Here is a video of a real thermin:
This is where I learned how to do this:
The original optical theremin
Step 1: Gather Materials!
This needs very few parts, I made mine for under $20.
Here is what you need:
One TLC555 timer IC
One .047 uF capacitor
One 100 uF capacitor
One 1 megohm resistor
One 10k ohm resistor
A battery pack that holds 4 AA batteries
A small speaker
A wire stripper
Step 2: Putting It Together
This is a really easy circuit to build. Just make sure that you follow the directions. If any problems come up, I'll gladly try and help you out. Just send me a message.
And yes, the image came from here. It's a fascinating website.
Step 3: The Finished Product and Video
At this point in the game, everything should be working. Congratulations on the build, have fun with it!