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!


Don't forget to visit my site:
http://www.wix.com/SimpleCircuits/Simple-Circuits

Step 1 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)

Comments

[luudvig]

Thanks, I built it and it works great!!

[rtty21]

Looks cool! I'm subbed!

[bibbibbib]

is the voltage rating for the 100uf capacitor 25v? or something else

[TXTCLA55]

The voltage my capacitor says is 16v at 100uf.

[blinkyblinky]

104 capacitors are 0.1uF!

[TXTCLA55]

Thanks, but apparently it works with both.

[mgrc]

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]

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]

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!

[raisin_brain747]

where can we get all the materials?

[TXTCLA55]

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.

[GreenD]

 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]

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!

[raisin_brain747]

Would it be possible to add an oscillator and a pot. to control said osc.

[TXTCLA55]

Yes. My first model worked like that, but I wanted to add something special, so instead I used photo resistors to do the job. 

[kappish028]

oh i see.hehehe!!! thanks your the best! before i forgot can i see the back of this light theremin that you made if that is possible but if not its ok. last question can i bend this theremin?

[TXTCLA55]

There's not much to the back of it...just the wood the box is made of and the hinges for the lid. And you may do what ever you please with this circuit expect mass produce it and sell it on a consumer market! Hope that answers your questions.

[MottGia1]

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]

Opps my mistake. Its a 1.0uf capacitor. they should have a "104" marked on the side. Sorry for the confusion, its corrected now.

[MottGia1]

Thank you

[edspegeddd]

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?

[TXTCLA55]

Try using a new battery I had this problem to. The capacitors you are using could also be the ones to blame. If you cannot hear it with the new 9V battery I would suggest finding new capacitors; try opening a radio there will be lots in side.  Hope this helps!

[kappish028]

can i use any 555 timer? what kind of 555 timer did you use? sorry i dont know anything about electronics kindly help me thanks.i saw that there are LM555 and NC or NE 555 timers what is the differences in those timers?thanks!

[TXTCLA55]

Nope, there is no difference in the timers you have/saw. The letters simple stand for the company's model, not the type. All of those you listed above will work.

[luudvig]

Does it matter how many volts the capacitor is on?

[TXTCLA55]

yes, in this circuit it does. Capacitors are essentially store houses, imagine it slowly filling up and then all at once emptying out. This is how capacitors work, they slowly build up electricity then all at once, lets it all go. They are normally used to stabilize the current in a circuit. In short you should probably use the ones I did or find something really close to it. Hope this helps!

[blindrulz]

hey guyz comment this simply like wat is did

[Laogeodritt]

Hello, This looks like an interesting project, thanks for posting. I have a few questions regarding the light theremin: Does it allow controlling the amplitude of the output with one control and frequency with another (as with the real theremin)? From what I understand of the IC and this circuit, it doesn't seem so... If not, do I understand the 555's specs correctly in that the amplitude of the signal is proportional to the input voltage, and so I could implement this feature by varying the voltage at the +V pin? What is the max voltage this puts out? Is there any risk of damaging drivers with an impedance in the 8-16 ohm range by hooking them up directly? (Or, in other words: what considerations should I make regarding the speakers - impedance, etc. - or the output to prevent damaging them?) Thanks, Laogeodritt

[TXTCLA55]

Hi! If I am reading this correctly these answers should help you out...

Does it allow controlling the amplitude? I am not sure what you mean here but, I think what you could be getting at is something to do with volume control. The answer is yes; you can put some sort of device or component to control the devices volume. If that doesn't help send me a message and I'll try to help more.

what is the max voltage this puts out?" Any attachable speakers ranging from as little as 4ohms to 16ohms can be used (at least thats what I have tested) anything more might loose the sound effects the Light Theremin produces.

I hope I was helpful and was able to answer both questions fully. any other questions you may have can be sent to mer via instructables mail.

[Laogeodritt]

Hello, Yes, essentially, volume - to me, a given instrument isn't musical if it's lacking the ability of expression, a lot of which is done through dynamics. I was hoping it implemented or I could implement something similar to the left antenna using light-sensitive components. (I was looking at the circuit itself, but I stupidly neglected putting something at the output stage... I can pretty trivially add a voltage divider there.) All right, thanks. I was mostly concerned with damaging them. I plan on putting an output jack on it and playing around with the sound using a few (home-made) analog effects/filters, so I'd rather be sure. I'll probably check the output and see if I have cheapie speakers lying around just in case... Thanks for the reply. Laogeodrtt

[TXTCLA55]

Hey no problem! let me know how things turn out! TXTCLA55

[amplex]

very cool!! ive been wanting to make one of these with an antenna for awhile, picked up an RC antenna from radioshack awhile ago, how much different would that be?

[TXTCLA55]

Very different. You see the "regular" theremins use radio waves or IR signals to create sounds, and also use more complicated circuits. Mine however is pretty much a cheap, easy alternative to the regular theremins. Hope this helps you answer your question.

[amplex]

i understand that you are using resistances to determine the pitch of the 555 osc with the LDRs, not radio waves or IR, but im thinking that you could easily adapt it to the antenna type by having one pin on the 555 be the top of the antenna, and the other pin be the bottom (so the antenna acts as a variable resistor depending on where you put your hand on it and how much contact you make).. not exactly the original theramin idea (of not touching it to play it) but would this work? kind of like how a ribbon controller works?

[TXTCLA55]

Hmm...it might work. You could always give it a try. Let me know how it works! :P

[Gamernotnerd]

Sounds like a squirrel getting raped... On some sort of squeaky surface.

[TXTCLA55]

LOL. Thanks (I think).

[Gamernotnerd]

It was a good idea, lol.

[datenkrieger]

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.

[TXTCLA55]

Hmm that is strange. I went thorugh all my steps and looked at the project IC board, all was well on mine...oh well. I guess the imporant thing is that it worked.