony said:


> yep 240v.
> 
> the fan inside was an industrial electrical panel ventilation unit fan.
> 
> its run by a 240v fan controller...... well thats obvious
> 
> cheers



Off Topic I know Tony, but are you really as good looking as your avatar shows? I love it. :beerbang: 

:beer:


----------



## Tony

click on my name above the 3 toothed smiling dero and see a rum soaked dero at a B&S ball 

its the only photo i could find of myself

cheers


----------



## SpillsMostOfIt

For what it may be worth, I've documented to some extent my stirplate here ----> http://sillybeertricks.blogspot.com/

There's not much new, except that I'm using a different way to mount the magnets and it's mine...


----------



## Tony

has anyone had problems with heat from the fan heating the brew up.

my fan is a bloody heavy duty metal industrial unit, not a wimpy computer fan but im finding its getting warm and haeting the brew in the starter flask a bit.

that will be grouse in winter to keep ale yeasts healthy but im trying to start a lager yeast and wanted it cool. the heat from the fan has kept it at about 20 odd deg in a cold breeze in the garage.

also........

im thinking of making a bigger unit for a 50 liter firmenter and mounting it under a support in the brew fridge.

i figure it would give me better firmentation and hence, better beer.

anyone gone big with this?

cheers


----------



## Hogan

Tony said:


> has anyone had problems with heat from the fan heating the brew up.
> 
> my fan is a bloody heavy duty metal industrial unit, not a wimpy computer fan but im finding its getting warm and haeting the brew in the starter flask a bit.
> 
> that will be grouse in winter to keep ale yeasts healthy *but im trying to start a lager yeast and wanted it cool.* the heat from the fan has kept it at about 20 odd deg in a cold breeze in the garage.
> 
> also........
> 
> im thinking of making a bigger unit for a 50 liter firmenter and mounting it under a support in the brew fridge.
> 
> i figure it would give me better firmentation and hence, better beer.
> 
> anyone gone big with this?
> 
> cheers




Tony - when doing a lager starter I put the stir plate and flask into the temp cabinet and run it there during the start up process. Keeps the starter at pitching temp. No problem with a fan heating up that way.

Actually 20c is not a bad temp for a starter, particularly if you decant the liquid on a big starter and only use the grown yeast. Even if pitched at 20c there is a 12 hour window to drop it down to a low temp before bad flavours inhabit the wort.

As for a stir plate beneath a 50 lt fermenter I think Doc was moving in a similar direction some time back but don't know where that ended up. Maybe was Doc - maybe not.

Cheers, Hoges.


----------



## Doc

Hogan said:


> As for a stir plate beneath a 50 lt fermenter I think Doc was moving in a similar direction some time back but don't know where that ended up. Maybe was Doc - maybe not.



I was thinking about it, and even asked Chris White when he was in town last year. Basically, don't do it if you are making beer. If you are making yeast, no problem. Beer from a stirplate is not that nice flavourful beer that we want.
If you are making yeast for a micro, then go for the big 50 litre stirplate :beerbang: 

Doc


----------



## barls

i just finished mine which i made out of an old firewire case that stopped working so here it its




one question how long before i should see some form of action from the yeast and what should i be seeing as i know im not going to see a sediment layer due to the constant motion of the starter


----------



## razz

Evening Barls. I usually find that the stir bar slows down as the yeast starter hits high krausen and then picks up a little after high krausen. For example, bar spins at 200rpm then noticeably slows at high krausen and then goes back to it's 200 rpm. Also you should notice a thick head on top of the starter and the foam will change from cream to a brown scum top at high krausen. Time will depend on yeast age, temp, gravity and who knows what else.


----------



## Hutch

Hey Barls,
I don't know how you can see the rpm of the stir-bar, but I certainly agree with razz in that it seems to slow down, and looks thicker as the culture multiplies. I had meant to take some photos showing various stages of a recent Coopers Pale yeast culture on the stir plate, but the camera was full of baby photos...

In a few words, it starts off murky dark brown (wort colour), and gradually becomes lighter as the yeast multiplies, eventually ending up looking like iced-coffee BigM. While this is all happening, I usually see a constant swirling of small bubbles that can leave a frothy layer, depending on the temperature and vigour of the stir. I think it's generally best to stir as vigorously as possible to encourage continuous mixing of oxygen into solution, encouraging yeast growth. Obviously these observations will depend on the quantity you pitch into the starter, and the type of yeast being pitched.

You know it's pretty much done when the small bubbles cease to be driven off, and the liquid is a nice light chocolate milkshake colour.

At this point I take it off the stir-plate, and put the Erlenmeyer flask in the fridge for 24 hours. This settles out the yeast, enabling you to pour off the "beer", and pitch the thick layer of white yeast into your brew (making sure you don't pitch the magnetic stir-bar in the process!)

The stir plate is probably the most valued piece of brewing equipment I have made  
Hope it works for you too :beerbang:


----------



## barls

cheers guys im getting none of that with the irish ale i decided to try it with but thats not unusual for my starters as they normally kick on in the second day. unfortunately i need to change the yeast to the beer im brewing tomorrow. ill give this one a go and see.
cheers


----------



## razz

I used the 200 rpm bit as an example, but I guess Hutch was just taking the piss out of me. Don't stir your starter to vigorously as to much can cause sheer stress on the yeast, any stiring action will rapidly accelerate the starter which is what you want. Barls you may need to put your stir plate and starter in a warmer position. Wyeast have updated their website so read some of their pages on yeast starers.


----------



## barls

im going to have to change out my variable resistor from a 5k to a 2.5k as i dont have much adjustment at the moment, its ether just turning or flat out no in between. ill see how this one goes and ill let you know


----------



## barls

cheers guys i changed the yeast to the one i wanted yesterday and put the other one in the standard form of starter and they both have kicked the irish ale just took 2 days but the other has a nice little layer of froth. looks like my worrying was unnecessary. cheers guys


----------



## Jye

Im bored so heres a pic of some polyclar on the stir plate for a pils and ofest.


----------



## Plastic Man

have some fun with the kids with the rare earth magnets (apologies for off topic....)

linky


----------



## rwh

barls said:


> im going to have to change out my variable resistor from a 5k to a 2.5k as i dont have much adjustment at the moment, its ether just turning or flat out no in between.


Mine has a 500 ohm potentiometer in it, and it's still touchy as all hell. Actually, I think I put a 100 ohm resistor in parallel with it too, but still touchy. Usable though if you're careful. 500 ohm was the lowest I could find.


----------



## drsmurto

Hutch said:


> At this point I take it off the stir-plate, and put the Erlenmeyer flask in the fridge for 24 hours. This settles out the yeast, enabling you to pour off the "beer", and pitch the thick layer of white yeast into your brew (making sure you don't pitch the magnetic stir-bar in the process!)



Hutch

Is that the normal practice or can you just dump the whole thing into the wort?

Cheers
DrSmurto

p.s. not technically home made but it cost me $0.....


----------



## Jye

rwh said:


> Mine has a 500 ohm potentiometer in it, and it's still touchy as all hell. Actually, I think I put a 100 ohm resistor in parallel with it too, but still touchy. Usable though if you're careful. 500 ohm was the lowest I could find.



Check that its not a *log* pot which could be the cause of your sensitivity.



Jye said:


> You may have a log pot which could explain why the control is sensitive, a linear pot should remove the sensitivity. To check look for an *A* (log) or *B* (linear) printed on the back of the pot somewhere.


----------



## rwh

> Is that the normal practice or can you just dump the whole thing into the wort?


Well, it's a matter of opinion, and also the size of your stater. If you have a 3L starter brewed at 25C, is that going to add good flavours or bad flavours to your brew?

The choice seems to be pitching the whole thing at high krausen or cold pitch only the slurry after it's flocculated. I tend to do the latter because I'm too lazy to time it to high krausen, and there is very little additional lag introduced by doing it this way. See:

Cold Pitching Yeast


----------



## rwh

Jye said:


> Check that its not a *log* pot which could be the cause of your sensitivity.


Nah, it's a linear 500 ohm, though adding the resistor in parallel destroys the linearity.


----------



## barls

couldnt get what i wanted so i ended up putting a couple in series and got what i wanted in the end so its now working fine


----------



## domonsura

Joined the stirplate club today (couldn't resist), made mine with a magnet ripped out of a computer HDD.







Test drive Saturday with Wyeast Bo Pils yeast that's been in the fridge for 4 months..............looking forward to much healthier lager ferments now....


----------



## Sammus

I re did mine recently with a 240VAC fan from jaycar and a ceiling fan speed controller (damn those those things are $$, not long ago I saw a pack of 5 go in ebay for the same price I paid for a single one :angry: - oh well, too late to return now).

It got a bit warm after running for 4 hours, so I drilled a few holes around the sides of the case and it doesn't have that problem anymore. The speed control is good, being a continuous adjustment one instead of a 3 point one. I only ever use it flat out at the moment, though I'm sure that'll change when I start making my starters from slants. Its much torquier fan than the computer one, definitely a good thing.


----------



## Jye

A heads up for anyone using one of these as a stir bar, I found one of mine had cracked. Im unsure if it happened while boiling it in water/wort or if it was dropped.

So just remember to check them before use.


----------



## Sammus

Hi, has anyone pitched their starter straight from the stir plate? I imagine their could be issues with oxidised wort - but I'm hoping ~1L of oxidised wort in 25L brew wont show itself too much because I just realised my yeast is on its stir plate still and I've already started my mash!

I'm thinking that the stirring drives off a lot of co2, so maybe theres like a constant upward draft of it and it doesnt get a chance to dissolve more oxygen after a while? has anyone actually pitched starter wort thats been on a stir plate to know the results?

Sam


----------



## goatherder

Do it all the time Sammus, mainly for ales though because the starters are only 1-2 litres. With lagers I tend to ferment them right out and decant off most of the liquid. I haven't noticed any oxidation problems with the beer. I assume the yeast is taking up the oxygen while it is growing.


----------



## Gulf Brewery

Sammus said:


> Hi, has anyone pitched their starter straight from the stir plate? I imagine their could be issues with oxidised wort - but I'm hoping ~1L of oxidised wort in 25L brew wont show itself




Sam 

You should oxgenating your wort after pitching the yeast, they need oxygen to grow.

Cheers
Pedro


----------



## Sammus

Gulf Brewery said:


> Sam
> 
> You should oxgenating your wort after pitching the yeast, they need oxygen to grow.
> 
> Cheers
> Pedro



I was thinking more of oxidation as opposed to dissolved oxygen - that is, what I understand happens if you dissolve oxygen in fermented beer.


----------



## Gulf Brewery

Sammus

The oxygen from when the wort is on the stir plate will be held within the wort - oxidation at time shouldn't be a problem.
If the wort was hotter, like mash temperatures, then the oxidation may be an issue. 
Let's not start the war on HSA  

Cheers
Pedro


----------



## MVZOOM

Team, 

I'm about to take delivery of my stir plate. Here's what I intend to do to enact some good yeasty action:

- Mash some pale malt to obtain a few L of wort at around 1044.
- Sanitise some PET 800ml bottles and fill with aforementioned hot wort
- Freeze bottles, pending use for starters

When I need a starter, I'll then:

- pitch a VERY small amount ofyeast (say 2-3g of dried or 1/5 of a tube of liquid) to 100ml of wort
- Wack on the plate in a steralised container, with a glad wrap and a pin hole up top
- as it grows, add more wort to the existing flask, until I get full utilisation

Does this method look ok?

Cheers - Mike


----------



## newguy

You can never be too careful with a starter. If the starter gets contaminated, you're hooped. I'd recommend reboiling the wort after taking it out of the freezer, immediately before using it. I'd also recommend you put an aluminum foil cap on the top of your starter flask. Make it large, so that it overlaps the top of the flask quite a bit. Sanitise the foil and the outside of the flask near its top.

Someone else will have to chime in regarding incrementally feeding the starter.


----------



## Sammus

Also you didn't mention boiling the wort in the first place, you should probably do that if you weren't intending to. Personally I'd never store wort without pressure cooking it, but i think the debate has been done to death and bags not starting it again 

edit: Also, According to studies I've read somewhere, they recommending stepping up in 5 to 10-fold steps.

I personally start from yeast stored under distilled water. I plate it, then after about a week pick a culture and drop it into 20ml of sterile wort. I'll usually give that a day or two to ferment out (probably happens in much less) then transfer to the stir plate in either 100ml (ale) or 200ml (lager) of sterile wort for a day. Then another step to 1L (ale) or 2L (lager). For wheats etc (haven't tried this yet but I plan to...) go from 20ml to 100ml to 500ml or something. That might even be too much if your looking for that stressed yeast flavour. time will tell! 

FWIW, I also read that the greatest cell count in a step/starter is 12-18hrs after pitching - which i think is around high krausen, so this is a pretty good time to step up starters and pitch them also. Ensures maximum count and already active yeast.


----------



## MVZOOM

Umm, yes, sorry - I'd boil and re-boil the wort. Forgot to mention that. Why would an alu foil cap be better than glad wrap?? Also, any thoughts about incrimental wort additions?

Cheers - Mike


----------



## Sammus

MVZOOM said:


> Also, any thoughts about incrimental wort additions?



The pro's recommend going in steps, like my process outlined above.


----------



## razz

MVZOOM said:


> Umm, yes, sorry - I'd boil and re-boil the wort. Forgot to mention that. Why would an alu foil cap be better than glad wrap?? Also, any thoughts about incrimental wort additions?
> 
> Cheers - Mike


You can keep the aly cap on the flask while you're simmering the wort.


----------



## MVZOOM

Sammus said:


> The pro's recommend going in steps, like my process outlined above.



Sorry Sammus, actually missed your post! I guess there will be some trial and error with this stuff, will experiment and see.

Cheers - Mike


----------



## johnno

Anyone know anywhere in Melbourne city I can get a stir bar?

cheers
johnno


----------



## Hutch

johnno said:


> Anyone know anywhere in Melbourne city I can get a stir bar?
> 
> cheers
> johnno


I saw some at G&G the other day, same as the ones you can get from the chem-lab supply joints mentioned on here. 
Only one size though.


----------



## tk75

johnno said:


> Anyone know anywhere in Melbourne city I can get a stir bar?
> 
> cheers
> johnno



I'm also wondering if there is a place in the CBD to get some stirbars.


----------



## SpillsMostOfIt

I bought my stuff from here:

http://www.ssapl.com.au/

which is not in the CBD, but they do have every variant of every thing you might ever want and at decent prices. I found them to be very easy to do business with - they're not really set up for over-the-counter sales, but did so happily when I drove out there to pick up stuff I'd previously discussed via email.


----------



## Simon W

MVZOOM said:


> - Sanitise some PET 800ml bottles and fill with aforementioned hot wort
> 
> Umm, yes, sorry - I'd boil



Get an empty coke bottle and pour in some boiled water to see what happens to PET.
Dunno what temperature is safe for PET, but some experimenting will get you an answer.


----------



## KHB

i need a little help im building my stir plate, i had the power wired up to a switch and then wired up to the pot, but i managed to kill the pot??

I wired it up positive and negative to the pot like the guy in the shop told me. Just wondering if i should of wired it different i really want the swith in the circuit as i have already fitted it to the box cheers ben


----------



## crozdog

KHB said:


> i need a little help im building my stir plate, i had the power wired up to a switch and then wired up to the pot, but i managed to kill the pot??
> 
> I wired it up positive and negative to the pot like the guy in the shop told me. Just wondering if i should of wired it different i really want the swith in the circuit as i have already fitted it to the box cheers ben


KHB,

the pot should be "in series" with the +ve line on the output side of your power switch (assuming 12v DC here).


----------



## KHB

crozdog said:


> KHB,
> 
> the pot should be "in series" with the +ve line on the output side of your power switch (assuming 12v DC here).




When you say in series what do you mean i had the positive and negative in line from the power outlet to the swith to the pot and to the fan fan wires and pot wires where connected together, i got a bright red light at the pot then smoke.

???????


----------



## KHB

Just thought of this wondering if my power sorce was to much for it??

the output is +5V DC
3000MA

The pot was a 500(cant remember the simble that follows)it looks like an upside down u with legs!


----------



## chovain

KHB said:


> Just thought of this wondering if my power sorce was to much for it??
> 
> the output is +5V DC
> 3000MA
> 
> The pot was a 500(cant remember the simble that follows)it looks like an upside down u with legs!



Are you sure you didn't have the pot connected directly across the power connector? It sounds like you overloaded it, which can only really happen if you connect it directly across the power, and turn it all the way down. Can you upload a photo of the circuit? It's difficult to solve problems like this without knowing exactly how you've connected things up.

Edit:


KHB said:


> i got a bright red light at the pot then smoke.



You let the magic smoke out!


----------



## crozdog

it sounds to me like you were running the pot in parallel with your power supply. The pot therefore carried a lot of current and therefore destructed. There are 2 basic methods of connecting something - in series (which is inline with the current flow), or in parallel which is across the current flow. 

The power supply isn't the issue, it will supply the power which is "demanded" by the circuit - if the pot is wired incorrectly there will be a lower resistance path which the power supply will happily push electrons down. 


something like this (sorry about the crappy ascii art)
/
+ ----------/ ----------POT----------------------------------------------------Circuit to be controlled-------------------------------- -ve/earth

+ve, switch potentiometer (connect to 1 side & wiper) (don't have details of what you're doing here) -ve

Use the "ohm" scale of a multimeter to measure the resistance of the pot and to confirm the connection. You can get pots where the resistance changes in either a linear or a log manner.

here is a primer on pots http://www.jaycar.com.au/images_uploaded/potprimr.pdf

This primer on ohms law & power will also be useful http://www.jaycar.com.au/images_uploaded/ohmpower.pdf

Edit - added ohms law/power link


----------



## KHB

Mark Chovain said:


> Are you sure you didn't have the pot connected directly across the power connector? It sounds like you overloaded it, which can only really happen if you connect it directly across the power, and turn it all the way down. Can you upload a photo of the circuit? It's difficult to solve problems like this without knowing exactly how you've connected things up.
> 
> Edit:
> 
> 
> You let the magic smoke out!




Red is positive Blue is negative sorry bout the crap drawing hopefully this helps


----------



## LethalCorpse

A pot wired inline is the worst way to control a motor's speed. It will fail eventually, particularly at maximum speed (minimum resistance). Most pots are only rated to 0.25W, and a 500ohm pot can handle a max of about 22mA. If you hook up a fan who's normal operating current is 100mA, it will kill the pot at the higher speeds. At lower speeds, the pot can protect itself a bit better, because it's limiting the current, but it's still decidedly inadvisable. 
A decent switchmode controller would be ideal, but if you've not played with much electronics, or you don't want to buy an off the shelf fan controller, this is a simple circuit which will do the job, it's three parts which can be bought at Jaycar/DSE and will give a regulated output between 1.25V and 10.5V from a 12V supply. Use a heatsink on the LM317 if your fan draws more than 200mA normally, and don't use it for motors bigger than 1A.


----------



## KHB

The above circuit confuses the hell outta me.

What was wrong with my circuit can anyone explain that


----------



## chovain

KHB said:


> Red is positive Blue is negative sorry bout the crap drawing hopefully this helps



That circuit is far to simplistic to do the job, and will let the smoke out any time you turn the pot all the way down.

Your pot is just a resistor that varies from 0 to 500 ohms. Now, when it's at 500 ohms, things will behave kind of sensibly: Some current will go through the pot, while the rest will go through the fan. The fan will spin. As you turn down the pot, more current will go through it, bypassing the fan. When it gets to 0 ohms, it'll short out the power completely.

Now, if you put everything in series (so the power, switch, pot and fan form a "loop"), things will behave slightly better, but it's still not what you want. All the current will flow all the way around the loop every time you turn the power on. At 0 ohms, there will be no voltage drop across the pot, so the fan will get "full power". As you turn the pot up, the resistance will rise, and you'll get a voltage drop across the pot, and power will be taken away from the fan. That's the opposite of what you want, and 500 ohms will never take enough power to completely stop the fan.

There's a good control circuit at http://brewiki.org/StirPlate. It's a little hard to describe how it works, because it uses a semiconductor to regulate the voltage that the fan will receive. If you follow it though, it'll work.

Edit: Beaten to it by LethalCorpse. His circuit is simpler than what I linked to, and will do the job fine. 

If you don't understand it, get a friend with a better understanding of electronics to throw it together for you.


----------



## LethalCorpse

Take another look at it, it's as simple as it gets, simpler even than the diagram you posted. It's the same as the circuit mark posted, but I left off the capacitors to make it simple for you, and it should survive without those caps. Just follow the wires - buy an LM317, a 20k pot, and a 2.7k resistor. The left leg of the LM317 is connected to the middle leg of the pot and one end of the resistor. The other end of the resistor is connected to the middle leg of the LM317 and the positive lead on the fan. The left leg on the pot is connected to the negative leads for the power supply and the fan. The right leg of the LM317 is connected to the power supply. That's it.

If you want to add the caps as suggested in the brewiki page, buy a 100n ceramic cap, and a 10u electrolytic cap (you don't have to know what all of these components are or how they work - the folks at Jaycar should be able to find them for you. DSE staff won't know where to look though). Connect the two legs of the ceramic to the two leads of the power supply - doesn't matter which way around. Then connect the two legs of the electrolytic to the two leads of the fan - this one does matter, but there's a stripe to indicate the one that should go to the negative lead. This will make the circuit more stable, and reduce the small risk that pulses will kill the LM317. If you don't use them, and it fails, it's only another few dollars to replace the LM317.


----------



## KHB

LethalCorpse said:


> Take another look at it, it's as simple as it gets, simpler even than the diagram you posted. It's the same as the circuit mark posted, but I left off the capacitors to make it simple for you, and it should survive without those caps. Just follow the wires - buy an LM317, a 20k pot, and a 2.7k resistor. The left leg of the LM317 is connected to the middle leg of the pot and one end of the resistor. The other end of the resistor is connected to the middle leg of the LM317 and the positive lead on the fan. The left leg on the pot is connected to the negative leads for the power supply and the fan. The right leg of the LM317 is connected to the power supply. That's it.
> 
> If you want to add the caps as suggested in the brewiki page, buy a 100n ceramic cap, and a 10u electrolytic cap (you don't have to know what all of these components are or how they work - the folks at Jaycar should be able to find them for you. DSE staff won't know where to look though). Connect the two legs of the ceramic to the two leads of the power supply - doesn't matter which way around. Then connect the two legs of the electrolytic to the two leads of the fan - this one does matter, but there's a stripe to indicate the one that should go to the negative lead. This will make the circuit more stable, and reduce the small risk that pulses will kill the LM317. If you don't use them, and it fails, it's only another few dollars to replace the LM317.




Cool so using the switch i have drawn above where and how would i wire this in i wanna use it i have already cut the hole


----------



## chovain

You should be aware of a couple of things with the LM317 though: 
* Jaycar sells LM317 in a few different packages. You want the TO-220 package, aka LM317T. Jaycar's catalogue number is ZV1615 (Ask them for that, and they'll give you the right thing - it looks like a transistor that's been run over by a train).
* These things are more sensitive than components you'd be used to handling. Try not to handle any of the metallic contacts if you can avoid it: A zap of static electricity, even one too small for you to feel, could destroy the LM317.
* The big metal "tab" on the back of the LM317 is electrically connected to the centre pin. Make sure it doesn't touch any other components, or you could get a short. You're probably not going to kill it even if you short it out, but it can get awfully hot if shorted.


----------



## LethalCorpse

I wouldn't worry about static electricity frying an LM317. They're really not that sensitive. Even CMOS components, which most people think you can't go near without a wrist strap and a blessing from a priest, are these days pretty bloody resilient.

Attached is the circuit updated to show the caps, and the switch


----------



## KHB

LethalCorpse said:


> Take another look at it, it's as simple as it gets, simpler even than the diagram you posted. It's the same as the circuit mark posted, but I left off the capacitors to make it simple for you, and it should survive without those caps. Just follow the wires - buy an LM317, a 20k pot, and a 2.7k resistor. The left leg of the LM317 is connected to the middle leg of the pot and one end of the resistor. The other end of the resistor is connected to the middle leg of the LM317 and the positive lead on the fan. The left leg on the pot is connected to the negative leads for the power supply and the fan. The right leg of the LM317 is connected to the power supply. That's it.
> 
> If you want to add the caps as suggested in the brewiki page, buy a 100n ceramic cap, and a 10u electrolytic cap (you don't have to know what all of these components are or how they work - the folks at Jaycar should be able to find them for you. DSE staff won't know where to look though). Connect the two legs of the ceramic to the two leads of the power supply - doesn't matter which way around. Then connect the two legs of the electrolytic to the two leads of the fan - this one does matter, but there's a stripe to indicate the one that should go to the negative lead. This will make the circuit more stable, and reduce the small risk that pulses will kill the LM317. If you don't use them, and it fails, it's only another few dollars to replace the LM317.




Just thought id get someone to check this for me.

Been on jaycar and have product numbers

pot RP7516


----------



## KHB

LethalCorpse said:


> Take another look at it, it's as simple as it gets, simpler even than the diagram you posted. It's the same as the circuit mark posted, but I left off the capacitors to make it simple for you, and it should survive without those caps. Just follow the wires - buy an LM317, a 20k pot, and a 2.7k resistor. The left leg of the LM317 is connected to the middle leg of the pot and one end of the resistor. The other end of the resistor is connected to the middle leg of the LM317 and the positive lead on the fan. The left leg on the pot is connected to the negative leads for the power supply and the fan. The right leg of the LM317 is connected to the power supply. That's it.
> 
> If you want to add the caps as suggested in the brewiki page, buy a 100n ceramic cap, and a 10u electrolytic cap (you don't have to know what all of these components are or how they work - the folks at Jaycar should be able to find them for you. DSE staff won't know where to look though). Connect the two legs of the ceramic to the two leads of the power supply - doesn't matter which way around. Then connect the two legs of the electrolytic to the two leads of the fan - this one does matter, but there's a stripe to indicate the one that should go to the negative lead. This will make the circuit more stable, and reduce the small risk that pulses will kill the LM317. If you don't use them, and it fails, it's only another few dollars to replace the LM317.



Looked on the jaycar website
pot RP7516
2.7K resistor RR0582

Are these the right ones??
Cheers Ben


----------



## LethalCorpse

bugger, thought they had 20K pots. Use a 680ohm resistor and a 5k pot instead. Pot can be RP3508 or RP7508, resistor should be RR0568, or if for some crazy reason they've run out (it's been a few years since they stocktaked resistors) RR2770.


----------



## schooey

I don't know if it's been mentioned in the umpteem posts before, but I reckon your ideal stir bar is a 40 mm teflon job. I went all out with my first effort and got a 3L conical flask and a 60mm stir bar (building a big starter for a 50L batch) and it was a pain in the arse to keep the stir bar centred. I have since got a 40mm bar and it works an absolute treat.


----------



## Franko

This is a question for the electronics gurus 
Ive acquired a few 48 Vdc 120mm fans from work and would like to know what type of circuit would be best to use these for a stirplate.
The fans are 48 Vdc at .11 amps
The power supplies I have are 48 Vdc at 250ma

Many thanks
Franko


----------



## LethalCorpse

a 12vdc power supply, along with the circuit I posted before, should do nicely. You'll not want to run them anywhere near full speed, so as long as they start at 12V, they should be good to go.


----------



## Franko

LethalCorpse said:


> a 12vdc power supply, along with the circuit I posted before, should do nicely. You'll not want to run them anywhere near full speed, so as long as they start at 12V, they should be good to go.



can only get it to start at 12v by spinning the fan manually thats with a 12V 200ma transformer.
12V 500ma did nothing at all

Franko


----------



## LethalCorpse

the current rating makes bugger all difference - it's just a maximum that the pack can deliver, the load determines the current draw, which is 110mA max at 48V, and rather a lot less at 12V.

So 12V didn't work eh? Hmm...A 48V controller is quite possible, but rather a lot more complex than 12V. Can you get your hands on a 24V supply? That should start it, and you can use the same controller by replacing the resistor with a 3kohm and the pot with a 50k. You might find the speed is fine with 24V straight off. 

If all that fails you'll need a 48Vin switchmode variable PSU design.


----------



## Franko

LethalCorpse said:


> the current rating makes bugger all difference - it's just a maximum that the pack can deliver, the load determines the current draw, which is 110mA max at 48V, and rather a lot less at 12V.
> 
> So 12V didn't work eh? Hmm...A 48V controller is quite possible, but rather a lot more complex than 12V. Can you get your hands on a 24V supply? That should start it, and you can use the same controller by replacing the resistor with a 3kohm and the pot with a 50k. You might find the speed is fine with 24V straight off.
> 
> If all that fails you'll need a 48Vin switchmode variable PSU design.



just got it spinning with a 15vdc 1amp plugpack it spins straight away on startup

would like to slow it down a little

Franko


----------



## newguy

Here is a circuit that will do the trick. Look at the "Typical Application" schematic in the middle of the page in the link. It's the same one I use for my stir plate but I use a 12V supply and 12V fan for mine. The adjustable resistor (R2) is what allows for voltage (speed) control.


