BAD-TRIP: Microcontroller VCO + vactrol VCF module - PCB, panel and firmware
1 in stock.
Hear it here: https://soundcloud.com/yorkmodular/badtrip-vcovcf-sample
VCO + Vactrol LPF = Bad Trip ... ... which is pretty much what it is.
Combines a switchable square/saw VCO with a vactrol-based resonant low-pass filter for generalised acidic wonkiness. As well as the usual front-panel controls, there are a bunch of trimpots on the back-side of the board to allow you to alter the response of the filter vactrols - depending on the settings you choose, hilarity may well ensue.
⚠️ IMPORTANT NOTE ⚠️ - since the VCO part of the module is microcontroller-based there are limits on the range of CVs that can be handled. Basically, a negative CV will be 'rejected' (ie. treated as 0V) and anything over 5V will be clipped to 5V, thus limiting the range to 5 octaves - there are ways around this, but they're pretty hacky.
This is v1.5 of the module, which now has a fine-tune pot on the rear of the board - people asked for it, so here it is.
If you're having problems with range (or lack of it) then make sure that the CV pot is turned fully clockwise _and_ that your CVs fall within the appropriate range - some MIDI-to-CV modules work on a -5 to +5V range, meaning you're only likely to get a response in the upper octaves - a range of 0-5V is what you need.
The firmware for the VCO can be found at https://github.com/yorkmodular/bad-trip-vco - it is available under a permissive license so feel free to hack on it. The BOM and schematic are also here - the board requires a single surface-mount pot, which is pre-soldered.