During the course of Weekend Projects there were several projects that I was personally excited about, to both tinker with and write about. But there was one obvious crowd favorite among the fifteen beginner projects we built. While there was no competition per se, the Light Theremin was the obvious winner. Even before drafting this article, the theremin had potentiometers and other components modded to the circuit, had been converted into a Snap Circuit, and was enthusiastically breadboarded by a first-time maker. Take a look at the following eight mods of this fantastic project, ranging from a full copper plate mod to a mod using a tiny DC motor in lieu of a speaker – this project is clearly intended for all skill levels and available components.
Perfboard mod by Bjarni:
Perfboard mod with photodiodes by Mike:
I actually built the optical theremin when I first saw it on breadboard, and wanted to make it more permanent, so I moved it onto a PCB from RadioShack that is designed for IC’s that I had laying around. I used alligator leads to hook it up to any of the large number of scrap speakers I have laying around, and for the power so I can use a power supply. I build these things and take them to school to get kids’ attention (I teach Physics). It usually works really well!
Workshop mod by Daniel:
Learning lab mod by Leif:
I built the light theremin on a RadioShack electronic learning lab. I wanted to see how she would play with it because I am gathering parts to build her a more traditional one. I’m in no hurry, she is 18 months old! I decided to play with it a bit. I think the speaker was a bit too big for this circuit. It got a lot better when I wired in the audio transformer. It is 500 to 8 ohms. I used the center tap though so if I understand right it is 250 to 8. I tried replacing the 1M resistor with the 1M pot. That pretty much was just an on/off so I put it back. I tried the same with the 10k one and found I could adjust the tone.
Portable tin mod by John:
I squeezed my light theremin into an Altoids Smalls tin on perfboard. I trimmed the fat by ditching one of the capacitors and switching to one CR2032 battery (although two makes it much louder).
Motor mod by Hikus:
As I went through the build, I found I didn’t have capacitors in the right amounts, but that turned out not to matter so much. I played around with what I had, and found ways to hack my way through. For the .47 microfarad capacitor, I used five .1 microfarad capacitors in parallel. For the 100 microfarad capacitor, I think I used a 350 microfarad capacitor from a junk box. I have a speaker, but plugging it in didn’t do anything. Instead, I used a small DC motor. I’ve been playing with them a bunch lately with Arduino, and found out they can make pitches just like speakers. I laid it against the computer which was recording, and the pitch came through just fine. I had a photo resistor handy, so that’s what I used for my light sensitivity.
Manhattan mod by Kendrick:
Manhattan style construction has appeared a few times on the Make blog and is popular with the ham radio crowd. It involves an un-etched piece of copper clad board with small “pads” of clad board super-glued to it. These little islands act as the connection points between components and can be added quickly or snapped off if needed. The larger piece of board serves as the ground so it is always easy to solder into.
Spare parts mod by John:
The speaker is from an old musical book that had long ago been torn up by the kids. I harvested the circuit board for future circuit/noise bending, and had thrown the small speaker in my junk/parts bin before recycling the cardboard book. All the other components came from my junk/parts bin. It was a fun easy build.
There you have it! Now the real question is, how will YOU mod the Light Theremin?
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