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]
Step 1: 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
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.