BOOLs is a 'chained' logic module which gives gates and CVs derived from the input signals.

This is a PCB only set in the Eurorack format.

Availability: In stock




This is a multi-purpose module that can be used in a number of ways. It can be used for basic logic functions to generate complex gates. Using multiple inputs allows the creation of a variety of different but related gates which can be used to create complex but nicely sync’d patches. There is a R2R ladder to create a stepped CV signal that corresponds to the gate outputs, this is also fed thru a gate (or CV) controlled sample & hold/Slew circuit to create a smooth output.

Some tricks (depends on your choice of logic):

  • Use the module to process audio signals and feed the outputs back into other inputs.
  • The BOOLs can be used as an envelope generator. Choose an input to determine the height (1 = low, 4 = high), set the slope with the Slew pot, feed the S&H input with various signals to vary the envelope shape.

Suitable chips are

  • 4001 NOR
  • 4011 NAND
  • 4071 OR
  • 4081 AND
  • 4077 XNOR
  • 4030 or
  • 4070 XOR

For me, the OR, XNOR & XOR chips are the most interesting. What makes this circuit a little different is the way the inputs and outputs are related. There are four inputs, call them A, B, C & D, say we have an XOR chip installed and signals on all four inputs Output 1 will be A xor B Output 2 will be B xor C Output 3 will be C xor D Output 4 will be D xor A

The input signals can be pretty much anything that crosses 1.1V. Outputs will be 5V. Audio rate signals are fine; XOR chips give a crude but useful ring modulation effect.

Specs & Downloads

Specs & Downloads

manufacturer Non-Linear Circuits
HP 8
Depth No
+12V 25mA
-12V 25mA
+5V No
Additional Resources Build Guide


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