Doepfer A-143-2 Quad ADSR

Quad ADSR type envelope generator with time ranges of 0.2ms to 5min. Each ADSR units has a gate- and a retrigger input as well as one output and a time range switch.
Quite interesting are the "end-of" outputs which provide you with gate signals after the corresponding time stage has been finished. You can use this gate signal to start further ADSRs and thus for creating complex envelopes, pseudo LFOs etc.

Each of the four envelopes is identical. They are attack-decay-sustain-release type envelopes with a gate input for fireing the envelope and a re-trigger input for restarting the envelope once it has reached the decay phase.
A switch serves as a time range selector - slow, medium or fast.

Each ADSR of the A-143-2 has three special digital outputs - digital in the sense that they emit on/off signals, or in modular language: gate signals. This happens for each output after having finished the attack phase, the decay phase and the release phase.
If you, for instance, connect the End-Of-Decay output with the envelope's gate input, the looping attack-decay stage turns into a LFO with adjustable waveform. You might as well use these outputs to start other envelopes with a delay ... and if you mix them with a polarizing mixer you can realize longer envelopes which work bidirectionally.