24-04-2019, 11:12 AM
I tried making a 317-based controller when I was at college as I filled in my spare time with model train layouts. Maplin magazine published a better controller using low-frequency pwm techniques which I built, just a couple of 8-pin op-amps and a transistor, and this gave superior control especially at low speed, so much so, I ditched the 317 controllers. The pwm was audible at low speeds as a buzz, rising to a whistle, and the lower frequencies seemed to overcome the stiction in the motors.
