I have build a few of these and use them quite a lot. I have some spare pcb’s and panels in my drawers to build even more of these. (If you looking for a set contact me). The ADSR does what it should do and like most of Haralds design it very well designed. Harald based his ADSR on an Elektor Formant ADSR schematic. It has pretty good spec’s, if you want to know more about this one be sure to check out Harald’s website.
https://www.haraldswerk.de/CV_Sources/ADSR_Euro/ADSR_Euro.html
Difficulty to build: Easy