This Module is currently available.
Envelope Generator
The Q109 Envelope Generator is one of the basic modules every synthesizer must have. It generates a voltage envelope in response triggered by a gate signal from a keyboard, oscillator or other source. The envelope voltage is used to control amplifiers, filters, oscillators and other modules.
The operator has complete manual control over Attack time, Decay time, Sustain level, and Release time. A manual gate button can be used to trigger the Envelope Generator at any time, and an LED gives a visual indication of the output level.
These merchants probably sell this module. Huh?