I am looking to hand build a fan controller (bought one, uses PWM, don't like the "growl" at low to mid speeds), using potentiometers, and SPST switches to allow a complete off for the fans. The circuit I've got in mind, is something like the following (forgot to put the fans on it, they'd go between the potentiometers and ground) I'm not looking for anything "fancy", I don't need (but wouldn't mind) LEDs to indicate which fan is on or off. The fans I am going to be controlling are 120mm w/LEDs, and 80mm without LEDs. I am estimating around 2.8a for each fan, and the pots would be 3-4ohm max, maybe with a "full on" if I could find such a thing. I've tried to find articles on building such a circuit, almost all the ones I found are using PWM, instead, or are thermally controlled. BTW, I did try searching here for anything on "fan bus circuit" with no joy. Thanks.