----------



## LethalCorpse

If it won't start on 12V but is too quick on a 15V, the regulator circuit won't help you much, unless the 12V was a regulated pack and the 15V wasn't. You need to use a thing called Pulse Width Modulation (PWM) which works by switching the power on and off very quickly. If it's on for 70% of the time, then the fan gets an average of 70% full power. The big advantage for you, though, is that fans can be driven to much lower speeds, and still start under their own power, than they could with a linear regulator like the LM317. Jaycar has a circuit designed for this purpose, though it's intended for much bigger motors. It's called the 12/24VDC 10A motor speed controller, linky. From memory its input range is 10-28VDC, so your 15V supply should be fine.


----------



## Zwickel

Hi LC, thats a beautiful little thingy, would be great to control the spin of mash stirring motors, such like car wiper motors, as well.

very nice :icon_chickcheers:


----------



## kabooby

Why not use a light dimmer or fan controller. Should still work at the lower voltages

Kabooby :icon_cheers:


----------



## LethalCorpse

nope, sorry. Those things only work on AC power


----------



## kabooby

Of coarse, I looked over the fact that it was a DC motor.

A PWM is the best way to control the speed. If the speed does not need to be controlled than reducing the supply voltage will work. The speed of a DC motor is directly proportional to its supply voltage.

Kabooby :icon_cheers:


----------



## crozdog

Franko,

i have some 240v fans which you could use an off the shelf light dimmer or fan controller with. 

Swap you one for a logo or 2 - hang on aren't i still waiting on 1 for a keg :lol:


----------



## SJW

I am not an electronic wiz at all, so why can't I just use one of the two phone chargers I have, a 12v and a 9.6v, and just hook that up to the fan/stir plate and just use the one that spins at the right speed? Does it need to be variable?


Steve


----------



## Ross

SJW said:


> I am not an electronic wiz at all, so why can't I just use one of the two phone chargers I have, a 12v and a 9.6v, and just hook that up to the fan/stir plate and just use the one that spins at the right speed? Does it need to be variable?
> 
> 
> Steve



Hi steve,

Yes, they really do need to be variable. For starters (no pun intended) you need need a higher speed to get the vortex happening which then needs to be backed off or you'll have yeast flying everywhere.

cheers Ross


----------



## schooey

If you have a phone charger for the power source, Steve, it's only a matter of wiring in a pot between it and the fan to make it variable, no rocket surgery involved.


----------



## LethalCorpse

No, it's not schooey, unless he wants to replace it regularly. Have another read of the thread.

Steve, if you're not confident enough to wire it up yourself, buy a cheap fan controller from any computer parts store. It will do the job.


----------



## schooey

LethalCorpse said:


> No, it's not schooey, unless he wants to replace it regularly. Have another read of the thread.
> 
> Steve, if you're not confident enough to wire it up yourself, buy a cheap fan controller from any computer parts store. It will do the job.



*scratches head*

Buggers me, LC, mine seems to be still going solid after 12 months.

edit: You are right with the fan controller suggestion, quick easy and relatively cheap


----------



## LethalCorpse

Well, then you're very fortunate, aren't you? It's not a good idea dude.


----------



## schooey

Ahhhh... Ithink we're on the same channel here, LC. What I meant by wiring in a pot was by following the diagram in your post here. I meant by using the 12VDC phone charger, you don't need to muck around with transformers and bridge rectifiers etc etc (like I did  )


----------



## LethalCorpse

Gotcha. Well, I wouldn't call that wiring in a pot, the pot is just a part of the regulator circuit, which is what you're wiring in. Plenty of people have tried to do it by _only_ using a pot, which will more or less work for some period of time, but will give lousy linearity of control and will burn out eventually. 

The fan controllers you can buy from computer stores will probably do a better job than the circuit I gave in the post schooey linked. This is because they usually use a simple PWM controller circuit, which can control the fan down to close to 0RPM, whereas a fan driven by a linear regulator will cutoff at around 3-5V.


----------



## SJW

I will just go to Jaycar and ask them what they reckon.


----------



## LethalCorpse

You just did - I was a store manager for three years. Jaycar don't currently have a suitable fan controller, so the best they're going to be able to recommend is the linear controller circuit I posted earlier. Any computer shop should have a fan controller, they may call it a "fanbus" or a "rheobus" but they're all designed for the same thing - making computer fans run slower.


----------



## SJW

DONE, I went to Jaycar and told then what I was doing and in the shop we got a fan, power supply and a POT and hooked it up and made it all work with no melt downs. So I got this little pot (thingy) and nice flash knob, 4 little rare earth magnets, a project box and a little switch with a light in it to turn the power on and off. All up about $20. 
Too easy. I then went over to a lab supplies and got a 2 litre conical flask for $19 and to stir bars for $4 and $5. Good day in the end.


Steve


----------



## LethalCorpse

*sigh* idiots.


----------



## rich_lamb

Don't worry LC, good beer will come of it anyhow  
And incidentally SJW seems to have found pretty good value for glassware. Is that cheaper than buying flasks from the HBS? Do you know how much the 5L flasks were SJW?

Personally I use a linear reg to drive my fan, and yes it cuts out at about 5-7V which hasn't been too big a problem. I should probably convert it to a PWM-type as slower control would be nice.


----------



## SJW

I don't know how much the 5l flask's were as I did not ask.

The test one we made up in the shop went from flat out to stopped so I can't see any probs with the pot.

Steve


----------



## Screwtop

Really no need to overdesign these things, they are what they are "A CHEAP ARSE STIRPLATE" Seriously doubt that some little 240VAC plug pack fixed 12vDC output adaptor rated around 200mA is going to fry a linear potentiometer in series with the load. So what if you get two or three years out of the thing before needing to replace a $2.25 pot.



LethalCorpse said:


> *sigh* idiots.




Thats a bit rude :angry:


----------



## LethalCorpse

Rather like bacteria, just because you can't see the problems, doesn't mean they're not there. You were warned, but good luck to you anyway.

Of course it goes from flat out to stopped, but you're missing a wide range of possible speeds in the middle - the control is, as I said, non-linear. Probably that's not a problem for you, but that's what we mean by PWM being able to go down to zero - it has the full range of speeds. The pot burning out will be a problem though, let us know when this happens - I'm curious as to just how much abuse Jaycar's pots can take before failure. When it does fail, might I suggest you do it properly next time?


----------



## LethalCorpse

Screwtop said:


> Thats a bit rude :angry:


Well, yes, but it's not just coming off the back of this post. Like I said, I used to be a manager there, and I've had years to build up a head of steam about staff handing out incorrect advice which can only be to the detriment of the customer and hence the company's reputation. Many Jaycar staff do know their stuff, but over recent years they're fewer and further between. I've got no problem with staff not knowing the answers, but I used to fire them for bluffing instead of finding out.


----------



## Fents

LethalCorpse said:


> *sigh* idiots.





> Well, yes, but it's not just coming off the back of this post. Like I said, I used to be a manager there, and I've had years to build up a head of steam about staff handing out incorrect advice which can only be to the detriment of the customer and hence the company's reputation. Many Jaycar staff do know their stuff, but over recent years they're fewer and further between. I've got no problem with staff not knowing the answers, but I used to fire them for bluffing instead of finding out.



yea but you dont turn around and tell customers they are idiots just because they may be wrong. you at least wait till they come back injured and for a refund :lol:

edit - sjw that dosnt mean it wont work...try it would be sick if it worked.


----------



## LethalCorpse

Not when you're still working there you don't. I'm not worried about keeping a job there anymore, or about upsetting the workplace apple cart, so I'm free to call it as I see it.
EDIT: to clarify, I'm not calling SJW an idiot here, he's not supposed to know better. Though I do wish he'd listen to advice, it's his own brewery.


----------



## schooey

Bitter & Twisted said:


> And incidentally SJW seems to have found pretty good value for glassware. Is that cheaper than buying flasks from the HBS? Do you know how much the 5L flasks were SJW?






SJW said:


> I don't know how much the 5l flask's were as I did not ask.



If you got them where I think you did, Steve, (Aust Scientific @ Kotara) the 3L flasks are about $30-$40 and the 5L were around the $80 mark.


----------



## pokolbinguy

Damn wish I found this thread earlier. I'm deffinatley going to try out this little project. 

Cheers, Pok


----------



## SJW

OK how the hell do I wire these things up. I think I blew up the pot by wiring it up wrong as there was a flash and smoke coming from the pot. The problem I have is I know nothing about electronics. So when I go back tomorrow do I just ask for a "PWM" instead of another "POT"? If so or not how do I wire them up?
I have 2 wires coming from the power source, they go to a on/off switch, one wire to the middle pole and the other to a side pole. Then what? from the centre pole of the switch to the cetre pole of the POT and from the empty switch pole to a side pole on the POT? Then from the middle pole to the fan and the empty pole on the pot to the fan?
This is not easy for me.

Steve


----------



## kabooby

You dont want to have the power supply going straight into the switch. All you will do is blow up your plug pack when you switch it on

This is not easy to explain in a post. Best of going to see someone that knows what they are doing


----------



## SJW

> You dont want to have the power supply going straight into the switch. All you will do is blow up your plug pack when you switch it on
> 
> This is not easy to explain in a post. Best of going to see someone that knows what they are doing



I did that too, with the first plug pack.


----------



## Screwtop

Doesn't anyone bother to search anymore, years ago there was a thread and info by Peter Fitzsimons including a parts list from Jaycar and assembly instructions. Go search!

I did it for you, lazy bunch of.....b...brewers. Go to Page 1 of this thread Post #1 and search around for the parts list etc.


----------



## schooey

Screwtop said:


> Doesn't anyone bother to search anymore, years ago there was a thread and info by Peter Fitzsimons including a parts list from Jaycar and assembly instructions. Go search!
> 
> I did it for you, lazy bunch of.....b...brewers. Go to Page 1 of this thread Post #1 and search around for the parts list etc.



Here... had it bookmarked from when I first looked into building one. I ended up going with the LM317 circuit though.


----------



## goodbrew

SJW said:


> OK how the hell do I wire these things up. I think I blew up the pot by wiring it up wrong as there was a flash and smoke coming from the pot. The problem I have is I know nothing about electronics. So when I go back tomorrow do I just ask for a "PWM" instead of another "POT"? If so or not how do I wire them up?
> I have 2 wires coming from the power source, they go to a on/off switch, one wire to the middle pole and the other to a side pole. Then what? from the centre pole of the switch to the cetre pole of the POT and from the empty switch pole to a side pole on the POT? Then from the middle pole to the fan and the empty pole on the pot to the fan?
> This is not easy for me.
> 
> Steve




SJW, think of the wiring as a circle, take one wire from your power pack and go to the centre post of your switch, then from the other post on your switch go to the centre post of your pot, then attach one wire from your fan to one of the outer posts of your pot, and finally join the second wire of your fan to the second wire on your power pack. I've recently made one myself using a 1kohm pot from jaycar which does the job really well, doesnt even get warm when you slow it right down.  

cheers


----------



## SJW

OK it works great, but it does not work :huh: Well its all wired up and works great except for the little light on the switch, it does not come on now when it live, but dont care.
The problem I have is the stir bars appear to either attract or repell depending on which way they are orientated. So if I fill a flask with water and get the bar pointing the right way when I turn up the power it spins once or twice then gets thrown to the outside of the flask. I am using 4 (2 each side) of those little rare earth magnets, so should I be trying to get the fan/magnets closer to the top of the box or have I bought the wrong stirres. I got 2 a 40 and a 60mm long and one has a band in the middle.


----------



## pokolbinguy

What are you using as a power supply there SJW?


----------



## schooey

I tried at first with those liddle iddy biddy magnets, even when I put all four of them together (two on either side, and all on top of the fan) they weren't strong enough to keep the bar centred. I had to go for the next size up.


----------



## lagers44

That's one of my quesations SJW.

When positioning the magnets which way around do they go ? One north up & one south up , or both the same way ?

I'm guessing it's one up one down ( guessing the stir bar is N & S ) to lock the stirbar to the magnets so it spins with them ?
If i'm correct then that may be SJW's problem his magnets could be both the same way repelling the bar.

Lagers 

edit: finish the sentence before sending.


----------



## PostModern

SJW said:


> OK how the hell do I wire these things up. I think I blew up the pot by wiring it up wrong as there was a flash and smoke coming from the pot. The problem I have is I know nothing about electronics.



This is why LC called the sales guy at Jaycar an idiot. You ~can~ wire a pot in series with a fan and a power supply and it ~will~ change the speed of the fan until it fails. Pots aren't meant to handle 5W loads. You probably got a .25W pot which eventually did what an overloaded component will do - which is let out the "magic smoke" that makes it work. Once the smoke is out, you can't stuff it back in.


----------



## SJW

All is well now. Just took a bit of practice. I have the two magnets doubled up and once I get the bar centred I just need to ramp it up slowly then back it off once it gets going. I had it going for a couple of hours going so slow you could see the bar spinning and it did not heat up the pot. Its a 500ohm, 3w pot. But even running at an optimal speed its near flat out anyway, but not quite.
Thanks for all your help again, any reason why the light is not coming on when its live?




> What are you using as a power supply there SJW?


A 12v phone charger I picked up for $2 at a junk sale.


Steve


----------



## newguy

lagers44 said:


> When positioning the magnets which way around do they go ? One north up & one south up , or both the same way ?



One N, the other S. That way the N and S of the stir bar will each be attracted to a magnet on the fan and the stir bar will have a stronger hold.


----------



## kabooby

SJW said:


> any reason why the light is not coming on when its live?



At a guess you may have blown the globe when you connected up the power supply wrong.

Kabooby


----------



## LethalCorpse

It's a 0.5W pot, not 3W, as PoMo said, it's not designed for a 5-10W load, but then you've ignored that one already.

The light on the switch doesn't come on because it's wired up incorrectly, or because you wired it incorrectly before and blew it up. There are two wires coming from the PSU, a positive and a negative. The positive is red, or the middle wire if it's a coaxial cable. The back of the switch is labelled 'Supply, Load and Earth'. The positive from the supply goes to the "supply" pin on the switch. The negative from the supply goes to the "earth" pin on the switch. The load pin goes to the middle of the pot. Then one side of the pot goes to the positive (red) wire of the fan. The negative wire of the fan goes to the earth on the switch (same as the negative of the supply).

And all of that will still fail.


----------



## Screwtop

SJW said:


> All is well now. Just took a bit of practice. I have the two magnets doubled up and once I get the bar centred I just need to ramp it up slowly then back it off once it gets going. I had it going for a couple of hours going so slow you could see the bar spinning and it did not heat up the pot. Its a 500ohm, 3w pot. But even running at an optimal speed its near flat out anyway, but not quite.
> Thanks for all your help again, any reason why the light is not coming on when its live?
> 
> 
> 
> A 12v phone charger I picked up for $2 at a junk sale.
> 
> 
> Steve




Steve I glued a length of acrylic strip across the fan so I could position the magnets further out, that seemed to help with the positioning problem.



LethalCorpse said:


> It's a 0.5W pot, not 3W, as PoMo said, it's not designed for a 5-10W load, but then you've ignored that one already.



Don't see a problem, he's using a phone charger.


----------



## LethalCorpse

Screwtop said:


> Don't see that as a problem if he's using a phone charger.


Makes no difference whether he's using a phone charger, a car battery, or a 40A heavy duty benchtop supply. 12V is 12V, the current is determined by the fan and the pot, and for most of its deflection, the pot will need to handle well over 0.5W. 

You said earlier there's no need to overdesign this. That's true, but there's also no need to _under_design it, which is what a series pot is. A simple linear regulator circuit is a minimum design, with an off-the-shelf fan controller being appropriate for those that lack the expertise to hook up a regulator. As SJW has demonstrated, if you can't wire up a regulator circuit you may not be able to wire up a pot either, so simplifying it to the point of inadequacy doesn't necessarily make it any easier, and certainly doesn't make it better.


----------



## SJW

> Makes no difference whether he's using a phone charger, a car battery, or a 40A heavy duty benchtop supply. 12V is 12V, the current is determined by the fan and the pot, and for most of its deflection, the pot will need to handle well over 0.5W.
> 
> You said earlier there's no need to overdesign this. That's true, but there's also no need to underdesign it, which is what a series pot is. A simple linear regulator circuit is a minimum design, with an off-the-shelf fan controller being appropriate for those that lack the expertise to hook up a regulator. As SJW has demonstrated, if you can't wire up a regulator circuit you may not be able to wire up a pot either, so simplifying it to the point of inadequacy doesn't necessarily make it any easier, and certainly doesn't make it better.


I guess that fact is it works and even if I only get a couple of years out of it $2.25 for a new pot still puts it in the Tight Arse Stir Plate catagory. I appears that heaps of people use the pots with no problems. If it does blow I will try the 500ohm 3w Wirewound jobs that Goathearder uses. 
The light still works so I wil double check my wiring when I get home.


----------



## PostModern

I haven't read the whole thread, but an LM317, a resistor, a bit of experiment board and the off-cuts of your resistor for tracks is all you need. Piss easy to wire up. I did one for a 120mm fan controller a couple years ago. Took about 5 mins (plus soldering iron warmup time) to assemble. I believe it still works. I might pull it out, dust it off and make a TASP myself.


----------



## schooey

If you want to do it really tight arse and crudely, you dont even need the board. Just solder the resistor to the LM 317, and the other to the wiring and put some heatshrink over it, and yep, its a 5 min job


----------



## Benniee

Earlier in this thread there was a few people who got their magnets from old hard drives. Does anyone have any pics of this?

Benniee


----------



## PostModern

schooey said:


> If you want to do it really tight arse and crudely, you dont even need the board. Just solder the resistor to the LM 317, and the other to the wiring and put some heatshrink over it, and yep, its a 5 min job



I screwed my LM317 to an appropriate heatsink with thermal compound and everything. Not quite as fussy as LC, but gettin' there 



Benniee said:


> Earlier in this thread there was a few people who got their magnets from old hard drives. Does anyone have any pics of this?
> 
> Benniee



About halfway down this page http://www.dansdata.com/magnets.htm
Further down that page is a really cool liquid called Ferrofluid. Like magnetic motor oil!


----------



## LethalCorpse

For the more adventurous, here is a simple PWM circuit using a 555 timer. <$5 worth of parts.


----------



## Screwtop

LethalCorpse said:


> Makes no difference whether he's using a phone charger, a car battery, or a 40A heavy duty benchtop supply. 12V is 12V, the current is determined by the fan and the pot, and for most of its deflection, the pot will need to handle well over 0.5W.
> 
> You said earlier there's no need to overdesign this. That's true, but there's also no need to _under_design it, which is what a series pot is. A simple linear regulator circuit is a minimum design, with an off-the-shelf fan controller being appropriate for those that lack the expertise to hook up a regulator. As SJW has demonstrated, if you can't wire up a regulator circuit you may not be able to wire up a pot either, so simplifying it to the point of inadequacy doesn't necessarily make it any easier, and certainly doesn't make it better.




Do the math - Voltage (12V) total series resistance (max 50K + typically 160) therefore Current and Power = 2 fifths of Fcuk all


----------



## hockadays

Lethal,

I've seen the circuit diagram but have you got any pictures of how to wire it up. You could call it the "Lethal method". Ps excuse me if you already have as I haven't looked back over this thread for a few weeks.

cheers


----------



## barls

LethalCorpse said:


> For the more adventurous, here is a simple PWM circuit using a 555 timer. <$5 worth of parts.


is this running on 12 volts mate.


----------



## Screwtop

Could have a couple of versions, the Tight Arse Stirplate, and the Slightly More Seriarse Stirplate :lol: 



Disclaimer: No seriousness is meant or implied in this post, there has been far too much of this already.


----------



## LethalCorpse

Screwtop said:


> Do the math - Voltage (12V) total series resistance (max 50K + typically 160) therefore Current and Power = 2 fifths of Fcuk all


eh? Let's assume the fan is a purely resistive load (it's not, but it'll do for argument's sake). If the label says 12V 300mA, it's a 40ohm load. If you use a 500ohm, 0.5W pot to slow it down as SJW has, the responses are shown in the chart below.

Note that the system current drops off sharply, which is what I mean when I talk about non-linearity of control. If we assume the fan speed to be roughly proportional to system current, this means it'll be very twitchy at the top end, with a long tail - it takes a small turn to cut the speed to very low, where it will stay over most of the pot's range.

Note also that the power dissipated in the pot peaks at about 8%FSD, with 0.9W. This nearly doubles the rated power of the pot, but the pot's rating is across the entire range. If you're using 8% of it's length, you've only got 8% of its power rating, or 0.04W. You're therefore overpowering the pot by 22.5 times. The power is only within rating above about 340ohms, in which range the system current is pretty well constant.

Since the pot is probably well underrated, this isn't likely to cause immediate and catastrophic failure, but I'd say it's a fair way north of 2 fifths of Fcuk all.

Is there any other math you'd like to suggest I do, Screwy?


----------



## LethalCorpse

hockadays said:


> Lethal,
> 
> I've seen the circuit diagram but have you got any pictures of how to wire it up. You could call it the "Lethal method". Ps excuse me if you already have as I haven't looked back over this thread for a few weeks.
> 
> cheers


There's a modified version on this page down the bottom, which gives nice clear board layout instructions.




barls said:


> is this running on 12 volts mate.


yep, sure is


----------



## SJW

:lol: Thats gold. LC, do you ever get the feeling like your Robinson Crusoe on this one?


----------



## LethalCorpse

More Don Quixote mate. 

I'm not banging on about this to be pedantic, but since the questions keep coming I'm happy to oblige. I do have some modest body of experience and qualifications in this area, and I'm always keen to share what I know.


----------



## schooey

... and I think it's very gratefully recieved on the most part, LC. Like I said, I built mine almost 12 months ago to your previous diagram on the LM317 and it took 5 mins, cost me about $6 and worked a treat. It;s always very handy to know an electronics geek whizz.....


----------



## Screwtop

LethalCorpse said:


> Is there any other math you'd like to suggest I do, Screwy?




No, that basically proves that it is very nearly 3 fifths of fcuk all. I'm certain that you have impressed the whole of the AHF community with your absolute and infinite knowledge of electonics theory.

Your nearly as much fun as darren :lol:


----------



## goatherder

I used a 1k 0.5W pot in series circuit and ran into exactly the troubles LC mentioned - the control was very touchy and it died pretty quickly.

I simply substituted a higher rated pot (500 Ohm 3W wire-wound). It's been running for 2 years with regular use. The 500 Ohm pot gives a pretty good range of control over the magnet. The controller option seems the 'correct' way to solve the problem but there is no reason a properly sized series pot won't do the job.


----------



## LethalCorpse

Screwtop said:


> No, that basically proves that it is very nearly 3 fifths of fcuk all. I'm certain that you have impressed the whole of the AHF community with your absolute and infinite knowledge of electonics theory.
> 
> Your nearly as much fun as darren :lol:


It's neither absolute nor infinite, but within its bounds you'll find me more than willing to hold forth. Whoever the AHF community are, I'm sure they can appreciate that.

It's only beer at the end of the day. I think I've said a few times now, it's your brewery, you do what you like, you learn from your own mistakes. If I can perhaps prevent some of those mistakes by steering folks in the right direction, so much the better.


----------



## LethalCorpse

schooey said:


> ... and I think it's very gratefully recieved on the most part, LC. Like I said, I built mine almost 12 months ago to your previous diagram on the LM317 and it took 5 mins, cost me about $6 and worked a treat. It;s always very handy to know an electronics geek whizz.....


I'm happy enough with geek


----------



## PostModern

goatherder said:


> I used a 1k 0.5W pot in series circuit and ran into exactly the troubles LC mentioned - the control was very touchy and it died pretty quickly.
> 
> I simply substituted a higher rated pot (500 Ohm 3W wire-wound). It's been running for 2 years with regular use. The 500 Ohm pot gives a pretty good range of control over the magnet. The controller option seems the 'correct' way to solve the problem but there is no reason a properly sized series pot won't do the job.



What does a 3W pot cost compared to a LM317, a .5W pot and a couple of 5c resistors? When I built my 317 based controller, Jaycar, David Reid and so on had them, but for crazy amounts of money.


----------



## SJW

> What does a 3W pot cost compared to a LM317, a .5W pot and a couple of 5c resistors? When I built my 317 based controller, Jaycar, David Reid and so on had them, but for crazy amounts of money.



I just got the std type of Pot from Jaycar (technically speaking) for $2.25. I went to DSE and they had the ones Goathearder is talking about, the 500ohm 3w wirewound jobs for $8.95. But whatever I got, I know its a 500 ohm one, there is good control over the full range of speeds and it is not getting hot at all. 
I did thank LC, its just a fact of nature that some/most blokes in brewing get right into the nuts and bolts about some part of our craft and if something is your specialty than it would really piss u orf to see information going out there that is not 100% correct.

Steve


----------



## hockadays

Managed to finally get my stirplate going using the LM317 circuit and the caps for extra protection. Thanks Lethal for you help.


----------



## SJW

Looks great man


----------



## LethalCorpse

No probs, happy to be of service, sorry we couldn't diagnose your PWM version issues though.

You sure your spacers aren't too big?


----------



## MCT

Can I ask what sort of a vortex I am looking for? I've got my fan flat out and am getting a vertex that probably goes down 1/3 of the flask. Is that OK, or do you want it bottoming out?


----------



## the_fuzz

MCT said:


> Can I ask what sort of a vortex I am looking for? I've got my fan flat out and am getting a vertex that probably goes down 1/3 of the flask. Is that OK, or do you want it bottoming out?



What size flask?

I have a 1 litre version and get about 1/2 way down - still works a charm. Obviously the vortex gets smaller as the yeast population grows


----------



## MCT

Whats_Wrong_with_Hahn said:


> What size flask?
> 
> I have a 1 litre version and get about 1/2 way down - still works a charm. Obviously the vortex gets smaller as the yeast population grows




Hmm, that's gonna be my problem. I'm using a 1L flask with just water in atm as I'm testing it out.
Might have to get a more powerful fan.... or pump more than 12v into it.

Cheers for that mate.


----------



## schooey

MCT said:


> Can I ask what sort of a vortex I am looking for? I've got my fan flat out and am getting a vertex that probably goes down 1/3 of the flask. Is that OK, or do you want it bottoming out?



If that is just with water, you may be in trouble when you start growing the yeast. The liquid may become viscous enough for the fan to run out of grunt and stop (I have had this happen with a 60 mm stir bar in 3L starter). 

But AFAIK, as long as the yeast is being agitated, you don't need a big ass whirlpool.


----------



## Screwtop

schooey said:


> If that is just with water, you may be in trouble when you start growing the yeast. The liquid may become viscous enough for the fan to run out of grunt and stop (I have had this happen with a 60 mm stir bar in 3L starter).
> 
> But AFAIK, as long as the yeast is being agitated, you don't need a big ass whirlpool.




Might throw the stirbar into a whammy but i don't think you would stop the fan, maybe disengage the magnetic drive is about all. Besides, you only want the stirplate running to aerate the wort for good yeast growth, then turn it off, don't aerate the fermenting beer and risk oxidation if you want to pitch a nice clean starter. I turn the stirplate off as soon as there is a good krausen formed, fermentation keeps going and finishes out all by itself, thats when I refrigerate.


----------



## schooey

Screwtop said:


> ...maybe disengage the magnetic drive is about all.



Yep.. which is what happened, it was just sitting there with the stir bar centred, making an ear piercing whirrrrrr noise. I kinda thought that was the same as stopping the fan...


----------



## hockadays

I forgot the initial test photo with my new flask. Oh yeah. I'm going to grow up some german lager yeast just to check out the performance..


----------



## SJW

> I simply substituted a higher rated pot (500 Ohm 3W wire-wound). It's been running for 2 years with regular use. The 500 Ohm pot gives a pretty good range of control over the magnet. The controller option seems the 'correct' way to solve the problem but there is no reason a properly sized series pot won't do the job.



I know I should just shut up and say nothing, but you was right LC. The POT stopped today. So I went to DSE and got a 500 Ohm 3W wire-wound job. If GH reckon his is still going strong that good enough for me.

Steve


----------



## Fents

Cue Lethal - I Told you SO!

ahhh well steve was worth a shot, you didnt hurt or mame yourself so its all good.


----------



## LethalCorpse

I don't need to say I told you so, but it's always nice to be proven right. Good on you for telling us, Steve.

Even the 3W pot won't be happy at the higher end of speed, but it should last much longer than the 0.25W. If/when it fails, or you become unhappy with the non-linearity, we'll help you through the process of building a proper one.  I do hope it doesn't though - you've mucked about with this enough.


----------



## SJW

Dumb question time, as I am no Lectronic wiz are these Pots under more strain when turned down low or when running the fan flat out?

Would it help to change the power supply unit to a lower output type, say 9v or similar?



Steve


----------



## LethalCorpse

There's a peak point for the "strain" you're referring to (the power that the pot has to handle) close to the full speed of the fan. Check the graph that I posted a few pages back. There's a point at which it crosses over so that the power it has to handle is within the rating. The curved line is the power it has to dissipate, and the green slope is the power it can handle. The x axis is the resistance, with top speed being on the left. For a 3W pot, the crossover point is much further to the left than for a 0.25W pot, but there's still a range at the top end where you're pushing the pot too hard.


