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.
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
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
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...