circuit bending

Wires can be soldered directly between the points marked as pairs on the circuit board. In the middle of these wires would be soldered toggle switches so that these new sound-activating connections can be turned on and off at will. Use the simple mini toggle switch, the common "SPDT" (Single Pole, Double Throw). One wire will go the switch's middle terminal, the other will go the terminal OPPOSITE the direction of the switch's toggle handle when in the ON position. These toggle switches can usually be mounted on the device's housing, creating the new control panel. If you are using "SPST"s (Single Pole, Single Throw), there will be only two contacts to solder to; either of the two wires of your pair can go to either terminal.

Note: It is assumed that the soldering skills of the bender (you) are such that quick and precise connections can be made. This is important and not hard to learn. Quick, because some components can be damaged by the heat of excess soldering, especially since the bender may at times find it necessary to solder directly to integrated circuit (IC) pins leading to micro-miniature delicate electronics inside the IC. Precise, because, as in the example of IC pins, clearances can be minimal. The danger here is accidentally creating a "solder bridge" between IC pins (or other tightly-spaced metals... printed circuit traces, component leads, etc.) that were not meant to be soldered. There are several devices available to remove solder mistakes from a circuit. These work either by heating the solder and drawing it away from the circuit by means of vacuum, or by drawing the heated solder, through osmosis, into a metal braid. Both techniques are a hassle. Practice soldering until you feel comfortable with "quick and precise"; avoid the solder mistakes and their correction tools.

The wiring procedure begins with counting how many pairs of connections you'll need switches for. Next, decide how the switches will be mounted on the device's case (remember to check for internal clearances so that the backs of the new switches don't hit the device's internal parts when the unit is reassembled). Holes are drilled, the switches are mounted, the pairs of circuit-bending connections are then soldered through their respective switches and the device is reassembled.

Instead of switches, potentiometers (variable resistors) can be soldered in the middle of the pairs of connections. In many cases this will allow the adjusting of the new effect with the turn of a dial. Potentiometers, like non-adjustable common resistors, come in a variety of values measured in ohms of resistance. Experiment with different values to learn their effects. Potentiometers usually have three soldering points, or lugs. Solder your two wires so that one connects to the middle lug and the other to one of the outside lugs. Which outside lug you choose depends on what you want the effect to sound like as the potentiometer's dial is turned in a pre-determined direction. Example: The volume control on your stereo is a potentiometer. If you were to reverse its outside lug wiring the volume would go DOWN when you turned it up (clockwise).

Switches can be used along with potentiometers between the pair of circuit-bending connections as well. In this way, effects can be pre-set with the potentiometer's knob and turned on and off with the switch. A wire would be soldered to one of the points in a circuit-bending pair, through the toggle switch, then through the potentiometer and back into the circuit-board to the other point of the pair. This switched component wiring may be used with any components, including the following...

Capacitors, again available in a wide range of values, can be wired between the pairs of points. These may change the tone of the effect produced or pulse the sound in differing ways.

NOTE: Some larger electrolytic capacitors can hold a substantial charge and can transfer it to you in the form of a very real shock. These are cylindrical, two-lead (usually) devices, the ones of concern most often being larger than a cigarette filter. These capacitors appear in the circuitry of strobe lights, power supplies and other higher-voltage dependent applications. They practically NEVER appear in the circuits here under discussion. However, all beginner's guides to electronic circuit design cover this subject. If you're not familiar with how the electrolytic capacitor looks, get a guidebook, like the one by Forrest Mims Jr. at Radio Shack, and learn these basics. Such capacitors are easy to recognize and discharge, in the very rare event that you should ever find one in the way.

These are light-sensitive buttons (at times called "cadmium sulfide cells") with two wire leads. They convert light into electrical resistance, so to speak. They have the same effect upon a circuit as a potentiometer. However, instead of turning a dial to vary the resistance and thereby the sound, hand shadows are allowed to fall upon the photo resistors. These sensors can be used in many wonderful ways, including environmentally directed instrument designs since ambient light and shadow -- tree leaves, water reflections, clouds passing, etc. -- may be employed as player.

These are light-sensitive wafers that convert light into electrical energy. They can be used to inject their small voltage (or resistance in some situations) into the circuit between the paired bending points and change the sound thereby. Of course, wired in series these wafers can be used to supply the operating power to an instrument, connected "end to end" just like, but instead of, batteries.

LEDs- (Light Emitting Diodes) are usually, for the sake of circuit-bending, low-voltage light sources. Like all diodes, their core function is to act as a one-way valve for electrons, but their nice glow and long life nearly obliviates this concern in much electronic design. You may find points on the circuit you're bending between which LEDs will glow or pulse. These can serve as function indicators or pilot lights. An LED wired to the speaker leads may work as an envelope light also, flashing with the intensity of the sound waves.

LEDs are "polarized" components; if they don't glow when connected between promising points on a circuit, try reversing the leads. If they still don't glow, there is not enough power available to activate them. An over-driven LED will burn out. Might even pop. Be aware of the LED that, when tested in a circuit, momentarily lights brightly but then dims to an off-color glow. Or lights too brightly while shifting color. Or simply lights too brightly. These are all signs of too much power being applied. Burn-out will eventually result. LEDs may also affect the sound of the circuit depending upon where they are connected.

These are sensors that convert airborne moisture into electrical resistance (as found in Weather Service "radiosondes", balloon-suspended devices that measure atmospheric conditions and radio this information back to the ground tracking stations). This can give a breath control function to an instrument, changing a pitch, perhaps, as the sensor is blown upon.

There are many other components that can be wired into the path of the pairs of circuit-bending points, but the above will launch hundreds of possibilities as well as pave the way towards the understanding of wider concepts.

To quickly try different components between the discovered pairs of points, a modified test-lead system can be used. This consists of the two screwdrivers as before, two alligator clip test-leads instead of one, and the component to be tested (potentiometer, photo cell, LED, etc.). Clip a screwdriver at one end of each test lead. Between the empty ends of the leads now clip the component to be tested. The screwdrivers again serve as probes with which to search the circuit, now sending the signal through the component clipped in the middle between the two test leads. Beyond direct electronic component wiring await other expansions...

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