Picture of Light Theremin
The Light Theremin is a simple to build instrument that uses light and shadows to create sound. The theremin circuit used nomally for these insruments are quite complex, this one however is as simple as a 555 Timer IC and some basic components from your scrap box. so with out any more delay...Lets get started!

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Step 1: Materials

Picture of Materials
Your materials list is really quite short. You will need the following parts...
Please note that the quantity of each part is in the [ ].

-555 Timer IC [1]
-100uf Electrolytic Capacitor [1]
-1.0uf Disk Capacitor (Marked "104") [2]
-Photo Resistors [4]
-1K Resistor (colours: Brown, Black, Red, Gold) [1]
-a Switch [1]
-9v battery [1]
-A speaker [1]
-A IC proto board to keep it all nice and tidy [1]
-Some machine screws and nuts to hold down the board (optional)
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braintrain3 years ago
I am really sorry but I have one more question. I hooked it all up and it didn't work, so I moved C1 between 1 and 2 and the first two resistors work, but the other two don't, what can I do to fix this problem?
TXTCLA55 (author)  braintrain3 years ago
I heard some people have had this problem before. As far as I can say it can be a bad spot on the bread board or your using the wrong components. However one user had a issue like this awhile back, this is his message:

I tested it on a breadboard, didn't work until i removed C2 and put it between pins 1 and 2. But then it worked like you described. Nice casing btw.

I'd try that and see if it works. If not I suggest you try putting in 100k resistors where the light dependent resistors are and see if you get any results. I hope you get this project working, all the best. 

jensenr304 years ago
Looks cool! I'm subbed!
luudvig5 years ago
Thanks, I built it and it works great!!
KMSherni3 months ago

I made this and was able to get sound, but just barely. It was almost inaudible. Do you have any suggestions?

KMSherni3 months ago
pvoss12 years ago
Only change I'd make to the schematic diagram is jumper wire between pins 2 and 7 should be between pins 2 and 6.
Great article. Thanks!
tedixxx3 years ago
hola tengo una duda el capacitor de 100 uf exactamente omo esta conectado para proto no entiendo bien ya lo hice tres y no me funciona no se que pueda estar mal ya lo revise todo ayuda que puede ser lo mas común que este fallando y como resolverlo
Leeleelilac3 years ago
I wish the instructions on step one were more specific
I mean step 2. Maybe more of a step by step way of putting all the pieces together
TXTCLA55 (author)  Leeleelilac3 years ago
Step 2 is just soldering the circuit. I skipped over that bit because there is really isn't too much to get into. Next time around, I'll be sure to add some more pictures and captions.

adairo163 years ago
thanks for posting this great idea but i have a question
how can i add a jack female output and a volume potenciometer?
please it is very important to me.
TXTCLA55 (author)  adairo163 years ago
The female output can be put in place of the speaker, or in parallel to the speaker. As for volume control I am sorry, I cant help you there.

darockerj3 years ago
So where did you get your 1.0uf Disk Capacitor? I looked on the Radio Shack site and I couldn't find one, and I don't want to get a $30-something box with a bunch of capacitors I won't use.
TXTCLA55 (author)  darockerj3 years ago
$30? Really? Wow, I just pulled mine out of a radio. I could have sworn they had them in an assorted pack for less than $7.
sevusz3 years ago
Hello! I tried to make this light theremin but i didn't succeed to do that. I have just one question for you, what kind of photo resistor did you use? 5k-10k? Please help me if you can because i should finish it until thursday:(
TXTCLA55 (author)  sevusz3 years ago
I am pretty sure they are 10K. However I have no way to truly test out their resistance. Like I said I just bought a pack of them from Radio Shack (The Source).
Ezra Fike3 years ago
I can appreciate theremin. I used a digital recreation of one in my song "Charlie the Ghost". Get my song at http://ezrafike.bandcamp.com/track/charlie-the-ghost.
braintrain3 years ago
I bought a AVX 1.0uf 35v thru-hole tantalum capacitor radial 10%. Will this work instead of a 1.0uf disk capacitor? I also bought an audio jack instead of a speaker, so I can get it louder. Please respond because this is my science class instrument. I will get a grade for this. I am also asking if you can play any simple songs like twinkle twinkle little star or something along those lines.
TXTCLA55 (author)  braintrain3 years ago
I cant say for sure if it will or not. Really the best way is to just hook it up and see what happens. I do believe that radio shack (or the source) sells a packet of assorted capacitors, you might be able to find one in there. Hope this helps.

Thank you,
One other question, I just got the photo receptors today from radio shack, and I was wondering if it matters what size the photo receptors are. They came in a package of five, but all different sizes.
TXTCLA55 (author)  braintrain3 years ago
No size doesn't matter. It just means your larger ones will be a bit more sensitive as they can gather more light than the smaller ones. If anything it means you'll just get more funky tunes from it.

Thanks so much. BTW great instructable.
TXTCLA55 (author)  braintrain3 years ago
Glad to have helped, and thanks.

bibbibbib3 years ago
is the voltage rating for the 100uf capacitor 25v? or something else
TXTCLA55 (author)  bibbibbib3 years ago
The voltage my capacitor says is 16v at 100uf.
104 capacitors are 0.1uF!
TXTCLA55 (author)  blinkyblinky4 years ago
Thanks, but apparently it works with both.
mgrc5 years ago
Mine won't work...I put in on a breadboard and re-checked everything twice. Does it matter if 2 of the photorisistors are slightly different sizes? Are they polarized (+, -). I also tried what datenkrieger said and removed C2 and put in between pins 1 and 2, but still nothing. I'm using an adjustable power supply set to 9v, so it's not that. my 555 timer said LM 555CN. I'm using a 100uf cap and two caps marked '104', just like you said. The speaker is marked at 8 ohms and it makes crackly sounds when I hook it straight up to a AA battery, so that works. I'll ask my dad, but do you have any ideas?
mgrc mgrc5 years ago
Nevermind, I got it. It turned out I had a bad spot on the breadboard, so I just moved everything over a bit, and still using Datenkrieger's idea, it works. I might need a better speaker because it really sucks with low pitch, it just makes ticking noise. Has anyone wired it up so a pair of photoresistors changes the pitch and the other pair changes the volume? It would be like a radio-wave theremin. Good instructable BTW. Thanks
TXTCLA55 (author)  mgrc5 years ago
Sorry to hear you have been having some problems, but I am also glad to hear that you managed to fix the issues as well. I think the problem some of you may be having with the capacitors is that some 555 timers may require different connections (probably due the manufactures design) in any case this should happen to any one in the future I would suggest trying this solution first before commenting. As for your issue with the sound (pitch and tone) the photo resistors should work like that already if not try using a fresh battery and the volume should improve. Hope this helps!
where can we get all the materials?
TXTCLA55 (author)  raisin_brain7475 years ago
You can get most of the materials from radio shack or the source as it has come to be known. Or you can get the components from online sellers like solarbotics.com thats probably the cheaper option, however if you still cant find some of the components just rip open a old radio and your more than likely to find what you need sooner or later. Hope this helps you in your project(s) let me know if you are still having trouble location the components.
GreenD5 years ago
 I'm assuming light allows for current to pass through the photoresistors?

I wonder if there is a way to make the sound more pleasing...?
TXTCLA55 (author)  GreenD5 years ago
I don't know about that, I prefer the electronic whine of the device so I never really went much further to improve it; but if you can figure something out send me a message!
Would it be possible to add an oscillator and a pot. to control said osc.
TXTCLA55 (author)  raisin_brain7475 years ago
Yes. My first model worked like that, but I wanted to add something special, so instead I used photo resistors to do the job. 
MottGia15 years ago
Hey, you said we needed 2 "0.1uf Disk Cpacitor" but on both the next images you say we need 1.0uf capacitors, which ones do we really need then?
TXTCLA55 (author)  MottGia15 years ago
Opps my mistake. Its a 1.0uf capacitor. they should have a "104" marked on the side. Sorry for the confusion, its corrected now.
i'm confused about the capacitors as well.  I bought 0.1uf disc capacitors because they read "104Z" on the side, and look exactly like the ones in your picture.  the electronics store did not know of any 1.0uf capacitor with '104' marking... just the 0.1uf.  anyway, my circuit works it's just the volume output is very very low.  you can barely hear it.  any ideas?
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