[sdiy] VERY cool/bizarre: Buchla noise

[Grant Richter]

> I think a module which let you control the shift register rate and perhaps
> also feedback length/pattern under voltage control would be an interesting
> thing.

See

http://www.wiard.com/1200/NR/Noise_Ring.html

for a module based on a similar idea. Shipping since August 2003. A real
white noise source is converted to telegraph waves by comparators. These
maximal time domain entropy levels are then reduced.

The module varies the time domain entropy by varying the rate of introducing
new data bits to a recycled bit stream. Clocking is made non-periodic by
feedback into the clock voltage control input.

With this topology, the sonic effect doesn't change that much if the shift
register length is made longer than 8 bits.

In the Buchla Model 266, the entropy level is directly controlled by
switching bits to the DAC in or out from the PRSG.

See:

http://www.musicsynthesizer.com/Buchla/source_of_uncertainty.htm

for schematics.

The new Buchla 266e is advertised to contain both modes, and the DAC is
expanded to 24 bits from the 6 bits of the original 266.