After experimenting with MIDI and Raspberry Pi Pico, maker Jeremy Cook wondered if he could set up a theremin-like device using ultrasonic sensors. He managed to create this theremin-like instrument with just two HC-SR04 sensors and a Raspberry Pi Pico H.

There-what?
First of all, I had to DuckDuckGo what “theremin” means. To save some of you the same administrative task, I can tell you that it’s named after the person who invented it in 1928 — someone called Leon Theremin — and it’s that eerie-sounding instrument you play by moving your hands near it without touching it.
So, yeah. One of those metal sticks that people wave their hands around rhythmically to coax sound out of. For my money, it’s as close to wizardry as the music world gets.
Take a look around the build
What you see in this video is Jeremy playing around with the MIDI input on a Mac using Garageband. His CircuitPython code is open source and is available for you to copy here. He also created a MIDI button program to use with Raspberry Pi Pico W as shown here.
Jeremy would like to give a shout-out to the affordable enclosure he used to keep the Raspberry Pi 4 used in this project safe.
Mega maker
Jeremy has his own Tindie store where he sells self-made innovative devices, including a macro keyboard kit and a tiny fan controller.
You can also support him for free by subscribing to his YouTube channel. If you liked this musical project, you’ll probably be into this playlist detailing all the other instruments he has built. If you didn’t know what a theremin is, I’m betting you don’t know what a whamola or a hank drum is either. It’s a veritable Who’s Who of unusual musical instruments on that there playlist.