ADSR Envelope Generator 2019 Black/white

This Envelope Generator is a classic design that is at least as old as 1980.
Rene Schmitz designed one, Thomas Henry designed one, Yvess Usson designed a couple versions, and countless others have built their own flavor of this 555 timer IC based, four stage EG which was likely designed by Randall Kirschmann, as published in Electronics in July of 1980.

This module has been most closely inspired by the EFM Synthesizers module 3508 ADSR, the layout in Eagle was done by myself, with the EFM schematic and documentation as my starting point.  I designed it for use in Eurorack systems, with +12/-12V standards (though it should still perform well under different dual supply voltages).  I have included some power filtering, and an LED Gate indicator.

Please see pictures for some lovely wave shapes of the non-inverted output.

Features:

• Ins:
  Gate/trigger w/Gate input indicator LED
• Outs:
  Non-inverted output, >0V (scalable)
  Inverted output, <0V (scalable)
  

Technical Specifications:

• Width: 9hp
  
• Depth: 22-28mm
  
• Power consumption: ~13.50 mA +12V; ~1.00mA -12V

This project was mostly an exercise in EagleCAD, and in panel design, but I learned a great deal more along the way.
I did the panel layout in FPD and had them fabricated by Front Panel Express.  They are black anodized aluminum, and the knobs are white, heavy duty Davies clone knobs.