Make Noise shared this video that demonstrates using their Maths module as an envelope follower.

Maths is an analog computer designed for musical purposes, including:

Generate a variety of linear, logarithmic, or exponential triggered or continuous functions

Integrate an incoming signal

With no signal applied, generate a variety of linear, logarithmic, or exponential functions

Add, subtract and OR up to 4 signals

Generate analog signals from digital information (Gate / Clock)

Generate digital information (Gate / Clock) from analog signals

Delay digital (Gate / Clock) information

Voltage Controlled Envelope or LFO as slow as 25 minutes and as fast as 1khz

Apply Lag, Slew or Portamento to control voltages

Change the depth of modulation and modulate backwards!

Combine up to 4 control signals to create more complex modulations

Musical Events such as Ramping up or Down in Tempo, on command

Initiating Musical events upon sensing motion in the system

Musical note division and / or Flam

Pricing and Availability

The Maths module is available for US $290 from the Make Noise site.