the blue wires hanging out of the rear end of my homemade crackle box clone are connected to one of the six touch points in the circuit. here's a recording and a patch diagram:
last weekend, i put the gray box up at the top together. it houses two 4049 preamps, a 2x1 active mixer (because i'm mono like that), and two voltage-controlled attenuators.
they are extremely simple - an led coupled with a photoresistor (before you say anything, i do have some vactrols on my bench, but i'm saving them for other, potentially more exciting things, and i've had a bunch of photoresistors lying around for the better part of two years, so whatever, synth-snobs), a 2n3904, and a pot and three resistors. the circuit craps out with high frequency control signals, but it has some neat behavior - as you decrease the amount of attenuation, the output signal has a longer decay time. if you increase the attenuation, the output is more percussive and momentary.
here's a demo recording using the setup pictured above:
and here's the schematic for y'all:
i built a little noise-maker circuit for a book made and bound by nick kanozik last month. we presented the book prototype at nick's "sonically minded book" lecture at mills college.
the circuit uses two 555 oscillators and a single transistor vca. i don't have a complete schematic readily available, but i've put together a simplified signal flow diagram.
the two oscillators are built using 555 timer ic's with photoresistors added to add an element of light sensitivity to the oscillators' respective pitch content and switching rate. the r-c low pass filter before the output also uses a photoresistor to further alter the light sensitivity of the electronics. when building the circuit, i wanted to ensure a good variety of behaviors given different ambient light conditions.
the circuit also employs some feedback paths in order to add a chaotic element to the behavior. there wasn't much of a logic to choosing the particular feedback paths - i simply listened and soldered up what i liked.
overall, i think the circuit can be tweaked more to prevent it from bottoming out - it generally works best in lower light conditions, i've found.