BOOLs

Nonlinearcircuits

Manufacturer Page

4 chained logic gates with stepped and smooth outputs

This module is like a hybrid between the NLC quad logic module and the Sauce of Unce. There are 4 inputs driving chained logic gates (you can choose what logic you want - OR, NOR, AND, NAND, XOR or XNOR by the chip installed). There are 4 gate outputs giving the boolean logic result of the signals on inputs 1&2, 2&3, 3&4 and 4&1. A resistor ladder network gives the stepped output based on what these 4 outputs are doing. From this a S&H circuit with a slew processor gives a smooth output.

Inputs

IN1: any signal crossing 1V
IN2: any signal crossing 1V
IN3: any signal crossing 1V
IN4: any signal crossing 1V
SAMPLE : trigger, gate or CV

Outputs

1:2: boolean logic resultat of IN1 and IN2
2:3: boolean logic resultat of IN2 and IN3
3:4: boolean logic resultat of IN3 and IN4
4:1: boolean logic resultat of IN4 and IN1
SLEW: smooth output derived from outputs (you can control the slew via pot)
STEP: stepped output derived from outputs

Tips/Tricks

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.