I needed a rotary encoder — I pulled a cheap one out of one of those “49 boards for Arduino” kits you see around. Not the finest encoder in the land, I’m sure, but it should do the job.

Now suppose your latest self-quarantine project needs a rotary shaft encoder. Not having one ... Of course, an Arduino reads the pulses. We love using things for unintended purposes.

Arduino Board: The heart of the project. An Arduino Uno or similar board will work perfectly. 2. Rotary Encoder: Used for adjusting the frequency and amplitude of the generated signals.