WIRING DIAGRAMS

 Here are the wiring diagrams for the PCB's.

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Precision ADSR

 Steiner-Parker filter

Resonant Lopass Gate old version

Resonant LPG new version

Moog ladder filter

State Variable Filter

Korg MS20 filter

Digisound-80 VCO bi-polar version

These are updated versions as of 13-nov-2025. The older versions have the grounding switch wiring the wrong way around. Sorry about that.

Digisound-80 older version (updated diagram)

555VCO Thomas Henry

If you run this vco on +/-12V and you can't make the rampwave connect at the zero volt level than solder a 1M resistor in parallel over the 1M resistor R22. That's the second 1M resistor from the left underneath the V/Oct trimmer. (R49 in the original schematic. It connects straight to pin 6 of U4 from the wiper of the Ramp Conn. trimmer).

X4046 VCO by TH

Utility LFO

8 step sequencer

I want to advise anyone building this to change the feedback resistor R12 from 100K to 150K for higher tonal range and lower R14 and R15 from 47K to 22K for better offset range. You can do that by soldering 47K resistors over the ones already there to half the total resistance value. I would also advise to lower the timing cap from 4,7µF to 1µF. Leave R18, the 10K resistor, in place though.