A stepper motor is an electric motor that is brush-less and synchronous. It converts digital pulses into mechanical shaft rotations. Each rotation of a stepper motor is divided into a set number of steps, sometimes as many as 200 steps. The stepping motor must be sent a separate pulse for each step. The motor can only receive one pulse and take one step at a time and each step must be the same length. Since each pulse sent results in the motor rotating a precise angle, typically1.8 degrees, the position of the stepper motor can be precisely controlled without any feedback mechanism. As the digital pulses from the controller increase in frequency, the stepper motor movement converts into a continuous rotation, with the velocity of the rotation directly proportional to the frequency of the control pulses. A Stepper motor is widely used because of low cost, high reliability, high torque at low speeds and rugged construction that allows a stepping motor to be used in a wide environmental range.
Read more by visiting site http://www.circuitspecialists.com/stepper-motor