Diy Computer-fan Stir-plate Build

[Wolfy]

can anyone point me to a site that i can buy the exact rare earth magnets and a stir bar i need pls, i cant be assed to trawl through 50 pages. shanks.

Except this thread has only 3 pages ...

thanks du99, rang SSL. only problem is i have no idea what size magnets or stir bar....guess i'll have a search hey argon?

The pictures and text on the first page should give you good/easy answers, you might have to read a bit but I'm sure it's there.

 

[Fents]

yep argon already gave me the 'your a lazy prick' reply, but thanks wolfy i guess i just didnt read your first post proper, apologies to all and sundry for being shit, i've been here long enough to know better.

i went with these - http://www.dealextreme.com/p/super-strong-...10mm-x-1mm-5962

can anyone tell me if this stirbar will be ok as someone on the last page suggested the ones with the line in the middle are noisy?? http://www.ebay.com.au/itm/Stirbar-Egg-Sha...=item2eb916f462

 

[benno1973]

Hey Fents,

Your stirbar should ideally be around about as long as the magents are far apart (or vica versa), so it can depend a bit on the fan you're using. Measure the fan and estimate where your magnets are going to go, then measure the distance between the centres of the magnet.

Having said that, 25mm is what I use, but not egg shaped. It's a little noisy - I hear that the ones with the ring in the middle are much louder. I bought mine from seratech when sera was selling them (I think?). I can't see them on his website anymore, but I think he used to sell them.

And those magnets will be fine. You might need to glue some together, but you have 10 of them, hey?!!

 

[argon]

:icon_offtopic:

yep argon already gave me the 'your a lazy prick' reply... snip

yeah sorry... had the cranky pants on this morning, wife had the shits with me this morning and i get into work and the coffee machine is broken. :angry:

 

[felten]

yep argon already gave me the 'your a lazy prick' reply, but thanks wolfy i guess i just didnt read your first post proper, apologies to all and sundry for being shit, i've been here long enough to know better.

i went with these - http://www.dealextreme.com/p/super-strong-...10mm-x-1mm-5962

can anyone tell me if this stirbar will be ok as someone on the last page suggested the ones with the line in the middle are noisy?? http://www.ebay.com.au/itm/Stirbar-Egg-Sha...=item2eb916f462

I use an egg shaped bar though it looks to be a different shape, it does the job, and it's silent as well.

It's the same length as the hub on my CPU fan too, which means it sits well on the magnets at either end.

 

[benno1973]

Quick question, maybe it's already been asked but I can't see it in this thread, and it's been a while since I read the Tight Arse Stir Plate thread, so here goes...

I see lots of people using LED dimmers in these projects, 12V 0-8A. As most of the fans we're using are around 0.3A, doesn't that mean that the max draw by the fan is 0.3A? So how does a 0-8A dimmer work? I assume that it adjusts the amps between 0 when the dial is at minimum, and 8A when the dial is at max? So wouldn't the fan be at max speed after turning the dial just to the right a little?

Obviously I haven't used one myself, so I don't know. And I know nothing about electronics, that's probably obvious.

These are the dimmers. They specify output power 96W, output current 8A. I assume that they are for a bunch of LED lights, not just a single light. Still, as you point out, LED lights draw bugger all, so I'm not sure how these work exactly...

They are pretty cheap. About half way on the dial is the fastest I get get a stirrer to spin. And lower produces a slightly slower spin so you do have some control with it.

So I bought an LED dimmer as referenced in the above link. I hooked it inline between my power source (12V, 500mA) and the fan (12V, 170mA). The problem is, the fan spins at full speed, no matter what the dial is set to. Even if I turn it all the way around to 'off' the fan is going full tilt. I would expect that all the way to the 'off position' would supply 0A, so there's be no power? Has anyone else got experience with these dimmers, and do they stop the fan in the off position? Maybe my dimmer is dodgy?

 

[Wolfy]

So I bought an LED dimmer as referenced in the above link. I hooked it inline between my power source (12V, 500mA) and the fan (12V, 170mA). The problem is, the fan spins at full speed, no matter what the dial is set to. Even if I turn it all the way around to 'off' the fan is going full tilt. I would expect that all the way to the 'off position' would supply 0A, so there's be no power? Has anyone else got experience with these dimmers, and do they stop the fan in the off position? Maybe my dimmer is dodgy?

Sounds like it's broken, or you're doing something wrong.

 

[Dazza88]

Wire up differently I am guessing. Inline? Have you wired fan into one side and ac onto other?
My guess . . .

Actually, wiring is pretty obvious prob dodgy dial. Weird it runs all the time.

 

[booargy]

check the supply output is DC. It probably won't work on AC

 

[Dazza88]

The positive wires sit next to each other on the device, are they touching? This would bypass the dial

 

[benno1973]

Thanks guys.

