potentiometer for muffin fan control

[wsemajb]

Is a simple potentiometer ok for controlling DC muffin fan speed?
I'm using a 12vdc 1.5amp switching power supply to run a couple of .5amp 12vdc muffin fans and would like to be able to adjust speed. Just stick it in between them.. no?

What Ohm range is appropriate for this? I'd just like to drop into radio shack and grab one.

 

[justDIY]

this site has lots of great fan control information

http://www.cpemma.co.uk/index.html

you can use a pot as a rheostat, but it has to be heavy duty, rated for the wattage it's going to dissipate. at 12v * 1.5a you're talkin an expensive pot.

better off using a transistor to burn off the extra power, or better yet, pwm - it's all in the website.

 

[audioguru]

If you use a pot to control the speed of a fan then you will need another fan to blow away the smoke from the burning pot.

Also, the resistance of the pot linits the current in the motor. DC motors need a high current to start running so the pot will stop the fan from starting.

 

[wsemajb]

compromises, compromises..... every time you turn around.

Since I'm getting power out of the wall in any case, I decided to just simplify my life and control the ac before the 12vdc transformer. But the PWM wall plate dimmer I had on hand doesn't get along with the switch mode power supply transformer - I guess that makes some sort of sense even to a circuit dimwit such as myself.

I got out a 12vdc 1 amp regular old stacked plate transformer and things work just splendidly. I was so hoping to use the 12vdc switch mode though since this project is supposed to be portable and I just added about two pounds of weight.

Oh well.

 

[justDIY]

controlling the DC is far easier than controlling the line voltage ac.

read the site I linked, there are several very easy solutions there, which don't involve much "circuitry" - check under "simply transistors"

 

[wsemajb]

I think I found just about the right item..

**broken link removed**

By the time I end up robbing two controllers out of it I'll have two extras for other projects sitting in my parts drawer. Not bad for three dollars per controller.

Here's another..
**broken link removed**

I realize that buying instead of assembling from scratch this sort of thing may be a mild anathema to some of you. But identifying and using items for cross purposes is, to me, a satisfying part of diy as well. Many odds/ends I end up buying from Menards or Home Depot go to some purpose other than what was intended.

Thanks again for the links and comments. I hope I can reciprocate with something useful at some point.

 

[things]

even this will work, and it's cheap!.http://www.dse.com.au/cgi-bin/dse.storefront/46ca5f750bb05db62743c0a87f9c0753/Product/View/K3070