Servo Motor
Motor
A motor that can be precisely positioned at specific angles using a control signal. Commonly used in robotics, RC vehicles, and automation.
Schematic symbol
Motor
How servo motor appears in a circuit diagram.
Types & variants
Key specs
Operating voltage
V (Volts)Nominal voltage required for operation (typically 4.8V-6V for hobby servos).
Stall torque
kg-cmMaximum torque the motor can produce when stalled. Higher values mean more strength.
Speed
s/60°Time to rotate 60 degrees at no load. Lower values mean faster movement.
Rotation range
degreesAngle range the servo can move (typically 0-180° for standard servos).
Weight
g (grams)Weight of the servo motor, important for mobile applications.
Markings
Label typically shows voltage, torque, and speed. Connector color coding: black (ground), red (V+), yellow/white (signal).
Standard values
Common voltages: 4.8V, 6V, 12V. Common torque ranges: 1.5kg-cm to 30kg-cm. Common weights: 9g to 150g.
How to choose
1) Determine required torque based on load. 2) Check voltage compatibility with your controller. 3) Consider speed requirements. 4) Select appropriate size/weight for your application. 5) Choose metal gears for durability or plastic for lower cost.
Pinout & package
3-wire connector: Signal (PWM control), V+ (power), Ground (GND). Standard servo horn size is 24T (24 teeth). Packages vary by size: micro, standard, large.
Example circuits
- Robotic arm joint control
- Camera gimbal stabilization
- RC steering mechanism
- Automated door latch
- Pan-tilt camera mount
Common failures
Gear wear (stripping teeth), motor burnout from voltage spikes, potentiometer failure (jitter or unresponsive), connector wire breakage. Signs: clicking noise, limited movement, no response to signal.
How to test
1) Connect to a servo tester or microcontroller. 2) Apply appropriate voltage. 3) Send PWM signal (typically 50Hz with 1-2ms pulse width for 0-180°). 4) Check if servo moves smoothly to expected positions.
Substitutes
Use servo with similar torque/voltage. Can substitute continuous rotation servo with speed controller for rotational applications. Stepper motors for precise non-continuous rotation.