ENVELOPER

An envelope follower also known as peak detector, is a device that tracks and respond to amplitude's changes of an audio signal. Commonly employed in music synthesis, it converts volume fluctuations into control signals to modulate other parameters, providing expressive and creative dynamics. 

The circuit structure of an envelope follower typically involves a rectification circuit to convert the audio signal (commonly a diode or rectifier bridge), followed by a smoothing circuit for obtaining a control signal (usually composed of a capacitor in parallel with a high-value resistor for a controlled discarge ). 

Enveloper is a double peak detector module, the knob is used to adjust the sensitivity of the module.
Turning the knob counterclockwise will discharge the capacitor more quickly, while turning it clockwise will discharge the capacitor more slowly.
Between the input and output connector there is a trimmer that allows us to adapt the circuit to the signal frequency, in this way we could make the most of the module both to use it as a reference to extract the envelope and as an element of modulation, related to the frequency of the control signal.