----------



## LethalCorpse

This is what it looks like for your situation, assuming your fan is rated to 200mA (my first chart was 300mA), again assuming the fan is a constant resistance, which it's not really. See how it's still over the rating until you get to about 100ohms? The maximum power is 0.6W, but at that point the pot can only handle 0.1W. Unfortunately, all your control is in the region where you're overpowering the pot - see how the current (blue curve) drops away up to about the 100ohm mark, then flattens out, meaning you get no real speed adjustments past that point.

All of that said, the 3W pot will be much more robust than the 0.25W, and will cope with the flogging much better. They generally underrate these things, so it's probably more like a 5W pot. Going down to 9V would improve matters, but would lose even more control.


----------



## tynian

I just wanted to say thanks to LC for the little circuit that he posted.

I just made it up this arvo and it works a charm. $5 worth of parts and 10 minutes work, could not be easier.

Rob.


----------



## SJW

So now I got it working do you leave it spinning for the entire time the starter is fermenting? and how fast should I have it going. With a bit of patience I can get 2 litres going so the vortex goes down to the stir bar, but thats obviously too fast, I guess it only needs to be just ticking over?
I went and got 2 25mm dia rare eather magnets as I was gaving trouble keeping the bar centred but these were no beter than the 4 (2 per side) 10mm dia rare eather ones. I did find that having the magnets on the outside of the washer (max away from each other) and going to a smaller 45mm stir bar works better. With large volumes of water its still a bit tricky to get it going without throwing the bar to the outside of the flask. Smaller flasks and water volumes work better.

Steve


----------



## Simon W

LethalCorpse said:


> ....
> see how the current (blue curve) drops away up to about the 100ohm mark, then flattens out, meaning you get no real speed adjustments past that point.



If a 50R Pot was connected up as a Pot (Potentiometer) instead of a Rheostat there would be linear control, problem is the power is even worse, so no win.

I'm really struggling to understand why people aren't using the LM317 circuit?

Cons:
none?

Pro's:
Linear control.
No power issues.
Not much more difficult to build.
Almost half the price of a 3W wirewound.

Also, it should be easy enough to modify with a couple of extra resistors to provide min and max speed range.
That is, if you find that you never use the higher speeds, or that the lower speeds don't have enough oomph(fan stops) then dial in so you have full control over the useable range. This would probably get the circuit to about the same price as a wirewound.


----------



## LethalCorpse

tynian said:


> I just wanted to say thanks to LC for the little circuit that he posted.
> 
> I just made it up this arvo and it works a charm. $5 worth of parts and 10 minutes work, could not be easier.
> 
> Rob.


My pleasure mate. Did you build the LM317 or the PWM driver?


----------



## LethalCorpse

Simon W said:


> If a 50R Pot was connected up as a Pot (Potentiometer) instead of a Rheostat there would be linear control, problem is the power is even worse, so no win.
> 
> I'm really struggling to understand why people aren't using the LM317 circuit?
> 
> Cons:
> none?
> 
> Pro's:
> Linear control.
> No power issues.
> Not much more difficult to build.
> Almost half the price of a 3W wirewound.
> 
> Also, it should be easy enough to modify with a couple of extra resistors to provide min and max speed range.
> That is, if you find that you never use the higher speeds, or that the lower speeds don't have enough oomph(fan stops) then dial in so you have full control over the useable range. This would probably get the circuit to about the same price as a wirewound.


It would cost $0.76 to do this, 0.38 if they're both the same resistor.

EDIT: actually, you only need to add one resistor, to set the min. The max is set by your choice of the fixed resistor and pot. It's a little more difficult to explain how to do this, so if anyone does want to, let me know.


----------



## therook

LethalCorpse said:


> My pleasure mate. Did you build the LM317 or the PWM driver?




I'm going to make the trip to Jaycar tomorrow and buy the parts for the LM317 cct, doesn't seem as complex as your other cct LC

Thanks for your efforts

Rook


----------



## tynian

LethalCorpse said:


> My pleasure mate. Did you build the LM317 or the PWM driver?




I built the LM317 with a switch for on/off.

This would have to be one of the simplest yet effective circuits i have come accross.

Rob.


----------



## Screwtop

SJW said:


> So now I got it working do you leave it spinning for the entire time the starter is fermenting? and how fast should I have it going. With a bit of patience I can get 2 litres going so the vortex goes down to the stir bar, but thats obviously too fast, I guess it only needs to be just ticking over?
> I went and got 2 25mm dia rare eather magnets as I was gaving trouble keeping the bar centred but these were no beter than the 4 (2 per side) 10mm dia rare eather ones. I did find that having the magnets on the outside of the washer (max away from each other) and going to a smaller 45mm stir bar works better. With large volumes of water its still a bit tricky to get it going without throwing the bar to the outside of the flask. Smaller flasks and water volumes work better.
> 
> Steve



Heres my finding, there'll be plenty of others. Used to leave on the stirplate continuously Steve, but had probs with infection like results in the beers, reason - oxidised wort. I use yeast nutrient in the wort and give a squirt of oxygen for 20 sec then start the stirplate, when the wort reaches a good krausen turn off the stirplate. I use a tiny 30mm bar which works well, natch, the outer circumference of one rotation is smaller, end of the bar travels less distance in one rotation so less resistance. If you use a small torch to look through the sides of your flask, it's much easier to see fermentation activity in the wort with yeasts that don't form much of a krausen.

Screwy


----------



## LethalCorpse

tynian said:


> I built the LM317 with a switch for on/off.
> 
> This would have to be one of the simplest yet effective circuits i have come accross.
> 
> Rob.


It sure is. Its only real downfall is the limitation on the minimum speed that the fan will go to when being driven by a constant voltage. If that speed is lower than the minimum speed you need for the stirplate, it wins hands down.


----------



## LethalCorpse

therook said:


> I'm going to make the trip to Jaycar tomorrow and buy the parts for the LM317 cct, doesn't seem as complex as your other cct LC
> 
> Thanks for your efforts
> 
> Rook


Don't forget I changed the resistor values a few posts later because Jaycar don't have 20kohm pots. use 680ohm and 5k pot.


----------



## SJW

> Heres my finding, there'll be plenty of others. Used to leave on the stirplate continuously Steve, but had probs with infection like results in the beers, reason - oxidised wort. I use yeast nutrient in the wort and give a squirt of oxygen for 20 sec then start the stirplate, when the wort reaches a good krausen turn off the stirplate. I use a tiny 30mm bar which works well, natch, the outer circumference of one rotation is smaller, end of the bar travels less distance in one rotation so less resistance. If you use a small torch to look through the sides of your flask, it's much easier to see fermentation activity in the wort with yeasts that don't form much of a krausen.
> 
> Screwy



Thanks mate. I think I started with 70mm stir bars and keep taking them back and getting smaller ones. I have a 45mm one now and it works good. I might take back the 55mm one and get a 30mm. I bet the 30mm bar looks small in a 2 litre flask? I think the trick is not to have the thing running flat out, just enough to keep it moving. It's a shame I have 4 full kegs at the moment otherwise I would love to give this a crack on some yeast. I am guessing it may perform a little different in yeast slurry rather than water too!

Steve


----------



## Screwtop

SJW said:


> Thanks mate. I think I started with 70mm stir bars and keep taking them back and getting smaller ones. I have a 45mm one now and it works good. I might take back the 55mm one and get a 30mm. I bet the 30mm bar looks small in a 2 litre flask? I think the trick is not to have the thing running flat out, just enough to keep it moving. It's a shame I have 4 full kegs at the moment otherwise I would love to give this a crack on some yeast. I am guessing it may perform a little different in yeast slurry rather than water too!
> 
> Steve




Why wait Steve, have a play, bet you want to. Make a big ass starter, chill, drop out, pour off the beer and store under sterile water till you need to pitch. If you stir until the yeast starts to drop out of suspension the bar has it's work cut out, whirlpool reduces in size until just about invisible. 

Screwy


----------



## LethalCorpse

updated diagram to make it a bit neater and include the new values.
Jaycar parts:
LM317T - ZV1615
5k linear pot - RP3508 or RP7508
knob to suit - pick one. Not the ones which say "spline" or suit 9mm pot
680ohm resistor - RR0568
switch - pick one. Any will do, so long as it's a latching type, not momentary. Pushbuttons, toggle switches, rockers, etc.
10u cap - RE6070
100n cap - RC5360


----------



## SJW

> Why wait Steve, have a play, bet you want to. Make a big ass starter, chill, drop out, pour off the beer and store under sterile water till you need to pitch. If you stir until the yeast starts to drop out of suspension the bar has it's work cut out, whirlpool reduces in size until just about invisible.
> 
> Screwy



Good point. I wondered if the unit would strugle to keep a load of yeast movin once it had fermented out. I guess by that time its done its job and reproduced to sufficient levels.


----------



## SJW

I now have a 25mm, 35mm and a 45mm Teflon stir bars. The 25mm one looks way too small for the 2 litre conical flask but it still gets a good vertex going. My point is that the smaller the stir bar the easier it is to control the speed and keep it in the centre of the flask. I think I will settle on the 35mm for the large flask and the smaller one for the 1 litre & 500ml flasks.

steve


----------



## goatherder

Can I ask where you got the teflon stir bars Steve?

I'm thinking of converting my rig from the oblique spheroid magnet pairs to a real stirbar unit. I've cracked a few flasks using the big magnets.


----------



## SJW

At Australian Scientific at Kotara. If you know where Red Funnel is, go down that street and turn left and they are down there, you cant miss em. 35mm teflon stir bar with the ring in the middle was $4 the 45mm one was about $6. Too easy. They have very cheap Schott Duran conical flasks too!

Steve


----------



## goatherder

Thanks mate - I've been meaning to go there soon to replace my broken flasks.


----------



## Screwtop

SJW said:


> I now have a 25mm, 35mm and a 45mm Teflon stir bars. The 25mm one looks way too small for the 2 litre conical flask but it still gets a good vertex going. My point is that the smaller the stir bar the easier it is to control the speed and keep it in the centre of the flask. I think I will settle on the 35mm for the large flask and the smaller one for the 1 litre & 500ml flasks.
> 
> steve



Them's the ones


----------



## WitWonder

Thanks to LC for the original circuit and others on this board I managed to build my own TASP. Parts from Jaycar - about $6, container from Bunnings about $5, pwr supply - free, rare earth magnets also free (one slightly broken from childrens demonstration...), flasks and stirbars from Perth Scientific around $40.


----------



## LethalCorpse

Just had a thought - it might pay to remove the fan blades to reduce the drag on the fan motor from pushing against a flat surface. You don't need the fan to produce any airflow, so there's no point making it try. Comments?


----------



## benno1973

Hi guys,

Thanks for the info on this - a good little project.

I've been putting this together and it's all working fine. However I'm now at the point of mounting the magnet on the fan.

I managed to salvage 2 magnets from an old hard drive I had lying around. Unfortunately the magnets each appear to be glued on to a piece of metal and I can't work out a way to get them off! I tried bending the piece of metal to see if the magnet would 'peel' off, but just managed to crack the magnet instead (so I'm now down to 1). I can't seem to get a knife between the magnet and the metal either to prize them apart.

Anyone got any advice on how to get the magnet off the metal?


----------



## LethalCorpse

Maybe acetone? You need to two magnets anyway, so perhaps you're better off just buying some cheapies off fleabay.


----------



## WitWonder

Boiling water?


----------



## benno1973

Yeh, both good ideas. Does boiling water do anything to magnets (i.e. demagnetise them or reduce their magnetic strength or something)?


----------



## PostModern

Kaiser Soze said:


> Anyone got any advice on how to get the magnet off the metal?



I play around with these in quiet times at work. We've pulled apart maybe 7-8 old drives now. Easiest method I found for the glued ones was to put a flat screw driver on the edge of the magnet with the frame on a desk/bench and give the end of the screwdriver a good bang with the heel of your hand.


----------



## benno1973

Actually, I just found this for separating the magnet from the metal. Wish I'd found that before breaking the other magnet! <_< Will try it tonight when I get home...


----------



## danman

for the more electrically savvy out there,i built myself a stirplate yesterday and used a LM317 and made the circuit below which i got from an electrical website,very similar to everyone elses but different resistors and pots. 

the question i have is that, with my limited understanding, the motor should be recieving 12V at all times and the current should be adjusted :huh: 

have i got this right or are we just adjusting voltage or have i fudged it up somehow.

with my multimeter across the motor i get awesome linear control of the motor speed (voltage) from 1.2V thru to 15.98V (output from laptop power supply) but i would like to have 12V always at the motor so the motor starts spinning easy.
at the moment with the magnets on (13mmx5mm) on an 80mm fan i have to crank up to 14V before the voltage can overcome the strength of the magnets,surely not good for longevity <_< 

any help welcomed,these things will turn out great i hope :lol: 

cheers,dan


----------



## LethalCorpse

Nope, with the LM317 circuit you're adjusting the voltage, not the current. They're inextricably linked - you can't change one without changing the other. But the 317 is a voltage regulator - it delivers a fixed voltage no matter how much current is drawn from it. It is unusual to have to turn it up so far to get it spinning. Once it's spinning, what's the minimum voltage you can turn it down to before it stalls? This, BTW, is the reason I've been advocating PWM-based controllers, because with a pulsed 12V supply the fan should be able to start no matter how low you've got it set, whereas with a fixed voltage reg you've got a minimum start voltage and a minimum hold voltage. 
Perhaps your magnets are too large or (more likely) not balanced on the fan. If you can, reposition them so the weight is evenly distributed. If the minimum you can tun it down to without stalling is low enough for your purposes, though, I wouldn't worry too much about it. Cranking it up to 14 for a few seconds won't hurt it appreciably, or you can always just start it by hand.


----------



## danman

thanks L.C.,i was sure that you couldnt change one without the other but thinking too much made me doubt my trade school teachings.

the magnets are very centered,a ive used plastigage extended out from the edge of the fan to see which magnet touches it first,and theyre so close i cant measure much variation between the mounting of the 2.

the lowest hold voltage is 4.8V before it stalls and the start voltage is around the 14V mark,but sometimes i can wind up to max without seeing no movement of the fan. 

i still am in the process of finding the sweet spot with mounting height too,all in good time.

if the magnets are further apart are they going to have more "pull" on the stir bar eg larger magnetic field or is closer better? maybe at 15mm they are too close...?

cheers,dan


----------



## danman

any ideas on wiring diagrams for PWM-based controllers?

im from the old school of "poor man pays twice" and "only build it once-to last" so i would rather play around now than have to rebuild it in 12mths because of a shortcut i took

cheers for your advice L.C.,dan


----------



## Doogiechap

danman said:


> thanks L.C.,i was sure that you couldnt change one without the other but thinking too much made me doubt my trade school teachings.
> 
> the magnets are very centered,a ive used plastigage extended out from the edge of the fan to see which magnet touches it first,and theyre so close i cant measure much variation between the mounting of the 2.
> 
> the lowest hold voltage is 4.8V before it stalls and the start voltage is around the 14V mark,but sometimes i can wind up to max without seeing no movement of the fan.
> 
> i still am in the process of finding the sweet spot with mounting height too,all in good time.
> 
> if the magnets are further apart are they going to have more "pull" on the stir bar eg larger magnetic field or is closer better? maybe at 15mm they are too close...?
> 
> cheers,dan



G'day Dan,
I know I had issues with my rare earth magnets enjoying the attraction to the screws holding my fan together so I replaced them with some stainless jobbies. It's much happier starting now. Just thought that may be a relevant solution for you 
Cheers
Doug


----------



## newguy

danman said:


> [snip]at the moment with the magnets on (13mmx5mm) on an 80mm fan i have to crank up to 14V before the voltage can overcome the strength of the magnets,surely not good for longevity <_<



Something that just occurred to me.....Do you have the fan attached to a plastic, wood or metal plate? Plastic and wood are okay, metal would be bad. The spinning magnets would induce currents in the metal.....kind of like an invisible brake. It would mean that the fan wouldn't want to start spinning. But on the plus side you'd have a heated stir plate.


----------



## Simon W

danman said:


> any ideas on wiring diagrams for PWM-based controllers?



Many years ago, before internet and cheap microcontrollers, I 'invented' a simple(well, simpler than other methods at the time) way to do PWM with a 555 timer IC, I was very pleased with myself..... untill I discovered later that the manufacturers datasheet for the 555 had a circuit for PWM . .. could have saved me some time! Since then I keep reminding myself that someone else has always done it before you.

Anyway, here is a simple cheap circuit to do what you want: 555 PWM
If not very readable(I didn't read it), a search with '555 PWM' on google will return many many pages on the subject.

Have just scanned the linked page, a couple of tips, make sure the 555 chip you buy(DSE, Jaycar, Altronics) is a CMOS part, it can then be used at voltages up to 18v.
Shoot for a higher frequency than the 144Hz in the design, maybe 2kHz(2000).


----------



## haish

LethalCorpse said:


> Just had a thought - it might pay to remove the fan blades to reduce the drag on the fan motor from pushing against a flat surface. You don't need the fan to produce any airflow, so there's no point making it try. Comments?



I'd be wary of cutting off the fan blades because I think they help balance the fan.



Kaiser Soze said:


> Hi guys,
> 
> Thanks for the info on this - a good little project.
> 
> I've been putting this together and it's all working fine. However I'm now at the point of mounting the magnet on the fan.
> 
> I managed to salvage 2 magnets from an old hard drive I had lying around. Unfortunately the magnets each appear to be glued on to a piece of metal and I can't work out a way to get them off! I tried bending the piece of metal to see if the magnet would 'peel' off, but just managed to crack the magnet instead (so I'm now down to 1). I can't seem to get a knife between the magnet and the metal either to prize them apart.
> 
> Anyone got any advice on how to get the magnet off the metal?



Screwdriver, hammer and a light tap work well for prising the magnets from their hard drive mount.


----------



## benno1973

PostModern said:


> Easiest method I found for the glued ones was to put a flat screw driver on the edge of the magnet with the frame on a desk/bench and give the end of the screwdriver a good bang with the heel of your hand.





Kaiser Soze said:


> Actually, I just found this for separating the magnet from the metal.



Thanks PostModern. I actually ended up bending the metal plate back (as per the link) which allowed me to get a screwdriver under the magnet, and after a gentle tap with the heel of my hand it popped off. Thanks for the help...


----------



## The King of Spain

Sorry to keep this one going....

But I'm going to anyway. After stuffing around I found that I got way better control with a 5k Linear pot. I tried 500 Ohm, 1 k OHM and finally 5. I can adjust the 5k Ohm using a magnet that gets thrown with all the others as the sensitivity is just not there. I am using a 12V DC 1.5A transformer on a 80mm 12V fan. I am waiting for a serious rare earth bar magnet from aussie magnets (Link that will allow me to turn bigger vols then its done.

Cheers KOS


----------



## LethalCorpse

That's good, but at some point, you might want to have a read through the rest of this thread at all of the theoretical and anecdotal evidence of pots burning out when used for this purpose. Good luck.


----------



## clean brewer

Found this nice basic one today..

here here..


----------



## Screwtop

LethalCorpse said:


> That's good, but at some point, you might want to have a read through the rest of this thread at all of the theoretical and anecdotal evidence of pots burning out when used for this purpose. Good luck.




But then again you could read about all of the slap dash ones still going strong after 3 years, never having to replace a dreaded sub $2 pot :lol:

Don't ya love forums designed as places for points of view to be aired.


----------



## white.grant

I've finaly assembled all of my parts for my stir plate. I've got a couple of rare earth magnets, a 12v puter cooling fan and a 12v variable speed transformer.





I was thinking that I would use a single magnet glued across the fan hub but have found that the magnet "sticks" to some metal in the fan hub and loads it up. Any ideas how to overcome this problem?

cheers

grant


----------



## Doogiechap

Grantw said:


> I've finaly assembled all of my parts for my stir plate. I've got a couple of rare earth magnets, a 12v puter cooling fan and a 12v variable speed transformer.
> 
> View attachment 24513
> 
> 
> I was thinking that I would use a single magnet glued across the fan hub but have found that the magnet "sticks" to some metal in the fan hub and loads it up. Any ideas how to overcome this problem?
> 
> cheers
> 
> grant



I had this problem too ! I found the main culprits in the fan to be the screws holding the winding assembly together. I carefully pulled the fan off the hub and replaced the screws with SS ones  There is still some attraction but not enough to pose any problems.
Cheers
Doug


----------



## SJW

> Sorry to keep this one going....
> 
> But I'm going to anyway. After stuffing around I found that I got way better control with a 5k Linear pot. I tried 500 Ohm, 1 k OHM and finally 5. I can adjust the 5k Ohm using a magnet that gets thrown with all the others as the sensitivity is just not there. I am using a 12V DC 1.5A transformer on a 80mm 12V fan. I am waiting for a serious rare earth bar magnet from aussie magnets (Link that will allow me to turn bigger vols then its done.
> 
> Cheers KOS



I don't doubt what LC is saying BUT, I used a 500 Ohm 3W wire-wound job and its works great. Loads of control and no more burn outs.

Steve


----------



## white.grant

Doogiechap said:


> I had this problem too ! I found the main culprits in the fan to be the screws holding the winding assembly together. I carefully pulled the fan off the hub and replaced the screws with SS ones  There is still some attraction but not enough to pose any problems.
> Cheers
> Doug




Thanks Doug,

I just pulled it apart to check and found that there is a circular magnet around the fan hub and a steel spindle. My magnets stick to it like a bad smell. Think I might be scrounging a new fan.


cheers

grant


----------



## samhighley

Grantw said:


> I was thinking that I would use a single magnet glued across the fan hub



That oddly shaped magnet looks to me like it'll make the whole system horribly unbalanced. 

I would think this would fry the fan pretty quickly with that oddly balanced load.


----------



## Wolfy

Sammy said:


> That oddly shaped magnet looks to me like it'll make the whole system horribly unbalanced.
> 
> I would think this would fry the fan pretty quickly with that oddly balanced load.


I think you'll find its a magnet from a computer hard drive, and there are examples all over the 'net of people using these. If centered as well as possible, I'm not sure it would cause any more problems than 2 single magnets.


----------



## Sammus

FWIW, I had a computer fan and pot that was crap, it had no control between full and off, and barely enough torque to stir in a 2L flask, I went and got a 240V fan and ceiling fan switch (stole the idea from someone here.. maybe tony or something) and it's about a billion times better, plus I don't need to lug around my power supply with the stir plate.


----------



## LethalCorpse

Those HDD magnets would probably work better if you used two of them, and put them out over the fins by gluing them to a paddle pop stick or similar glued to the hub. Removes the loading issue, and removing the fins would lighten it further still.


----------



## white.grant

LethalCorpse said:


> Those HDD magnets would probably work better if you used two of them, and put them out over the fins by gluing them to a paddle pop stick or similar glued to the hub. Removes the loading issue, and removing the fins would lighten it further still.



Thanks LC, I'll give that a go.

cheers

grant


----------



## white.grant

It Lives.





This photo doesn't do it justice but it makes a pretty impressive vortex with the kitchen measuring jug full and half a nail for stir bar. The noise of the thing is fantastic.

I attempted the two magnet and a paddle pop stick approach, but found the wider magnet placement would attract the stir bar to one side and just drag it around instead of making it spin. In the end I went with a modified plan A and glued one magnet to a piece of thin mdf and then glued both to the hub. This has reduced the attraction enough for it to spin happily.

Now just got to get my flask and proper stir bar and I'm away.

thanks for the help guys

cheers

grant


----------



## TidalPete

Sammus said:


> I went and got a 240V fan and ceiling fan switch



+1

TP


----------



## Tony

YEah that was me 

I even broke all the fan blades off.

IT has to run at the lowest speed as the stir bar flips out. 

After reading this i may get a shorter one. mine is about 50mm long

cheers


----------



## jimmy01

Hope someone can help

I am building a stirplate using the circuit recommended by LethalCorpse. Jaycar were out of 3 pin LM317. They only had 2 pin units with the body of the unit being the output terminal. However I cant work out which pin is th input and which is the adjust. The brand is STMicroelectronics. Looked on their website but the drawing is not real clear.


Anyone know?

Cheers
Jimmy


----------



## LethalCorpse

Odd, they should always have heaps of those in stock. Is it the small, surface mount type, or the hulking great round job? Either way, here is the datasheet with the pinouts. Note that the pinout diagrams are a top-view, which means it's flipped if you're looking at the bottom.


----------



## jimmy01

LethalCorpse said:


> Odd, they should always have heaps of those in stock. Is it the small, surface mount type, or the hulking great round job? Either way, here is the datasheet with the pinouts. Note that the pinout diagrams are a top-view, which means it's flipped if you're looking at the bottom.




Hi LC

Its the great hulking round job. I saw that diagram but was not sure which way the top on this regulator. If you hold the regulator the same way as it is in the diagram then the writing on the device is running from the bottom of the device to the top not left to right. 

Thanks
Jimmy


----------



## LethalCorpse

The side that the pins come out of is the bottom, the side with the writing is the top


----------



## jimmy01

LethalCorpse said:


> The side that the pins come out of is the bottom, the side with the writing is the top



Yes I understand that. What I am unsure of is which pin is the input. When looking at the underside of the reg there is no discernible top or bottom pin. It depends which way you hold it and there is no reference point on the device

I might have to go to DSE and get a 3pin LM317


----------



## LethalCorpse

Have another look at the underside. Note the the two pins are closer to one end than the other. If you hold it so that you're looking at the bottom of the reg, with the two pins towards the right, the top pin is adjust, the bottom pin is input.


----------



## jimmy01

LethalCorpse said:


> Have another look at the underside. Note the the two pins are closer to one end than the other. If you hold it so that you're looking at the bottom of the reg, with the two pins towards the right, the top pin is adjust, the bottom pin is input.




Thanks LC

Will give it a try

Cheers
Jimmy


----------



## atkinsonr

jimmy01 said:


> Yes I understand that. What I am unsure of is which pin is the input. When looking at the underside of the reg there is no discernible top or bottom pin. It depends which way you hold it and there is no reference point on the device
> 
> I might have to go to DSE and get a 3pin LM317



If you're looking for pin outs on any component, you can google the product name and look for a datasheet, they're usually in PDF format and from the manufacturer.

eg: http://www.national.com/ds/LM/LM117.pdf

I'm not sure exactly which one you have, but if you look on page 2 of the above link, there are a few pin outs. Otherwise - google the exact product code written on the side of the component.

Hope this helps

Richy


----------



## litre_o_cola

After having a quick read of the first couple of pages I threw one together from the spare puter parts in the shed.
All works well although I don't have a proper stir bar yet but as I found out the young fella's magnetix have rare earth magnets in them and does the job quite well for the time being.


----------



## Uncle Fester

litre_o_cola said:


> After having a quick read of the first couple of pages I threw one together from the spare puter parts in the shed.
> All works well although I don't have a proper stir bar yet but as I found out the young fella's magnetix have rare earth magnets in them and does the job quite well for the time being.



I used an old 12v PC case fan and glued 2 rare earth magnets from jaycar onto it.

I use a variable power supply from Tricky Dicky. I find 9v gives a really nice vortex.


Cost nuffin. To buy new, about $20.

Festa.

{Edit} I use a commercial stir bar - cost me $12 {/Edit}


----------



## Damian44

What would be a good size stir bar for a 5 liter flask? Could you pick one from link, as i have an account with them? TYVM

http://www.livingstone.com.au/search_resul...search=stir+bar

Ive got a multi voltage adaptor and a PC fan, so im off to Jaycar for a jiffy box, some magnets and something to connect my fan to the power adapter.


----------



## Wolfy

Damian44 said:


> What would be a good size stir bar for a 5 liter flask? Could you pick one from link, as i have an account with them? TYVM


I believe that the size of the stirbar is more related to the spacing of your magnets than anything else - you want a stirbar that is slightly smaller than the spacing of your magnets for it to work best.


----------



## haysie

LethalCorpse said:


> updated diagram to make it a bit neater and include the new values.
> Jaycar parts:
> LM317T - ZV1615
> 5k linear pot - RP3508 or RP7508
> knob to suit - pick one. Not the ones which say "spline" or suit 9mm pot
> 680ohm resistor - RR0568
> switch - pick one. Any will do, so long as it's a latching type, not momentary. Pushbuttons, toggle switches, rockers, etc.
> 10u cap - RE6070
> 100n cap - RC5360




Heading too Jaycar over the weekend for the parts, any suggestions re what size magnets I should purchase whilst there? 120mm fan, 2ltr flask


----------



## litre_o_cola

The magnets at Jaycar I bought were in a belt arrangement (for hanging light tools up) about 12mm x 3mm you get about 8 of them for $14


----------



## haysie

Thx litre o cola,
they only had 2 sizes small 8-10mm then about 15mm, $10.95 for 4 small  

I am having trouble with magnet placement, they come flying off, using double sided tape, wrapping them in electrical tape around the blade, nothing is making them stick, i didnt want to use super glue cos i figure i might need to move them, and another question does it matter which way fan is facing up or down?
Thx



i am placing 1 of each nth and sth


----------



## smudge

haysie,

If you are using the rare earth magnets and not the long bar magnets, secure them to the hub not the blades. Mine are only
sticky taped on and haven't moved.

