All parts for this device are available off the shelf from Radio Shack. It is, of course, not a true theremin, but it does produce a theremin-like sound which can be controlled through hand gestures. It uses two photoresisters as input devices. These are not as nimble as a true theremin and therefore must be augmented with potentiameters. This means you can't completely control the pitch by eclipsing the pitch photo resister, but you can move it up and down half an octive or so. This allows you to create the characteristic theremin warble.

Missing in the above diagrams is the values of the photoresisters. I'm afaid that I have no experience with these and there are no markings on the ones that I used. I purchased them in the assorted photoresister pack available from Radio Shack. I used two of the smallest sized ones. They work best when kept in shadow so I build recessed mounts for them out of the LED holders in the list below.

Since the case I chose must be unscrewed to get to the batteries, I used six C batteries for power. I expect these to last a long time. They haven't run out yet, but they only have a couple of hours on them. I epoxied the battery holders to the bottom of the case, but these made ominous cracking sounds as I inserted and removed the batteries, so I added some bolts for reinforcement.

Please note that in the design I used an LM272 op amp. You can subsitute any other one you want. It was just what I had at the time. Radio Shack does not carry this one stock on the shelf, but it does carry a single amp chip and a quad amp chip that will probably work. Just change the pins around.

Radio Shack Parts List

Lastly, I'd like to say that the above circuit could probably be both simplified and improved on. Please email any ideas or suggestions to me and I will include them in the page.