A rotary encoder can come in many forms – in this case it is designed as a rotary input like those found in car stereos. Unlike a potentiometer, which has a set range, these can be spun continuously in either direction and do not have any internal means of tracking their “position”. Instead, the encoder works by having two slightly offset outputs; depending on which one of these two outputs triggers first you can determine direction of travel. Usually the position tracking is done with a microcontroller (like an Arduino); this allows you to determine the start point, the range, and the sensitivity needed.

This encoder has a built in momentary button when the knob is pressed in and features a 24 pulse per revolution resolution. There is a solid, noticeable, detent as the knob is rotated. Since the trigger of each pin happens very quickly, the coding for this can be a little more difficult for beginners.