Usually, when you want a servo motor, you simply buy one already made. But if you need something unusual, you can turn any DC motor into a custom servo you can control just like [Dejan] did.

[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 ...

ST’s EVLSERVO1, a turnkey reference platform for servo motor control, enables sensorless or sensored field-oriented control (FOC) with one, two, or three shunts. It drives three-phase brushless motors ...