This is a fairly simple, dual, voltage controlled ADSR.  It is considered to be voltage controlled, because all paramters (Attack, Decay, Sustain, Release and Shape) are all controlled by voltages.

Features:

    Atack: Voltage controlled.  Three inputs.
    Decay: Voltage controlled.  Three inputs.
    Sustain: Voltage controlled.  Three inputs.
    Release: Voltage controlled.  Three inputs.
    Shape: Voltage controlled.  Two inputs.  This controls the shape of the decay.  It varies between your typical RC timeconstant type decay (exponential) to linear ramps.
    Trig: Edge sensitive.  One input.  The trigger input starts the Attack cycle.  Envelopes can be re-triggered.
    Gate:Controlls the Decay/sustain cycle.  Level sensitive.
    Output: 3 outputs, each with it's own current limit resistor.
    Status LED's: There are three status leds.  One to indicate the Attack cycle, one for the Decay cycle, and one for the Release cycle.
 

    Schematic