The DC motor is a two-wire (power and grounding) continuous rotating motor. When you supply power, the DC motor will start to rotate until the power is disconnected and stops. Most DC motors operate at high RPM, such as computer cooling fans or radio operated wheels!

The speed of DC motor is controlled by pulse width modulation (PWM), which is a technology to quickly turn on and off the power supply. The percentage of time it takes to cycle the on/off ratio determines the speed of the motor. For example, if the power supply is cycled at 50% (half open, half closed), the motor will rotate at half the speed of 100% (open). Each pulse is so fast that the motor seems to rotate continuously without jamming!

The orientation of the servo motor can be controlled more accurately than the standard DC motor. They generally have three wires (power supply, ground wire and control wire). The servo motor is always powered on, and the servo control circuit regulates the traction of the drive motor. Servo motors are designed for more specific tasks that require precise definition of orientation, such as steering the rudder or moving the robotic arm or leg within range.

The servo motor cannot rotate freely like the standard DC motor. Instead, limit the rotation angle back and forth to 180 degrees (left and right). The servo motor receives the control signal representing the output orientation and supplies power to the DC motor until the shaft rotates to the correct orientation determined by the orientation sensor.

Source: Jiangmen vacuum cleaner manufacturer www.jmchiyang.com