[Frank Herrmann] had an interesting idea to turn a geared DC motor into a servo motor assembly, but with a stepper motor-like interface. By stacking some small PCBs behind the motor body, it was po… ...

Apart from the X12.017 driver silently driving the motors, the stepper motors also conveniently only need a ‘direction’ and ‘step’ pin, reducing the pin count needed for the microcontroller.