How to build a stir plate for less than ten quid

[mitchmalt]

Chuffed with my mornings work! Thanks Steve for the guide. I had been borrowing one from work, but this is much more satisfying and totalled less than £7 with some bits found in the garage. Still ‘borrowing’ the conical though!

 

[Oneflewover]

Decided to upgrade my stirplate from the roses tub. Dad was getting rid of some electrical bits and bobs so I took this box off his hands. Works a treat and is very compact and tidy

 

[BeerCat]

What size is the box?

 

[Oneflewover]

What size is the box?

About 4x6x2.5". The fan just fits underneath the lid - I glued it in place and there is just enough room for it to spin with the magnets. The flask is wider than the stirplate but that's not a problem. It's a good upgrade on what I had

 

[Justin Dean]

When i connect the fan straight to the 12v supply it spins away happily. but when connected through the 12v controller form the link you put up, nothing doing.....must be a dud. I have checked everything else.

Ordered another one and see if that works

 

[Dutto]

I know this sounds daft, but have you got the Regulator connected with the right +/- polarity?

I think (though I have been known to be wrong) that most Regulators need the polarity to be connected in the right direction for it to work; whereas connecting a 12v fan directly to a 12v source will just make the fan turn in a different direction if the polarity is reversed.

If you find I am correct, then you will have a spare Regulator when the new one arrives!

 

[Justin Dean]

It is all connected right, , Regulator has power as red light on and fades and brightens as I turn knob. . No idea why it is not working. With knob on full and when power connected the fan sort of shudders but that is it

 

[Justin Dean]

Any ideas?

 

[Oneflewover]

What's the voltage output from your power supply? I found different voltage outputs made a difference in the speed of the fan even with the regulator

 

[Justin Dean]

12v 3 amp

 

[Justin Dean]

View attachment 19703 View attachment 19704 12v 3 amp

 

[Justin Dean]

Sorry 12v 2 amp

 

[Oneflewover]

Dunno then mate, looks pretty much the same as my set up. Sorry.

 

[Justin Dean]

Thanks anyway. I have tried two now. Will try a different fan though this one is perfectly happy connected direct to plug.

 

[Dutto]

Maybe .... ?

I've only EVER used a 12v battery as a power source!

I use an old (at least fifteen years) battery from my Mum's scooter. As the battery depletes the spinner slows down and I have to adjust the regulator to keep the speed up.

Maybe the 12v regulator shown in the photograph isn't giving the regulator enough "oomph" so I suggest that you try using a 12v battery instead.

 

[strange-steve]

@Justin Dean I dunno what to tell you I'm afraid, maybe @foxbat might be able to help.

 

[Drunkula]

this one is perfectly happy connected direct to plug.

When you link it up to the power supply directly does it spin mad crazy fast, literally throwing itself around on the table, like a pc when you're using loads of CPU? If it doesn't the power supply might not be outputting at full power any more. I've had that happen a few times.

Have you got the specs on that pwm controller? It's got a heat sync on it so it might be a 6v up to 24v one. That you see it judder suggests it's getting voltage but not enough to make it spin so the pwm might be soaking up just enough so that fan doesn't run if the power supply is running short. I'm guessing you don't have a multimeter.

I'm using a 1.8v -> 12v one and anything about 4 volts will get my fan working. I use it with a selectable voltage transformer.

 

[Justin Dean]

Thanks all. It is something like that . I will examine. Bloody useless on this. I just followed the links on the thread

 

[foxbat]

At 100% it should work more or less as if it's plugged directly into the supply since the PWM output should be DC. Unfortunately I would need my oscilloscope to tell you what's actually happening.

My opinion of any level less than 100% is that it shouldn't work at all and the PWM output should be averaged to DC with a capacitor but the experience in this thread shows that most fans are tolerant to the abuse.

 

[Justin Dean]

It is a
DC 6V - 28V 3A PWM Motor Speed Varible Regulator Controller Switch. It should work but obviously something is wrong, should I get a different regulator? If so what?

below piccies are with knob full to left and full to right