I been wanting to make a simple fan controller for my PC using rotary pot's with knobs on the front panel and some LED's. I have an old AC to DC adapter that outputs 12V DC at 1A, to use as a test bench for my project.

This is what I have came up with using simple 1k pot's and two 80mm fans that I had from old non working power supplies.

I have the pots set around 80 ohms, and the I have a red LED running parallel acros the source with a 470 ohm resistor.

Instead I would like to put an LED for each fan that I want to control with a rotary pot with a built in switch. So when I do turn the switch off, the LED turns off and the rest of the fans remain on.

This is what I came up with so far...I know it needs more work.

 

Do you wish to control speed, or is it enough to turn the individual fans on and off?

 

Well I built this last night, and with a 1k pot I was controlling the speed of the fan.

Now i have been looking on the net and i know they have some rotary pots with a STDP in them, but I would like to have an LED with each individual FAN to indicate which FAN is turned on and off. How would I go about and wire them?

When I tried placing the LED after the pot BUT before the fan, the LED brightness changes with the speed of the fan.

 

Using a pot in series with a motor to control the speed of the motor is not a good idea. There is a large loss of motor torque. PWM is much better, but much more complicated.