Synth Schematics --::-- Envelope Generator ADSR This schematic shows a variation of the ADSR envelope generator with a 7555 timer IC. That is the circuit that I'd recommend. The key difference is a buffer between the Sustain pot and the Decay Pot. This makes the decay time independant of the setting of ADSR Envelope Generator Module - Synth DIY with Mich Jul 11, 2017Circuit description The full schematic of one ADSR envelope generator. Click for a larger black on white version, or download as a PDF (121 KB). I initially built this rather sloppily on breadboard, and blamed several glitches I was experiencing on bad connections on the breadboard.