This is taken from Phil Moffa's Artist in Residence program, and is just one of many in-depth tutorials in that program.

by Phil Moffa

Have you ever heard about circuit bending?  This hobby/art/way of making very interesting sounds has been around for a while and has gained lots of popularity in recent years.  The web is full of resources on this topic and now there are even some very informative books out there, most notably Circuit-Bending: Build Your Own Alien Instruments by pioneer Reed Ghazala, the man who coined the term. 

In short, circuit bending is the modifying of electronic devices in the interest of making sounds that the manufacturer did not intend.  It can be as simple as a wire that connects two points on the circuit board, or as complex as adding countless knobs, buttons, switches, patch bays, jacks, and rehousing the unit in a new case.  If you don't know anything about electronics, do not be intimidated.  Circuit bending requires no knowledge of electronics.  All you need is a little patience, some tools, some time, and something to bend.  Old toys, drum machines, Casio keyboards, or basically anything that is electronic and generates sound can be bent.

Circuit bent Speak & Spell, also known as an incantor.  I did this one with Ghazala's help a few years back.

Although I will shed some light on this toopic, the world of circuit bending is way beyond the scope of this blog post.  I recommend the above book by Ghazala or the article that I found in Electronic Musician magazine back in 2003 that got me interested in this cult hobby.  From there, you can google many sites, youtube vids, etc that will all give you a little knowledge.  Keep in mind that this is an art of discovery and you will also be teaching yourself a lot along the way.  Note about safety: wear goggles, ventilate the room, and never bend something that is plugged in.  This is for low-voltage, battery-powered devices only.

Bending basics:  After opening the case and exposing the guts (circuit board and components) of a noise-making toy or instrument, your first mission is to make connections of different points to see if they change the sound in any way.  This can be done with a your fingers (you are a conductor), the tips of an rca cable, any wire or probe.  So, you need to continually make a sound while poking around to find potential "bends".  If something sounds interesting, make a note of it.  From there you can try any number of switches, pots, or body contacts that can later be connected and used to engage or tweek your new found effects. One of the easiest and most essential bends is to put an output jack, either 1/4" or 1/8", on the unit so you can send it to an amplifier or mixing board.  The full frequency range is never head thru a one inch speaker.  In fact, the first bend I ever did was putting a 1/4" jack on a toy piano from a board game.

Notability, my first bend. Check out the output jack and the volume knob.  Suprisingly, this sucker was LOUD.

This video shows my first recording of a bent Roland TR-626 - a 1 bar loop and some of the possible bends that are now easily achieved by swapping RCA cables.  This is just the beginning of the possiblities here.

The above video and the description below are of a slightly advanced bend, but very do-able to say the least.  You may want to start with something easier if you've never soldered before.  All props to Burnkit 2600 for their extremely informative page where I learned about the 626 bends. 

Basically, in the 626 there is a chip with 32 points that stores the samples that make up the drum kit.  It is known as IC15.  (IC stands for integrated circuit.)  When simply connecting any of these 2 points with a wire, the sounds get scrambled, distorted, flanged, and become atonal.  32x32 leaves for a lot of possibilities.  I connected 25 of these to a DB25 port like the kind you would see on an old printer.  Then I made a RCA patch bay out of 4 panels of 8 RCA jacks glued into a project enclosure.  This new box has the 32 jacks and a DB25 port on it, with 25 of the jacks connected to the DB25 pins.  By using an old 25 to 25 pin SCSI cable, the two boxes are now joined and by using the RCA patch bay, many combinations can be made.  I regret not doing this with a larger DB port, but these are the parts I had and I figured it would still present a lot of possibilites.

Inside the 626, here's the IC15 chip connected to the lugs on the DB25 port.

Interior of the RCA patch bay

The 2 ports on the exterior of the Roland and on the RCA bay

Tools you will need: a soldering iron and solder, wire, wire cutters & strippers, pliers, screwdrivers (small and regular), fresh batteries, and whatever components (pots, knobs, switches, etc) you want to experiment with. A dremel or drill is good for making holes in things for surface mounting components.  There's plenty more that will be useful but these are essential.  Just round up whatever tools (especially small stuff) you can.

Good luck, and if you need help, let me know.  If you make anything interesting, we want to hear it and see some pics.