The Serge Dual Negative slew is one of my favorite 1970’s Serge modules. Ken Stone now makes a PC board for it.
The output tracks the input and gives voltage-control over the rate at which the output voltage can fall. As the output reaches zero the Pulse out goes high. When Pulse is patched back to In, it becomes a VCO with a negative ramp shape. An initial Rate pot and reversible CV attenuator complete the design.
The PC board is mounted above the DUSG board in the CGS Serge panel, on 1-inch nylon standoffs. Here’s how it looks from behind. Click image for more detail.