Hills & Valleys

Peak and Trough

This module is a variation on the 1973 Classic Serge Peak and Trough module. Both the Peak (Hills) and Trough (Valleys) 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 (Valleys) section does respond to input voltages going a volt or two below 0V.

Source text from Ken Stone’s CGS website
”The Peak (Hills) 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 (Valleys) 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.”

https://www.low-gain.com/shop/p/lge084