One of my project needed, few rotary switches for it’s functions. So I found few from a old amplifier. This article will describe how to wire a 3 pole rotary switch.

The way rotary switch works is, when spindle rotates in clockwise or anticlockwise, it will change the contacts based on the number of poles switch have.

Different rotary switch have different build however, the basic idea is same. The one I’ve salvage is a open frame rotary switch.

Current will flow in through the copper plates and complete the circuit. Each plate is separated from other plates. So the current on each plate will not short circuit.

So rotary switch is ideal if you need to select one voltage, from several voltage contacts. My salvaged rotary switch have 3 poles and I used them to select one voltage out of 3 voltages (3v, 5v and 12v).

I found this similar diagram for single contact . Function of this switch is same as in the diagram