Servo Motor Generic Metal Gear (Micro Size)

A servo motor is a linear or rotary actuator with a rotation detector (encoder) mounted on the back shaft side to detect the position and speed of the rotor. The servo motor is not a specific type of motor but rather a combination of a DC motor coupled with a control unit and encoder.


  • Versatility
  • Easy to control and program via digital output
  • High Precision
  • does not require control loop computations


  • High power draw
  • Usually more expensive than other motors
  • Not suitable for heavy loads (when plastic gear)

Servo Motor Circuits

How to wire servo motor to Arduino Uno

How to Wire servo motor to NodeMCU

How to wire servo motor to Arduino Gemma

  • servo motor
    Servo motor generic metal gear micro size.

Projects with Servo Motor

A servo motor is a combination of a DC motor, an Encoder (sensor) and a control unit. These are connected together in a position control loop.

Servo motor control loop
Image Source: Wikipedia

In our circuit we use a microcontroller, e.g. Arduino, to send a PWM signal to the servo motor that corresponds to a specific location. In a rotary servo motor this is the angle of rotation.

What is a Control Loop?

  1. The control unit translates the PWM signal to the desired location – this is used as Reference.
  2. Reads the encoder and calculates the error between measured and reference values.
  3. Calculates and sends a control command to the motor.
  4. Execute 2 and 3 continuously until the error is 0 – meaning the shaft arrived to the desired position

The servo motor has a built-in driver that controls the order of electrical impulses sent to the motor through the amplifier.

 Motor Range Speed (sec/60°) Torque  (oz-in) Operating Voltage (DC) Price
Servo – Generic Continuous Rotation (Micro Size) 360° 0.14 30.6 4.8-6V High
Continuous Rotation Micro Servo – FS90R 360° 0.36 20.86 5V Med
Servo – Generic Metal Gear (Micro Size) 180° 0.18 38.88-44.43 4.8-6V Med
Standard Size – High Torque – Metal Gear Servo – MG995 120-170° NA 138.87 5-6V High
9G Micro Servo 180° NA 22.22 5V Low