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Fan speed regulation....options?

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Dec 22, 2000
I have been using the LM217T voltage regulator setup, but with the inherant 2v drop across the circuit, the resulting 10v is not quite enough for what I am doing. I want to know what pots or variable resistors you guys and gals are using to control fan speed. The only thing is I NEED a large enough one to handle the 3w that the 120mm fan will pull at full speed...the majority of the little pots you find at Radio Shack wil burn up under such a load. I don't care about a pot wasting some power, I have enough....hopefully the Shack will still have something that can work, or else I will try to figure an optimum resistor value to cut down on voltage, although I really would prefer a variable solution. Any help? Thanks folks...
A lot of people use rheostats, which is a funny name for a higher pwer rated pot. I believe Swiftech sells one for their MC-462A. Since your fand draws considerably less current than the fan on the 462A, the rheostat may not reduce the voltage as far as you would like it to go, but we all know that the last volt or two is where most of the increase lays in anyway.

You could try some ceramic resistors, they have them at Radio Shack. These are available in high wattages. You will loose the ability to adjust but if you find the right value there will prob be no need to. Pick up a selection from just a few ohms up to maybe 20 ohms so you can test for the right 1 by trial and error.
I just use switches to adjust voltage. When running rheostats I found that they were either running at minimum or maximum. So when I built my next system I put in on-off-on switches and wired them to either 7/5V and 12V. Works great. The majority of the time they sit at 7/5V, nice and quiet.