Anyone who’s shivered in the dark at a scary movie or laughed at the unintentional cheese-ball of a bad sci-fi (paging Ed Wood) knows the eerie sounds of the theremin. In the classic theremin design, two antennas control pitch and volume, and you play the instrument by moving your hands near the antennas without touching them.
This simpler design uses interrupted photons (light) instead of radio waves, and can be built with a handful of common components, including the versatile 555 timer chip. When we’re done, we’ll have a decent sounding mini-theremin. You can experiment with its sound by changing the type of light sensor used and the capacitance of the circuit.
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Can you tell me anything about what the circuit is doing? It might help to diagnose what could be wrong.
Steve
I now have it working. I posted my results on a blog. I made a modification by adding a 10k pot into the mix and am using two different .22uf capacitors so those variations give a lot of variation and flexibility to the pitch. I ended up going to Radio Shack to get the .22uf capacitors from the parts list. The rest of the parts I mail ordered. This is the first non Arduino based project I have gotten to work. Lots of fun to play with and irritate some of my older children. Thanks for a great project. If you would like to see what I did here is the link. http://sdmadeit.blogspot.com/2011/11/no-30-light-theremin.html
We posted Ed’s Snap Circuit photos on the makezine blog:
http://blog.makezine.com/archive/2011/11/snap-circuit-light-theremin.html
Sorry, I should have mentioned… I built mine on a RadioShack Learning Lab and used the speaker that comes in it. I suspect that might have something to do with why I didn’t get good volume until I used the audio transformer (which is also built into the Learning Lab).
Great idea. I have used LEDs with mine, but hadn’t thought to try IR LEDs. If you don’t have your camcorder, try using your TV remote…
hi Priit, Check out Steve’s mod here on the blog: http://blog.makezine.com/2011/11/17/weekend-projects-light-theremin-mod/ – click through to his blog & send him a message if you need more info, but it looks like his 10k pot sits between ground and the electrolytic capacitor.
hi Ian,
A capacitor stores charge, at a certain rating (.22uF and 100uF for this project). They’re composed of two plates (pos & neg) with a non-conductive material (dielectric) between them; the plate material and dielectric, along with other factors, determine the rating of the capacitors. Look at the cross-section of a Leyden Jar to understand the design. There’s a good picture in this How Stuff Works article from 2007 also: http://electronics.howstuffworks.com/capacitor.htm
Hola Brenda. Prueba a conectar cátodo del capacitor al carril de tierra.
Congratulations! If you have photos, please send them to weekendprojects@makezine.com – thanks!
Interesting hack – please send photos to weekendprojects@makezine.com – thanks!
Does anybody know if there’s a way to make this circuit work without the photoreceptor — more like a traditional theramin where you’re body’s EMF interferes with the EMF of an antenna? I’ve seen it done with a 555 timer very simply before so I know it’s possible…
This is not technically a theremin since it uses photo-resistance for voltage control of a single oscillator and does not use capacitance controlled heterodyne interference. Not a big deal, but noting it might be interesting for those with an interest in the history and development of the theremin and theremin-like devices. :-)
(hopefully this comment is not seen as hating/trolling)
Not by me :-)
You are quite right, it’s not a Theremin internally, but externally it gives you an idea of how it feels to play the real thing.
I built a vacuum tube Theremin a few years ago, and still find this to be the most playable/expressive of all the designs.
Definitely very fun to play with! And there are many mod possibilities. Thanks so much for sharing this project.
what is the value of the resistors?
Hi ! where does the bottom black cable come from , my theremin is not working yet :(
I had some trouble getting it all together, and had to get help from the surplus store crowd. Here’s my video… http://youtu.be/zk85jgmLU58
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Funny, I’ve just been reading Us Conductors, a fictionalized account of part of Lev Termen’s (inventor of the theremin) life. Maybe when I’m finished the book I’ll try making this!
Serendipity is weird.
If anyone checking out this project is interested in going the opposite route, here’s the book’s site: http://usconductors.byseanmichaels.com/
Yes! Built it! It’s presently driving the neighbor’s dogs crazy. Thanks for the guide. It was fun:)
I cannot see the list of supplies. Can anyone suggest what type of speaker I should use?
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Wanda , i also was confused but i just used a pizo
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He was also a soviet spy: https://en.wikipedia.org/wiki/L%C3%A9on_Theremin
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