Understanding Rotary Encoders

Rotary encoders are rotary switching devices used for changing things like radio frequencies, DG headings, and altimeter settings. For all its versatility this is a modest device having only two internal switches, each with minimal electrical capacity. The role of an encoder is simply to inform circuitry when a control knob has been turned and in which direction. It needs only enough capacity to switch logic signals. All the details of controlling radio frequencies, altimeter and heading settings are left to other bits of circuitry or firmware.
...