The Art of the Creative Short Circuit

Jan 1, 2003 12:00 AM, By Qubais Reed Ghazala

A Beginner's Guide to Circuit Bending

ADVERSE EFFECTS

Your new circuit paths may have no adverse effect upon a circuit when they are switched on by themselves. Problems may occur, however, when some of the paths are used simultaneously. For example, the volume may decrease or drop out altogether when two or more switches are on.

Be aware of such switching combinations; avoid them or modify the wiring behind them by finding another pair of points to wire one of the switches to. Retest the device. Feel the ICs, resistors, and other components on the circuit board as you test the connections. If you make a connection that causes a component to become unusually hot (some components warm up a bit normally), it's a good idea to avoid that connection. Good circuit-bending connections create unusual audio behavior without taxing the circuit or draining power, and without destroying the electronics.

There is no way to experience all the switching combinations as the new wiring is being charted on the circuit board. Not until the instrument is complete can the designer fully explore it, because it is not until then that all of the connections and new controls are in place and can finally be combined. At that point, the instrument reveals itself in ways not evident during the initial, one-effect-at-a-time discovery process. This is a wonderful moment.

INCANTOR ENCOUNTER

The Incantor streams shattered phonemes, bridged with unusual tones and noises, that combine with recognizable words as the speech synthesizer's linear predictive coding lattice is rearranged by the creative short circuit (see Fig. 2). It is possible to set loops on an Incantor. That provides a means of control within the chaos and allows you to divide the abstractions into approachable measures. I also add a master pitch control so that the sounds can be clocked very slowly.

You can induce a real-time vibrato using body contacts. Those usually take the form of small metal balls wired directly to circuit points. When you touch the contact points, changes occur within the circuit that might adjust pitch, volume, or timbre or initiate other circuit activity such as triggering a voice or incrementing a loop.

You should become familiar with how the Speak & Spell works before you begin to bend it (see the sidebar “Parts for the Incantor”). There were many different circuit boards in the Speak & Spell over its manufacturing run (see Fig. 3). While the instructions here show one of the most common boards, yours might not match. Just dive in with the general bending advice provided earlier and use Fig. 3 as only a very general guide. (You can e-mail me directly with questions if your board doesn't match the one presented here or if you want to inquire about a prebuilt Incantor.)

After removing the batteries, remove the two screws at the bottom back of the instrument (you might need a Torx driver). Next, remove the back of the unit by prying the locking tabs in the four square holes inward with a screwdriver blade. Some people leave the clear gray display lens intact, while others pry it off. That's up to you.

Steering clear of the keypad and circuitry, drill three ⅛-inch pilot holes for the toggle switches and one for the pot (you will need to locate a space where that will fit). It's convenient to drill the hole for the push-button reset switch in the void to the bottom-left of the battery compartment, below where the black battery wire runs (be careful not to hit it by accident). The pilot holes can be enlarged with a hand bore, the tapered blade of some scissors, or a spherical burr bit. Mount all components.

Wire the push-button reset switch in the middle of the black battery wire. That switch cuts power to the circuit when pressed. Remember, the reset switch is an NC switch: it breaks, not makes, the circuit.

Wire the pitch pot to the circuit points as shown in Fig. 3. One wire goes to the middle lug of the pot, and the other wire goes to the lug counterclockwise from the middle lug (as viewed from the back of the potentiometer). Note that turning this pot down all the way (fully counterclockwise) will crash the circuit. When you get into the speed range where the fluorescent display begins to flutter, you're near a crash. (You can install a trimmer pot to limit the low-end of this range, in order to avoid crashing, if you like.)

Wire the group of two bending switches. These are the “bends” that turn the output into unusual audio sequences. Finally, wire the remaining loop toggle switch (see Fig. 4).

TESTING PROCEDURES

Now it's time to load the batteries. Hold them in place with a strip of tape and begin the testing procedure. Press the reset switch immediately if the circuit crashes in any of the following:

1. Turn all toggles off, and turn the pitch dial up all the way (fully clockwise).

2. Turn the Incantor on: you should hear its intro as you did before you modified the unit. If you hear nothing, turn the pitch dial the other way, press the reset switch, and try again (just in case the pot was wired backward).

3. With a voice in progress, press the reset button. The instrument should turn off.

4. Again, turn the Incantor on. With a voice in progress, turn down the pitch dial. The pitch should drop. If you turn it too far, it will crash. Press reset if it crashes.

5. Turn the Incantor on once more. With a voice in progress, flip the loop toggle switch. A loop should result. Some voices and games might not loop; try the Say It game and flip the loop switch at various points.

6. With a voice in progress, try flipping one of the two bending switches. The audio should begin sounding strange. Try the other switch. You should hear more strange audio. The bend, loop, and pitch controls can be used in combination. Try all games and all keypad entries; you'll get different effects.

The Speak & Spell/Incantor has a built-in ⅛-inch headphone output jack, so you can immediately plug the instrument in to your audio-playback system. Now you can add effects or sample the instrument and layer the voices. Build several Incantors to fade in and out and combine live with a mixer. Or just sit back with an Incantor in your lap and explore.