Tight Arse Stir Plate

[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]

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]

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]

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]

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]

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 ******* 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]

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

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 ******* 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]

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 **** 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.