Available as an assembled Module and as a DIY project.
This Module is currently available.
VC Slope Generator
The ES75 is an adaptation of the Dual Universal Slope Generator with a few new features.
The ES75 is a unity gain voltage follower. The rising and falling slopes are independently and jointly voltage controllable over a wide range.
VC Transient Envelope Generator
A pulse at the trigger input will start the envelope, or a gate input will sustain the level and the envelope will fall when the gate goes low. Rise and fall are independently and jointly voltage controllable, with variable linear and exponential wave shapes.
VC Portamento
Voltage is slewed according to the rise and fall times.
VC LFO
When the cycle switch is thrown, the trigger input is connected internally to the end trigger output, creating a VC clock with variable waveform and independent rise and fall times.
VC Oscillator
While not as wide ranged, or accurate as a dedicated oscillator module, the VCS is still an excellent audio source. The [EXP CV] input is scaled approximately to the 1V/Octave standard. The Output wave can be swept from triangle to saw with linear and non-linear waveforms. [END OUT] also produces a pulse waveform.
VC Non-Linear Audio Processor (Low-Pass Gate)
If an audio rate signal is slewed, the module responds like a VCF, and a rough VCA. The signal is low-pass filtered down to silence, similar to a low-pass gate.
Envelope Follower
Positive and negative peak detection envelope follower.
VC Pulse Delay
Trigger input starts the envelope and a trigger will be produced again at the End Out when the envelope completes its cycle.
Sub-Harmonic Generator
If a series of triggers are applied to the VCS faster than the total rise and fall times, the module will divide the incoming signal by a whole number. In the audio range the output will be the sub-harmonic series.
https://www.elby-designs.com/webtek/euro-serge/es75-serge-vcs/es75.htm
These merchants probably sell this module. Huh?