Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at [aritrakdebnath2003]’s MIDI THEREMIN, we see it works differently, but it does play in the manner of the exotic radio instrument, so we suppose it can use the name.

The MIDI THEREMIN is purely a MIDI controller. It sends note data to a computer or synthesizer, and from there, you can get whatever sound at whatever volume you desire. The device’s brain is an Arduino Uno, and MIDI-out for the Arduino has been a solved problem for a long while now.

In fact, we’ve seen Arduino-based Theremins before, but where this project differs is in the use of TOF sensors over the traditional ultrasonic sensors. In this case, the instrument uses VL53LOX TOF sensors controlled over I2C, along with an Adafruit library to interface with them.

As with all theremin-style instruments, distance from one sensor manages pitch and the other volume. Time-of-flight optical sensors are designed to provide a smoother, more precise, and more stable output than ultrasonic ones, and this tends to be the case in our experience. According to [aritrakdebnath2003], this makes the instrument more playable, and we believe it. You can download a demo video as an MP4 from the project at Step 5 if you want to hear it in action.

If you haven’t gotten enough theremins yet, we’ve covered many over the years–including one based on a Commodore 64. Be warned. If you want to build this one, you’ll need a lot of bread.