Serge Modules
Produced under license from Serge Tcherepnin, these kits bring you the world of the Serge Modular System
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CGS75 - VCS

The VCS module is an extremely versatile control voltage generator and audio source. In the early 1970s, Serge Tcherepnin developed the Positive Slew and Negative Slew modules for the original Serge synthesizer. In time these merged into the classic Dual Universal Slope Generator. The CGS75 is an adaptation of Serge's original circuit with a few new features. The CGS75 is a unity gain voltage follower. The rising and falling slopes are independently and jointly voltage controllable over a wide range

CGS76 - 1973 Envelope Generator

This is an adaptation of the original Envelope Generator from the early "R" series PCBs. This is NOT an ADSR style generator, and can be used as a voltage controlled LFO. The HOLD function only works when the Window Pulse Output LED is lit.
The RISE and FALL pots are wired to control rate, not length. As such they seem backwards for envelope generator functions, but correct for LFO functions.
To use it as a VCLFO, patch END to CYCLE, and feed a CV into DURATION.

CGS77 - 1973 VCF

This is a licensed adaptation of the original VCF and is a 2 pole state-variable filter with 12dB/oct slopes on the LP & HP outputs and a 6dB slope on the BP output. the filter does not self oscillate but can be modified to achieve this if desired.

CGS79 - Ring Modulator

This module is a variation on the 1973 Classic Serge R6 Ring Modulator.
From the catalog (abridged): The RING MODULATOR (MOD) is an AC or DC coupled Ring Modulator featuring superior audio processing capabilities. The Ring Modulator offers two VC inputs in addition to the two signal inputs which may be used to perform voltage controlled transitions between full ring modulation and amplitude modulation.

CGS82 - Negative Slew

The CGS82 is a variation on the 1973 Classic Negative Slew module. It is a forerunner to the popular Dual Universal Slope Generator. There are two Negative Slew modules on the PCB. It can be used as both a falling slew rate controller, or a downwards sloping ramp LFO by hooking the pulse out into the input.

CGS83 - Positive Slew

The CGS83 is a variation on the 1973 Classic Positive Slew module. It is a forerunner to the popular Dual Universal Slope Generator. There are two Positive Slew modules on the PCB. It can be used as both a rising slew rate controller, or a upwards sloping ramp LFO by hooking the lower pulse out into the Start input. In this configuration it also operates as a utility oscillator, suitable for fixed key sequencing and general sound effects and noise making. It is not suitable for tracking a keyboard.