Servo motors are designed for more specific tasks where position needs to be defined accurately such as controlling the rudder on a boat or moving a robotic arm or robot leg within a certain range. Power to servo motors is constantly applied, with the servo control circuit regulating the draw to drive the motor. The position of servo motors can be controlled more precisely than those of standard DC motors, and they usually have three wires (power, ground & control). Servo motors are generally an assembly of four things: a DC motor, a gearing set, a control circuit and a position-sensor (usually a potentiometer). Each pulse is so rapid that the motor appears to be continuously spinning with no stuttering! if the power is cycled at 50% (half on, half off), then the motor will spin at half the speed of 100% (fully on). The percentage of time spent cycling the on/off ratio determines the speed of the motor, e.g. The speed of DC motors is controlled using pulse width modulation (PWM), a technique of rapidly pulsing the power on and off.
Most DC motors run at a high RPM (revolutions per minute), examples being computer cooling fans, or radio controlled car wheels! When you supply power, a DC motor will start spinning until that power is removed. Need a motor for your project, but not sure which type to get? We stock a few different varieties on ModMyPi, so hopefully this rundown on the difference between DC, Servo and Stepper Motors will help you decide!ĭC (Direct Current) Motors are two wire (power & ground), continuous rotation motors.