Envelope Follower (Aluminum Panel)

The EMW Envelope Follower module is capable of creating control voltages from an audio source, trigger pulses, gate signals and also from other control voltages. It can also generate trigger and gate pulses when the incoming signal goes above a certain threshold (that can be adjusted on the front panel via the threshold level control). You can set the response (attack/decay) time for fast or slow response. Extract the envelope of an audio signal or change the time characteristics of other control voltages with the EMW Envelope Follower.

http://www.electronicmusicworks.com/eurorack/envelope-follower.html