Here’s a schematic for a quad envelope generator. I own a dopefer A143-2 but I don’t use it fully and only use it as a Attack and Decay so I decided to save some space.
The plain is to build it as a QUAD module. Good thing being, the CD4066 comes in quad package and the flip flop as well. Not build yet, I have to make the faceplate. Although I’ve to test the CD4066 switch at the input to see if everything works as planned. If you’re accustomed to this type of circuit the lack of values shoudn’t be a pain.
Talking about pain, I bought a second doepfer case (LC9). The best advice that I could give to someone interested in modular is…to not start at all ! this is a really addiction (fun and relaxing though).