Computer Power Supply and Switch Wiring Questions

[BrianG]

Most fan controllers do use pots, but in the PWM control circuit, so they aren't directly controlling the current flow to the fan.

No, RS doesn't have any 4 position slide/toggle switches that I see, the best they have is a 6 position rotary switch.

Yeah, the wiring would essentially be the same. If you were to use the rotaty switch, the common terminal would go to the fan, and each of the other contacts would go to different diode banks (one diode, two diodes, etc). I can provide an exact schematic if you end up getting a rotary switch.

Yup, the 3 position switch would the low, off, and high. Actually, the center position just doesn't contact either of the two internal contacts, so it is off. It's still technically a 2 position switch, but with an added "center off" detent in the middle that hooks to nothing internally.