Tight Arse Stir Plate

[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.

*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]

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]

*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 ***** here, he's not supposed to know better. Though I do wish he'd listen to advice, it's his own brewery.

 

[schooey]

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?

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]

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.