Cheers,
smudge


----------



## Wolfy

haysie said:


> I am having trouble with magnet placement, they come flying off, using double sided tape, wrapping them in electrical tape around the blade, nothing is making them stick, i didnt want to use super glue cos i figure i might need to move them, and another question does it matter which way fan is facing up or down?


You should be able to stick them to the outer edge of the hub without too many problems.
Then you can face your fan up or down depending on how you can best stick your magnets to the hub, in general you'll only be able to stick your magnets on one side.

_PS: Had you said you were going to make one today, I could have given you one of the HDD's I have here to pull apart for the magnets, there are 2 in each drive._


----------



## Franko

Get yourself a decent sized washer and glue it to the fan and then place your magnets to the washer-works a treat

Franko


----------



## litre_o_cola

Franko said:


> Get yourself a decent sized washer and glue it to the fan and then place your magnets to the washer-works a treat
> 
> Franko



+1 exactly like franko has said, I glued a decent sized ( bout 1 1/4" ) washer to the hub and then placed the magnets on 1 N and 1 S, then mount it hub side to the board using small washers as packers giving about 2mm clearance. Using one of the young fellas magnetics I can get a whirlpool going that is about 4" deep and only gets unstable at max revs.


----------



## haysie

Thx Folks,
I sorted it with the big washer on the hub (50mm) and the rare earth magnets just on the outside of this, 30 mm stir bar ex G&G, i get a nice vortex initially going a little hard then crank it right back. I spun a new 1084 the other night dusk til dawn on 1.5 ltrs and in the morning had a lovely krausen, switched off. Later in the day there wasnt a lot of activity so cranked it up again for a further 2 hours. This morning I had a half inch bowl of yeast, no different to my previous method of shake rattle and roll (always temp controlled). I have seen the charts re. yeast counts, stirrer vrs shaken vrs oxy but i am not convinced the stirrer provides more good yeast vrs dead yeast therefore attentuation issues as per an earlier post/experiment by sosman in this thread.
I turned it off after reaching krausen thinking oxidation, but not thinking too good because i will be pouring off all liquid and resuspending with some cooled, boiled anyhow.My thoughts eliminating oxi factor?
Is there a specific method I have missed re, "more yeast per ltr of wort".
Maybe just another piece of kit , but gotta try new tricks........ or just too bloody goddamn ignorant to stick with what i know. 
Thx again. Haysie

edit, i am running this off an old exchange battery 12volt in my shed, i stick it on one of those 12v dick smith jobbies...... nothing??
it was made per LC`s latest


----------



## razz

I'm just spinning my latest yeast for the first time in a couple of years Haysie. I never looked at it from a larger amount of yeast point of view, I've always done it (stirrer) to get there quicker.


----------



## haysie

razz said:


> I've always done it to get there quicker.



 The joys of cut n paste.Done what?  
I hear you Razz but you can get there nearly as quick with a bit less and stepped up again and again yada yada. Only a newbie this stir thingy, take me with a grain of malt.

edit, dead yeast cells, i do think the stirrer creates more only on my thoughts alone, not backing it up with any tried n true tested methods, but i will be able too tell via attentuation and taste of my beers vrs current method i use


----------



## razz

I think I was sold when I read the the online doc by MB Raines Phd


----------



## captaincleanoff

is it really necessary to have the switch and pot when constructing a stir plate?

Could I just wire the fan directly to a 12V power supply, and not worry about the switch and pot?


----------



## schooey

No speed control, dude... Never a good thing


----------



## Fourstar

Im 1/2 way thru setting up mine, i coundt find the pot at dick smith so i will have to goto jaycar. ive got mine connected to a 7.5V 450mA VDC PSU. Spins up quite well and gets a hex drill bit spinning ontop of the case beautifully. 

I'm using a HDD magnet which is quite thin, apoorx 1mm. so ive stuck both of them together. is it best to stack the HDD ones or offset them like the standard rare earths? The magnets from a hdd seem strange when trying to offset them as 1 face does not seem to be a poloar side but center to edge is north and center to edge is south. flip it over and the same applies. Maybe i should just rip apart another old HDD and hope for a fatter magnet.


----------



## samhighley

captaincleanoff said:


> is it really necessary to have the switch and pot when constructing a stir plate?
> Could I just wire the fan directly to a 12V power supply, and not worry about the switch and pot?



This will never work. I very rarely run my fan at full speed, as the magnet just won't work at full speed.

Also, I usually need to start slow and ramp up the speed gradually, otherwise the fan spins too fast for the magnet, and they disengage each other.

Short answer: no, it will not work without speed control.


----------



## litre_o_cola

Fourstar said:


> Im 1/2 way thru setting up mine, i coundt find the pot at dick smith so i will have to goto jaycar. ive got mine connected to a 7.5V 450mA VDC PSU. Spins up quite well and gets a hex drill bit spinning ontop of the case beautifully.
> 
> I'm using a HDD magnet which is quite thin, apoorx 1mm. so ive stuck both of them together. is it best to stack the HDD ones or offset them like the standard rare earths? The magnets from a hdd seem strange when trying to offset them as 1 face does not seem to be a poloar side but center to edge is north and center to edge is south. flip it over and the same applies. Maybe i should just rip apart another old HDD and hope for a fatter magnet.



I found that it is important to have that "polar" advantage otherwise the stir bar can stand on one end and be less efficient, that is why I opted for two rare earth magnets with the opposed polarity and it made a massive difference in bar stability. The only time it goes nuts now is at full power and the cavitation from the whirlpool engages the bar.


----------



## Fourstar

Interesting to know. I been planning on getting some rare earth magnets from dealextreme.com maybe this is the excuse to get them... and a LED torch, some hop scales and a LED piggy keychain!


----------



## litre_o_cola

Fourstar said:


> Interesting to know. I been planning on getting some rare earth magnets from dealextreme.com maybe this is the excuse to get them... and a LED torch, some hop scales and a LED piggy keychain!


In the interest of saving on postage of course


----------



## captaincleanoff

is there a cheap alternative to the erlenmyer flasks? I'm going to need a size of about 5L, and a flat bottom for use with the stir plate. Can't think where else I could get a suitable glass container.. any ideas?

Got mine working today! Haven't got a stir bar yet, but it was stirring 2L fine just with a small nail. Very noisy though. Hopefully a proper stir bar will be quieter


----------



## Fourstar

captaincleanoff said:


> is there a cheap alternative to the erlenmyer flasks? I'm going to need a size of about 5L, and a flat bottom for use with the stir plate. Can't think where else I could get a suitable glass container.. any ideas?
> 
> Got mine working today! Haven't got a stir bar yet, but it was stirring 2L fine just with a small nail. Very noisy though. Hopefully a proper stir bar will be quieter



Why do you need a 5L? why dont you just do step ups in a 2L erlenmyer flask to say 1L, crashchill, decant and transfer to 1L of wort in antoher 2L flask?

I get away with doing stepups from a slant via 2 1L erlenmyer flasks. i would prefer a 1L and a 2L just ot make it easier though but 3-4days of growing the yeast i can have enough to pitch into a standard batch, another 2 days and i can attack a high gravity wort!


----------



## captaincleanoff

Fourstar said:


> Why do you need a 5L? why dont you just do step ups in a 2L erlenmyer flask to say 1L, crashchill, decant and transfer to 1L of wort in antoher 2L flask?



because I am doing starters for 65L batches, so I'm going to need to build it up to a bit


----------



## ~MikE

captaincleanoff said:


> because I am doing starters for 65L batches, so I'm going to need to build it up to a bit


i'm currently working on something, based on a 5.5L cookey jar i got at 'the general trader' - not a very flat bottom though- otherwise i was considering a 5L borosilicate beaker from pro-sci-tech - $50 delivered. i figure some silicone bakeware to seal a bastardised chopping board that will make for a lid and clamping ring...


----------



## captaincleanoff

cookie jar would be ok.. except it would need a flat bottom..

anyone else got any ideas what I could use for a 5L starter vessel, before I spend $100 on a erlenmyer 5l flask?


----------



## Juddy

Hello fellow brewers!

I have read with great interest both this thread and most others that are related to all things stirplate. Firstly I would freely admit that I am in no way electronically or electrically minded and can only talk of my own expirience. About two years ago I was convinced that a stirplate was the next gadget that was "essential" in my ever growing home brewery. I researched, and then I shopped! I ended up with a 12v computer fan $25, and a 12v 1 amp plug pack $25 from Jaycar, and some magnets from an old hard drive! Then, as recomended by the friendly if somewhat disinterested people at Jaycar I assempled the main components as shown below:~
The fan attached to a box made of scrap wood from the workshop. Fan attached to plug pack via twisted wire and some heat shrink!



The power pack looks like this.


And when I want the fan to go slow I set the voltage low! And then use the convinient slide switch to up the voltage and hence up the fan speed!
When combined I am able to adjust the speed of the stir bar from next to nothing, too she's gonna blow speed!



Now I have the horrible feeling that I am going to be told that I have done a dreadful thing and I am lucky to have survived tha last 2 years and countless brews! But my set up is this simple, and it works a treat! 

And the stirplate, and more importantly me are still in great shape! 

So if you have decided that a stirplate is the next "essential" item in your brewery, I believe that $50, some old timber and a scrap hard drive will see you right! It may not be as tight as some stirplates, but it is still one of the cheapest brewing gadgets that I've bought and the results are spectacular! :icon_cheers: 

Cheers

Juddy


----------



## raven19

Juddy, another great effort on stir plates.

Gotta get me one... one day.

Well done. Beers!!


----------



## Bizier

I have half built one of these.






I used an standard intel p4 fan and snapped off all of the blades and filed them back. I glued a mini CD onto the mobile part, and it is uncanny, there is about 1mm between it and the circular outer structure.

I currently have 2 magnets on there, and I want to know if anyone can say whether I am better with 4. And if so, do I place these diagonally opposite at the same diameter rather than "outside" the exising diameter?


----------



## litre_o_cola

Bizier, in that diagram does the red and white denote polarity?
If so that would disrupt the stir bar stability, as to the other question having them outside of the existing would enable you to use a longer bar.


----------



## Bizier

litre_o_cola said:


> Bizier, in that diagram does the red and white denote polarity?
> If so that would disrupt the stir bar stability, as to the other question having them outside of the existing would enable you to use a longer bar.



No, diagram is assuming grouped magnets are of same polarity. Sorry, I meant to put it there but I did it very quickly.


----------



## captaincleanoff

can anyone tell me if the stir bars without the pivot in the middle are quieter?

I got a stir bar with a pivot in the middle, but it is really noisy when using the stir plate. I borrowed professional stir plate from work, so its not because I have a dodge plate design.

i think I read somewhere in this thread that the stir bars without the pivot are quieter.. Can anyone confirm before I go out and buy one?


----------



## porky

captaincleanoff said:


> can anyone tell me if the stir bars without the pivot in the middle are quieter?
> 
> I got a stir bar with a pivot in the middle, but it is really noisy when using the stir plate. I borrowed professional stir plate from work, so its not because I have a dodge plate design.
> 
> i think I read somewhere in this thread that the stir bars without the pivot are quieter.. Can anyone confirm before I go out and buy one?



Yes they are, as it has been pointed out many times before.
A flat bottomed flask is the most important part for a quite operation, along with a stir bar without the middle pivot.


----------



## captaincleanoff

budwiser said:


> Yes they are, as it has been pointed out many times before.



thanks for the smartass response.. I didnt particularly want to look through 26 pages.

edit: shitty label by the way


----------



## wakkatoo

captaincleanoff said:


> thanks for the smartass response.



I agree, was a pretty simple question really. I've read all 26 pages at various times and no doubt it is in there somewhere but I've managed to miss it. Now I've learnt something new as well, so thanks for asking (despite the tone of the answer).


----------



## Batz

I buy a few things from this Kiwi site,this looks like it would make building a stir plate a snap if you don't already have one

http://www.trademe.co.nz/a.aspx?id=212232576

I haven't seen them in Australia.

Batz


----------



## pdilley

Batz said:


> I buy a few things from this Kiwi site,this looks like it would make building a stir plate a snap if you don't already have one
> 
> http://www.trademe.co.nz/a.aspx?id=212232576
> 
> I haven't seen them in Australia.
> 
> Batz



Sorry Batz, wrong Triac design in that. Its a light dimmer not a Fan Controller. I already checked it out 

I ended up with a proper Fan Controller AC Triac circuit from the local Bunnings for my AC fan stir plate design.


----------



## Batz

Brewer Pete said:


> I ended up with a proper Fan Controller AC Triac circuit from the local Bunnings for my AC fan stir plate design.




That's what I have had for years as well,just found this thing and it sounded good by the dudes rave. (Will control most small AC motors like engravers and fans, exhaust fans etc, up to 300Watts)

Batz


----------



## Sammus

I disagree, I went on the advice to get ones without pivot rings and they just rattle and roll around on the glass. If you tune the speed right and use the right size bar, the pivot ring is the only thing that touches and its dead silent except for the swooshing of the liquid. I couldn't get this to happen without a pivot ring.


----------



## pdilley

Batz said:


> That's what I have had for years as well,just found this thing and it sounded good by the dudes rave. (Will control most small AC motors like engravers and fans, exhaust fans etc, up to 300Watts)
> 
> Batz



It will work, but not as well as a Fan Controlling Triac circuit and some stress out fan motors more than a Shaded Pole Fan Controller Triac circuit would.... That said I ran my original AC fan glove box design on a light dimmer for a while, though it did get pretty toasty 

*Light Dimmer* (Solid state phase angle firing of a triac) usually will not come with a minimum level adjustment control (this is important for fan motors). Solid state controls are real sensitive to line voltage and differences in load variations. If the voltage jumps around because of the air conditioner kicking on, etc. or flipping on or off a lamp on the same branch circuit that you are running your FAN controlled by a Light Dimmer triac controller, it may cause the dimmer to kick off, or worse, half cycle which sends half wave rectified DC to your AC motor....Not Good...Toast. (Ever notice how they say on the package "for incandescent use only"?) (Light bulbs don't care what you feed them they just average the power).

When you start a dimmer on high, then reduce the speed, you can go to a lower setting, than if you started the dimmer at the lowest setting and increased it slowly, it would start running abruptly at a higher speed. It's kind of like the flywheel effect in that the motor windings kick some voltage back to the dimmer that helps to keep "triggering" it. (If that makes any sense.) If the motor is not running initially, it takes more to trigger it. This is probably why you will notice, like I did when I used light dimmers you have to gun the buggary out of the control to kick start the AC Fan going before you can back it off. Its not a linear control either, so your adjustment ability is hampered if that ever is a concern (wasn't at the time when I first needed a control capability for my first AC fan project.)

The price for a Light Dimmer circuit is usually 1/2 of the price of a Fan Controller circuit when it comes to retail checkout time.


*Fan Controller* (Solid state phase angle firing of a triac with additional needed components for inductive load (motor) operation) I've seen them with a rotary switch or a slider control. They always turn on at high speed and then adjust to slow. Good ones have a minimum speed adjustment. (If they don't have a min. speed adjustment they don't go very slow.) (Get one with a user settable minimum speed adjustment) No solid state dimmer operates real well at real low speeds. These controls are quite efficient for AC Fan Motor operation.

The price for a Fan Controller circuit is usually double the price of a Light Dimmer circuit when it comes to retail checkout time.

Other options are: *Rheostats* which are the least efficient control. *Variac, Powerstat* which are very efficient its just that they cost the most and are huge and heavy and bulky.

Variac -> Fan Controller -> *Capacitive De-Hummer* (worst for variable speed, you usually get only 3).

Thats all that is best for Shaded Pole AC Motor control. Out for potential damage, and inefficiency would be Rheostat -> Light Dimmer.


----------



## Uncle Fester

captaincleanoff said:


> is it really necessary to have the switch and pot when constructing a stir plate?
> 
> Could I just wire the fan directly to a 12V power supply, and not worry about the switch and pot?




I used a variable power supply. 6v gives slow revs, 7.5 / 9 / 12V gives increasing vortex.

The switchable power supply I got from Tricky Dicky many years ago. Probably still available.

Festa Out.


----------



## gava

I used http://www.users.on.net/~pfitzsimons/MagSt...eticStirrer.htm as a guide.

differnce I did was holding the fan to the box and the magnets on the fan but all in all was pretty simple..

I used the following earth magnets (small) , and used what they came in to mount my fan on using strong glue..


----------



## Kleiny

I finally made a stir plate

Thanks to Lethacorpse for the diagram






Found a nice box





Printed the circuit board and soldered as per the diagram





just need to get the magnets and a flask and a little bar

All up $60

:icon_cheers: 
Kleiny


----------



## Bizier

I am using my stirplate for the first time right now just rehydrating some US05 into a weak wort.

Man, I have to get a smooth stir bar... it sounds like I have that mouse from the Jarlsberg packet jackhammering a xylophone.


----------



## KHB

I put one of these together the other day i put a pot in and it controlled the fan speed fine but has now gone to either being on or off. I think i killed the pot but not sure how. Any ideas??

Cheers Scotsman06


----------



## gava

Has anyone made a heat function on one of theses?


----------



## Josh

I had spent ages trying to get mine to work. After some poor advice at Jaycar and buying a kit I couldn't use, I wound up just with a simple pot and 12V fan. The pot doesn't really work as the fan will only spin when it's just about turned right up.

But that doesn't appear to be a problem. turned right up, I have about 1.5L stirring silently. Has been since last night. I bought the magnetic stirrer bars from Livingstone. I got 50mm and 60mm. The 50mm is stirring my starter at the moment.

Haven't tried my stir plate with the 3L Erlenmeyer flask yet. I'm hoping the magnets are strong enough to keep a hold through that glass. Currently I'm using a round lolly jar which is a bit thinner.

I also had trouble originally with the small rare earth magnets. In the end I used the medium size ones in the picture just above. 25mmx5mm.

I originally bought a box from Jaycar but it wound up being too small. Now I am using an old drinks tray like you see in clubs and pubs. The power connection is attached through the wall as is the pot switch.

I'll work on some pics and maybe video today.


----------



## KHB

Josh said:


> I had spent ages trying to get mine to work. After some poor advice at Jaycar and buying a kit I couldn't use, I wound up just with a simple pot and 12V fan. The pot doesn't really work as the fan will only spin when it's just about turned right up.
> 
> But that doesn't appear to be a problem. turned right up, I have about 1.5L stirring silently. Has been since last night. I bought the magnetic stirrer bars from Livingstone. I got 50mm and 60mm. The 50mm is stirring my starter at the moment.
> 
> Haven't tried my stir plate with the 3L Erlenmeyer flask yet. I'm hoping the magnets are strong enough to keep a hold through that glass. Currently I'm using a round lolly jar which is a bit thinner.
> 
> I also had trouble originally with the small rare earth magnets. In the end I used the medium size ones in the picture just above. 25mmx5mm.
> 
> I originally bought a box from Jaycar but it wound up being too small. Now I am using an old drinks tray like you see in clubs and pubs. The power connection is attached through the wall as is the pot switch.
> 
> I'll work on some pics and maybe video today.




I start mine on 500ml so it will prob spin to fast will test today


----------



## KHB

Just hard wired a 4.6V output charger to the fan and it spins well at 500ml upto 3lt. Works well for me, easy fixed!!


----------



## haysie

gava said:


> Has anyone made a heat function on one of theses?



Sometimes in the fermenting fridge, due too cold cold in mellyburn atm, its now come inside too live with the 20deg climate control.



Where there`s a will


----------



## rich_lamb

gava said:


> Has anyone made a heat function on one of theses?



I stick the whole thing in an esky with a heatpad connected to a timer switch - not accurate heat control but works fine for starters.

As my flask sticks out the top of the esky, I loosely cover it all with gladwrap to keep the heat in. Looks as ugly as crap, but works OK for the couple of days it's needed.


----------



## Sammus

gava said:


> Has anyone made a heat function on one of theses?



Not intentionally, but with mine turned all the way up if I'm stirring a lot (more than 2L) it warms up significantly. I can turn it down very slightly or put some thin insulating board between the stirrer and flask and it doesnt get much heat. Straight on the stirrer cranked right up and it seems to sit at a comfy 25-30C. I think ill add an exhause fan to my stirrer enclosure, shouldn't have to worry about overheating anything then.


----------



## pdilley

Would passive venting, drilled holes around top of enclosure work for you?

Im thinking of what to do with mine as Ive got a circular cutout on top to get the magnets up close to the jar as possible but plan to put a small plastic tub over and then the jar with stirbar to contain any spill overs so Ill be back to having to think about venting heat again.

I have not thought about heat as thats what Id worry about for mycelium but not yeast. Im thinking a small temperature controlled cabinet that the stir bar unit as a whole would fit inside while running. Or metal top and looking around pet shops for some electic heating item to mod into use for heating. eBay has temp probe / controllers for about $60 Aus and up that could be adapted but means probe in wort unless probe against glass and adjust for small temp
differential.

Cheers,
Brewer Pete


----------



## Batz

Brewer Pete said:


> Would passive venting, drilled holes around top of enclosure work for you?
> 
> 
> Cheers,
> Brewer Pete




I did this soon after using mine, the heat build up was a bit concerning. It still gets warm with the vents,fans where not meant to be locked in boxes.It also necessary to drill a couple of holes in the bottom so the air can flow through the box of course.
It's something of a plus as the weather cools.

Batz


----------



## Sammus

Yeah I've got holes, they helped, but not enough  The heat isn't really bad thing for propogation anyway I think.


----------



## pdilley

It would look quite the sight, but holes drilled and stuffed with drinking straws would vent the heat out far away from the immediate area around the stir plate unit and the jar


----------



## LethalCorpse

Now it's getting stupid. You've got an operable fan there. How had can it really be to use it to produce some airflow which passes over the heatsink on your regulator (or pot or whatever other thing you've got dropping your supply voltage)


----------



## newguy

gava said:


> Has anyone made a heat function on one of theses?



You could do a poor man's heater. All you need is some metal - standard kitchen grade tin/aluminum foil would do. Place a layer of tin foil directly under your starter flask. This method is based on electrical generators/motors whereby a changing magnetic field induces a voltage in a conductor, which in turn creates current in the conductor, which creates heat. You may have to experiment with the size of the foil sheet, or perhaps the shape - I'm thinking long narrow rectangle instead of a circle or square may be better. One thing you have to be aware of is that the foil will load the fan. Worst case is that it may not be able to start, go with a smaller size or different geometry if this is the case. Another issue is that you'll have to do some trial and error to find a right size/geometry to give you the heating result you want.


----------



## pdilley

Got a weekend night to myself away from SWMBO so started noodling around in the shed and by late evening got stuck into pulling the drill press out of storage and reassembling it.

Prototype 240Volt AC Stirplate.

Cooling holes on all sides, large venting holes below.

I have ditched the top for now as will use either clear acrylic top or simple idea of using a rubbermaid or tupperware style container, square in place of the lid. The Flask sits in the tupperware container which is a spill containment receptacle in case of excessive foaming.

I have to go look at plastic containers and see how much if at all they depress under different weights to build the magnetic disc height to get the magnets right up against the plastic container while not touching. This should get the magnets up close as possible to the flask while keeping them as far away from the fan as possible.

Full 240 Volt Shaded Pole Fan controlling Triac with 240Volt switch and noise suppression circuitry.

I have a conduit box I will cut down to make a sealed environment in which to do all the wiring. Thinking about a silicone seal around the Triac compression fittings.

As you can see this is a monster fan with enough guts to pull through some large batches. Not a bad eBay buy at $14 compared to Jar Car.


----------



## MCT

It may have been covered earlier but 27 is a lot of pages  
How fast does the whirlpool have to be? I've just built my stir plate and have a 2 litre starter on it but I can't get much of a vortex/cyclone going without the bar shooting off, but it is still mixing everything around well. Is this all I really need to achieve? Am I just sposed to keep everything moving to stop the boor buggers from having a rest, or is the idea to keep introducing oxygen into the wort to keep them breeding?


----------



## Sammus

LethalCorpse said:


> Now it's getting stupid. You've got an operable fan there. How had can it really be to use it to produce some airflow which passes over the heatsink on your regulator (or pot or whatever other thing you've got dropping your supply voltage)



I'm not sure it's the reg getting hot - I can't see how to heatsink it anyway, its about 1cm^2 and enlosed in the plastic behind the switch (it is a ceiling fan controller, all 240V here). I don't know/cant be bothered looking at what I might've claimed earlier, but I've recently realised it is only when its turned up that it heats up, and the heat is quite obviously coming from the fan itself - you can tell it is definitely straining under the load, lift the flask off and it nearly doubles in speed.

Have it a hair off full throttle and it doesnt heat up at all. Using a slightly smaller stir bar that I found, which actually stirs better, also reduces the load significantly and seems to reduce heating.


----------



## pdilley

You do not need a vortex going all the way down to the stirbar, or a violent vortex, just get one to form and be stable and you are set.

We just had a presentation on stir plates and preparing starters at the Canberra Brewers Club which was really good. What I came away with was with the number of steppings you need to do perform in order to prepare a starter for the correct number of yeast cells to do all the beer styles out there will require a 5 Litre flask. I was going to buy a 3 L but now I found out in time to get on the clubs next flask order for 5's.

The box is undergoing painting but should be ready to use in another week. I was predicting by christmas with SWMBO taking away all my mad scientist time but ive got a reprieve 

A very boring lab grey colour for the choice in paint.


----------



## MCT

Look forward to seeing it Pete, thanks for the info. The vortex I get is probably only about 5mm deep, pathetic really, but the whole wort is moving fast enough to stop anything settling.
What is the main point of a stir plate? To keep yeast in suspension or to oxygenate via a vortex?


----------



## pdilley

Did I mention I like AC over DC 

I saw a DC unit with 555 timer (better than the RC+pot+LM317 circuit) with the 5L flask but the flask was mostly empty so we could not see where the limits would be before the DC fan reached its torque limits regarding liquid volume in the flask.

The main purpose is oxygenating the wort so the yeast can all be shifted into respiratory metabolism and bud and reproduce like crazy.

Cheers,
Brewer Pete

PS 5mm sounds like you might be forming a dimple and not a true vortex. Picture would help.


----------



## sanmerah

Went to Jaycar to get all the bits for this project - thanks everyone for your input. Very valuable and interesting thread. Even after providing the exact part codes from this forum they managed to get the wrong

- potentiometer
- IC 

I got a log pot and something that was in the wrong box. Luckily I checked in the shop and the assistant didn't apologise for the mistakes but blamed bad stocking procedure ... anyhow worth double checking ..

Plugged everything together and it is working a treat, just waiting for a new soldering iron (my old one needed upgrading it seems, thanks ebay) to arrive along with the stir rod and flasks (thanks Grain and Grape).

Happy stirring...


----------



## LethalCorpse

Yeah, Jaycar stores often have their passive components and semiconductors mixed up. I worked there for four years, three as manager, and the only time we had company wide stocktaking of those components was in my first year. I did my own stocktakes of those when we could, but the reasoning, from a business perspective, is actually fairly sound - it just isn't economically feasible to count all the thousands of little components and make sure they're in the right bins. Good staff will recognise that the bits are likely to be mixed up and check each part as they sell them to you, sorting bins or adjusting stock levels as necessary, but it is retail, and they can't all be good staff. It pays to check that the bits they give you are the bits you asked for.

BTW, to check pots, make sure the pot they give you is marked with a B before the resistor value (B1k or whatever it was I recommended way back when), not an A. A logarithmic pot will still work, but will be much more difficult to control.


----------



## A3k

Hi guys,
I've got all the component for a stir plate, but don't have a proper stir bar. I've got a ferite rod, but i think it's too chunky for this purpose and will rattle like crazy.

Does anyone know where abouts in adelaide (preferably just southish) i can get a stir plate.

Sorry if this has been covered in this thread, but i couldn't find it in the 14 or so pages. It's the only thing holding me back from being able to use the stir plate.

Cheers,
Al


----------



## pdilley

MCT said:


> Look forward to seeing it Pete, thanks for the info.



The latest of the prototype AC StirPlate. -- what started off as a 12Volt Computer Fan project changed midway to AC design for more grunt.
-- Dedicated to finding my battery charger and getting the camera batteries charged again 


The first shot shows the interior "Post" design of the box. By running nuts and washers to specific heights and then locking in place a platform is built for the AC fan to slide down to towards a predetermined depth.

I do not plan on having to adjust the fan past the experiementation phase, then simple drop of lock-tite will help keep the final locked in height from shifting.

Reverse washer and nut allows the fan to be clamped down firmly. Once in place, it will not be going anywhere.

Already bolted on is a cut down version of an AC power junction box. All AC wiring will be contained in this box, and the AC cord will be routed to this box. Keeps open wires away from inquiring fingers.




