Servo and Stepper Motors
Hobby servos, stepper motors, and BLDCs — control signals, typical specs, drivers.
Reference
Hobby servo (RC)
- Control
- 50 Hz PWM, pulse 1–2 ms (1.5 ms = center)
- Range
- ~180° typical (360° continuous variant loses position feedback)
- Power
- Micro 4.8–6 V / ~100 mA; standard 6 V / 1 A peak
- Wiring
- Orange=signal, red=+V, brown/black=GND
Stepper motor
- Step size
- Typical 1.8°/step (200 steps/rev); 0.9° in high-precision
- Microstepping
- 16× or 32× common — smoother, slightly lower torque
- Unipolar vs bipolar
- Bipolar is standard for CNC (4 wires, full coil use)
- Common size
- NEMA 17 for 3D printers, NEMA 23 for CNC
- Drivers
- A4988 (1.5 A), DRV8825 (2.5 A), TMC2209 (silent, StealthChop)
- Torque drop
- Falls with speed — holding torque spec is at zero RPM
BLDC
- Control
- Three-phase, ESC or FOC driver — commutation by hall or sensorless
- Kv rating
- RPM per volt under no load
- Typical use
- Drones, e-bikes, HDD spindles, modern appliance fans
When to pick
| Need | Motor type |
|---|---|
| Precise position, hold power | Stepper (open-loop) or servo |
| Smooth continuous rotation | BLDC or DC brushed |
| Small angle, fast | Hobby RC servo |
| High torque at low speed | Stepper with gearbox |
| Low EMI, quiet | BLDC with FOC / stepper with StealthChop |
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