This module is a variation on the 1973 Classic Serge Peak and Trough module. It is much like the Analog Logic Peak and Trough, though a little less precise. It is presented here for those who want to build themselves a classic Serge. There are two of each of the Peak and Trough modules on the PCB, each having an additional input for use with a manual level pot. The second of each has additional inputs to allow for the unit to be built on an eight row panel instead of the original six row panel. A little additional circuitry has been added to remove the unit's dependence on a +6 volt power rail. Both the Peak and Trough operate in the range of 0V to half of the positive power rail, i.e. 6V on a 12 volt system, and 7.5 volts on a 15 volt system, though in practice, you may find the Trough section does respond to input voltages going a volt or two below 0V.
A little on how it works:
The schematic for one half of the dual Peak and Trough module. Both sections are identical with the exception of additional inputs on the second set.
The Peak module is effectively a diode OR gate. An emitter follower (the lower transistor) is used to cancel out the voltage drop of the input diodes. The upper transistor is a constant current sink acting as a pull-up.
The Trough module is the reverse of the Peak, based around a diode AND gate, again with an emitter follower (upper transistor) compensating for the voltage drop across the input diodes, and a current source acting as a pull-down.
|Brand||Cat Girl Synth (CGS)|
|Additional Resources||BOM & More Information|