stirplate question
 

I am making my own stir plate. I have a nice fan 24volt. I have an adaptor that plugs into the wall that feeds the fan 24volts. I need to slow it down with a rheostat/ potentiometer. Do they make rheostats for 12volts, 24 volts etc...or will any radioshack potentiometer work.

You need to understand circuits to answer that question. A potentiometer of any kind will work in theory, as they just increase resistance on the circuit, but the wrong kind can either not fully shut off the current, or if too strong shut it off so fast that basically it is either on or off. You really need to know exactly what you're putting into the circuit. Don't guess. if you're unsure, you should probably not do it. If you have some software that helps design circuits, then you would be safer.

I think I'm going to buy a light switch dimmer tomorrow and try that. Anyone know if a light switch dimmer will slow down a 24volt fan?

I don't know if you know anyone that could make a small electronic circuit for you, it is not to complicated and ideal for what you want if you fancy a go yourself.

The device is a voltage controller LM317
http://www.national.com/mpf/LM/LM317.html
Good luck
Cheers
Simon

See the link below it is for a device LM317
Voltage regulator.
http://www.national.com/mpf/LM/LM317.html
It's not to difficult to make just remember a heatsink on the device.
Good luck
Cheers

Um, those are for 120v no? Completely wrong kind. Not 12 or 24v.

I found a 12/24 volt 8amp dimmer on ebay for around 10 bucks.

I also recommend the LM317. I went the potentiometer route on my first couple plates and it sucked. Once I went with the LM317's it's been smooth sailing ever since. You can get them on ebay pretty cheap. Good Luck.

That is exactly what I did and it works awesome! I actually went an easy route and bought a 12 volt dc fan regulator for 6 dollars on amazon and wired it in.

This is my problem; the pot is either off or on, no variable resistance. Should I get a bigger/stronger pot? I hae a 6v DC power supply with a 12v fan.