ADSR

ADSR 555

This new version of the ADSR module provides a control voltage that makes possible shaping the envelope of a continuous sound. It is mainly used to control the gain of a VCA module or drive the cut off frequency of a VCF module. As usual it is not restricted to these two obvious applications and can be extended to the control of many others modules.
This module has a GATE input. The GATE signal determines the start and duration of the envelope signal. Four parameters can be set using potentiometers :
Attack duration : 1ms to 1s (short option) 5ms to 10s (long option)
Decay duration : 1ms to 1s (short option) 5ms to 10s (long option)
Sustain level : 0 to 10V
Release duration : 1ms to 1s (short option) 5ms to 10s (long option)
The direct ADSR signal is available on one output within 0 to 10V range and the inverted ADSR signal is available on a second output either within 0 to -10V range or 10V to 0V range.

A push button is available to manually generate a direct GATE signal. The intensity of the output signal can be visualised by means of a simple LED.

The power draw of this module is rather low : 10mA +15V rail, 3.6 mA -15V rail.

The heart of this circuit is based on an original idea by Jonathan Jacky (1980, see references at the end of this page).

The PCB provides jumpers to select the short ADSR versus long ADSR option (a DPDT switch can be added to toggle between).

Also, the power connector is now optional, it can be either a Synthesizers.com 6 pins MTA connector or a MOTM 4 pins MTA96 connector.
The module was designed to work with a +15V/0V/-15V PSU but can be used without modifications with a +12V/0V/-12V PSU, however the output levels will be lower (around 8V instead of 10V)

http://yusynth.net/Modular/EN/ADSR/index.html