Now I've put in the fan, put some magnets on top, and just placed the AC Triac Fan Controller with RFI filters in the other side to get a general idea of what it will all look like. All edges will light up perfectly from top of box to Junction box to AC Fan Triac controller so a clear acrylic sheet, a rubbermaid tub, or with the giant size, a 5L flask could sit easily atop everything and have the magnets right up next to the glass and the stirbar.

12 Volt DC computer fan shown for scale comparison to the AC fan size.




Quick mockup of the front view showing Power ON/OFF control plus fan-speed control.

12 Volt DC computer fan shown for scale comparison.




Experimenting with venting holes on this box design. Will test out after stirring up a monster sized starter to see how much heat, if any is released from the AC gear.

EDIT: However with the directional air flow from the fan being downwards, I'm still planning on cutting out a large circular hole on the bottom to vent air which will be drawn in through the side air holes. That should eleviate any heat build-up worries.

Cheers,
Brewer Pete


----------



## sanmerah

Lethal, thanks for your input to this thread for your circuit that I used and thanks to all who contributed, I must have read all 27 pages a couple of times!!

Here is the finished product:






Magnets: Rare earth from Jaycar, 4 doubled up.




Circuit: Lethal Circuit, with 2 capacitors
Power: Nokia charger 3.7v output - still manages to drive the 12v fan perfectly
FAN: taken from a old computer case (includes coloured LEDs)
Case: slimline 2.5ltr freezer pantry plastic case from Foodland. Ideal size, and shape. Originally considered leftover 3kg Honey container, but converted it into a waterproof housing just in case.





Glass vessel: standard flat bottom flask (works a treat)




Glass vessel: works with 2ltr old sherry bottles with concave base









Note: the Magnetic Stir Rod has No ring, is silent in operation!


----------



## LethalCorpse

Happy to help, glad it worked out so well for you.

Must admit i'm a bit stunned you've got it working off a 3.7V supply. The LM317 has a 2V minimum dropout, which means less than 2V that's going to your load. a 12V fan shouldn't spin up at all with that supply, especially with such a heavy load.


----------



## sanmerah

LethalCorpse said:


> Happy to help, glad it worked out so well for you.
> 
> Must admit i'm a bit stunned you've got it working off a 3.7V supply. The LM317 has a 2V minimum dropout, which means less than 2V that's going to your load. a 12V fan shouldn't spin up at all with that supply, especially with such a heavy load.



I didn't think it would work either ... but it did!


----------



## A3k

adelaidebrewer said:


> I didn't think it would work either ... but it did!



Hi Adelaide Brewer,
Where abouts did you get the stir bar from.
I'm in adelaide and want to get one. I have everthing else, but am just missing that. (and maybe a bigger flask)

Cheers
Al


----------



## orac

A3k said:


> Hi Adelaide Brewer,
> Where abouts did you get the stir bar from.
> I'm in adelaide and want to get one. I have everthing else, but am just missing that. (and maybe a bigger flask)
> 
> Cheers
> Al



I recently bought a couple of stir bars & flask from:

Asis Scientific 474 Port Rd, Hindmarsh 5007


They seemed quite happy to sell small quatities and were helpful when I phoned them...tried a couple of other scientific supply places from the phone book and they were only interested if I was buying a hundred or so.


Dave (1st post btw)


----------



## HoppingMad

Got inspired and now working on building one of these. The wiring might be interesting though, not much of a sparky myself.

Found some rare earth magnets in an old hard drive (pic below).
Found info about them here - EarthMagnets in stuff Now gotta prise them out somehow.






Hopper.


----------



## altone

HoppingMad said:


> Got inspired and now working on building one of these. The wiring might be interesting though, not much of a sparky myself.
> 
> Found some rare earth magnets in an old hard drive (pic below).
> Found info about them here - EarthMagnets in stuff Now gotta prise them out somehow.
> 
> 
> 
> 
> 
> Hopper.



Think that this has been covered already somewhere in the thread, but the way I've done it in the past is to get 2 sets of strong grips or pliers, one each end of the steel backplate and just bend it away from the magnets - try not to prize the magnets themselves as they can be brittle.

Trust me I'm a computer technician :icon_cheers:


----------



## gava

has anyone used a stirer for their fermenter?
what advantages would this bring? would the benifits outway the trouble of setting it up?



sosman said:


> Well not unless I use one of these:


----------



## jonocarroll

Sorry to have multiple questions on the go fellas, but I'm working on my TASP and I'm curious; is there a particular reason for sealing the fan up in a box? Seems a lot of people are concerned about heat extraction from their sealed box... why not just have a table arrangement with the wiring appropriately sealed up?

I'll hopefully be putting mine together over the weekend, and will post build pics for assessment. I'm hoping that the 10cm, 3-speed computer fan I got for nix will be strong/weak enough that I don't need to regulate the power.

Cheers to all contributors of this uber-thread.


----------



## Supra-Jim

No need at all QB. Having the unit build in a PVC box just makes it nice and asthetically appealing  

We recently had some different constructions demo'd a Melb Brewers meeting and the majority of the design variations did not have a sealed unit. One design was a peice of cork board with legs make from cork and the fan attached to the underside with PCB plastic stickon stand offs. Other designs used a plate sitting over a bowl.

I guess the main idea is to have a surface to support the flask, and a way of attaching the fan underneath, everything else is window dressing.

Cheers SJ

(edit: I built mine in a PVC enclosure so it looks cool!  )


----------



## gava

I put mine in a jiffy box because it's portable and water resistant.... Im sure it wouldn't matter as long as it spins the stirbar...


----------



## jonocarroll

Cool, cheers for that!

I'll likely go some sort of table setup - either varnished wood or plastic, I'll see what I can get my hands on.

:icon_cheers:


----------



## captaincleanoff

I made a tight ass plate that worked well, but have recently required a proper stir plate from work. Its a big stainless square thing.. will find out the model later if necessary

I'm stiring 5L starters no problem with this.

My problem though, is that the stir plate heats up quiet alot. I keep my starters and stir plate inside my fermentation fridge, at the appropriate temperature (usually 17c). However, when I recently checked a starter that had been stiring for about 24hrs, it was up around 30c  I touched the top of the stir plate, and it had gotten fairly hot.

Anyone got any ideas how to prevent this? One idea I had was to connect the stir plate to a timer, so it turns off for a period every hour or so to cool down. 

Or maybe a layer of foam between the stir plate and flask?

Just wondering if others have problems with this, and how they fixed it.


----------



## Supra-Jim

Thin layer of foam or neoprene could do the job there, or otherwise as you mentioned, use a timer switch and set it to switch the unit off every odd hour.

Cheers SJ


----------



## jonocarroll

captaincleanoff said:


> Anyone got any ideas how to prevent this? One idea I had was to connect the stir plate to a timer, so it turns off for a period every hour or so to cool down.
> 
> Or maybe a layer of foam between the stir plate and flask?


Anything you do like this will only (in the first case) prevent a lot of heat from building up, or (in the second case) heat up the foam, either melting it or bringing it up to the same heat as the plate, in which case it's no better.

You need to actually get the heat out - either by running the fridge, or by using BribieG's method of putting ice bricks in the fridge with the starter. Otherwise you're just moving the heat around inside the fridge.


----------



## newguy

captaincleanoff said:


> I made a tight ass plate that worked well, but have recently required a proper stir plate from work. Its a big stainless square thing.. will find out the model later if necessary
> 
> I'm stiring 5L starters no problem with this.
> 
> My problem though, is that the stir plate heats up quiet alot. I keep my starters and stir plate inside my fermentation fridge, at the appropriate temperature (usually 17c). However, when I recently checked a starter that had been stiring for about 24hrs, it was up around 30c  I touched the top of the stir plate, and it had gotten fairly hot.
> 
> Anyone got any ideas how to prevent this? One idea I had was to connect the stir plate to a timer, so it turns off for a period every hour or so to cool down.
> 
> Or maybe a layer of foam between the stir plate and flask?
> 
> Just wondering if others have problems with this, and how they fixed it.



If you switch back to a homemade stirrer with a plastic top you won't have a heating issue. You mentioned that the commercial unit you snagged has a metal top - it's responsible for the heating. Wave a magnet around a conductor (the metal top), and the magnet induces an electrical current in the metal. Electrical current flowing through metal creates heat. Eliminate the metal and you'll eliminate (or greatly reduce) the heat.


----------



## LethalCorpse

Heat is always going to be a problem with speed control, particularly if you're not using a PWM controller - linear controllers, like the simple circuit I've recommended, produce heat by their very nature. Sealed boxes are a good idea because they stop spillage (which happens more often than any of us would like) from buggering up your electrics. But sealed boxes trap the heat in. Perhaps the best option is to use the lid of a jiffy box, or some other flat panel, with the fan attached to it with spacers so there's a small airgap between the fan and the panel. The PCB/veroboard with all components soldered to it goes directly underneath the fan. Use a heatsink on the LM317 so that the airflow produced by the fan can cool it happily. You'll need to use a TO220 heatsink mounting kit. This consists of a rubber gasket and a plastic ferrule which ensures that the heatsink has a solid thermal interface with the LM317, but no electrical connection because the tab of the LM317 is connected to its output, and you don't want the heatsink to be live. You can buy it at Jaycar or wherever else you buy the other bits for a dollar or two for four sets. Appropriate selection of screws and standoffs will ensure you've got a nice flat surface for your flask to sit on, and the fan and pcb are at about the right heights. The attached diagram should explain it far better than I can here. If you use a panel which is a fair bit larger than your fan, PCB and flask, it should stop any spills from hitting the electrics, particularly if you use something with a lip.


Captaincleanoff, are you certain the commercial stirplate you're using isn't a heater/stirplate? They're fairly common, as you often wish to heat the liquid you're stirring in assorted scientific fields. If it's just the unit producing heat, and you've got it in a fridge, a small fan pointed at the unit should ensure it stays close to the same temp as the fridge. Also, what newguy says is 100% true, and could well be causing the heat you're getting. Hopefully the metal top can be easily removed if that's the case. If not, the fan should help either way.


----------



## 3G

A3k said:


> Hi Adelaide Brewer,
> Where abouts did you get the stir bar from.
> I'm in adelaide and want to get one. I have everthing else, but am just missing that. (and maybe a bigger flask)
> 
> Cheers
> Al



Hi Al

I got mine from Aim Scientific in Prospect a few years back. The guy there is helpful.

Cheers


----------



## altone

Supra-Jim said:


> Thin layer of foam or neoprene could do the job there, or otherwise as you mentioned, use a timer switch and set it to switch the unit off every odd hour.
> 
> Cheers SJ



That's what I'm doing - actually a mousemat cut to fit, makes the thing run quieter as a bonus.


----------



## jonocarroll

3G said:


> I got mine from Aim Scientific in Prospect a few years back. The guy there is helpful.


Just called him. I might try to get mine tomorrow. Will have to (try to) avoid also buying lots of funky lab equipment h34r: 

Cheers all!


----------



## Maple

I think I'm in need of a bit of help with this one. I've been collecting all the bits and bobs for building one of these lil beauties, and finally had the time to sit down and try to work out how it all goes together. Well, managed to get it all wired up, fan comes on with the switch, speed modified by the knob (yeah, one turning the other), but when I put a flask with a stir bar on and fire it, the stirrer begins to spin, I get all excited, and then it just starts flicking around the flask bumping all random-like until i turn it off. Tried turning the fan speed down to just before it cuts out, no change. 

The magnets are the small rare earth magnets from Jaycar, the stir bar is a 35 x 6mm cylindrical one. I've tried moving the magnets inward on the fan, outward, stacking them 2 high on opposite sides of the fan as well. pretty sure I have one N facing up and the other S facing up. 

I guess the questions are: are the magnets too strong/not stong enough? or is the fan still to fast (hard one to answer without seeing it i guess), is the distance between the flask and the magnets too big/small? (currently ~ 20mm gap, but tried smaller, no change), any advise would be welcomed. 
Cheers.
Maple


----------



## jonocarroll

QuantumBrewer said:


> I might try to get mine tomorrow. Will have to (try to) avoid also buying lots of funky lab equipment h34r:


Stirbar(s): WIN
Restraint in buying more equipment: FAIL.

Table setup built. Fan connected/tested. Magnets should arrive soon.


----------



## therook

Maple said:


> I think I'm in need of a bit of help with this one. I've been collecting all the bits and bobs for building one of these lil beauties, and finally had the time to sit down and try to work out how it all goes together. Well, managed to get it all wired up, fan comes on with the switch, speed modified by the knob (yeah, one turning the other), but when I put a flask with a stir bar on and fire it, the stirrer begins to spin, I get all excited, and then it just starts flicking around the flask bumping all random-like until i turn it off. Tried turning the fan speed down to just before it cuts out, no change.
> 
> The magnets are the small rare earth magnets from Jaycar, the stir bar is a 35 x 6mm cylindrical one. I've tried moving the magnets inward on the fan, outward, stacking them 2 high on opposite sides of the fan as well. pretty sure I have one N facing up and the other S facing up.
> 
> I guess the questions are: are the magnets too strong/not stong enough? or is the fan still to fast (hard one to answer without seeing it i guess), is the distance between the flask and the magnets too big/small? (currently ~ 20mm gap, but tried smaller, no change), any advise would be welcomed.
> Cheers.
> Maple



Maple,

I had exactly the same problem?

What size magnets are you using, I was using small ones and changed them to bigger ones ( 12mm wide i think ) and after that it works a treat.....

let me know if you want me to measure mine or give me a call at home tonight

Rook


----------



## captaincleanoff

this only ever happens to me when it is spinning too fast, so maybe thats the problem


----------



## Jez

i had the same problem. stirbar used to jump all over the place no matter what the fan speed.

I sat the flask on a piece of 15mm or so thick pine board on top of the jiffybox & it spins perfect for days.

Jez


----------



## Maple

therook said:


> Maple,
> 
> I had exactly the same problem?
> 
> What size magnets are you using, I was using small ones and changed them to bigger ones ( 12mm wide i think ) and after that it works a treat.....
> 
> let me know if you want me to measure mine or give me a call at home tonight
> 
> Rook


Rook, cheers for that, I suspect they may be too small. they are 10mm dia x 3mm, next size up was 25mm, figured that would have been a bit too big, perhaps something in between is what I'm after. Will tinker around with it tonight.

Jez, perhaps a few things to try, cheers Jez.


----------



## newguy

Maple said:


> I guess the questions are: are the magnets too strong/not stong enough? or is the fan still to fast (hard one to answer without seeing it i guess), is the distance between the flask and the magnets too big/small? (currently ~ 20mm gap, but tried smaller, no change), any advise would be welcomed.



There are a few things that will influence the coupling (hold) between the spinning magnets and the bar.

1) With magnets physical size is indicative of power (if material is the same). Larger magnet volume = more force. I have 20mm x don't know how thick - probably 3 or 4mm. You definitely want rare earth magnets.

2) Physical gap between bar and spinning magnets must be as small as possible. This means shimming your fan so that the magnets just barely clear the top of your enclosure. It also means thinner is better for the enclosure top, as long as the top is strong enough to support your flask when it's filled. Never use a metal top - only wood or plastic or some other non-magnetic material.

3) Separation between the magnets on the fan should correspond to your stir bar's length so that the ends of the bar are roughly centered over each magnet's center. This is a good starting point but you may find that a bar slightly longer or shorter than your stationary magnet's center to center distance works better. My best "holding" stir bar is about the c-c distance.

4) One stationary N up, the other S up is mandatory.

5) Start on slowest speed, then slowly turn up the speed. You'll find that most bars will eventually get flung off at some speed; either change the bar for a different size or just operate the unit below that speed.

6) It's important to center your flask above the fan. If it's off center, the bar will get flung off at a lower speed than if the flask is centered.


----------



## TidalPete

Jez said:


> i had the same problem. stirbar used to jump all over the place no matter what the fan speed.
> 
> I sat the flask on a piece of 15mm or so thick pine board on top of the jiffybox & it spins perfect for days.
> 
> Jez



Jez has the answer fellas,

There are two solutions to this:
1 -- Raise or lower your fan inside the box you are using it in to increase\lessen the magnetic force on your stir bar & if that doesn't work try "2".
2 -- Place a piece of whatever (Various thicknesses to suit) between your fan & your flask & Bob's Your Uncle.

I have a 240v stirplate with those those 25mm rare earth magnets & had to vary the height between them & the stirbar to avoid the problems above.

TP


----------



## Maple

Cheers guys. Had a bit of a go with adjusting the distance between fan and flask. With about a 1mm gap between the magnets and the bottom of the flask it works beautifully. To me that means these small size magnets are just not enough even when stacked 2 high. Thanks again fellas, will get some bigger Rare earth magnets tomorrow.


----------



## MattC

Hey all, I have gathered some parts to make one of these stir plates. I have a 12 V fan, 500Ohm Pot, switch, jiffy box, wires, panel mount socket, plug pack etc etc.

I was drilling the hole for the Pot to fit in the jiffy box. The Pot only came with a thin fastening nut. Does the hole for the pot only have to be wide enough for the first grooved cyilnder section to fit through, or does part of the threaded section need to fit through the hole and then the nut fixes the pot from the outside? There is a small piece of metal that potrudes and to me would seem to prevent a flush fitting to the jiffy box!

Silly question im sure but for me it aint!!

Cheers


----------



## LethalCorpse

Very silly questions. This should all make immediate sense. But, anyway, The nut fastens from the outside - how the hell could it fasten on the inside? The thread, of course, has to go through the hole - how could you fasten it otherwise? The only remotely difficult part of the whole thing is the little protruding bit. It's a key which prevents the pot from rotating as you turn it. You drill a small hole right at the point where that knob meets the faceplate, so that when you screw the pot to the plate the knob is in that hole and doesn't foul anything else.

It's all moot, as the pot will fail shortly because it's designed to handle a fraction of the power you're forcing it to handle. This has been discussed throughout this thread. If you don't have the nous to build one of the appropriate circuits, buy a fan controller from your local computer store and use that instead.


----------



## MattC

Gee thanks for being so understanding LC. I am not at all mechanically or electrically minded and i do realise that my question was simple for you. As mentioned it was the small key piece icouldnt work out! I have read elsewhere that a 500 ohm pot was suitable, ive already got it so time will tell! Anyway thanks for the advice, albeit with the accompanying lack of empathy for a person less suited to this task than yourself!!

Cheers


----------



## LethalCorpse

Stop whinging - I've flamed harder for less. If you thought about how things fit together for a minute before posting those questions wouldn't have been necessary, although as I said, the locking key might have presented some difficulty. 

There's nothing wrong with not being electrically or mechanically minded. In those cases, though, you need to consider if you should really be attempting a particular task. There are plenty of off-the-shelf solutions for what you're trying to do. I'm very handy with electronics and most mechanical stuff, but I don't attempt my own legal arguments, for example. I hire a lawyer.


----------



## MattC

I do not want to waste time entertaining someones ego, but i did look at how they went together before posting. It was the key that presented some difficulty, that part we at least agree on. I searched the net for advice on attatching a pot to a jiffy box but when i couldnt find it, i thought i would post my question here for some friendly advice from someone more electrically minded! As far as suggesting i dont attempt such a task, well i couldnt disagree more. I believe in having a go and if that involves asking what some may call " very silly questions" then i can live with that! As far as the lawyer thing goes, mate not even the same ball park! Get off your high horse and rethink your statement. 

To cut a long story short, I appreciate your constructive comments as i got the info i needed, however i did not expect to be ridiculed for asking these questions! May i suggest to you that if people like me ask questions that cause you to be frustrated, then ignore the question and do not post a reply!

Cheers!


----------



## gibbocore

**** you're a wanker, LS, get off your high horse for two seconds. The most annoying thing is that you're right.


----------



## LethalCorpse

The question wasn't just about the key, you also asked whether the thread had to go through the hole, and whether the nut locked from the inside or the outside. You're the one who called them silly questions, I just agreed with you. I'm not on my high horse, but if you can't figure out how the pot goes through the box, how are you going to figure out which wire is positive and which is negative? Are you certain of which end of the soldering iron you're supposed to hold, and which end you poke at stuff? All silly questions, but if you don't know the answers to those you're in more trouble than taking a bit of stick from me. 

The lawyer example is completely valid. It's something I'm not qualified to do, have no experience in, and, therefore, wouldn't attempt to do it myself. I couldn't use plumber, electrician, mechanic etc, because I know enough in those areas to do what I can and pass on what I can't. I'm not being an arse when I say you don't have the skills to do this properly - that's just how it is. More to the point, you don't need to do it - there are cheap, ready made solutions that will do a much better job than something you can bash together. I'm all for "having a go", but only within reason. You've got to have some idea of what you're attacking first.


----------



## MattC

I did say they were silly questions because I understand they were. I admit I have no idea where to start with this stri plate thingy, but called me determined, I want to do it. So what are these off the shelf thingys you referring to? Do you mean the computer fan controller?

Edit: although humerous LC, I do happen to know the correct end of soldering iron, im not a complete waste of space


----------



## brettprevans

well my newly aquired stir plate has been in action and not living up to scratch. it was struggling with a 2L flask. either the stirbar magnet is too small or the fan is too slow. Im actually thinking its a combo of both. so off to the IT boys to see if they've butchered any PCs lately and I can steal a fan from them. then off to get some bigger stirbars.


----------



## LethalCorpse

MattC said:


> So what are these off the shelf thingys you referring to? Do you mean the computer fan controller?


yep, any computer shop should have several different options. Plenty of fans of about the right size are supplied with a little controller that is supposed to go in a PCI slot. Otherwise, they'll have a few aftermarket controllers, though many of those will be multichannel and perhaps more sophisticated than you need.


----------



## Fents

have you finished my stir plate yet LC?


----------



## MattC

LethalCorpse said:


> yep, any computer shop should have several different options. Plenty of fans of about the right size are supplied with a little controller that is supposed to go in a PCI slot. Otherwise, they'll have a few aftermarket controllers, though many of those will be multichannel and perhaps more sophisticated than you need.



So using your diagram of the circuit, does the fan controller take the place of the LM317? and everything else is the same as in the diagram?


----------



## LethalCorpse

The fan controller would take the place of everything in the diagram - LM317, pot, caps, etc. You'd just connect 12V to one side of the controller, connect the fan to the other side of the controller and you're away. The knob for adjusting the fan speed is part of the controller.


----------



## LethalCorpse

Fents said:


> have you finished my stir plate yet LC?


I was just thinking exactly that, mate. Sorry 'bout the delay, things've been busy. I should have some time next week to have a bash, so stay tuned.


----------



## MattC

So the $15 from the computer guy who I just called on the phone for a fan controller seems like a bargain!


----------



## LethalCorpse

Yep, that sounds pretty good


----------



## Fents

LethalCorpse said:


> I was just thinking exactly that, mate. Sorry 'bout the delay, things've been busy. I should have some time next week to have a bash, so stay tuned.



Legendary. B)


----------



## jonocarroll

T.A.S.P. All done B) 

I think I'm quite happy with the result, and many thanks to all helpful contributors throughout this thread!

Total cost is a mere $15 for the bits I didn't already have or could obtain for free; about $1 of MDF, less than $3 for 20 magnets (delivered), $8 for the stirbar (80mm), $3 for the rubber feet. Got the 3-speed fan for nix from the computing officer @ work, and I had everything else (phone charger, computer cables, rocker-switch, legs, spacers, scotch-clamps, screws, screw-covers, heat-shrink) just sitting around the place.

(excuse my home-made light-box... )










Gets a vortex going with 500ml in a 1L conical flask from top to bottom on the lowest fan setting if I use the very technical 'coaster spacer'. Still stirs 1.5L in my 2L conical just fine. Can't seem to sync with the higher fan speeds, but it just needs to be moving, right?

Currently got this munchin' away on some 2308 munich. Can barely hear it.


----------



## A3k

QuantumBrewer said:


> T.A.S.P. All done B)
> 
> I think I'm quite happy with the result, and many thanks to all helpful contributors throughout this thread!
> 
> Total cost is a mere $15 for the bits I didn't already have or could obtain for free; about $1 of MDF, less than $3 for 20 magnets (delivered), $8 for the stirbar (80mm), $3 for the rubber feet. Got the 3-speed fan for nix from the computing officer @ work, and I had everything else (phone charger, computer cables, rocker-switch, legs, spacers, scotch-clamps, screws, screw-covers, heat-shrink) just sitting around the place.
> 
> (excuse my home-made light-box... )
> Gets a vortex going with 500ml in a 1L conical flask from top to bottom on the lowest fan setting if I use the very technical 'coaster spacer'. Still stirs 1.5L in my 2L conical just fine. Can't seem to sync with the higher fan speeds, but it just needs to be moving, right?
> 
> Currently got this munchin' away on some 2308 munich. Can barely hear it.



Hey QB,

That's a bigger vortex than i can get. Still mucking around with mine. My 2L flask with a 70mm stir bar seems to work better than the 500mL with a 40mm bar. think i need experiment some more, maybe add some spacers and some extra magnets.

managed to get the pilsner yeast (2007) started on it pretty well though. A bit temprimental to get it syncronised, but okay once it's going. 

excuse the scungy ferment behind it, 1469 overflowed.


You keen to swap the 2308 with some 2007 next month?

Cheers,
Al


Edit again: first pic is the 2L flask, second is the 500mL.


----------



## jonocarroll

A3k said:


> That's a bigger vortex than i can get. Still mucking around with mine. My 2L flask with a 70mm stir bar seems to work better than the 500mL with a 40mm bar. think i need experiment some more, maybe add some spacers and some extra magnets.
> 
> managed to get the pilsner yeast (2007) started on it pretty well though. A bit temprimental to get it syncronised, but okay once it's going.


I think I got very lucky with just the right spacing and strength. I have however fixed the magnets a fixed distance apart, roughly equal to the strongest points on the stirbar, which means my 40mm bar doesn't work as well. Syncing happens each and every time from standstill when I flip the switch B) 



A3k said:


> You keen to swap the 2308 with some 2007 next month?


Do you mean 2000? I've got some 2007 chewing through a pilsner already. If you mean 2000... you're on. This one's going into a Traditional Bock, and I'll steal a vial of the yeast cake for you before I dump a Vienna on top.


----------



## A3k

QuantumBrewer said:


> Do you mean 2000? I've got some 2007 chewing through a pilsner already. If you mean 2000... you're on. This one's going into a Traditional Bock, and I'll steal a vial of the yeast cake for you before I dump a Vienna on top.



Yep that's the one! I somehow got the yeast you are using mixed up with the one i'm using. Possibly cos i've just come home from the Avoca.

Cheers,
Al


----------



## Maple

therook said:


> Maple,
> 
> I had exactly the same problem?
> 
> What size magnets are you using, I was using small ones and changed them to bigger ones ( 12mm wide i think ) and after that it works a treat.....
> 
> let me know if you want me to measure mine or give me a call at home tonight
> 
> Rook


Thanks Rookie, and newguy & Jez and really to all who contribute to this thread. Have been meaning to followup and say thanks, we have success!


----------



## Jez

Nice work!


----------



## Adverse

you all seem to be useing a mechanical solution

has any one looked in to a solid state solution?

i carnt seem to find what i am looking for but this pic is close





now take the top disk off so you have a circular array of electro magnets

then wire them up to something like this in opposing pairs 

http://www.high-voltage-lab.com/169/led-chaser



> This schematic is my version of a simple 10 LED chaser. There is no 555 timer used because at my local electronics store they are over $4 Cdn. Instead, an oscillator made up of two sections of a 4011 NAND gate is employed. This chip is very inexpensive and extremely common.*Circuit diagram*
> 
> 
> 
> 
> *Parts:*
> R1 1 Meg 1/4W Resistor
> R2 100K Pot
> R3 1K 1/4W Resistor or 220Ohm if using blue LEDs
> C1 0.1uF 16V Ceramic Disk Capacitor
> U1 4011 CMOS NAND Gate
> U2 4017 CMOS Counter
> LED1-10 LEDs Of Any Colour
> MISC Board, Sockets For ICs, Knob For R2
> 
> *Notes:*
> 1. Use R2 to adjust the "chase rate".
> 2. You may need to use a lower value resistor if you wish to use blue LEDs. Try 220 Ohm.
> 3. You can also use incandescent lamps instead of LEDs. Use transistors to drive them by connecting the base of the transistors to each of the outputs of the 4017 through a 1K resistor. Connect one end of the lamp to the positive supply. Then connect the other end to the collector of the transistor. The emitter then goes to ground. Depending on the lamps, you may need power transistors that are heat sinked.
> 4. C1 may be replaced with a larger value for a slower "chase rate".
> 5. If you have problems with weird circuit behavior, try replacing R1 with a 33K resistor, and increasing C1 to 1uF.
> 6. If you plan to use this circuit in your car, be warned that in some areas it is illegal to have red, blue or yellow flashing lights unless you are an emergency vehicle.



tap off the LED's to i think there called triacs? to take the load of trigger the magnets

replace R2 with a trim pot and maybe even add in a trim pot for the power going to the magnets

i was looking at about 8 magnets (4 sets of 2) 

*DISCLAIMER* i have never managed to get/make any type of kit to work as i am hopeless with electronics it seems.
but am i heading down the right path for someone to design and construct something like this?


