Tiny optical theremins

Matrixsynth pointed out a couple incredibly small optical theremins that look like they’d make for a great afternoon project. [AlexArt] first built the simple circuit on a piece of protoboard (Google translated). Knowing he could go smaller, he then built it freeform with a buzzer instead of a full size speaker. The design is based around the common 555 chip and photoresistor. Here’s a simple circuit you can use to lay out your own. The optical theremin should not be confused with the traditional RF theremin since the name comes from the similar sound, not similar construction.

16 thoughts on “Tiny optical theremins

  1. Neat toy, good project, looks like fun, but it’s not a Theremin. At all. Not even kind of.

    Anybody out there have insights into actually constructing a Theremin? It would be really interesting to a lot of folks here I’m sure. I’d really love to see how to build one at any rate!

  2. It takes a pair of analog oscillators heterodyning, not just one, for the frequency control. Its raw and messy, as the different harmonics you >don’t< intend from the interaction of the analog coils is what makes the warm signature sound of a theremin. Digital square waves don’t work for that and make for a lousy emulation. There is also the touchless volume control on a Theremin through a similar setup, and that isn’t even attempted to be emulated.

    Again, cool synth/noisemaker/whatever. Not a Theremin though. Might as well just call it a guitar or a cell phone. They all make noise so they are the same thing, right?

  3. The Frostwave Spacebeam Theremin and CV controller is a developed version of something similar, that has been around for a while now. For potted Theremin history and Spacebeam overview see;

    @stunmonkey – It’s cute to make it very simple, but the real trick with theremin design is to make it *controllable* by a *musician*. /elektor/ published a design (and discussion) that, while pretty complex, looks ‘safe’ for performance work.

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