OPTOTHING: PCB/panel set
7 in stock.
A PCB/panel set for the OPTOTHING LPG/VCA - you can get a pre-built module here, if you'd prefer not to DIY it.
This module is based around the Vishay VO615A-5 phototransistor optocoupler, although you could use any pin-compatible unit from other manufacturers. Whilst it's theoretically possible to fit vactrols instead of DIP-4 optocouplers, vactrols tend to be a lot bulkier so you might need to get creative.
The build is simple, requiring only a pair of optocouplers, a couple of pots and a handful of resistors and capacitors. Whilst there's nothing to prevent you from using linear taper pots, I found that the best results were had with 20-25k audio taper pots - this is what I spec the pre-built modules with.
Once you've snapped the two boards apart, I recommend the use of a Dremel or similar too to take off any rough edges (you can use a hand file, but it's a faff) - since the boards are made of fibreglass, take appropriate precautions.
You can get the BOM and schematic here
The resulting module is 4HP wide and is passive, so no power cables are necessary.