94 Nicolas Collins
Chapter 24: Analog to Digital Conversion, Sort of
You will need:
- Something to amplify: a guitar, a cassette or CD player, etc.
- A breadboard.
- Gain & distortion circuits from the previous chapter.
- Quad NAND Gate Schmitt Trigger (#4093).
- Binary Counter/Divider (#4040).
- Assorted resistors, capacitors & pots.
- Some solid hookup wire.
- Assorted jacks and plugs.
- A 9 volt battery and connector.
- An amplifier.
- Hand tools.
The gain and distortion circuits in the previous chapter are useful on their own --
to boost a low level signal or make an electric guitar sound legitimate -- but also
in conjunction with other circuits. With enough gain and distortion, any analog
audio signal starts to look like a digital square wave (like that put out by our
oscillators) and can be easily interfaced to certain digital circuitry.
The circuit shown below is a variation on the gated oscillator in Chapter 20.
When the oscillator runs at low speeds (1uf timing capacitor) it effectively
“chops” the output of the distortion circuit on and off; at higher speeds (0.01 -
0.1uF capacitor) it interacts with the distorted signal to create a “ring-
modulator”-type effect.
“The Fuzzy Dicer”