Make: More Electronics

Chapter 33. Experiment 33: Reading Rotation

Everyone is familiar with that old-school favorite, the potentiometer. In this book alone, I have used maybe twenty trimmer potentiometers in the various circuits.

In consumer electronics, it’s a different story. Your car stereo probably still has a volume-control knob, but it will turn a full 360 degrees—and keep on turning. This suggests that something other than a potentiometer may be hidden behind it.

What component has taken its place? The answer is a rotational encoder, also known as a rotary encoder, or an incremental encoder, or an electromechanical encoder (because it has mechanical contacts inside it). A selection of them is shown in Figure 33-1. Their appearance is reminiscent of potentiometers—indeed, ...