----------



## A3k

Hi AE,
Kinda looks like a flat stepper motor stator. Could work, and if it did, youd be able to control the speed pretty well. 

If using the circuit diagram youve got, put each output through a Darlington Pair. You can buy a chip with 4 8 I pairs on it I thing for basically nothing.

Id like to see if you can get it to work, but itd be a pain to spend all that time on it for it not to work.

Cheers,
Al


----------



## Adverse

A3k said:


> Hi AE,
> Kinda looks like a flat stepper motor stator. Could work, and if it did, you'd be able to control the speed pretty well.
> 
> If using the circuit diagram you've got, put each output through a Darlington Pair. You can buy a chip with 4 8 I pairs on it I thing for basically nothing.
> 
> I'd like to see if you can get it to work, but it'd be a pain to spend all that time on it for it not to work.
> 
> Cheers,
> Al



well see there you have my problem i am grate at comeing up with idears and working out the basics BUT that is as far as i can go i have no idear about electronics at all (other than wireing a house dad taught me when i was younger or wireing a car as i am an ex motor mech)

the reason i am working on something like this is so i can add in to the center a small heating element that way it can be heat controlled as well with a small stick on temp guage like some computrer cases come with


----------



## Adverse

thinking about it you could smooth out the motion by having it set up like this

4 sets of oposeing coils

1 on
2 off
3 off
4 off

1 on
2 on
3 off
4 off

1 off
2 on
3 off
4 off

1 off
2 on
3 on
4 off

1 off
2 off
3 on
4 off

1 off
2 off
3 on
4 on

1 off
2 off
3 off
4 on

1 on
2 off
3 off
4 on

sorry didnt know a better way to display it


----------



## leiothrix

Yet another tight arse stir plate:







Using two rare Earth Disc magnets 20x5mm from aussiemagnets.com.au.

It has a 12V 80mm computer fan and a 555 based PWM speed controller.

That is it running at full speed. The good thing with the PWM controller is that the motor has enough power to start turning at a much lower speed. So if the power goes off, it will start running right where it left off. A linear power supply requires the speed to be turned up to start it moving, then turned back down to the speed you want it (and yes, that's what i tried first - being lazy usually doesn't pay off  )


----------



## Simon W

Adverse Effects said:


> you all seem to be useing a mechanical solution
> 
> has any one looked in to a solid state solution?
> 
> i carnt seem to find what i am looking for but this pic is close



I made a similar suggestion in the Arduino Dev Thread.


----------



## Wolfy

I couldn't edit my previous post for the new image location, so here's my Tight Arse Stir Plate (version 1).




It _was _made from an 80mm speed controlled computer fan, magnet from an old computer disk drive, drive bay bracket for mounting and it used an old computer power supply.
Worked well for a year, before creating fireworks in my lounge room. The stir plate was on a small table with the power supply under, unfortunately the yeast grew too well, overflowed the flask, spilled onto/into the power supply, creating some interesting sparks and sounds before it stopped working.


----------



## Pete2501

I so want to make one of these. :icon_drool2: 

All the pics are making me heaps jealous.


----------



## merrick

Hi All,

Catastrophe! Made my stir plate a couple of years with the same rare earth magnets used by Jye and Ross. Works brilliantly. Problem is the stir bar magnet has gone walkabout and I'm stuffed without it. I originally bought the magnets from Jaycar but they no longer stock this type.





Can anybody help with a replacement or point me in the right direction? Many thanks.

Merrick


----------



## canon1ball

merrick said:


> Hi All,
> Can anybody help with a replacement or point me in the right direction? Many thanks.
> 
> Merrick




Hi Merrick,
www.livingstone.com.au
sell all sorts of different stir bars. Very helpfull.
c1b


----------



## merrick

merrick said:


> Hi All,
> 
> Catastrophe! Made my stir plate a couple of years with the same rare earth magnets used by Jye and Ross. Works brilliantly. Problem is the stir bar magnet has gone walkabout and I'm stuffed without it. I originally bought the magnets from Jaycar but they no longer stock this type.
> 
> 
> View attachment 36795
> 
> 
> Can anybody help with a replacement or point me in the right direction? Many thanks.
> 
> Merrick



Managed to find my magnets at Jaycar, Brookvale. They were described as 'Rattlesnake Sound Eggs' and found amongst the toys. Still had a few packets in stock at $4.99. They work brilliantly in a stir plate as one magnet becomes the stir bar while the other is glued to the motor.



Just thought I'd pass on the info.

Merrick


----------



## Elbow

Alrighty then,

Just assembling a few bits and bobs salvaged from work:

1 x 12v computer fan
1 x power supply 9v
1 x HDD rare earth magnet

Although I've read all the pages, brain bad and can't remember stuff good no more.

So, a couple of questions:

1. I've got the fan spinning no problem connected to a 9v p/s (i got a small paperclip spinning and vortexing inside a coffee plunger jar). I can probably get a 12v p/s if need be. Should I use this instead?
2. Do I need more than one rare earth hdd magnet? I've extracted one ok (minus a bit of the metallic covering), the other one I managed to break in half. I can probably get more.

Cheers


----------



## leiothrix

HD magnets tend to be a bit crap.

I got some from aussiemagnets, pretty sure they're 20x5mm. I got a couple of different sizes and had a play.

For the power - get a 12V power supply and a PWM controller for it. PWM gives the fan full power, it just turns it on and off really quick to vary the speed.

If you use a linear speed controller (i.e. reducing the voltage) it means that the motor will spin slower, but will have absolutely no torque at the same time.

Rob.


----------



## Wolfy

Elbow said:


> 1. I've got the fan spinning no problem connected to a 9v p/s (i got a small paperclip spinning and vortexing inside a coffee plunger jar). I can probably get a 12v p/s if need be. Should I use this instead?
> 2. Do I need more than one rare earth hdd magnet? I've extracted one ok (minus a bit of the metallic covering), the other one I managed to break in half. I can probably get more.


If 9V is sufficient to turn your fan when you're using it as a stir-plate then thats all you need, but you'll need to test it and see how it goes.
You only need 1 HDD magnet, using 2 will not help. Again test it and see how you go, my first stir-plate used a HDD magnet, but now I find the small round magnets easier and better to use.


----------



## BjornJ

Hi,
my homemade stir plate burns out, is that common?  

The potentiometer seems to actually burn out with use.
After a while I had to turn it more and more "on" to get the fan spinning.
Eventually I noticed a burning smell and opened the project box (after working for several days).
Inside the potentiometer there was an orange spark like if the resistance or whatever is in there to reduce the voltage was being burned by the power supply.

I went back to Jaycar and asked for some help. The guy I talked with said I probably had a too weak potentiometer and gave me what I think was called a 1M strenght one.
Came home, replaced the potentiometer and straight away the same thing happened.
A slight smell of electics burning (not what I want on at night..) and a spark in the potentiometer.
So I turned it off and haven't looked at it since.

Is there a way to fix this?
Can it be the power supply is too powerful?
Can't remember what electric appliance I cut it from, but it is a "normal" small one, a little square thing that consists of a plug that sits in the power socket, not like a laptop power supply where you have a bigger "box" and I assume higher output.
It is definetly 12V but can't remember the Amp.

Would it help if I go back to Jaycar and ask about the pulse somethingorother changer in stead like mentioned here on the thread? The guy said this was another way of controlling the fan speed, and maybe this would mean no sparks  

Any advice will be appreciated,

thanks
Bjorn


----------



## leiothrix

You need a speed controller of some sort. The easiest way of doing it is with a linear voltage regulator. That may work, but the fan will have stuff all torque, esp at lower speeds.

PWM is better because you still get some torque at lower speeds, but is a bit more complicated to make. You can also get fan speed controllers made for controlling fans in a computer. 

Since you're using a computer fan, i'd imagine that would be perfect 

Rob.


----------



## crozdog

Bjorn, read back through this thread - as it contains several circuits to do what you need

See you on Sat, Croz.



BjornJ said:


> Hi,
> my homemade stir plate burns out, is that common?
> 
> The potentiometer seems to actually burn out with use.
> After a while I had to turn it more and more "on" to get the fan spinning.
> Eventually I noticed a burning smell and opened the project box (after working for several days).
> Inside the potentiometer there was an orange spark like if the resistance or whatever is in there to reduce the voltage was being burned by the power supply.
> 
> I went back to Jaycar and asked for some help. The guy I talked with said I probably had a too weak potentiometer and gave me what I think was called a 1M strenght one.
> Came home, replaced the potentiometer and straight away the same thing happened.
> A slight smell of electics burning (not what I want on at night..) and a spark in the potentiometer.
> So I turned it off and haven't looked at it since.
> 
> Is there a way to fix this?
> Can it be the power supply is too powerful?
> Can't remember what electric appliance I cut it from, but it is a "normal" small one, a little square thing that consists of a plug that sits in the power socket, not like a laptop power supply where you have a bigger "box" and I assume higher output.
> It is definetly 12V but can't remember the Amp.
> 
> Would it help if I go back to Jaycar and ask about the pulse somethingorother changer in stead like mentioned here on the thread? The guy said this was another way of controlling the fan speed, and maybe this would mean no sparks
> 
> Any advice will be appreciated,
> 
> thanks
> Bjorn


----------



## BjornJ

thanks, will look it up at Jaycar.

Bjorn


----------



## haysie

crozdog said:


> Bjorn, read back through this thread - as it contains several circuits to do what you need
> 
> See you on Sat, Croz.




When you read all 607 posts, Bjorn please add you knowledge.


----------



## crozdog

haysie said:


> When you read all 607 posts, Bjorn please add you knowledge.



start with LC's post #422 here http://www.aussiehomebrewer.com/forum//ind...5191&st=420


----------



## Elbow

LethalCorpse said:


> updated diagram to make it a bit neater and include the new values.
> Jaycar parts:
> LM317T - ZV1615
> 5k linear pot - RP3508 or RP7508
> knob to suit - pick one. HK7707
> 680ohm resistor - RR0568
> switch - pick one. ST0355
> 10u cap - RE6070
> 100n cap - RC5360




I got all the parts as listed above. I got a mate to wire and solder it up as per the diagram. It turns on fine, but the speed does not deviate at all, slow or fast. Any ideas?


----------



## MaestroMatt

Elbow said:


> I got all the parts as listed above. I got a mate to wire and solder it up as per the diagram. It turns on fine, but the speed does not deviate at all, slow or fast. Any ideas?



This happened to me at first as well......check to see if the wiring to the pot is going into the center connection and one of the outside connections.......if they are going into both outside connections then it is effectively bypassing the pot - you'll only get one speed....on


----------



## Elbow

No It was definitely a centre and a side one. Maybe it's the Pot. Might take it back to Jaycar.


----------



## BjornJ

crozdog said:


> start with LC's post #422 here http://www.aussiehomebrewer.com/forum//ind...5191&st=420



Crozdog,
thanks for the link.
That looks a bit complicated for me :lol: 

Maybe I will have to take Barls up on the offer of giving it to him and he will get someone at work to have a look at it. It seems my version without the resistors or whatever it is on the curcuit is giving the potentiometer too much power for its own good.

thanks
Bjorn


----------



## Elbow

MaestroMatt said:


> This happened to me at first as well......check to see if the wiring to the pot is going into the center connection and one of the outside connections.......if they are going into both outside connections then it is effectively bypassing the pot - you'll only get one speed....on




I think it's now the LM317T thingo. I got a voltage metre on the two outside pins of the LM317T and they are going up and down as the pot is turned, but the centre output is staying constant.

I'll grab another one from JC tomorrow and have another crack.


----------



## leiothrix

That's pretty much what the LM317T is supposed to do. It is an adjustable voltage regulator. Basically you have in, out and ground/adjust.

Rob.


----------



## LethalCorpse

If you're measuring between the left pin and the centre, it's supposed to stay constant, at 1.25V. To measure the output voltage, you put the black probe of the meter on the negative wire from the power supply, and the red probe on the centre pin of the LM317.

not sure why you're getting no speed change, perhaps the fan is connected to the input instead of the output. Can't diagnose anything without photos, though - take lots of photos with a decent camera (ie, not your phone camera). Then pick the ones which best show the overall circuit and what's connected where and post them here. We should be able to see what's gone wrong.


----------



## Elbow

LethalCorpse said:


> If you're measuring between the left pin and the centre, it's supposed to stay constant, at 1.25V. To measure the output voltage, you put the black probe of the meter on the negative wire from the power supply, and the red probe on the centre pin of the LM317.
> 
> not sure why you're getting no speed change, perhaps the fan is connected to the input instead of the output. Can't diagnose anything without photos, though - take lots of photos with a decent camera (ie, not your phone camera). Then pick the ones which best show the overall circuit and what's connected where and post them here. We should be able to see what's gone wrong.



I did the voltage thing again and it seemed to fluctuate a fair bit and closer to 2.5v. Apologies for the piss poor soldering job and mess of tangled wires shown.





The black wire on the left is the negative for the power supply







If I can't figure it out, i'll start again and hand over to a sparky who knows what they are doing. In the words of Homer "if it first you don't succeed, destroy all evidence you ever tried!"


----------



## LethalCorpse

You've got the fan backwards - swap the red and black wires. Also, with the switch turned off, check the polarity of your power supply wires. Red probe on the wire at the switch, black probe on the other wire. If it reads a negative voltage, you've got them backwards too. This would make sense - you said the fan is spinning, which it would not do if the supply wires were right, but the fan wires were backwards. This will also mean your lm317 has blown up. While you're at jaycar buying a new one, buy some veroboard and get them to show you how to use it.


----------



## Elbow

:icon_cheers: Now were talking!

Got another LM317T and some veroboard and I started again. When I say "I", I actually mean the 2 guys I work with who kindly agreed to wire it up for me. When I say "kindly agreed", I actually mean I locked them in a cell with no food and water until they fixed it.....thanks guys!

Works a treat this time, got it housed in cast off plastic box that was going to get scrapped. I've got my flask today, so I'm gonna fire that sucker up shortly and see how she goes. I'll post some photos to.

Thanks to Lethal and everyone else for input and advice. :chug:


----------



## LethalCorpse

A pleasure.


----------



## Fents

LethalCorpse said:


> A pleasure.


----------



## MattC

LethalCorpse said:


> updated diagram to make it a bit neater and include the new values.
> Jaycar parts:
> LM317T - ZV1615
> 5k linear pot - RP3508 or RP7508
> knob to suit - pick one. Not the ones which say "spline" or suit 9mm pot
> 680ohm resistor - RR0568
> switch - pick one. Any will do, so long as it's a latching type, not momentary. Pushbuttons, toggle switches, rockers, etc.
> 10u cap - RE6070
> 100n cap - RC5360



Would a similar circuit work with a 1K linear pot? if so what other components would I have to swap on the diagram?

Heading to Jaycar this WE want to ensure I have correct parts

Cheers


----------



## leiothrix

It wont really work with a 1k pot.

I'm not sure of the exact circuit you're using, but I'm assuming it's like the one in the attached image.

The formula for Vout is:
Vout = 1.25 * ( 1 + R2/R1 ) 

Where R1 is 680ohm (according to your parts list) and R2 is the pot.

With a 1k pot you get 1.25->3.1V
With a 5k pot you get 1.25->10.4V

So with the 1k pot you probably won't have enough power to get the fan spinning. In general, if you 1/2 the voltage the current will drop by 1/2 as well, leaving you with 1/4 the power (i.e. inverse square relationship).

I'd still recommend a PWM power supply though. Reducing the voltage really kills the performance of the fan. It's a slightly more complicated, but not by much.

I'm pretty sure that makes sense, but I've been 'sampling' some rather nice bourbon :icon_chickcheers: 

Rob.


----------



## MattC

Circuit is from LC's post a while back, The fan wont spin unless the pot is up high, then you have to turn it down. The max speed of the fan is lower than when connected to the fan straight from the 12 V power source. I guess this is the reason why?

Will grab a 5K pot and wire it up as in diagram.

I did have a fan controller but its a 4 terminal one and too large for what I need.

Cheers


----------



## LethalCorpse

leiothrix said:


> It wont really work with a 1k pot.
> 
> I'm not sure of the exact circuit you're using, but I'm assuming it's like the one in the attached image.
> 
> The formula for Vout is:
> Vout = 1.25 * ( 1 + R2/R1 )
> 
> Where R1 is 680ohm (according to your parts list) and R2 is the pot.
> 
> With a 1k pot you get 1.25->3.1V
> With a 5k pot you get 1.25->10.4V
> 
> So with the 1k pot you probably won't have enough power to get the fan spinning. In general, if you 1/2 the voltage the current will drop by 1/2 as well, leaving you with 1/4 the power (i.e. inverse square relationship).
> 
> I'd still recommend a PWM power supply though. Reducing the voltage really kills the performance of the fan. It's a slightly more complicated, but not by much.
> 
> I'm pretty sure that makes sense, but I've been 'sampling' some rather nice bourbon :icon_chickcheers:
> 
> Rob.


This.


----------



## Franko

where would one add a LED to this circuit as a power on display

Franko


----------



## leiothrix

Assuming that the 12V input is reasonably stable, between the + & - just after the switch would be fine.

If you do it after the regulator then the light will dim as the fan slows down. And it will probably turn off about half way across the range too.

You also want to put a resistor in series with the LED to stop it blowing up too. A value of around 500ohms will be fine. It depends on the source voltage and the power rating of the LED though. A 560ohm resistor at 12V will give you 18mA across the LED. They usually have a current rating of either 20 or 30 mA, so it's best to err on the low side first.

Rob.


----------



## Wolfy

My Tight Arse Stir Plate Version 1.0 went well until over-flowing yeast shorted out the power supply to create some interesting fireworks in the loungeroom in the middle of the night.

So now I have the _high-tech-spill-proof_ Stir plate Version 2.0:





Very simple and easy to make:
12V speed controlled super-bright-blue-LED computer fan
12V power supply (from and old cable-Internet modem)
4x small round rare-earth magnets
Plastic computer HDD bay fan mount
and the all important _high-tech-spill-proof_ 9L square plastic tub from the $2 shop.

In theory, if I ever needed a 5-6L starter, I could just I wash/sanitise the 9L square plastic tub (it has a lid) and use it directly.


----------



## LethalCorpse

Highly recommended. Don't leave your stirplate unattended without spill protection


----------



## 501

Hey Wolfy, 
are you using one of those 3 speed case fans ? 
no pot mentioned. 

Cheers


----------



## Wolfy

501 said:


> Hey Wolfy,
> are you using one of those 3 speed case fans ?
> no pot mentioned.


While we do use the 3-speed fans on the computers we have here, I don't think they would be that useful for the stir plate.
The fan used on the the stir plate comes pre-assembled with an adjustable knob/dial, which I presume is connected to a pot and any other electronics required.
Here is a picture (from some random Google'd website) of the fan I'm using:




I think you can buy the fully adjustable speed controlled fans at most PC shops now days.


----------



## 501

Thanks mate :chug:


----------



## praxis178

So if using this circuit what changes would need to be made to use it with a 5V supply and fan? Although I can solder (quite well, been doing it since I was ~10), I know next to nothing about electronic components etc.


----------



## BjornJ

I went to Jaycar again on Saturday, asking for some help to get that PMW "thingy" to control the fan speed.
After a bit of digging in their system they found that it stands for Pulse Width Modulator, and that they don't have any.
Or at least that there is nothing "ready" I could buy.

Am I looking for a 12 V power supply that has a "PWM" inbuilt and a knob to regulate the power, or is this PWM thing something I have to put between the fan and the power supply I already have?

thanks
Bjorn
(with no idea on this whole electronics thing :lol: but some of you may already have gathered that)


----------



## LethalCorpse

dude, you need a fan speed controller from any computer store.


----------



## Banshee

BjornJ said:


> I went to Jaycar again on Saturday, asking for some help to get that PMW "thingy" to control the fan speed.
> After a bit of digging in their system they found that it stands for Pulse Width Modulator, and that they don't have any.
> Or at least that there is nothing "ready" I could buy.
> 
> Am I looking for a 12 V power supply that has a "PWM" inbuilt and a knob to regulate the power, or is this PWM thing something I have to put between the fan and the power supply I already have?
> 
> thanks
> Bjorn
> (with no idea on this whole electronics thing :lol: but some of you may already have gathered that)



http://www.jaycar.com.au/productResults.as...keyform=KEYWORD

look here. I believe you through away the trimpot and wire in a 10k pot.

Others here may be able to help where and how to wire in the pot.


----------



## LethalCorpse

You've seen Bjorn's previous posts, and you want to point him at a soldering iron and say "have at it"?


----------



## Banshee

http://cgi.ebay.com.au/Voltage-Regulator-M...DefaultDomain_0

Again you would have to substitute the onboard pot for a dial pot.

http://cgi.ebay.com.au/Adjustable-Power-Su..._Electronics_R2

http://cgi.ebay.com.au/LM317-DC-AC-4V-30V-...DefaultDomain_0


----------



## BjornJ

LethalCorpse said:


> You've seen Bjorn's previous posts, and you want to point him at a soldering iron and say "have at it"?




HEHEHE, exactly what I was thinking!

Any electronics kit will be a bit to advanced for me by the looks of things.

That's why I was hoping for that PWM thingy to come and be a part I just buy and plug in  


thanks
Bjorn


----------



## Banshee

BjornJ said:


> HEHEHE, exactly what I was thinking!
> 
> Any electronics kit will be a bit to advanced for me by the looks of things.
> 
> That's why I was hoping for that PWM thingy to come and be a part I just buy and plug in
> 
> 
> thanks
> Bjorn




This would probably suit you best. Looks like a unit all you have to do is attach a dial pot and the power in socket wires and the fan wires. 

http://cgi.ebay.com.au/LM317-DC-AC-4V-30V-...DefaultDomain_0


----------



## beerbrewer76543

Correct me if I am wrong but isn't the blue box on that board a multi turn adjustable pot for controlling voltage?


----------



## Banshee

L_Bomb said:


> Correct me if I am wrong but isn't the blue box on that board a multi turn adjustable pot for controlling voltage?


Thats true but what good is the pot in the box?
Are you going to open your case every time you want to adjust your speed?
If you want to set and leave sure, but as you increase in flask and volume size you will want to alter your pot adjustment so for ease remove the trimpot and wire in a stand alone dial type pot.


----------



## beerbrewer76543

Sounds good. Any idea of the resistive value of the blue trim pot already on that board? 

Cheers


----------



## SJW

I have been away from this site for what feels like years, maybe it has, but I can't believe that this old thread was STILL at the top of the list.
Reminds me of the ol "NO CHILL METHOD" and "USERS OF THE NO CHILL METHOD" threads, that was a killer.

Steve


----------



## BjornJ

Banshee said:


> This would probably suit you best. Looks like a unit all you have to do is attach a dial pot and the power in socket wires and the fan wires.
> 
> http://cgi.ebay.com.au/LM317-DC-AC-4V-30V-...DefaultDomain_0




Banshee, 
appreciate you taking the time to help!

I have bookmarked the relisted version of that item, want to ask a question here before buying it.
Sorry for being somewhat slooow on the subject, but this talk of stripping this and that out and putting in a pot here and there makes me worried  

Q:
If I buy this thing from China, can I put it in a project box from Jaycar, connect the two wires from the 12 V power supply in one end and the wires to the 12 V computer fan in the other.
Then drill a hole in the project case and use a screw driver to adjust the fan speed by turning the little screw on the blue piece in the picture?

(I have the on/off button, the project box, fan, power supply, magnets, stir bar, etc from my first two attempts which failed miserably)







If so, I want one!

thanks
Bjorn


----------



## BjornJ

...I'm so bad at waiting..

I ordered one now, let's hope it works.


thanks again,

Bjorn


----------



## Banshee

BjornJ said:


> Q:
> If I buy this thing from China, can I put it in a project box from Jaycar, connect the two wires from the 12 V power supply in one end and the wires to the 12 V computer fan in the other.
> Then drill a hole in the project case and use a screw driver to adjust the fan speed by turning the little screw on the blue piece in the picture?
> 
> (I have the on/off button, the project box, fan, power supply, magnets, stir bar, etc from my first two attempts which failed miserably)
> 
> 
> 
> 
> thanks
> Bjorn



For the fan wire straight into the output sockets.
For the input go to Jaycarand buy a 12v power socket and drill a hole in your box and secure the socket on the inside wire to the circut boards input sockets and solder to the 12v power socket.
Yes you can drill a hole and use a screwdriver to adjust the onboard pot.


----------



## Banshee

You can strip the wires on your 12v power pack, but then it is dedicated for this unit only. With the socket the power pack can be use universaly.


----------



## BjornJ

Thanks again for clearing it up.

will give it a go as soon as it gets here.

thanks
Bjorn


----------



## Wolfy

LethalCorpse said:


> dude, you need a fan speed controller from any computer store.


As per my posts (and pictures) on the previous page, I have to say I agree with this.
It could not be easier than a speed-controlled fan from a computer store and an old 2nd hand 12V power supply (mobile phone charger or similar).
No need for messing around with electronics or other bits, no need to solder or for circuit boards, pots etc.


----------



## BjornJ

Wolfy said:


> As per my posts (and pictures) on the previous page, I have to say I agree with this.
> It could not be easier than a speed-controlled fan from a computer store and an old 2nd hand 12V power supply (mobile phone charger or similar).
> No need for messing around with electronics or other bits, no need to solder or for circuit boards, pots etc.




Sorry, didn't mean to ignore this answer, just forgot to go back and reply.

I tried this version, I bought on ebay a fan controller which was one of those pieces of steel that fits in the expansion slots in the back of the chassis. It connects to power on the motherboard and then to the computer fan, and has a potentiometer and a control knob on it.

The reason I didn't use it is that it is the same solution I have tried when burning two potentiometers with my power supply, the difference was only that now the pot is soldered to something rather than me attaching the wires crudely to the ones I bought from Jaycar :lol: 

Now I am sure the potentiometer solution is a good one, just didn;t work with the power supply I have, I guess. I even went back and bought a bigger potentiometer (1M?) and that one burned as well, so when I got my fan speed controller from ebay and saw that it had a potentiometer again it went straight into a drawer.

Maybe the problem is my power supply?
It's one of those small ones, a plug in the wall and a thin wire I have cut the plug off. (not like a laptop one that has a big box between the power socket and the lead that goes to the pc, so it doesn't look all that powerful but I have of course forgot what the output rating said)


In my defense, I did print out the parts list and drawing from page 28 as suggested by Crozdog as well. Went to Jaycar and just hoped I could get this mythical PWM thing to work. After trying to help me find something, the guy working there didn';t think buying parts and trying to solder something was an option either, heheh.

thanks
Bjorn


----------



## Banshee

Bjornj

Be aware that the unit I posted must not exced 1.5amp input. I think that is equal to 1500mA.

I use a 500mA 12v power pack with a 500k potentiometer. Mine has not burnt out yet, built up only one starter so far. I am aware and been advised that pots are not designed to regulate voltage. That is what the Lm317 is designed for. If and when my pot fails me I will be buying one of the units I posted prior.
When your unit arrives and you get it wired up and running, I would like to get you feedback/response on the unit please.
Cheers.


----------



## BjornJ

Banshee, happy to give feedback of course.
But again all this talk of wiring this and that up, will see if that happens  

Whenever there is talk of tools I think I should ask Barls, so maybe I will have to ask for his advice on this thing as well, hehe.

Bjorn


----------



## brando

MattC said:


> Circuit is from LC's post a while back, The fan wont spin unless the pot is up high, then you have to turn it down. The max speed of the fan is lower than when connected to the fan straight from the 12 V power source. I guess this is the reason why?
> 
> Will grab a 5K pot and wire it up as in diagram.
> 
> I did have a fan controller but its a 4 terminal one and too large for what I need.
> 
> Cheers




I used LC's circuit, but Jaycar didn't have a 5k pot so I bought a 10k pot, and doubled the 680ohm to 1.3k. Hope that is right - working ok so far, but early days.


----------



## BjornJ

checked my power supply now.

it says 13 Volts, 300 mA so hopefully that will be ok.


----------



## barls

bjorn, ill get it off you and have a look if you want.
btw just sent off the email we were talking about the other day.


----------



## BjornJ

Barls, let's have a look at it if you have time when I get the part from China.

Awesome on the other stuff, would be fun if we could pull it off as a small project


----------



## LethalCorpse

brando, you've got it spot on - 10k pot with 1k3 fixed will work just as well, should give you 1.25V - 10.9V


Bjorn, you've got the wrong end of the stick, again. Computer fan speed controllers are not (or at least, bloody well shouldn't be) simple potentiometers. Every one I've ever seen has a small circuit board attached to the pot, which contains a small linear regulator or PWM circuit. The pot is just there for adjustment.


