For my band at the time, I wanted to have a theremin-type noise. I don't have the cash to buy a theremin, and I didn't want to attempt to make another large Electro-Theremin (Tannerin). So, in May 2003 I decided to make a theremin sounding device built right into a guitar pedal style housing...
When you think about a theremin, the way you play it is quite silly. The reason it is so popular is the strangeness involved in how it gets played, and the theatrics involved in playing it. That's all good, except for the fact that theremins are quite expensive. I just want to have an oscillator type sound to mess around with, I don't want to actually play melodies on it. I just want to make some weird noises. So, I thought I'd make my own little device to do it.
I used a "cheap function generator" circuit from qkits and ordered a project housing and several other things (stomp switch, pots, resistors, jacks, blue LED) from small bear electronics. I dealt with them when I made my first guitar effect, a fuzz pedal, and I was quite pleased with the products and the price. The owner even shipped me a few resistors that I later realized I needed, since RadioShack doesn't sell resistors anymore. Don't even get me started on how stupid it is that radioshack doesn't sell resistors. The rest of the parts, knobs, switches, hook up wire, etc. were salvaged from my junk drawer and random radioshack discontinued parts collection.
There is an input and an output. The input is option and can be anything I guess, but I've only used it with my guitar. When the stomp switch is off, the output is just the guitar signal. It is also true-bypass switching, so the tone of the guitar isn't effected. When you stomp on the switch, the guitar signal still comes out, but so does the function generator sound. Two knobs control frequency and volume. The frequency range, which I haven't bothered to test I'd estimate to be from 100Hz to maybe 5000Hz. There are also switches to change the waveform to sine, square or triangle.
For this project, Unlike my Fuzz pedal, I wanted to make it look as professional as possible (without spending money). So I decided to paint the metal housing. I used Krylon Rust Paint, which my girlfriend bought for me. I also tried clearcoating it on a test patch, but the Krylon clearcoat made the Rust Paint bubble (how stupid)! I also used my girlfriend's label maker to make some labels. My favourite part is the big ultra-bright blue LED power indicator. I don't think the Rust Paint is good enough for typical guitar effect abuse though. I'd suggest trying some Enamel Paint, and then baking it.. something I may try if I make another guitar effect.
The internal wiring I found to be a little complex, so I used a full piece of paper to draw a "map" of where each wire will go before I started soldering. Once I finished, I checked the map to make sure I did every wire and then tested it and everything worked perfect!
My original purpose for this pedal was to actually strap it onto the guitar, so I could switch it on with my hand and start fooling around with the frequency knob. A strange oscillator sound coming out of my guitar would definately confuse a few people.
At the time of writing this, I haven't used the function generator pedal for any gigs, but I have used it on a recording. You can get the recording on the "Downloads" page, it is a cover of the Devo song "Smart Patrol/Mr. DNA" off of my band Revo's EP called "This Not This". The function generator solo happens at 3:40 into the song and is also run through an Analog Delay unit that has modulation. I am playing the function generator's frequency knob as well as the Delay's modulation speed knob. There's also a second solo at 6:00 into the song.
Overall, I think this pedal is really cool and definately unique. The paint could be better, and it cost around $50 or so to make. The sound is purely based on the function generator circuit that I used, which I think does the job. DIY Function generator circuits can be had for very cheap, just throw one in an enclosure and you are all set!!
Check out my Function Generator!
