Picture of Arduino Photocell Theremin Synth (glitchamin)
You know theremins, right?  Those cool-looking boxes with antennae that produce noise without being touched?  They are played by the likes of Jimmy Page of Led Zeppelin, and present in the soundtracks of countless films.  Well, with this instructable, I will show you how to build an approximation of a theremin (in principle, at least) using some basic electronics built on top of an Arduino, which I call a glitchamin.  This circuit features adjustable parameters and an optional kill switch, and information on hooking it up to an amplifier for the full-on concert glitchamin experience.

[Sorry for the blur in the photo below]
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Step 1: Part list

Picture of Part list
Before you can get started on any project, you need to make sure you have all the parts.  Here's a rundown of what's necessary for this build.

1x Arduino (I used a Duemilanove with a 328, but the circuit and code are light enough that any Arduino board should work)
1x half breadboard (the circuit could easily be replicated on perfboard)
1x momentary pushbutton (optional, for kill switch)
2x potentiometer (I used 1kOhm and 10kOhm, but similar values should be acceptable)
1x CdS Photocell resistor (the heart of the glitchamin)
2x 10kOhm resistors (brown-black-orange-gold, 1 is optional, for the kill switch)
1x piezo buzzer
1x 1/4" mono audio jack (optional, for attaching to amplifier)

Everything you need, with the exception of the piezo buzzer and the mono jack, is in the kit "Arduino Budget Pack" from Adafruit Industries.  I used Radio Shack to get the piezo and the mono jack.

Step 2: Attach the potentiometers

Picture of Attach the potentiometers
Take the two potentiometers, and insert them into the breadboard in some convenient location.  Then, take some wire, attaching the left lead on each to 5v, the right to gnd, and the middle (wiper) pin to Analog inputs 1 and 2.  The pot attached to a1 controls to some extent the pitch by trimming the sample time.  The pot attached to a2 controls the decay of the sample by mapping the number of cycles the sample lasts.
Tookkyyoo1 month ago

Anyone have a link to the code?

betadata16 months ago

Hi, great project! It was fun! Attached is my build of your theremin. Works great! I'm gonna hack it in a bit to get the sound I want. Will upload mod soon. Thank you for the great design, Gatesphere.

ICDab1 year ago

Hey man great project just finished! and thank you again :) i had one question is there any way to change the code to make the signal sound different?

faziefazie1 year ago
can i using this mono jack instead of yours?
leeseibert2 years ago
I did a project similar to this one. Then I shrunk it down to an ATTiny85 chip. Check it out here:
sokbok2 years ago
awesome. Id like to try some other CdS photoresistors. Any recommendations? What about using a full solar panel through some kind of transistor? An audio way to fine tune the solar gain of a panel
NolagTheOrc2 years ago
will two 5kohm potents work?
fatboy1063 years ago
You have successfully helped me annoy my family.
gatesphere (author)  fatboy1063 years ago
Nice. :)
arduino man4 years ago
I can't get the code
gatesphere (author)  arduino man4 years ago
I just clicked the link... it works for me. Anyways, here's an alternative link: