WIRING DIAGRAMS

 Here are the wiring diagrams for the PCB's.

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4046 SUPER VCO:

I made a special page on my website with the complete Bill of Materials and build instructions for those of you who bought the 4046 SUPER VCO PCBs and front panel for Eurorack.

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WIRING DIAGRAMS:

Precision ADSR

TB 303 Filter 

VC DELAY 

Steiner-Parker filter

Resonant Lopass Gate old version

Resonant LPG new version

Dual Voltage Processor V1.0

The dual Voltage Processor has two minor little errors in it that are easily fixed. First of all pins 6 and 7 of both TL074s need to be connected together. The easiest way to do that is to just put a blob of solder between the two pins. Then the resistors R8 and R19 need to be bridged. So instead of a resistor just solder in a piece of wire. C5 and C6 must be lowered from 470nF to 100nF. 

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 then 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). This lowers the value or R22 to 500K. You should really put in a 560K resistor for R22 from the outset and that will fix it rightaway.

X4046 VCO by TH (pre v3.1 version)

X4046 VCO latest version 3.1

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 otherwise the clock frequency can go too high which will stop the sequencer from running.

Transistor Curve Tracer with Ian Fritz matching circuits:

Bill of Materials: