Just converting a temperature to rotation took a big wedge of gears. Although gear-based computation is bulky, an analog computer was the best solution at the time.
I hope to power up the CADC soon and get it working. Inconveniently, it takes 115 volts AC at 400 Hz.
@kenshirriff use a vfd! They go up to 400hz, and probably cost $100. I use a vfd for... reasons... you can adjust, well, everything. I got a 3 phase output but turned out I only needed 1 phase