The Doepfer A-143-2 is a quad voltage controlled low frequency oscillator module for the Eurorack A-100 system. The module contains 4 independent ADSR-type envelope generators. Each sub-module has controls for Attack, Decay, Sustain and Release. The three-position Range switch allows to select the desired time range (low - high - medium). The adjustable envelope time ranges from several minutes to some milliseconds. On top of this each sub-module is equipped with three digital outputs (high/low): "End of Attack (EOA)", "End of Decay (EOD)" and "End of Release (EOR)". As soon as the criterion is valid (e.g. end of decay state) the corresponding digital outputs turns to "high". These outputs can be used e.g. to daisy-chain several ADSR sub-modules. For this the digital output in question (EOA, EOD or EOR) has to be connected to the Gate input of the following ADSR. Even automatically running envelopes (pseudo LFOs) or so-called "quadrature envelopes" with cyclical modulations of several ring-shaped, daisy-chained ADSRs are possible. To obtain a pseudo LFO simply the EOD or EOR output has to be connected to the Gate input of the same ADSR.