Available as an assembled Module and as a DIY project.
This Module is currently available.
Dual Slew Limiter
The NEGATIVE SLEW in one of the unique multi-functional patch-programmable modules in the system. The module features two independent sections with wide range voltage controllable slew rates. The slew is active in the negative direction only and can be patched to perform a number of synthesizer functions. With the pulse output applied to the input, the module will regenerate for uses as a voltage controlled sawtooth oscillator or a pulse generator. An audio signal applied to the input will be envelope detected, and the complex envelope will be available at the output. If a pulse is applied to the input, the unit will function as an envelope generator with a fast rise time and a voltage controlled fall time.
These merchants probably sell this module. Huh?