Electrical Help for Stir Plate

[ACarver]

Hello all, just got done a few days ago with my DIY PC fan stir plate. I have it working, but it seems a little underwhelming power wise and I need some advise on the potentiometer and rocker switched I used.

I used a 12v pc fan, a 9v DC outlet which I have read work and feel confident about. However, I purchased a 10k ohm/0.5 watt potentiometer and a rocker switch that is rated for 16A, 125 VAC. I have read the recommended specs are 25k Ohm 3 watt potentiometer, and 12V, 30 Amp rocker.

Like I said, it works somewhat well, and I get a vortex that goes maybe 2-3 inches downward, but I would like to know if by switching 1 or both of the parts I could get a higher speed stir plate.

I am sure this is a painfully stupid question, and will get many bad comments, but I am a geologist, not an electrician.

Thanks for any help!

 

[Copbrew133]

I bought a stir plate and I am also no electrician, however I just installed a 12 volt pc fan in my keezer. I wired it first to a 9 volt wall wart and then to a 12 volt. The 12 was quite a bit faster. Hope that helps.

 

[OKHopHead]

10k Ohm is probably way too much resistance. I doubt that you can get a useable adjustment range with that. To get an approximate value, you can divide the fan's rated voltage by the rated current. In my case 12 V/120 mA = 100 ohms. A potentiometer with the same value, 100 ohms, would give you an adjustment range of 50% to 100% of the power supply voltage. In your case, 4.5 V to 9 V. Anything much below 4.5 V and the fan probably will not start.

Theoretically, with your 10k ohm pot turned all the way "up" (zero resistance) your fan will see 9V. You could verify this with a multimeter. If this is not fast enough, the only way to increase speed is to use a 12V supply.

Don't worry about the switch. Changing it will have no effect.

 

[vnakkar]

Higher volt power supply will get you more power to be sure.

However, a 2 - 3 inch vortex is plenty awesome. You're cultivating yeast, not making a margarita.

 

[Bigcorona]

Get a 25 Ohm potentiometer at Radio Shack. I think 3 watts. That is 25 Ohm, not 25K Ohm.

 

[ACarver]

Thanks guys, don't know why I wrote 25k ohms.