Its quite interesting that people are for some reason not using the “Circuit Bent” keyword when selling these optical Theremin-like devices. Instead its just “Theremin” keyword. The reason I bring this up is because obviously people who are interested in making circuit bent sounds may also find these devices quite interesting, plus they will get more traffic to the auctions, but oh well. Today I present you my round up of the Light Controlled “Theremins” found on eBay while searching for the keyword “Theremin”.

Auction 1
Sound Sample 1

$20 for a 555 based oscillator seems fairly reasonable however it would’ve been cooler if the case closed. My suggestion for the builder would be to use an Altoids case, everything will fit for sure. However for tripping people out who have never seen or heard such a device this will do.

Auction 2
Sound 2 ( Light Theremin with Drums )
OMFG, if you have annoying neighbors, blast that sample over and over. Deadly combo.

Baby head, Flying saucer, and a black box on a mic stand are all versions of the XLPC theremin available from this seller. To me it seems that most of the these sound the same and use the same circuit, the only thing different is the case. Kudos for the variety though.

Auction 3
Sound 3

Waterhed seems to be selling more of custom looking wooden boxed optical theremins then circuit bent devices nowadays. Wood boxes are definitely a great choice for several reasons. First is that they are very cheap, less then a 1$. Old jewelry and storage boxes are all over Goodwills and flea markets. Second reason is the esthetics appeal of woodgrain, especially if it does something cool and looks like a piece of furniture. The circuit used in these is very tiny and can be purchased as a kit.

Auction 4-Kits

Getting a kit for an optical theremin or even a real Theremin may be also the way to go if you have something good to use as the case. However I would just suggest getting some 555s and buffing up on some soldering skills, cause really there is not much to making a very simple one.

My final word on the optical theremins is the gripe due to the fact that they do not work in dark places, well duh you say. But think about playing shows that most of the time happen on a dark stages. It simply will not work. Quite a few times I found myself in the position of using the backlight of my cellphone to provide the light for the photoresistor. This is the main difference between real and optical theremins. Real ones don’t need light, just your hands to interfere with the radio waves.