Pseudo

A pseudo-random binary sequence, noise and tone generator after Electronotes 76. As a pattern generator it gives four CVs and two gates, locked into loops of 8, 16 or 24 steps, reloaded by the switch or a gate at RELOAD; clocked fast from a VCO it makes harmonically rich tones, again in 8, 16 or 24 steps, and pseudo-random noise. CMOS rather than TTL, it needs an external clock. Two 24-stage shift registers: one moved by the clock with modulo-2 feedback, over 16.7 million steps before it repeats; the other loops after 8, 16 or 24 stages, or not at all (NOISE). U1 and U2 are binary weighted, like a DAC, U1 from six stages spread across the 24, U2 from six consecutive ones; G1 and G2 have a Gaussian, bell-curve distribution, taken the same ways, and often look like a slightly glitchy sine. The CVs range about ±5 V, the gates 0 to 5 V: LOOP gives 8, 16 or 24 step gate patterns, PSEUDO RANDOM a continuous pseudo-random series, fake white noise at fast clock rates.

Key features

• CLOCK and RELOAD in; U1, U2, G1 and G2 CV outputs; LOOP and PSEUDO RANDOM gate outputs, each output with its LED
• A MODE toggle: RELOAD, TONE, NOISE; a LENGTH toggle: 8, 16, 24 steps
• 8 HP; Nonlinearcircuits publishes no current draw, depth or assembled price (it sells the DIY PCB and panel), and ModularGrid lists none