Theremin in Detail

[Keystone Science] recently posted a video about building a theremin — you know, the instrument that makes those strange whistles when you move your hands around it. The circuit is pretty simple (and borrowed) but we liked the way the video explains the theory and even dives into some of the math behind resonant frequencies.

The circuit uses two FETs for the oscillators. An LM386 amplifier (a Hackaday favorite) drives a speaker so you can use the instrument without external equipment. The initial build is on a breadboard, but the final build is on a PCB and has a case.

This is the kind of project that could capture a kid’s imagination — especially one with an interest in music. We don’t have anything against microcontroller projects, but a circuit like this is great for exploring oscillators, amplifiers, resonant frequencies, and other details of electronics you don’t get with a typical Arduino LED blinker.

We’ve covered a lot of theremins in the past including some very simple ones. There’s even one that uses IR sensors.

4 thoughts on “Theremin in Detail

  1. I wonder if you could get the same effect with two or more of those really cheap based 2.4Ghz motion detector modules. Tap the circuit at the end of the analogue part of the circuit, before the chip, and feed it into the analogue in ports of an MCU then drive a synth from that data with audio output via PWM.

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