This is the circuit design of unipolar stepper motor driver to control unipolar stepper motors with 5, 6 or 8 wires. It uses four MOSFET IRFZ44. This circuit can be operated in free-standing or PC-controlled mode.

Unipolar Stepper Motor Driver Mode

In free-standing mode an internal square-wave oscillator based on IC2:B of the 4093 supplies timing pulses to the OSC output. The frequency of these pulses and thus the speed of the stepper motor is controlled by the trimpot VR1 (100K.) A series 1K resistor controls the maximum frequency. You may increase the value of this resistor for your own needs. These pulses are fed into the STEP input which is buffered and inverted by IC2:D. This helps prevent false triggering. Similarly, IC2:C buffers and inverts the DIRection input. A SPDT taking the input to +5VDC or ground controls the direction of rotation.

IC3:C and D (4030 or 4070 exclusive OR gates) invert the outputs available at Q and /Q outputs of each of the flip-flops (FF) IC4:A and IC4:B. The incoming step-pulses clock the FF, thus toggling the Q & /Q outputs and this turns the MOSFETâ€s on and off in sequence. The IRFZ44â€s have a low on-resistance and can deliver up to 6A each without needing a heatsink.

Power to the stepper motor is connected to V+ and GND terminals as shown on the overlay. There is a separate power supply, KITV, to the 78L05 to power the ICâ€s. 9V ??” 12VDC will be sufficient. R2/C2 form a low-pass filter to filter fast-rise switching transients from the motor.

Note that some stepper motor texts say to use a 4070 instead of a 4030. We have not worked out why this is. Certainly our testing with the 4030â€s showed no problems. I would like to hear from anyone who knows why this advice is sometime given.

In computer-controlled mode use the three pads with pins DIR, STEP and GND. Switch the SPDT switch to EXTernal. The direction SPDT has no effect in external mode.

Kit for this unipolar stepper motor driver is available:

Download kit PDF manual (schematic, part list, explanation included):

PDF Manual Unipolar Stepper Motor Driver Kit

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This bipolar stepper motor driver circuit will drive a bipolar stepper motor using externally supplied 5V levels for stepping and direction. These usually come from software running in a computer or from a microcontroller unit. The circuit uses IRFZ44 and MTP2955 MOSFETâ€s.

All the power inputs were connected together. The CLOCK was connected to STEP, and the RESET was connected to DIRection. Pushing the CLOCK button then advanced the motor one notch. Pressing CLOCK with the RESET button also depressed and pressed down advanced the motor one notch the other way.

Bipolar Stepper Motor Driver Part Lists

Resistors 1/2W
R1, R2 : 1K
R3, R4 : 10K
R5, R6, R11, R12 : 12K
R7, R8, R13, R14 : 2K2
R9, R10, R15, R16 : 150R
C1 : 100uF/63V ecap
C2 : 10uF mini ecap
C3 : 100nF
D1-D8: 1N4148 diode
IC1 : 4013
IC2 : 4030
IC3, IC4 : 4N25
IC5 : 7805

Bipolar stepper motors have two coils and are controlled by changing the direction of the current flow through the coils in the proper sequence. These motors have only four wires.

The unipolar stepper motor is connected as a bipolar motor (the 2 center wires of the 6 wire motor are unused.) 9V was used. The STEP and DIRection negative inputpins were tied together and connected to system ground.

Kit for this bipolar stepper motor driver circuit is available.

Download kit manual in PDF:

Bipolar Stepper Motor Driver Manual Kit

1 file(s) 132.50 KB

Download