This is an adaptation of the original Envelope Generator from the early "R" series PCBs. This is NOT an ADSR style generator, and can be used as a voltage controlled LFO. The HOLD function only works when the Window Pulse Output LED is lit.
The RISE and FALL pots are wired to control rate, not length. As such they seem backwards for envelope generator functions, but correct for LFO functions.
To use it as a VCLFO, patch END to CYCLE, and feed a CV into DURATION.