Módulo de entrada externa/seguidor de envolvente

Doepfer A-119 External Input / Envelope Follower

The pre-amp has two inputs: an unbalanced input for line level signals, with a gain factor of from 0 to 20, and a balanced input with a gain factor of from 0 to 500, for insertion of low level signals, for instance from a microphone or electric guitar. 

The Envelope Follower reads the signal level of the input, and puts out a proportional voltage as an envelope at its own output. 
The comparator generates a gate signal whenever the input goes above an adjustable trigger threshold. 

Three LEDs help you keep track of overload, the envelope, and the gate signal.