Logic Noise

Hacking Music out of Digital Chaos

Elliot Williams

Hackaday

Today's Menu

• 4000-series CMOS Logic ICs

• Some Analog

• Demos Galore and some Circuit Diagrams

• (Musical Philosophy)

What is Music?

• Bunch of notes...

• that you expect,

• but not too much.

• Rhythm and Repetition

• But also variety!

What??

• Does this have anything to do with CMOS ICs?

• Tricks up my sleeve

• Melody Generator ++

• First sounds, then rhythm, then structure

Oscillator: 40106

• It all starts with an oscillator

• Capacitor and resistor determine the pitch

Timbre

Diode Sync

More Timbre

• Analog tricks with 4069UB:
  triangle and sawtooth waveforms

• 4070 XOR Cowbell / Cymbals

Pitch: Analog

• Change resistance or capacitance

• 4051 Multiplexer switchable resistances

• Change the charging current

Pitch: Digital

• Octaves, divide by 2:
  Binary counters

• Divide by N:
  4017 decade counter w/ reset

• 4051 mux again:
  8 oscillators enter, only one leaves

Dynamics: Digital

• Power on and off

• Stall oscillator with diode

• 4066 quad switch

Dynamics: Analog

• Two-diode VCA

Booomm-Tss: 4040 Binary counter

• Rhythm is just pitch, slowed waaaaay down

• Whole note, half note, quarter note, eighth note...

• Four on the floor

Fixing the 4040

• Invert outputs you care about

• But keep the non-inverted too: backbeats

Rhythmic Shortcuts: 4089

• 4089 "rate multiplier" chip is beats in a box

One Pulse per Step: The Mighty 4017

• Puts out one of up to ten outputs per clock

• Use pulses to trigger arbitrarily timed events

It don't mean a thing...

• if it ain't got that swing (clock)

• 4017 + 4040 = regular, off-grid time

Melody Generator ++

• Melody generator

• 4017 makes pitches by division

• One of eight outputs to reset through 4051 mux

• Three digital lines into 4051 pick "note"

• My twist: add some octaves with a 4040,
  drive with SR

Melody Generator ++

Melody Generator ++

• Control pitch / octave through
  paired clock and data lines

• Inject sequence into 4-bit shift registers

• Feed clock / data with detuned oscillators

• Tweak until "just right"

What Else?

• Tremendous room for playing around

• Incorporate microcontroller, FPGA

• Build standalone instruments

• Priority encoders, shift registers, complex logic

• Turn away from "music", embrace noise.

Fittingly Offbeat References

• Stanley Lunetta

• David Tudor

• Peter Vogel

• Nicolas Collins

• Electro-Music "Lunetta" Forum

• Logic Noise on Hackaday

• Don Lancaster's CMOS Cookbook

Contact

elliot.williams@hackaday.com

https://hackaday.com/author/hexagon5un/