To link the digital signal processing on a laptop or Raspberry Pi to the analog synthesizer, I have made two usb-to-cvgate converters. The first one I designed and implemented was a one channel version that is able to output up to (approximately) 5 Volt. The second one is an improved version with four channels that can be controlled from 0 to 10 Volt.
Using the EAGLE PCB design software, I have drawn the schematics which should allow others to copy them. Also included below is the bill of materials (BOM) with links to component vendors. I have mainly been shopping on Ebay, you can also get it elsewhere of course.
Details of the one-channel USB-to-CV/Gate converter.