----------



## matho

i havent read thru the 33 pages and if pwm circuit has be dicussed before please forgive me.
i have just finnnished putting this circuit together and it works very well,I havent tried it with a stir bar in a flask yet but will soon




the parts cost about $10 from jaycar, i used a IRFZ40N instead of the stated mosfet because of availablity.

cheers matho


----------



## BjornJ

LethalCorpse said:


> brando, you've got it spot on - 10k pot with 1k3 fixed will work just as well, should give you 1.25V - 10.9V
> 
> 
> Bjorn, you've got the wrong end of the stick, again. Computer fan speed controllers are not (or at least, bloody well shouldn't be) simple potentiometers. Every one I've ever seen has a small circuit board attached to the pot, which contains a small linear regulator or PWM circuit. The pot is just there for adjustment.



This is a pic of the computer fan speed controller I bought.
Looks like just a potentiometer to me, but I am pretty thick on the subject in question so thougth I should put it up here for review  




[


thanks
Bjorn 

edit: forgot to add the pic.


----------



## leiothrix

matho said:


> i havent read thru the 33 pages and if pwm circuit has be dicussed before please forgive me.
> i have just finnnished putting this circuit together and it works very well,I havent tried it with a stir bar in a flask yet but will soon
> 
> View attachment 40566
> 
> 
> the parts cost about $10 from jaycar, i used a IRFZ40N instead of the stated mosfet because of availablity.
> 
> cheers matho



that looks like the one i made. B) 

I used a power darlington instead of a mosfet, also due to availability.

kicks the crap out of a linear power supply.


----------



## Ade42

Adverse Effects said:


> you all seem to be useing a mechanical solution
> 
> has any one looked in to a solid state solution?
> 
> i carnt seem to find what i am looking for but this pic is close
> 
> 
> 
> 
> 
> now take the top disk off so you have a circular array of electro magnets
> 
> then wire them up to something like this in opposing pairs
> 
> http://www.high-voltage-lab.com/169/led-chaser
> 
> 
> 
> tap off the LED's to i think there called triacs? to take the load of trigger the magnets
> 
> replace R2 with a trim pot and maybe even add in a trim pot for the power going to the magnets
> 
> i was looking at about 8 magnets (4 sets of 2)
> 
> *DISCLAIMER* i have never managed to get/make any type of kit to work as i am hopeless with electronics it seems.
> but am i heading down the right path for someone to design and construct something like this?




ahah, thats the "motor" used in my Pioneer Direct Drive Turntable, the motherboad that had the windings on had snapped, so i picked up the complete turntable for nothing, a few weeks micro soldering and is good as new!


----------



## BjornJ

All right, I got the thingy I ordered from ebay.
($10 delivered if anyone else wants one)

It looks like this:




I have a new 12V computer fan ripped out of an old computer, and my 12V power supply.

I understand I connect the 12V power supply on the left where it says "DC AC In" but does it matter where I put plus and minus or will this only impact which direction the fan spins?

On the right side I will connect the black and yellow cables for the fan, again does it matter which is which?

(the thing has no markings for plus/minus positive/negative wires)

Appreciate any help from the electronic wizards on here  

thanks
Bjorn


----------



## matho

Bjorn,
On the input it doesn't matter because it goes thru what is called a bridge rectifier that will make sure the positive goes to the right place. On the output I'm not too sure but I don't think a reverse polarity will hurt the fan it just won't turn so try it and if the fan spins then it will be right but I could be wrong about the fan

Cheers matho


----------



## BjornJ

Awesome, thanks for your help Matho.

Bjorn


----------



## BjornJ

it doesn't work...

Connected the power supply and the fan to the little "voltage controller" and plugged the power supply in the wall.
The fan spins like crazy, the little LED is lit.
Turning the little screw say 10 turns left or right does nothing.
There is no stop either in or out, but screwing quite a bit both ways and no difference in fan speed that I can see.
how is this thing actually controlling/regulating the voltage?


----------



## matho

Bummer

Mate Briton lesands isn't to far from where I work (south Sydney) I could make you a pwm controller like the one I just made for about $15 it will be on proto board but it will work  let me know if you would like one and I'll make it for you 

Cheers steve


----------



## BjornJ

Matho, I've been needing this thing for a year!

:lol: 

And when I log back in to say it WORKS when I swapped the fan for a 0.56A model from the 0.4A one I used first, it suddenly started working.
Maybe the output from the thingy is too high in A for the smaller fan so even when it is set to low it will be too high.

Back on track:
If you can build a "thingy" that I can connect a computer fan to in one end and a 12 V power supply in the other and a way to control the fan speed from outside of the project box (or tell me what size potentiometer to put on it), I will please take two. 
I am sure you could sell a hundred of them on here..

Will PM you my details in case you are willing to build some.


thanks
Bjorn


----------



## matho

Mate I i don't need to make anymore money so a production line is out of the question 
But I'll put two together for you, the one I put together took me just under an hour. I'll get the parts sometime this week and start on it soon. I'm thinking maybe a donation to ahb as payment. Speak to you soon 
Cheers steve


----------



## BjornJ

woohoo, can't wait  

thanks!

Bjorn


----------



## LethalCorpse

BjornJ said:


> Maybe the output from the thingy is too high in A for the smaller fan so even when it is set to low it will be too high.


Not possible - the current rating of a supply in A is simply the maximum current it is able to provide. A load will (for a given supply voltage (V)) draw as much current as it requires. If the load tries to draw too much current, the supply will begin to have problems - fail to regulate the voltage, overheat, catch fire, etc. In short, the current rating on a supply can't be too big, it can only be too small.

And stop saying "power thingy". It gives me the screaming heebie jeebies 



@Matho: Love your work, mate.


----------



## BjornJ

thanks for clearing that up, always interesting in learning more.

I have read a little about the LM317 3 terminal adjustable regulator tonight, more out of curiosuity than anything else  

I have now made it make a whirlpool in my 1 litre erlenmeyer flask by adjusting the height between the magnets and the stir bar with stacking DVD covers on each side, real high-tech!
But it seems really flakey, and doubt it would be able to do a good job of a heavy yeast slurry.
One of my server hard drive supermagnets seems to work better than two of those small super magnets I bought at jaycar glued to a bigger disk to spread them out.

Hoping matho's power thin...eh PWM will work better  .

thanks
Bjorn


----------



## matho

matho said:


> i havent read thru the 33 pages and if pwm circuit has be dicussed before please forgive me.
> i have just finnnished putting this circuit together and it works very well,I havent tried it with a stir bar in a flask yet but will soon
> 
> View attachment 40566
> 
> 
> the parts cost about $10 from jaycar, i used a IRFZ40N instead of the stated mosfet because of availablity.
> 
> cheers matho



putting two together last night i realised that i used a IRF540N instead of the IRFZ40N that i quoted above just thought i would correct myself.

thanks leathal but i can't claim the circuit as my own stole it off the net  

cheers steve


----------



## aussiechucka

Here is a pic of my Stir plate. Thanks for all the info on how to build one. :super: 
HAve already used it a couple of times. 
Thanks
Chucka


----------



## Ade42

matho said:


> Mate I i don't need to make anymore money so a production line is out of the question
> But I'll put two together for you, the one I put together took me just under an hour. I'll get the parts sometime this week and start on it soon. I'm thinking maybe a donation to ahb as payment. Speak to you soon
> Cheers steve



Gday mate, Just wondering if you could take some pic's of your PWN proto board, both sides please! 
I'm going to make up a couple and could do with the help, if its no trouble of course!


Is the circuit that you have posted before 100%? (don't wanna buy the wrong bits, or ask you to make me one! but if you are cool with a donation ahb i'd be up for that as well!)


Cheers
Ade


----------



## matho

hey ade
yes this circuit does work with the parts that are shown, as i said i used an IRF540n mosfet instead of the IRFZ46n just because jaycar doesnt stock it. I have just about finnished the one's for bjornj so i can take a few pics tomorrow for you.
about making one for you i dont really want to get into the hassle of posting and stuff like that, as luck would have it bjornj works just around the corner from me so its convenient for me sorry mate

cheers steve


----------



## matho

here is some pics as i promised hope this helps out






 is a link of a video i took of the controller in action its not the best but i took it from stopped up to full speed and back down again it can go down to just over 1 revolution a second.

cheers steve


----------



## BjornJ

Does that mean I soon will have a working stir plate!!?

woohoo :lol: 


Happy.Very.

Bjorn


----------



## Ade42

matho said:


> here is some pics as i promised hope this helps out
> View attachment 40930
> 
> 
> View attachment 40931
> 
> 
> is a link of a video i took of the controller in action its not the best but i took it from stopped up to full speed and back down again it can go down to just over 1 revolution a second.
> 
> cheers steve





Thanks, I'll help!. Just got all the bits from Jaycar, They don't have any IN5818's so i opted for the IN5819 Ive looked at the spec sheets and i hope it works. ok if i blow some 555's. I just found a box of dozens!


----------



## LethalCorpse

That's fine - the only difference between the 1n5818 and the 1n5819 is the maximum reverse voltage they can handle - not a problem in this circuit


----------



## matho

As lc has said the diodes rating in this circuit isn't critical so the ones you have got will be ok. There is two easy ways to blow a 555 timer one is reverse polarity and the other one is overvolts. I put 2 extra diodes in the circuit that I made for bjornj so that if a reverse polarity was put on the input then it would not hurt the 555 timer it just wouldn't work until the polarity was fixed. Thinking about it now I should have put a zenner diode across the input too so it would limit the supply voltage. I did tell him not to go over 13 volts


----------



## BjornJ

Point taken, will stay with the current 12V power supply I have  

Thanks again for your help, I can now stir plate away like a proper homebrewer!








thanks
Bjorn


----------



## Ade42

LethalCorpse said:


> That's fine - the only difference between the 1n5818 and the 1n5819 is the maximum reverse voltage they can handle - not a problem in this circuit
> i dont really want to get into the hassle of posting and stuff like that, as luck would have it bjornj works just around the corner from me so its convenient for me sorry mate



Thought thought the 19's would be ok. 

No probs, I should build one myself anyway! spent about 5 years recently hot iron in hand fixing big power amps and all manner of cinema electronics including digital cinema which i helped desighn the boards/software etc (left as there was no money in it, was paid 12$ an hour!), one thing i miss is my Cro! I asked in a moment of lazyness, sorry!


----------



## matho

Ade42 said:


> Thought thought the 19's would be ok.
> 
> No probs, I should build one myself anyway! spent about 5 years recently hot iron in hand fixing big power amps and all manner of cinema electronics including digital cinema which i helped desighn the boards/software etc (left as there was no money in it, was paid 12$ an hour!), one thing i miss is my Cro! I asked in a moment of lazyness, sorry!



Don't be sorry, give it a go and if you can't get it to work let me know and we will sort it out. But by the sounds of it you'll be right, I'm an electrical fitter by trade electronics is just a hobby.

cheers steve


----------



## matho

My 2l and 3l flasks turned up today so I could try out my stir plate for real
I'm using an 80mm 0.2A fan with 2 10mm rare earth magnets an a 40mm * 7mm stirbar I'm very happy with the results 

Cheers steve


----------



## Silo Ted

Just built a circuit for a stir plate this afternoon, and the fan I have has four wires, black, yellow, blue and green. which is (+) and which is (-) ?


----------



## Silo Ted

Silo Ted said:


> Just built a circuit for a stir plate this afternoon, and the fan I have has four wires, black, yellow, blue and green. which is (+) and which is (-) ?



Anyone ?


----------



## leiothrix

On 3 wire computer fans black is negative, red is positive and yellow is clock out (which you can ignore). what blue and green are I have no idea.

According to this black is negative and yellow is positive.

I'd suggest getting a 9V battery and playing around. or finding a 2 or 3 wire fan.

Rob.


----------



## argon

Trying to put a stirplate together with a few bits an pieces i have lying around.

I have one of these speed controllers; 




It has one male 3pin connection that is connectd to an 80mm 3 pin cpu fan and a female connection that would normally pug into cpu 3 pin male connection to supply power.

I was going to cut the female connection and hard wire it to the 12v power adaptor. But wasn't sure if this would just kill it 

Question is how do i supply power to the speed controller? Can i get a power source that can be connected to a 3pin female plug.

Was thinking something like this where i could just connect the adapter to this and then plug them together?



Any help?


----------



## sav

Mines done TP will be proud,havent got a stir bar yet and a flask

sav


----------



## TidalPete

sav said:


> Mines done TP will be proud,havent got a stir bar yet and a flask
> 
> sav



Sure looks good Jamie. Bring it around after work one day soon & we'll give it a trial run. :icon_cheers: 

TP


----------



## sav

TidalPete said:


> Sure looks good Jamie. Bring it around after work one day soon & we'll give it a trial run. :icon_cheers:
> 
> TP




no worrys mate I have some r earth magnets out of hard drive if you want them,I ended up buying them strong 20 cent size from jaycar


----------



## Nevalicious

Dont know if its been posted earlier in this thread, not really prepeared to go through 27 pages of text, but this is where I got my rare earth magnets from

Cheap as, relatively fast delivery (from Hong Kong I believe)

Jaycar are a rip off and is staffed by people who dont know what they're talking about. Working in an electronics store and dont know what PWM stands for... Huh??


----------



## LethalCorpse

Most of the people on this forum didn't know what PWM stood for before this thread. I didn't know what PWM stood for until about the second or third year of a computer engineering degree, and I majored in embedded systems. My point is that there's a vast wealth of information in the field that, unless you've got to use it in every day life, you've probably had no reason to learn what it means. I can guarantee you're the first customer that staff member has ever had who wanted to talk to them about a PWM circuit, and almost certainly the last for a fair while. They might go away and learn about it, though from the tone of your post, I suspect they're going to go away and talk about the asshole who chewed them out for not knowing what PWM was. 

Just because it's simple doesn't mean everyone should know it already. At the same rates as staff in any other retail store, you're extremely fortunate that most Jaycar stores have employees who do know a fair bit about their products. They could stand behind the counter and ring up your purchases, but you'll find they generally make an effort to assist you - provided you don't give them unnecessary attitude.


----------



## Nevalicious

BjornJ said:


> I went to Jaycar again on Saturday, asking for some help to get that PMW "thingy" to control the fan speed.
> After a bit of digging in their system they found that it stands for Pulse Width Modulator, and that they don't have any.
> Or at least that there is nothing "ready" I could buy.



Should've quoted this LC, but this was what I was reffering to. I personally didn't go in there and "chew him out". I stand by what I wrote though. Jaycar are a flat out ripoff and definitely, SOME of the staff couldn't give a rats arse about helping you. Same goes for alot of the retail sector I think



LethalCorpse said:


> Most of the people on this forum didn't know what PWM stood for before this thread. I didn't know what PWM stood for until about the second or third year of a computer engineering degree, and I majored in embedded systems. My point is that there's a vast wealth of information in the field that, unless you've got to use it in every day life, you've probably had no reason to learn what it means. I can guarantee you're the first customer that staff member has ever had who wanted to talk to them about a PWM circuit, and almost certainly the last for a fair while. They might go away and learn about it, though from the tone of your post, I suspect they're going to go away and talk about the asshole who chewed them out for not knowing what PWM was.
> 
> Just because it's simple doesn't mean everyone should know it already. At the same rates as staff in any other retail store, you're extremely fortunate that most Jaycar stores have employees who do know a fair bit about their products. They could stand behind the counter and ring up your purchases, but you'll find they generally make an effort to assist you - provided you don't give them unnecessary attitude.



Now who has the unnecessary attitude?


----------



## LethalCorpse

Nevalicious said:


> Now who has the unnecessary attitude?


Still you. Sure, some of the staff are retail bunnies - it's a retail store, you get that. I've not yet walked into a store that didn't have at least two people who knew their stuff, though. If you can't find them, maybe you're unlucky enough to be in a store full of n00bs and idiots. Maybe they just have a reason for not wanting to help _you_ beyond the bare minimum. 

You're unlikely to be able to buy a PWM controller off the shelf by saying "I'd like to buy a PWM please". That's like saying I'd like to buy some elevation, when what you want is a ladder. You can buy controllers which use PWM, such as fan controllers and motor speed controllers. Or, you can buy the components as I specified earlier in the thread and build it yourself. The fact that you didn't know what you were looking for is not the salesperson's fault, and it's not their job to work out what you're trying to build and design a circuit for you on the counter. If you go in with a circuit, they'll sell you the parts. BjornJ had all the information, parts list etc he needed to get it working, but he went in and said "I'd like a PMW thingy". Nothing wrong with having no idea what the hell he's doing, but you also can't expect the staff to do it all for you.

As for them being a flat out rip-off, do you have any basis for this, or are you just throwing shit out there? Do you have an in depth understanding of the retail electronics market segment? Do you have price comparisons against similar businesses? Or are you going on the fact that you can buy components cheaper on ebay or online wholesalers? Ebay sellers don't need to pay for shop frontage, or for all those staff for whom you have so much disdain. Their marketing is basically free, and their freight costs are low because they come direct from the distributor (or even the factory). It's also far less convenient than being able to walk into a store on a Sunday afternoon and walk out with all the parts you need - hardware, tools, etc included. If you go in and buy a whole bag of electronics components, and the salesperson spends an hour with you rooting through the bins and counting resistors, and the total bill comes to $12.50, so you seriously think they're ripping you off? How much do you think they spent on that hour of salesperson time? Never mind the cost of the components. Based on the costs of running a retail operation, Jaycar is actually very competitive, and it's the reason they're still operating when most other electronics retailers have shut shop or started selling TVs and toasters. You don't have to like them, or even shop there. But don't rubbish the business or the staff in a public forum.


----------



## argon

so i've got my stir plate built... i can control the speed of the fan with magnets attached... However the stir bar won't rotate... it just jumps around all over the shop. I can slow the fan right down or speed it up... same thing. I can lower the fan or get it really close.. same thing. doing my head in. Can't figure it out.

The fan and magnets are setup pretty much exactly like this;



and i'm using the stir bars from digitalhomebrew


----------



## DU99

i got my magnets from http://aussiemagnets.com.au/..make sure the vessel has a flat bottom..i mounted some 3mm rubber in each of the corners,and used a piece of 2mm glass and it works fine


----------



## mika

Have you got the same pole of the magnets towards the glass ? Pretty sure they need to be opposite, can't remember. Got it wrong when I built mine and had to swap the magnets over.


----------



## argon

mika said:


> Have you got the same pole of the magnets towards the glass ? Pretty sure they need to be opposite, can't remember. Got it wrong when I built mine and had to swap the magnets over.




errrr... dunno... gonna be fun getting home tonight and un-glueing one of the magnets from the fan, then turning over. So you're saying 1 magnet with positive up and the other magnet with negative up?


----------



## leiothrix

Yup, one N up and the other S up. A hot air gun (or hair dryer i suppose) will soften the glue up nicely.


----------



## argon

Ended up sorting it out... magnets were marginally too far apart.

Goes like a rocket now in 2L... psyched to get a starter going soon


----------



## a1149913

Just curious, do you run the the stir plate just at the start to airate it, or for the whole starter ferment proces?

Thanks


----------



## barls

just the starter


----------



## BjornJ

Thanks for keep bringing up my name and "has no idea what the hell is he is doing" all the time, guys  

Just wanted to say a big THANKS again to Steve/matho for taking pity on my electronics skills and building a controller "thingy" (I know, I know..)

It works brilliantly, it spins the fan beautifully and by turning the little bar I can control it from slowly moving yeast around to full-on tornado.
Very cool little thing!

thanks again
Bjorn


----------



## matho

It's good to hear that you got it working bjorn I have a 2l starter going at the moment

Cheers steve


----------



## argon

Jacob Thomas said:


> Just curious, do you run the the stir plate just at the start to airate it, or for the whole starter ferment proces?
> 
> Thanks


For an active "starter" just run the stir plate until you see some signs of fermentation... ie bubbles running up the side of the flask, start of a krausen etc. Then turn it off. You don't want to be adding oxygen to the wort once fermentation is underway. This will oxide the wort giving off flavours when you add the entire contents of the active "starter" to the waiting wort. You want to pitch active "starters" to the wort at the peak of fermentation, this gives the yeast a running start at the main wort.

For yeast culturing/stepping up, keep the stir plate going the whole time until fermentation is complete. Then crash chill the wort to settle the yeast. Decant the oxidised beer from the yeast cake and either pitch just the slurry to the wort or add more wort to the flask for a step up, in order to produce more yeast.


----------



## a1149913

Thanks, thats exactly what i was after. My plan it to run it during the step up phase and then following crash chilling, re suspend using fresh wort and then pitch.



argon said:


> For an active "starter" just run the stir plate until you see some signs of fermentation... ie bubbles running up the side of the flask, start of a krausen etc. Then turn it off. You don't want to be adding oxygen to the wort once fermentation is underway. This will oxide the wort giving off flavours when you add the entire contents of the active "starter" to the waiting wort. You want to pitch active "starters" to the wort at the peak of fermentation, this gives the yeast a running start at the main wort.
> 
> For yeast culturing/stepping up, keep the stir plate going the whole time until fermentation is complete. Then crash chill the wort to settle the yeast. Decant the oxidised beer from the yeast cake and either pitch just the slurry to the wort or add more wort to the flask for a step up, in order to produce more yeast.


----------



## technoicon

definatly on my to do list


----------



## argon

jimmy01 said:


> Hi Argon
> 
> I built one of these but can't get it to work properly. I have a feeling that the magnets may be too far apart.
> What size stir bar do you use?



In response to the above that was in the other thread (not wanting to derail that one)

I use the 25mm stir bars as available from digitalhomebrewer.com 

I too had a problem with the bar "taking" so I moved the magnets much closer together. This sorted it out immediately. The bar was kinda jumping about and would spin. Definitely move them in a bit and see how that goes.


----------



## jimmy01

Thanks Argon.


----------



## jpScarfac3

Brewer Pete said:


> Got a weekend night to myself away from SWMBO so started noodling around in the shed and by late evening got stuck into pulling the drill press out of storage and reassembling it.
> 
> Prototype 240Volt AC Stirplate.
> 
> Cooling holes on all sides, large venting holes below.
> 
> I have ditched the top for now as will use either clear acrylic top or simple idea of using a rubbermaid or tupperware style container, square in place of the lid. The Flask sits in the tupperware container which is a spill containment receptacle in case of excessive foaming.
> 
> I have to go look at plastic containers and see how much if at all they depress under different weights to build the magnetic disc height to get the magnets right up against the plastic container while not touching. This should get the magnets up close as possible to the flask while keeping them as far away from the fan as possible.
> 
> Full 240 Volt Shaded Pole Fan controlling Triac with 240Volt switch and noise suppression circuitry.
> 
> I have a conduit box I will cut down to make a sealed environment in which to do all the wiring. Thinking about a silicone seal around the Triac compression fittings.
> 
> As you can see this is a monster fan with enough guts to pull through some large batches. Not a bad eBay buy at $14 compared to Jar Car.
> View attachment 26847




I ordered all the gear for an AC stir plate but I only got a 80mm fan. As long as the stir bar is the right length, I'm hoping it'll still work. Obviously I haven't put it together yet but wanted an opinion.


----------



## Wolfy

Its time to build up some large lager-yeast starters so I needed another stir-plate.
Here is my DIY Stir-Plate V3.

120mm speed-controlled PC cooling fan. ($12 on special at PC Case Gear)
12V power adapter. ($2.05 Ebay)
8x small rare-earth magnets. ($4.50 for 20 from DealExtreme).
On/off switch. (~$2 Electronics shop)
Solder, a few bits of wire and some gaffer-tape so the screws don't scratch the glassware.




... and a good use for old fermentor lids, no need for them if you cling-wrap.

Total cost was under $20.

There is an abundance of 'LED Dimmers' on Ebay now that also make good speed-controllers, but I was lucky and got it built-into the fan.


----------



## bullsneck

Nice one there Wolfy!! I'd love to see the underside in pics.


----------



## Wolfy

bullsneck said:


> Nice one there Wolfy!! I'd love to see the underside in pics.


Didn't really think to make it neat on the underside, but here you go:





Assembly:
_(If you were happy to turn it on/off via the wall-plug, wire the red/black wire from the adapter-cable to the matching red/black wires from the fan and mount/house it - nothing more!)_

What I did for what you see above:

Cut adapter plug and fan connector off.
2 lengths of wire to run the power from the 'back' to the 'front' where the controls are.
Then black wire from the adapter goes straight to the black wire from the fan.
Red wire from adapter goes to one terminal on the switch, then the red wire from the fan goes to the other switch-terminal (essentially connecting the two red wires together when the switch is turned on).
(Yellow fan wire is cut/not used).
The white wires are for the control pot, and come pre-assembled with the fan (I had to cut/rejoin them since the fermentor lid has a double-lip).

Fan is "Scythe 120mm Blue LED with VR Fan (SY1225SL12VBL)" and setup like this seems to stir stuff well through the speed range of the fan which the specs say is 800-1600RPM.

Magnets are super-glued to the fan-hub same as my old one: http://i184.photobucket.com/albums/x37/k_w...r/stirplate.jpg
From my limited tests, seems best to place the magnets as far apart as the length of the stir-bar, just the 2 inner ones are fine for a small stir-bar, but the longer one needed the addition of the extra magnets. There are 8 magnets used (stacked 2 high) I don't know if doubling them up makes it stronger or just lifts them a little closer to the 'surface' but it works better for me that way.


----------



## felten

very cool, sure beats spending $50 to get one from O/S


----------



## lagers44

Hey Wolfy , I hear the little green men want their ride back ! S.E.T.I may come knocking at your door too.





Wolfy said:


> Its time to build up some large lager-yeast starters so I needed another stir-plate.
> Here is my DIY Stir-Plate V3.
> 
> 120mm speed-controlled PC cooling fan. ($12 on special at PC Case Gear)
> 12V power adapter. ($2.05 Ebay)
> 8x small rare-earth magnets. ($4.50 for 20 from DealExtreme).
> On/off switch. (~$2 Electronics shop)
> Solder, a few bits of wire and some gaffer-tape so the screws don't scratch the glassware.
> 
> 
> 
> 
> ... and a good use for old fermentor lids, no need for them if you cling-wrap.
> 
> Total cost was under $20.
> 
> There is an abundance of 'LED Dimmers' on Ebay now that also make good speed-controllers, but I was lucky and got it built-into the fan.


----------



## Dazza88

Awesome stuff, planning and visiting ebay now. 

It's difficult to search for speed-controlled fans on the net and that model isn't on PC case gear. In the spirit of being a tight arse, i am looking for the cheapest option. Are the LED dimmers easy to connect up to a PC fan? Would i be looking for a specific type of fan if i went the LED dimmer route?


----------



## keifer33

DazDog said:


> Awesome stuff, planning and visiting ebay now.
> 
> It's difficult to search for speed-controlled fans on the net and that model isn't on PC case gear. In the spirit of being a tight arse, i am looking for the cheapest option. Are the LED dimmers easy to connect up to a PC fan? Would i be looking for a specific type of fan if i went the LED dimmer route?




Found this one for around $15 shipped from US which isnt too bad. http://www.ebay.com.au/itm/Antec-3-Speed-1...=item53e7ef8e3e

They have a little switch that you can flick and it changes the speed.


----------



## supachikn

Hi fellas.
Here are a couple of pics of my cheapo stirplate. It's in use at the moment so I can't provide detailed shots of the internals.
I took a 25 CD-R spindle and cut the middle pole out of it. I used an 80mm fan from a disused PC, and put a couple of zinc plated dome head 4-5mm thread screws and put them in the mounting holes so I could adjust the distance of the fan from the top of the spindle and also this provides the structural support for the glass flask. I hot glued it into place as the polypropylene spindle doesn't much like superglue, and epoxy was a PITA. I used small 3x5mm neodymium magnets out of those magnetix childrens toys that were taken off the market (the plastic rods would crack and the magnets fell out, no good for kiddies to eat  .) Had alot of trouble initially trying to get the stir bar to bind to the magnets on the fan. Using a 12V supply the bar would whip away from the centre of the flask and just sit at the side and wiggle. Using a 5V supply the fan didn't have the balls to make the thing spin at all. Ended up using a small 7.5v switch mode supply that I just turn on and off at the mains. I did glue the magnets pretty far apart (maybe 25-30mm) so I wonder if putting them more centrally might have worked better at 12V. As you can see from the action shots it doesn't quite have the same punch as a lot of other DIY units out there but it keeps the yeast in suspension well enough. I find I have to use another magnet to locate my stir bar in the centre of the flask before placing it on the plate because the magnets don't have the strength to pull it into place, and my flask isn't totally flat on the bottom, it has a central plateau.


----------



## Wolfy

DazDog said:


> Awesome stuff, planning and visiting ebay now.
> 
> It's difficult to search for speed-controlled fans on the net and that model isn't on PC case gear. In the spirit of being a tight arse, i am looking for the cheapest option. Are the LED dimmers easy to connect up to a PC fan? Would i be looking for a specific type of fan if i went the LED dimmer route?


Google search for the model number brings up a few Australian suppliers, but if you can't get them on special using a 2nd-hand computer fan and an LED dimmer might be cheaper/easier.
The dimmer should be very simple to wire up since only has 'in' and 'out' ports which are clearly labeled (according to the Ebay pics I looked at).


keifer33 said:


> They have a little switch that you can flick and it changes the speed.


