The PCB masks from the amazing book, Sound Synthesis – Analog and Digital Techniques, by Terence Thomas.
Too rushed for an amusing title…
Here are a number of ADSR circuits, taken from the fantastic Yusynth website (which I came across after reading StackExchange – Building a synthesizer with no prior experience) – in particular the Archives page.
The circuits are described within PDFs, and I drew up the corresponding schematic and board files in EagleCAD.
The EagleCAD files available on github, although seeing as Micro$oft have just acquired Github, they may not be there for very long… Five minutes later – #movingtogitlab!
The EagleCAD files available on Gitlab: Testkins/ADSR-Waveform-generator