Yes, the power supply is 12V DC, not AC.
It is wired up correctly, otherwise it wouldn't run at all I'm guessing. DC supply into the INPUT (V-/V+) and the fan into the OUTPUT (V-/V+). I checked that the wires aren't touching - you're right they are pretty close together but I made sure they weren't in contact.

Just wondering if there's an easy way to test it to confirm deny whether it's working.

 

[Brewman_]

I like the ideas about stir plates, very simple and cheap, and I am thinking about making one, but always considered a stir plate with an aeration or oxygen injection. But looking at the pics I don't see any of that. I am I missing that bit? Or do you get good results with just the stir plate?

Fear_n_loath

 

[benno1973]

You get great results with just the stir plate. I tend to shake (aerate) the starter, then on the stirplate you're constantly moving the surface of the wort around in contact with air and this introduces further oxygen. That, in conjunction with keeping the yeast in suspension, makes things move fast. I factor in a day for each step up from a slant, but I could easily get away with half a day given how fast things move with a stirplate.

 

[ledgenko]

Ok guys .... I am building as we speak but as luck would have it I happened upon a 240v 12cm ball bearing rotary fan made by none other than D- word smith (as my son calls Dick Smiths - ok its kinda cute and funny at the same time) but made in none other that Taiwan .. Dick would and should be ashamed !!!! see photo .. but what I want to know is it going to be too powerful and because it is 240v can I use a ceiling fan control to adjust the speed ??? and also will I need the same number , more or less magnets ???

For your consideration and comment...

BTW ... I have no idea where this came from and what its original use was but thought hell this could be a more funner build

Yes I meant it !!


Matt

 

[Wolfy]

.. but what I want to know is it going to be too powerful and because it is 240v can I use a ceiling fan control to adjust the speed ??? and also will I need the same number , more or less magnets ???

It's not likely to be too 'powerful' - when built (with a ceiling fan controller) - it will likely put out the same RPM.
However, you'll be playing with lethal 240V and not mostly-harmless 12V so it's not something I'd recommend.

 

[spog]

just remembered (bit late now),but i think it was the december aussie issue of the silicon chip magazine had a section on building a stir plate.
maybeyour library has it or someone you know.......cheers.......spog.........

 

[alfadog]

Ok guys .... I am building as we speak but as luck would have it I happened upon a 240v 12cm ball bearing rotary fan made by none other than D- word smith (as my son calls Dick Smiths - ok its kinda cute and funny at the same time) but made in none other that Taiwan .. Dick would and should be ashamed !!!! see photo .. but what I want to know is it going to be too powerful and because it is 240v can I use a ceiling fan control to adjust the speed ??? and also will I need the same number , more or less magnets ???

I am not sure how the magnets work with the AC, but give it a go and let me know

 

[pyrosx]

I love this thread. Never had the chance to continue high school chemistry onto Uni levels - so never got to play with a stir plate - always wanted to though. (Edit: forgot to say "Thanks!")

Couple of purchases from dealextreme (followed by the customary agonising couple-week-wait), and i've got a stir plate!

The stir bar was delivered much quicker than the dealextreme gear, so I had it ready - attaching the magnets in the right place on the fan was actually pretty straight forward: I left the stir bar in the small plastic bag it came in (just as a superglue insurance policy), organised both piles of magnets into place on the stir bar. Because I know knew that the magnets were the right space apart, the hard part was done. Superglue was applied directly to the other side of the magnets, then stuck into place as close to centre on the fan hub as I could - an hour later, I tested it out, and it worked perfectly. Liberal applications of cardboard and electrical tape have it looking like a proper ghetto unit. I was thinking i'd go back and glue or otherwise more-permanently attach stuff later on, but right now, my thinking is "why bother?".




My only worry is the speed i've achieved: I used an old 5V nokia charger, and have not had to use the separate speed controller I bought - 5V with the fan I bought seemed to get a pretty decent amount of agitation going - I don't get a massive vortex in 2L flask when it's pretty full, but i do get a pretty decent (2-3cm) indentation, and shit is definitely being stirred around... anyone experienced know if a more forceful agitation is required? This picture shows about 4-500ml of starter and some cooperspaleale yeast (stepped up overnight with 100ml starter), and while there's not a massive vortex, there's a definite indent, most of the liquid is moving even at the edges, and there's definite bubbling - that's all thats really required, right?

 

[Dazza88]

Looks good to me, after two days take it off the stir plate, let it settle and see how much of a yeast you have.

 

[bruce86]

I was looking into all this tonight and sussed out from my elecy mate if i could use a charger (5v) with the fan that needs 12 v he said that it will try drawing the whole 12v out of the transformer and prob cause the fan to burn out quicker (im pretty sure that is what he ment) If u already have the 12V power supply you may as well use it may save your fan in the long run.