I find the variable adjustment much easier to get things going well, rather than just a couple of set-speeds.


Supachikn said:


> Here are a couple of pics of my cheapo stirplate. It's in use at the moment so I can't provide detailed shots of the internals.


Nice work, I'm just not sure I'd trust a 2L flask or 5L demijon on one of those CD spindles. 
I found that if you put the magnets as far apart as your stir-bar is long it seems to work well.
If they are not glued on too tightly you might like to adjust the magnets and/or how far from the bottom of the flask they are, because they should easily 'grab' the stir-bar when you move the flask over the top of them.


----------



## keifer33

Ah very good point Wolfy. Will have to get onto making one of these soon as I have most of the parts lying around.


----------



## Dazza88

So Wolfy, led dimmers wire up like a switch? Red wire in then out? Looking at the ebay listing l guess that the power supply wire go into v in and then the wires coming out will connect s per your above explanation.


----------



## argon

DazDog said:


> So Wolfy, led dimmers wire up like a switch? Red wire in then out? Looking at the ebay listing l guess that the power supply wire go into v in and then the wires coming out will connect s per your above explanation.


Dazdog and alternative to a speed controlled fan is to use an adjustable voltage power pack like this one. 






They're available at Jaycar reasonably cheap and can be used for all sorts of things. 

I use one in my stirplate and just adjust the voltage, which in turn adjusts the speed of the fan. I've also installed a small plug in the jiffy box, which the fan is connected to, so i didn't have to cut the chord. This way i can use the power pack for other stuff.

All you really need is a pc fan, some magnets, a stir bar, an adjustable power pack and something to house it in to have a workable plate.

Unfortunately reading this entire thread gets pretty confusing for a guy like me who doesn't really understand electronics too well. All this talk about capacitors, potentiometers and wotnot... did my head in. But i ended up getting it worked out.




(i tried some speed control as you can see by the little knob... but ended up by passing it)


----------



## Dazza88

Thanks argon, 
That might be better as I have old computers with fans. 

Hey, you being a brisbanite, was going to ask about water additions for mash. If there was a general suggestion for brissy water? But typing on phone is annoying so ask more detail later.


----------



## Wolfy

DazDog said:


> So Wolfy, led dimmers wire up like a switch? Red wire in then out? Looking at the ebay listing l guess that the power supply wire go into v in and then the wires coming out will connect s per your above explanation.


The LED dimmers have in/out ports for both the + and - (red and black) wires.
You'd attach the red/black power-adapter wires to the 'input' side, and the red/black wires from the fan to the 'out' side.
That would work for the two main types of LED dimmer on ebay:
http://www.ebay.com.au/itm/LED-Light-Dimme...=item2a1175b21c
http://www.ebay.com.au/itm/Wireless-Remote...=item2a11438358

If you need to buy a power-adapter getting a variable voltage one as *argon *suggested works fine (but can be more expensive), however they only allow speed control in steps (exactly the same as the 3-speed fans linked by *keifer33*), not gradual changes from slow to fast, which can be nice.


----------



## Dazza88

Yeah, might go the dimmer route. 

Thanks guys.


Anybody buy stirrer bars from o/s (e.g. china) or just go local? Are pivot or egg stirrer bars better?


----------



## Wolfy

DazDog said:


> Anybody buy stirrer bars from o/s (e.g. china) or just go local? Are pivot or egg stirrer bars better?


I assume that even the 'local' ones are made in China, so if you find a (cheap) O/S supplier let me know, I need a couple more.

But no, pivot bars tend to be very noisy and do not work any 'better' for growing yeast-starters.


----------



## Dazza88

I have checking ebay, pivot type are by far the most common. 

I was thinking this one. http://www.ebay.com.au/itm/New-1-5-egg-PTF...3#ht_2341wt_905 

says suitable for 500 ml to 1000ml .

This shop appears cheap: http://www.ebay.com.au/itm/VWR-Scientific-...05#ht_500wt_922 

But i am not sure what the local prices are. 

Noise isn't a huge concern as my brew room is far away from my bedrooms (and is small and reasonably constant temp)


----------



## Dazza88

labdirect dot com dot au seem reasonable?


----------



## jonw

Here's my TASP. Had to buy the magnets (from Jaycar) and the film cannister from Reverse Garbage (so almost free), but otherwise it's completely scrounged. Also bought my stirrer bars from Livingstone - ordered yesterday, arrived today.

Here are the inner workings. I'm using a Zalman "fan mate" fan speed controller (i.e. voltage not PWM) I had around.




and with the lid on..




and in action...




The 20mm stir bar gets a slimline vortex going and is almost silent. The 40mm bar is shown in the pic above, but makes quite a rattle - might have to save that for starters done in the ferment fridge. Looking forward to getting to work on some yeast!

Cheers,

Jon


----------



## a1149913

I've got 1.5L flasks and was wondering what size stir bar would be alright for 800mL starters?

Also do the stir bars have to be magnetic?


----------



## Wolfy

Jacob Thomas said:


> I've got 1.5L flasks and was wondering what size stir bar would be alright for 800mL starters?
> 
> Also do the stir bars have to be magnetic?


Yes they need to be magnetic or they will not work.
I find that a size between 20 and 30mm works fine for my DIY-computer-fan-setup.


----------



## MaltyHops

Here is my attempt ... had all the parts from my bit-n-pieces collection
except for the magnets (ebay) and thanks to DrSmurto for the stir bar.



 



T.


----------



## felten

Finally put mine together tonight for a test run, the magnets took over a month to arrive. >_<

Stirbar, fan controller and magnets sourced from eBay thanks to Wolfy's DIY thread. Here it is at full power 3L flask, 1.5" egg shaped stirbar, and it's ineffably quiet.



The case is an old Tupperware container. Also an 80mm fan and 10 x 10x2mm magnets stuck on, split evenly on both sides. They're spaced the same length apart as the stirbar.


----------



## Gar

Finished my T.A.S.P this morning, It'll get christened this weekend on a strong scotch ale  

















How long before brew day do you guys make your starters with a stir plate?... 24hrs?


----------



## mika

Sweet looking case ! what's it from ?

After all the talk earlier in the thread about people burning out the pot's and LC's real simple explanation of the speed control circuit, I don't understand why people are still building stirplates with an inherently flawed design ?


----------



## Gar

mika said:


> Sweet looking case ! what's it from ?



It's from a wine tools gift set



mika said:


> After all the talk earlier in the thread about people burning out the pot's and LC's real simple explanation of the speed control circuit, I don't understand why people are still building stirplates with an inherently flawed design ?



Oh ohhh, have I missed something important here?

I'm using a simple circuit with a 1k pot, it's been running all morning on close watch so far


----------



## mika

The pots seem to burn out over time. They'll last for quite a while, but then ultimately die. Hence the circuit LethalCorpse came up with. Pretty simple and cheap, lot of people built it and using it quite happily as far as I'm aware.


----------



## Gar

Bummer, I might have to have a re-think....

I'll use it for this one brew though (in a safe place), cheers mika :beer:


----------



## kjparker

Gar said:


> Bummer, I might have to have a re-think....
> 
> I'll use it for this one brew though (in a safe place), cheers mika :beer:


By burn out though, I would think they mean stop working, not burst into flames....


----------



## mika

clueless said:


> By burn out though, I would think they mean stop working, not burst into flames....



Yup...


----------



## Gar

These things are like lava lamps, I keep catching myself standing, staring at it's swirly goodness ^_^ 

Eat, fart and be merry my little children... the main course will be coming soon


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## ben_harvey

Bam.




That's a Wyeast 3068 on the plate for my first ever Weizen. Can't wait!



That's a structural toilet roll holding the fan up. Don't use a Sorbent roll or you'll have issues with torsional rigidity.

But seriously I didn't want screws poking out the top and it was the best thing I could find. I have a feeling that it will be a temporary solution that works so well that I never get around to...


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## Gar

batman said:


> Bam.



Nice, I thought that was a toilet roll  



mika said:


> The pots seem to burn out over time



Well my pot survived one starter pfffft lol

Ah well... like the 6 million dollar man... "we can rebuild him, we have the technology!"


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## Wolfy

Gar said:


> Well my pot survived one starter pfffft lol
> 
> Ah well... like the 6 million dollar man... "we can rebuild him, we have the technology!"


Mine have been working fine for 2-3 years now, so you should not need to rebuild it too often.


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## Gar

Well I finally got off my bum and rebuilt the stir plate, thanks very much to everyone suggesting the LED Dimmers, seems to work a treat :beer: 






I was quite surprised that all the components fit snugly into my existing box.... the dimmer box itself was quite bulky but the guts are nice and small.


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## lickapop

I didnt really feel like reading thru 38 pages but I was wondering.. can I just connect the little nob thingy to the mountable jack without having to build that LMthingy circuit? 
oh and where do I buy earth magnets from and what size?

lolz sorry just taking the piss.


great thread. I have read it 3 times already. love your work, especially LC's noob friendly circuit instructions

I am going to knock a DC version up over the next couple of days but I was also wanting to build an AC version.

I happen to have a HPM fan controller laying about, and also a 240V 120mm computer fan. I would like to know how I should wire this up. I cannot find clear instructions especially from brewer petes build or Doc.

I am extremely confident in wiring 240v if given enough instruction. The STC-1000 thread was great for that

So if anyone gets a bit of time can you please just throw up a little sketch please or some written instruction

Thanks all


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## Wolfy

lickapop said:


> I am extremely confident in wiring 240v if given enough instruction. The STC-1000 thread was great for that
> 
> So if anyone gets a bit of time can you please just throw up a little sketch please or some written instruction


Either you are confident or you need help ... not both.
Its 240V, it can kill you or someone else, if you're asking for help - stick with the 12V computer fan not a 240V one.


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## lickapop

No worries. 
I didn't think about it until now but the same controllers are in my house. When I get the chance I will pop them off the wall and see how the are wired up

Or I will just stare at it long enough that it will come to me. I bet it is real simple lol


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## [email protected]

lickapop said:


> No worries.
> I didn't think about it until now but the same controllers are in my house. When I get the chance I will pop them off the wall and see how the are wired up
> 
> Or I will just stare at it long enough that it will come to me. I bet it is real simple lol



I have the same kind of fan. I was thinking of buying one of these http://www.ebay.com.au/itm/Fan-Speed-Contr...9#ht_500wt_1202

only $35 - although some of the comments say it looks homemade, they would have to be a sparky to sell such a thing you would think?
Would be good to know how to wire one up with a diagram like stc 1000, but all in all it would prob be safer to get a local sparky to wire one
up for me, whether or not that would work out cheaper than ebay option?


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## lickapop

Yeah some of those stc1000 diagrams are awesome. I built a couple of them. 
Thanks I saw one of those controllers on eBay. I have a professional manufactured one at home already but you know how it is... It's just another box hanging off your stir plate that gets in the way of your beer mug
I want mine to look sexy.


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## lickapop

Wolfy said:


> Either you are confident or you need help ... not both.
> Its 240V, it can kill you or someone else, if you're asking for help - stick with the 12V computer fan not a 240V one.



 I am confident that I can copy someone who knows their stuff. not a problemI don't want to die. I can strip a wire while it is not plugged in


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## lickapop

yet another stir plate.
240V this one. It whirlpools 4-5L right to the bottom 

Thanks all... Im stoked.


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## Truman42

Just built myself a stir plate but not sure what size stir bar to use. Ive used a hard drive magnet which is 35mm long. So not sure if I should buy a 30mm stir bar or a 40mm one.

Those of you that have used hard drive magents, what size stir bar did you find worked best?

Thanks.


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## sp0rk

So after reading the whole thread I've decided I'd like to make a stir plate
while cleaning out a wardrobe today i pulled out an old pc to put out for the council clean up
but first I stripped it of all fans, useful wires, power supply and the old 40gb HDD that was in it
I've gutted the HDD to remove the magnets and also pulled out the drive motor
after about an hour of googling and watching youtube videos, I've figured out I can use the drive motor to power my stir plate
an R/C servo tester for rpm control and a brushless speed controller to convert from DC power to the 3 pole motor
the servo tester was $2.70 and the speed controller was $7.20, both on ebay
the speed controller is rated 20A 6-12v so I can either use a 6v torch battery, phone charger or the computer power supply (which i'm planning on customising into a 12v power supply for other projects)

I'll post more on the progress of this once the servo tester and speed controller get here


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## ledgenko

argon said:


> For an active "starter" just run the stir plate until you see some signs of fermentation... ie bubbles running up the side of the flask, start of a krausen etc. Then turn it off. You don't want to be adding oxygen to the wort once fermentation is underway. This will oxide the wort giving off flavours when you add the entire contents of the active "starter" to the waiting wort. You want to pitch active "starters" to the wort at the peak of fermentation, this gives the yeast a running start at the main wort.
> 
> For yeast culturing/stepping up, keep the stir plate going the whole time until fermentation is complete. Then crash chill the wort to settle the yeast. Decant the oxidised beer from the yeast cake and either pitch just the slurry to the wort or add more wort to the flask for a step up, in order to produce more yeast.



Totally OT ... Cheers Argon.. My 5 brews I have done each at 50lt which have had a yeasty / off taste ... Maybe explained by your sims explaination... 
Cheers


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## sp0rk

Well, my hard drive motor stir plate experiment is over quicker than i thought
because of the shaft in the centre of the motor, i can't mount the hdd magnet over the middle
so i ended up just grabbing a project box and switch from jaycar
and using a variable voltage power pack from bunnings
8cm fan and a hdd magnet sourced from old pc
i've got some rare earth magnets coming in the mail, as the hdd magnet seems a little too strong


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## peterl1981

hey lads,



I have just made a stir plate, but the pot dose not work properly, it only goes flat out or off, so it only uses one end of pot...



what would be the problem??


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## christmas

I pimped mine out with a glowing blue fan and a six buck ebay temperature display


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## OneEye

I'm throwing together the bits and bobs to get a build for myself going. I've done a few simple circuits before but just have one question for those out there who have a bit more of a grasp on this than me.

Following along with LC's circuit, it calls for a 680Ohm Resistor. From what I already have laying around, I have 6 100 Ohm and 1 80 Ohm resistors. If I place them together in series will that give me the same result?


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## leiothrix

Yes it will, resisters values are additive when placed in series.


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## OneEye

I thought so but wasn't 100%. I've knocked it all together and she's working a beauty!


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## christmas

When I turn the speed down to a reasonable level, mine emits a horrible high pitched noise. Pretty much anything under full speed will get it.

Anyone know why this could be?

I think it's because I tried to make mine all flash and used a fan with LEDs in it, and they don't take kindly to being dimmed.

I might try stuffing the box full of foam to try and limit it a bit. Failing that, starters are gonna have to be made in closed room somewhere. I really don't feel like replacing the fan, this thing has already been a whole load of dicking about.


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## blotto

christmas said:


> I think it's because I tried to make mine all flash and used a fan with LEDs in it, and they don't take kindly to being dimmed.


I'm not sure why it would be making noise but I cut the cables to the LEDs on my fan in my brew fridge because light is bad for the yeast, you could give that a go?


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## NewtownClown

Wort said:


> I'm not sure why it would be making noise but I cut the cables to the LEDs on my fan in my brew fridge because light is bad for the yeast, you could give that a go?



As far as my limited research has revealed, visible light only has an effect on brewers yeast when grown at/below 12C.
Ultraviolet light actually increases the growth rate of yeast and studies proved that beer ferments quicker under UV, however there is a fine line between intensity and exposure time, the UV will eventually kill the yeast.

From that, I'd argue your little LEDs wont cause harm.


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## blotto

NewtownClown said:


> As far as my limited research has revealed, visible light only has an effect on brewers yeast when grown at/below 12C.
> Ultraviolet light actually increases the growth rate of yeast and studies proved that beer ferments quicker under UV, however there is a fine line between intensity and exposure time, the UV will eventually kill the yeast.
> 
> From that, I'd argue your little LEDs wont cause harm.


Fair enough please disregard my uneducated comment. I think I'll still ferment in the dark, in more ways than one it would seem 

Christmas you could still try disconnecting the LEDs if you think that might be the problem.


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## bond

Just fired mine up, my 5L demijohn has quite a concave bottom, it threw the stir bar until I double stacked extra magnets.

It's quiet enough when the whirlpool is only an inch deep, but quite loud when on full tilt - do flat bottom flasks help with this?



I think I'll remove the potentiometer from the PWM board, and mount it and a DC socket into another piece of perspex - more tweaking first though

The pwm controller I used : DC 5V-40V 3A PWM Controller (ebay)


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## felten

Are you using a stirbar with the pivot ring? Apparently they can be quite noisy.

Oh I can see it in the pic, you might want to look at an egg shaped bar.


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## Wolfy

Stir bars with a pivot ring tend to be more noisy, however they are probably better on the curved base of the demi john.


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## yum beer

bond said:


> View attachment 57477
> 
> 
> Just fired mine up, my 5L demijohn has quite a concave bottom, it threw the stir bar until I double stacked extra magnets.
> 
> It's quiet enough when the whirlpool is only an inch deep, but quite loud when on full tilt - do flat bottom flasks help with this?
> 
> 
> 
> I think I'll remove the potentiometer from the PWM board, and mount it and a DC socket into another piece of perspex - more tweaking first though
> 
> The pwm controller I used : DC 5V-40V 3A PWM Controller (ebay)




Hey bond,

how do you have the fan attached to the perspex....


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## bond

yum beer said:


> how do you have the fan attached to the perspex....



http://www.pencomsf.com/mechanical/fan_screws.aspx - Had these which came with fan's I've bought in the past


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## Aydos

Wow i just finished reading all of this thread, there is some really good info in here.

Need to stop being so lazy and get mine built!


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## mkstalen

I bought the parts to do this build a little while ago, and finally got some time yesterday arvo to put it together (little bloke was sleeping, wife was quilting).

Here's the breakdown:
1 x 120mm PC fan (12v, 0.3A) $2.99
1 x LED dimmer (12-24V, 8A) $3.21
1 x Old power supply (12v, 450mA) Free
10 x 8mm x 1mm neodymium magnets. $1.42
1.2L square plastic container pinched from cupboard. Free (I think they're about $5.)
Screws, wingnuts, and rubber feet things $6 maybe.
Total = $20 tops


Pics in the following galley.
http://aussiehomebrewer.com/gallery/album/1010-stir-plate-build/

(Can't figure out how to easily insert them into this post)

My only question is when I have the dimmer turned down all the way the fan is still running, anyone got any ideas why this might be? I thought it'd be off when turned right down...


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## Amber Fluid

It is possible the "knob" to control your fan is not set correctly....
Pull the knob off (pardon the pun) then turn the fan down as far as it will go with your fingers. Replace knob and it should be fine.


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## LethalCorpse

Most switchmode drivers have a minimum on time for stable regulation. If it's a cheap controller, this can be quite a high duty cycle. The designers of your LED controller may have added a series resistance with your control pot to allow for this, and erred on the side of caution. Either way it's likely to be inherent to your controller and not easy to remove


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## KingKong

Quick question my power 12v power supply adaptor. How do i easily know which is positive and which is negative when both are black ? One cord has white dash's on it?

Further im running to a dimmer that says .8 amps my power supply is throwing out 1 amp. Ok or not?


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## treefiddy

I think the white stripe is usually positive.

Might be that the dimmer is rated at a maximum of 0.8 amps, but if you're using something that uses less that 0.8 amps (such as a PC fan) then the rating of the dimmer will not be exceeded.


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## MCHammo

Just came across this thread, and thought I'd put up my design. Rigged up an old 555 timer I had lying around with a pot, a diode, and a few resistors + caps. I see there is a different 555 design floating around here somewhere. I might as well add mine to the mix.



Schematic for the PWM driver. I used a 100k pot and... can't remember the two resistors. 1k maybe? I'll need to dig out my stir plate later on to check. I've opted for a mosfet to drive the fan rather than a plain transistor. Personal preference - a few less components required, and more efficient.



Circuit board I etched for this purpose. About 25x30mm in size.



Assembled plate (with a few extra switches, plugs, etc.) You can see the PCB between the pot and the fan. Powered by an old PC power supply that I turned into a bench-top power supply... At least until I can be arsed looking for a suitable plugpack. I'm sure I've got one somewhere.


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## BrewDaddy

I'm slightly confused and can't find an answer amongst this mass of pages.

This guide says to use a 500ohm linear pot from Jaycar. Is this the right one?

http://www.jaycar.co.nz/productView.asp?ID=RP3502

I'm confused about the wattage. All the American guides suggest a 3w pot is needed. This one from Jaycar is only 0.5w. 

I'm using a 12v power supply and a 12v fan that pulls around 150 mha. 

Will that pot from Jaycar work?

Thanks.


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## shmang

The minimum you would need is 1.8 watts.
P=V*I
P=12*0.15
P=1.8 watts
So 3 or 5 watt would be the go


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## BrewDaddy

Ok thanks.

Seems to be very hard to find a 3w one in New Zealand at a reasonable price. 

Are there other options that are real cheap?


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## MCHammo

shmang said:


> The minimum you would need is 1.8 watts.
> P=V*I
> P=12*0.15
> P=1.8 watts
> So 3 or 5 watt would be the go


False.

This is the power dissipation of the fan, not the pot. You're right that P=VI. But this is different for each component, as the voltage drop across each will be different, and there won't ever be a 12V drop across the pot.

Very basically (slightly wrong, due to the complex nature of electric motors under load, but close enough for a basic approximation):

at 12V, the fan draws 150mW. This makes the armature resistance 960Ω. We then have our pot, which is 0 - 500Ω. We can assume a constant 12V across both resistors (Rp and Ra). Current can then be determined for any Rp (pot resistance). Pp = I²Rp. I did a plot of this, and came up with a max value of 0.0338W < 0.5W

This is all assuming that the maximum power dissipation (as quoted 150mW) occurs at maximum power, and not at stall. If the measurements are taken at different points, the calculations will vary. If you could put a multimeter across the fan while it is unplugged, I can update those calcs and give you a better response.


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## LethalCorpse

I know I've been gone for a while, but I thought we'd cleared this up a long time ago. Do not use a pot. Use a variable regulator or a pwm (switchmode) fan controller. There have been several circuits posted in this thread, including one of my own.


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## MCHammo

It probably has been covered, but you can forgive someone for not reading through 40-odd pages. I posted incomplete specs for my design on the previous page. I've updated them (filled in the blanks, everything is a little neater now), and produced a new board layout - one optimised for a Veroboard or similar. Same components, etc, and all available at Jaycar.




Parts:

2 x 1kΩ resistors (RR-0572) $0.46
1 x 100kΩ linear 9mm pot (RP-8518) $2.75
1 x 1N4004 Diode (ZR-1004) $0.50
3 x 0.01μF Ceramic Caps (RC-5348) $0.64
1 x STP16NE06 mosfet (ZT-2277) $2.45
1 x NE555 timer (ZL-3555) $1.25
Plus a 1" x 2" piece of 'veroboard' style prototyping board, and whatever connectors/bling you feel necessary. I found that putting a polarised fan header on the board (pictured) with mating connector on the fan to be very handy. You could always do that with the power too, but I just soldered mine in.



Veroboard Layout. Dark blue lines are active lines / signals that we want. Red lines are wire bridges that we need to add to the board. Cyan lines are verobard traces that must be cut. You do not need to remove the entire length - as long as electrical contact is broken. I usually just use a stanley knife to cut a clear (2mm or so) break.


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## BrewDaddy

Yeah sorry for not reading every page, I tried but got confused. 

Anyway, I did get the feeling that a pot is no good so I have just bought an LED dimmer. Sorry for bringing up an old topic.


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## breakbeer

I'm glad you brought up this old thread, made me realise I already have all the parts to build one!


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## sp0rk

My stirplate died some time after I went to bed last night and after some tinkering this morning I found that the PC fan controller (just a pot) must have crapped out 
Luckily i'm using a variable power supply so I can vary the voltage that way, but I might have to make a new controller going off MCHammo's plans some time this week

Also decided to throw out my old stir bar this morning and try out my new 30mm one from Wiltronics
Very happy with it, it take much higher speeds for it to fling off than the old one did


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## RobB

I've just knocked my stir plate together using the link provided by Zwickel as a guide. Four bolts and a scrap of perspex and it's done. I think it's a pretty elegant design.

From my collection of orphaned chargers, I found one with variable output which gives me as much control as I need, so no need for pots etc.

6V will produce a good vortex in 2 litres, 4.5V is good for 1 litre and 3V in 100 mL is plenty. 9V in the larger volumes produces a full depth vortex with lots of bubbles being ejected up the sides of the flask. This might be a good setting to use for 10 minutes before adding the yeast to get some oxygen into solution. 12V just throws the bar.


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## evvy.rogerson

I finally got my stir plate together today. It's not pretty (I can't solder for shit) but I'm happy with it. 

My experiences:
I initially purchased a PVM LED dimmer like this one




But I was unhappy with it as it caused the computer fan I was using to emit a constant whine as the pulses were sent to the fan at low speed. 

With my limited electronics knowledge I removed the control knob inside (potentiometer) and twisted the wires together for a quick circuit. My 9V 200mA AC adaptor made short work of frying the potentiometer so I figured more research was required. 

Lethal Corpse seemed to know what he was on about, and others had followed his recommendations with success so I collected the necessary parts, and a cheap soldering iron ($13) from Jaycar and sat down to it. 



LethalCorpse said:


> updated diagram to make it a bit neater and include the new values.
> Jaycar parts:
> LM317T - ZV1615
> 5k linear pot - RP3508 or RP7508
> knob to suit - pick one. Not the ones which say "spline" or suit 9mm pot
> 680ohm resistor - RR0568
> switch - pick one. Any will do, so long as it's a latching type, not momentary. Pushbuttons, toggle switches, rockers, etc.
> 10u cap - RE6070
> 100n cap - RC5360


Perhaps 2 hours later (did I mention I can't solder very well?) I was done. I haven't mounted it yet, but the circuitry works, and from my experiments with the LED dimmer I know that the fan doesn't need to spin very fast, and that the width of the magnets, and proximity to your vessel and hence your stir bar, are very important. 

I bought this 30x16mm stir bar (http://www.ssapl.com.au/store/001630.html)%C2 Science Supply Australia in Mitcham. The guy on the phone was reluctant to sell me just one, so whilst I wanted to push him to ask if it could be posted, I settled for making a trip out there. 
It seems to be a good size, although the jar I am using has a convex base which makes for an unstable stir bar as the speed increases. 

I purchased round 8x5mm rare earth (neodymium) magnets which seem to do the job, but I might upgrade to something bigger as they're only just coping. Stacking them on top of each other gives a stronger field, but at the expense of having to mount the fan lower which isn't ideal. Does anyone know if mounting them side by side will be effective? They definitely won't sit like that by themselves, but I figure I could glue them down it'll work.


----------



## MaltyHops

I started with a PC fan and when I upgraded to a PWM power supply circuit and more powerful magnets, found it wasn't working as well as expected. Had a thought the magnetic field of the magnets may be messing with the current in the PC fan (which constantly goes on and off due to the PWM supply) so made a change as shown and works really well now.


----------



## megabyte

Nice work malty,

You're right, mounting strong magnets directly onto PC fans can render them temporarily useless. They use an internal magnetic sensor (hall effect sensor) to know when to power the different electromagnets to make it spin. Adding a strong external magnetic field can trick the fan into thinking it isn't spinning.

We currently get around this by adding some metal behind the magnets to shunt the magnetic field before it interferes with the motor, but your solution of separating them is great too so long as you can keep it balanced.

Looking good!


----------



## MaltyHops

Thanks ... interesting about the use of hall effect sensor in the PC fans. I have stuck the magnets onto a strip of galvanised steel to keep the magnetic field away from the fan side but it didn't seem to quite do it.


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## Lord Raja Goomba I

Necro this tiger.

A couple of questions for those in the know:

1. Does this need a nice neat vortex? Mine is flinging around the stir bar in my 500ml Erlenmeyer. If if does ;

2. What causes the flinging stir bar? Speed, position on stir plate, magnet position, crappy stir bars?


----------



## mofox1

1. Not really, just needs to keep moving so that the yeast stay suspended and (assumption here) to provide continued O2 uptake at the surface.

2. Either not enough hold from the magnets (too far away or not strong enough), or more likely magnet position.

The magnets need to hold the bar very well centred on the centre of rotation, otherwise it will throw the bar when the speed is high enough.

Same thing happened to mine after one of the magnets broke loose, didn't glue it back in exactly the right position and I can't get it near full speed.

Timely reminder to fix it before I need it again (I've got two, so I keep stalling!)


----------



## Lord Raja Goomba I

Sweet, thanks. Not sure if it's a speed thing, but relooking at the two biggest stir plate build threads, it appears mine are too far apart on the fan.


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## Danscraftbeer

(only read latest posts so prob just repeating here) - Place the magnets on the stir bar when you set them in the epoxy.
When I made mine I took care when setting the magnets in the epoxy. I placed the stir bar on the magnets so that they set as they want to. Eg. You can fight with magnets, They have poles etc. Just play with them a little. If they aren't comfortable with each other with the stir bar then it maybe hit and miss to work well.


----------

