The Catwalk Scratch Pad Keyboard is a passive-ish resistor that takes up no HP by attaching to your Eurorack system over top of existing modules, where they rise above the faceplates of the modules they're over top of so there's no contact with the modules below (other than the screw holes where the standoffs are). The mounting holes span about 183mm and this fits perfectly over the top of between a 35-37HP span.
Feed the input of the Catwalk Scratch Pad Keyboard some voltage from an offset, LFO, or envelope, and patch the input of a 1/V Oct from a VCO or another sound source, and use the unpatched cable end of that 1V/Oct input to touch the Scratch Pad Keyboard at various points, and you have a fast, fun, keyboard in which to scratch out some melodic ideas, broadcasting approximate tones of a western-scale 12-note octave. Paired with the Catwalk Pressure Sensor to control the CV of a VCA (with the output of your sound source patched into the input of the VCA) and you can get some expression along with your playing of the Scratch Pad.
These are very easy to build, just solder the two jacks into place on the circuit PCB, the LED (pay attention to the direction), the lone resistor, and the power wire from the bottom PCB to the factplate, put on the faceplate, attach the nuts to the jacks, and away you go! Faceplate is black and copper and might have some discoloration or markings due to manufacture. They'll get more of that character the more you use the Scratch Pad as touching the cable to the keyboard faceplate produces marks. It looks cool. Rugged!
Note: These come with M3 screws and standoffs.
Note: Not all incoming voltage will be enough to light up the eyes of the cat.
