This is a quad implementation of the Formant ADSR module. As in most cases I made a new layout because the single ADSR eurocard layout offered in the book seems to be a waste of place for this small circuit. And as I needed more ADSRs anyway I put four of them on one eurocard.
The knobs, connectors and LEDs are organized in a more efficient way and I ommitted the AR switch, so I could compress the frontend elements. The functionality of the module is described here.
Board of Quad ADSR module: