Hardware Hacking 85Remember to connect all shields/grounds together as we did for our first
photocell circuit. If you choose to solder up this circuit you can use switches or
y-cords to tie A and B or C and D together, according to your application, or you
can hardwire one of these configurations if you’re sure you will only be using it
either as a panner or a mixer.
Flashlight controlled circuits like these gates, panners and mixers and our earlier
photocell-controlled oscillators occupied a distinguished place in the history of
live electronic music: similar circuits could be heard in early work of David
Behrman (“Runthrough”), Larry Austin and David Tudor, as well as in Voice
Crack’s wonderful performances throughout the 1980s and 90s.
Blinkies
An LED (Light Emitting Diode) is a small cheap source of light that can be
controlled electronically. The LED has one shorter leg, and if you look closely
you will notice that one side of the lower rim of the LED is slightly flattened --
the short leg and flat side indicate the - connection of the LED, the other leg is +
(Figure 1). Breadboard the circuit shown in Figure 2.
Figure 1: LED connections Figure 2: simple LED circuitSwap the polarity of the LED and observe that it only lights in one configuration.
Substitute different values for the resistor and note the change in brightness: the
smaller the resistor, the brighter the light, but only to a point, after which the
LED will burn out. Don’t use a straight wire -- with a 9 volt battery supply
1kOhm is a good value to start with.
Rule #19: Always use a resistor when powering an LED, otherwise the circuit
and/or LED might blow out.