Fast and cheap stepper motor drive

Stepper motors are widely used in many industrial applications especially in the applications that need high precise control position. Stepper motor is used in most applications which require discrete movement. Today most robotic systems, automatic digital camera focus and zoom functions, use stepper motors. Medically stepper motor used inside scanners, multi-axis stepper motor microscopic or nano-scopic motion control of automated devices, dispensing pumps, samplers, and chromatograph auto-injectors, and in aircraft sensors, stepper motors are used in antennas, scanning equipment etc. In general sensing signals that represent the shaft position of any motor may be a difficult due to high cost and some restricted limitations. Stepper motor drive doesn´t need any sensing device to sense the shaft position and can be considered as cheap drive compared by other drive systems. This paper is focused on controlling uni-polar stepper motor by a simple decoder (CD4017) ignited from a timer 555 circuit also by using a microcontroller as PIC 16F84A and the output of the decoder or the PIC are fired the MOSFET Bridge or the transistor bridge (S8050). The Bridge in its turn allows the motor to rotate in both directions with highly procession speed control technique. The proposed system is simulated by Proteus program and tested through a small prototype system including stepper motor and its control circuit.