[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 ...

Stepper motors are DC (direct current) electric motors designed for precise motion control. They consist of multiple sets of coils and magnets which are designed to allow rotor movement in angular ...

And this single-motor mechanical seven-segment ... The three shafts are geared to turn together by a single stepper in the base. Each wheel has ten magnets embedded in the outer circumference ...