ADSR Envelope Generator

IC1D and associated components R1, R2, and C1 comprise a low frequency square wave oscillator which is used to provide a repeat gate source. R3 is a current limiting resistor to prevent damage to the output of IC1D if the Repeat Gate out is grounded or inadvertently connected to an output. R1 controls the rate of oscillation which varies between a few seconds per cycle to approximately 100 HZ.

The modified ADSR operates as an ADSR should (the old one was kind of funky). The gate or trigger can start an attack cycle. Both should be logically clean and not simply noisy switch closures! The trigger pulse can be as narrow as 1mS.

Applying Trigger only starts an attack cycle. When the attack cycle reaches its peak voltage the release cycle is entered. At any time during the release cycle applying another trigger will restart an attack cycle.

Applying Gate only starts an attack cycle and if the gate is continuously applied until the peak voltage is reached a decay cycle begins and if the gate is continuously applied the output voltage decays to the level set by the sustain pot and remains there until the gate is removed at which time the output decays at the release rate.

If the gate is being continuously applied and triggers occur they will only have an effect after the attack cycle is complete at which time they will restart the attack cycle.

Removal of the gate signal always begins a release cycle. Thus this ADSR can also function as an AR if desired.

The pots and switches should all be panel mounted. The circuit requires plus and minus 12 volts to operate.

Modified ADSR Envelope Generator Schematic

Pre-Modification ADSR Envelope Generator Schematic

I left this here so you can compare the two versions.

ADSR Envelope Generator PCB Layout (Component Side View)

ADSR Envelope Generator Parts Layout