:: fluxmonkey pcbs ::

208 Random Voltage Generator

Pseudo-random control voltage generator, based on one section of the Buchla Music Easel. One clock input, 4 pseudo-random voltages out. Two CMOS chips & 2 LM3900s. Original circuit design by Scott Stites; original PCB by vtl5c3.

PCBs are $15.00 @ — ORDER HERE

Bill of Materials

  • Resistors
    • 1k x5
    • 68k x1
    • 82k x2
    • 100k x2
    • 150k x4
    • 330k x4
    • 680k x9
    • 1M x5
    • 2M2 x4
  • Capacitors
    • 22pf x1
    • 470pf x1
    • 0.01uf x5
    • 10uf electrolytic x2
  • Semiconductors
    • LM3900 x2
    • CD4015 x1
    • CD4016 x1
  • Misc.
    • Ferrite beads x2
    • .156" power header x1
    • in/out jacks x5

Build Notes

  • The CV outs are fairly "hot"—you may want to add fixed voltage dividers on the outputs, or potentiometers to vary the level.
  • Some folks have reported the circuit "locking up" at very high clock frequencies (like, >10khz). I haveve not experienced this, but I suspect it's due to different manufacturers or batches of the CMOS chips. Works fine as a sequencer, and in any event this was never intended as a white noise source (which is what those fast clock speeds will give you).