Possession of low-voltage consumer electronics. A love of very noisy things. A do-it-yourself aesthetic - Do you possess these items and/or attributes? Then come join the Circuit Bending hoedown! It's disturbing and easy! Here's the how and why (no, actually, the how and what)...
Circuit Bending is the art of messing with the electronics inside of stuff that makes noise, in order to make new and more useful random noise. The goal is to augment gadgets, kids toys, guitar pedals and cheap synths with new knobs, buttons, switches and "body contacts" that boldly go where no manufacturer would ever be bothered going.
The idea dates back to the 60s (so I just read on Wikipedia), and is very easy and super fun. And the easiest, funnest way to learn is to attend the workshop run by Nick from Toydeath - If you're going to learn, you may as well learn from the master. The workshop (and this blog post) runs through the two main activities of circuit bending: Soldering and Rubbing Spit on Things.
You can spit all day long and not get a cool instrument out of it, so let's start with soldering...
Soldering. I've always feared it. A mystical and esoteric practice, learned from the ancient and wise soldermonks over a period of several decades, during which time your mortal clothes transgress in to short-sleeved collared shirts that tuck into your jeans.
But it turns out it's really easy.
The trick is to "tin" the wires - melt a small amount of solder over the wires - before you join them. Then just bloody do it. Soldering components to the circuit board is pretty easy too. After about 10 or so goes, my shirt even started to tuck itself in a bit.
[This isn't me, by the way]
Let's move now to the good bit - making scary noises. Your best bet is to head down to Chinatown and pick up an arm full of the most annoying looking toys you can spy - the kind of toys that parents give their kids on buses and aeroplanes to make your life more pleasant. A good rule-of-thumb is the more copyright violations the better.
Now pull them apart with a screwdriver. Be gentle, and put the screws somewhere you can find them - you will want to re-assemble the item when you're done.
Once you're looking at the guts of the toy/synth/thing, it's time to find the circuit board (or boards) and start looking for bends.
Trigger the item so that its making noise, then press the circuit board with your thumb. Move around the board pressing and prodding at random. Hopefully (and usually) you will hear things go nuts. You've found a bend!
What is happening is that your thumb is conducting electricity to parts of the circuit that it wasn't supposed to get to. To really get some wacky results, lick your thumb and have another go. Awww yeah! Saliva makes an excellent conductor.
Find the source
Once you've found some crazy noises, it's time to narrow down the source of the new sounds. Get a short length of wire and start joining contacts on the circuit board, approximately where your thumb was pushing. A good way to do it is to pick one "spot" on the board with one end of the wire, then test a bunch of other spots with the other end.
Keep scouring the board until you've found all the bends you can find, or get bored.
Now that you've discovered the crazy connections, it's time to wire it up to something usable. The choice of interface depends on the kind of noises the bend produces - an "on or off" type effect could use a switch or a push button. If it's a sound that changed as you pressed harder or softer, then perhaps a potentiometer (a knob) is a good choice - or possibly a "body contact".
A body contact is cool if you have found a bend that works best when you pressed the circuit board, rather than when joined with a wire. To make a body contact, you wire each connection point on the circuit board to a screw (or some other metal object) that protrudes from the toy.
When you touch the two screws with your thumb (or whatever body part you want), it completes the circuit, and the toy goes nuts - just like pressing the circuit board directly. Add some spit into it, and you've got instant chaos!
Once you have your killer noise-making machine, it's just a matter of mounting all the knobs, switches and body contacts in an attractive manner on the toy, adding in an RCA output for an amplifier, then putting it all back together. Um, good luck with that.
Circuit bent machines in hand, you can now form your post-folktronica-pre-post-post-Nouveau-rock band (perhaps called Soldermonk Hoedown). You'll tour the world, using your lack of electrical knowledge to benefit small parts of Mankind - so if you're not embarrassed to be seen at Dick Smith, go grab yourself a soldering iron and get to it!