This stepper motor driver circuit is designed using UCN5804B driver IC especially designed to drive 6 lead unipolar stepper motors .
This stepper motor driver circuit is designed for 5, 6 & 8 lead unipolar stepper motors (the four lead
bipolar stepper motors are not supported by this circuit).
The direction of stepping can be changed by a switch and three stepping modes are possible.
Unipolar motors may have 5 leads but generally have 6 or 8 wires.
This circuit is designed so that the stepper motor can be run continuously at a fast or low stepping rate then, when it nears the desired position, it can be switched to single step mode and manually pulsed into final position.
Another switch controls the direction and two other switches bring out halfstep and one phase control modes supported by the IC (Pins 9 and 10 control one phase and half step operation).
UCN5804Bcan be powered off by another switch and any power to the motor is removed.
The driver circuit will operate motors at up to 35V and 1.25A. The step input is to pin 11 and direction goes to pin 14.
An 555 IC is configured to deliver a continuous stream of pulses to pin 11 of the 5804. The frequency is determined by the values of the potentiometer and C1. Alternatively, the single step switch allows individual pulses to be delivered manually to the 5804 using a tact switch. A switch debounce circuit is present using R4 & C5. LED’s are included on the output of the 5804 to show which phases of the motor are powered.