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.


  1. kurf says:

    I would love to see a whole group of these working together.

  2. Drew says:

    I made one of these for a project; I used the schematic on the last link, but I translated it to use on a breadboard. It worked well, and it makes awesome sounding square waves.

  3. Louis II says:

    SWEET <– capslocked.

  4. Tony says:

    This is pretty sweet, very low parts count too. This is by far the simplest theremin (if you can still really call it that) that I’ve seen. Good find.

  5. stunmonkey says:

    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!

  6. Gert says:

    How about a theremin on nothing but standard PC laptop hardware:


  7. ragnar says:

    do a google for “theremin schematic”. and as i see it, a theremin is an oszillator with a touchless frequencycontrol, which this little project offers.

  8. stunmonkey says:

    That is a >truly< brilliant hack on that laptop!

    Still not a theremin though :(

  9. stunmonkey says:

    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?

  10. strider_mt2k says:

    Careful man, those Theremin guys will cut you if you even pretend to emulate a Theremin and call it by the only name you could possibly reference.

    They’re mean and quick with the sharp steel!


  11. j-striker says:

    Yeah, that laptop thing IS neat. Too bad the code doesn’t run :/

  12. medix says:

    Let’s grow a pair and build it with tubes.. then you really *can* call it a theremin..

  13. googfan says:

    that dick! he stole my idea!! go to http://www.instructables.com/id/Googfans_Can_of_Sound

  14. Roly says:

    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.

  15. Ching Durnil says:

    Wow! Was für eine Idee! Was für ein Konzept! Beautiful .. Amazing …:)

  16. jcocchia says:

    googfan is right! I’ve seen his can o noise 1st hand when he made it a few years back.

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