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Comment by _spduchamp | Hacker News Reader

Skip the complexity. You can connect a photovoltaic cell directly to an audio jack and hear vibrations in light.

I've used this technique for building DIY instruments that I occasionally play at electronic music open mic nights.

This was my first light based instrument... https://youtu.be/ZF2Rn5YfBC8

Then I made a "solar pedal" like this... https://www.instagram.com/p/C2ONSOYti1p/ and did a set like this... https://youtu.be/3sHR2oSeqcY

I highly recommend if you are into sound stuff, go crack open an old solar garden light, attach an audio jack and have fun exploring the hidden vibrations in light.

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This is specifically mentioned in the article:

"Due to the expense and tuning problems with a “real” theremins a number of “light” theremins have been produced. These all use some form of light sensor to detect the position of the players hands, but all suffer the same problem they are sensitive to changing light conditions and have very restricted range of detection."

If you have a decent laser cutter and a preamplifier you can send music out that way. https://www.youtube.com/watch?v=iyDwPJ8CUF8

How can this be attributed to light instead of other EM waves floating around

Try it. It is most definitely the fluctuations in the light. Yeah, there is likely some EM interference, but the rapid fluctuations of artificial light are the source.

LEDs, CFLs, even incandecents, all have vibrations that are audible when you pull audio out of the solar cell. Sunlight, not much. No audible vibrations at all.

IR remotes are fun. For the last show I played, I put a couple layers of garbage bag over the solar cells to make an IR pass filter to block the stage lights from interfering.

Really, give it a try.

Cover it and see if the signal goes away. Then take it to a dark room and shine light on it.

If it goes from sound to silence in the first case and from silence to sound in the latter, you can be reasonably sure that light has an effect.

If you want to rule out other radiation, you can try shielding the contraption.

If it’s an artificial light source not really

If that concerns you, then you might want to conduct the experiment with a „non-artificial“ light source. Use a candle that you wave your hand around to modulate the signal if you like. If you suspect that it‘s not visible light but infrared that affects the effect, then selectively shield visible light with a (black) garbage bag and try again.

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