NEWBIE QUESTION: Stepper problem

I'm getting a strange problem when trying to drive a nema 17hs4417 stepper from a L298D driver board.

If I use 6 AA batteries, the motor runs fine (until the batteries die) with no dropped steps. However, I dont want to run off batteries so I purchased a 12V 2A ac adapter,when I use this the motor judders and jumps missing many steps. The stepper motor is rated at 2.55v 1.7A.

I've tried switching the wires on the A and B connectors on the driver board, but it is almost impossible to get it not to work when using batteries, but it will never work correctly when using the mains adapter. I've checked the output from the adapter on a voltmeter and this reads 12.14 volts with no fluctuation.

On the driver board, I currently have

out1 A2 Blue out2 A1 Red out3 B1 Green out4 B2 Black

Can anyone offer any insight as to what may be happening?



The stepper motor is rated at 2.55v 1.7A.

Neither the power supply nor the L298D driver is capable of driving that low voltage, high current motor.

If you carefully follow the directions to set the current to 1.5 amperes/phase or lower, the Pololu DRV8825 will work with that motor.

If you need the full 1.5 amps/phase, you will probably need a power supply capable of more than 2 amperes, but you can always set the winding current to a lower value.

Have a look at stepper motor basics.

Your 12v 2A power supply should work OK with a specialized stepper driver. It can produce 24 watts. The motor only requires 4.33 watts. Use a large capacitor across the motor supply to even things out.


To clarify you need a current-controlling chopper driver to drive a low impedance bipolar stepper, not a pair of H-bridges. The motor is not voltage driven.

If the motor was 12V 0.4A, then yes you could use the L298, and you might get 300rpm or so from it max.

With your motor and the correct driver running from 24V you may get 2000+rpm...

Thanks for the replies guys, very useful, especially the pointer to the "stepper motor basics" post. The link from that to the mechanism to estimate torque was also very useful since I have been struggling with that too.

I am trying to motorise and remotely control a telescope focusser, so I dont really need any high speeds, in fact quite the opposite. I am following an article on the web that gives instructions on how to put one together, but I am having problens sourcing some of the components (Motors) here in the UK. I can import from the US but the shipping is more than the motor, thus my (failed) attempt of identifying a suitable alternative motor.

Anyway, next job is to follow the suggestion for estimating the torque.

I do have a DRV8825 which I believe is similar to the A4988 mentioned in the stepper motor basics article so I will probably switch to that, and perhaps try and find another motor as I suspect the one I have may be a bit overkill.

Once again, many thanks for the advice


The DRV8825 should be fine - it can handle a little more current than an A4988.

I have these motors for a small lathe - they may have sufficient torque for your needs.



What is written on the label in the 12V 2A power supply? Can you post a picture of it.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png or pdf?

Can you please post a copy of your sketch, using code tags? Please use code tags.. See section 7,148850.0.html

Tom.... :)