I currently have what I've gathered is a rather old custom made stepper motor driver attached to a stepper motor and am unsure how to actually operate it. I have looked around online and gathered a typical setup for driving this type of motor involves 2 H-bridges but I'm not sure how the setup I have will translate to properly operating them.

I believe the stepper motor is a bipolar 2-phase stepper motor. You can see several specs at the top including TTL, input voltage, output current, and clock input (I don't exactly know what clock input means).

Here is a picture of the driver:enter image description here

The inputs and outputs are labeled (and in parentheses are the configuration I found them in):

1-Motor Phase 1 (hooked to motor) 2-Motor Phase 2 (hooked to motor) 3-Motor Phase 3 (hooked to motor) 4-Motor Phase 4 (hooked to motor) 5-Outputs off (grounded) 6-4 phase/3 phase (no wire) 7-Enable (looks like it is wired to 13) 8-Enable A (wired to nothing) 9-Clock Selection (wired to 12) 10-Direction ccw (wired to nothing) 11-Clock cw (wired to nothing) 12-GND (wired to 9) 13-Voltage supply (wired to 7 with another wire going to nothing)

I have found some information for other products that seems to indicate I would need to put the specified input voltage to 13, pulse 9 with 15 microsecond square pulses, then hold 5-8 and 10-12 either at 5V or ground to change basic operating configuration. Is it that simple or am I missing something critical? I apologize that this may be rather low level stuff here but any information on how to operate this would be very much appreciated because there is no manual for this piece of equipment.

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    \$\begingroup\$ There may not be a manual, but that is a very informative sticker. Assuming the driver is matched to the motor, you have most of what you need - the input signals are comparable to those on lower power stepper chips as used in Arduino projects, 3d printers, etc. \$\endgroup\$ Commented Apr 3, 2018 at 16:33

1 Answer 1


Connect a momentary switch or a low frequency 5V CMOS logic relaxation (Schmitt Inverter)oscillator with a pot. and Connect to Step. with Vdc =24V

Each positive pulse ( and switch bounce) will rotate CW 1 step with typ 200 steps per rev so 200 Hz is 60 RPM

Then vary pot from 1Hz to 1Khz to change slow RPM in steps


simulate this circuit – Schematic created using CircuitLab

15 us is the shortest STEP CLK pulse spec and it is edge sensitive.

  • \$\begingroup\$ Thank you very much Tony. To be clear, what exactly is "step clock"(your first sketch) in relation to the driver, (ie what pin)? And where does the power supply go here? I apologize, this is pretty foreign to me. \$\endgroup\$
    – John A
    Commented Apr 3, 2018 at 19:08
  • \$\begingroup\$ It says Input Voltage 20~35V and pins are marked for Input Voltage and Gnd (0V). The pulse goes to a logic circuit to count pulses and shift transistor switches Voltages to change polarity to windings and rotate rotor to next tiny phase in the rotor's magnetic teeth to line up with the many repeating powered coils energized around the rotor \$\endgroup\$ Commented Apr 3, 2018 at 19:40
  • \$\begingroup\$ The Enable/disable is to keep it cool if you stop moving and it starts to get warm using max voltage (32V). Acceleration / holding torque is proportional to current from V+/motor R in the coil. Often some steppers have a reduced voltage for idle. When you take it for a spin ( pun intended) come back with youtube video links. Keep the logic wiring short and neat. with cap on 5V IC and gnd unused inputs. \$\endgroup\$ Commented Apr 3, 2018 at 19:44
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    \$\begingroup\$ Okay, that clears things up for me. Thank you very much for all your help! \$\endgroup\$
    – John A
    Commented Apr 3, 2018 at 20:10
  • \$\begingroup\$ OK so you need a 150~250W power supply or else you can go really slow with 12V on ATX \$\endgroup\$ Commented Apr 3, 2018 at 20:12

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