Doepfer A-143-1 Quad AD Generator

The Doepfer A-143-1 is a complex envelope generator and LFO module for the Eurorack A-100 system. The module contains four separate envelope generators of the Attack / Decay type. Each unit can be switched on independently of the LFO function. However, the LFO mode differs in some points from a regular LFO (eg A-145 , A-146 or A-147 ): The edges of the LFO - in contrast to other LFOs - not linear, but an exponential curve, and the frequency of the LFO is determined by both regulators. The Attack control determines the time of the rising edge, the decay knob to the falling edge. Each unit has a built-in comparator with adjustable trigger threshold (Threshold). Falls below the envelope in the decay phase the set threshold, the comparator output switches in question (Cp1. .. 4) to high. By default, each comparator is connected via a shift sleeve to the gate input of the next AD generator. Thus, the first unit triggers the second, the third, the second unit and so on, in each case the trigger threshold is set. 
The output signals of the AD generators are summed with an internal "Polarizing Mixer" to a sum signal (Mix Out). The mixing polarizer controller determines whether the envelope in question is added to positive or negative of the sum signal and in what proportion.