troubles with stepper motors

Thread Starter


Joined Nov 20, 2007
Hey guys...I just have a quick question on stepper motors...

I have a five hybrid (four control lines - stepper motors being controlled by a pile of BS2's and propeller chips...When modeling the circuit on breadboards everything worked swimmingly. Now everything is on PCBs, and if I hook LED's up to the outputs of the H-bridge drivers all the sequences run fine. But when I hook the steppers up I just get vibrations. The system is controlled by PC and the rotation of each stepper can be controlled per-step on the C++ interface. So the amount of vibrations of the motor does correspond to the value sent from the PC.

I've tried connecting the control lines to the steppers in every possible configuration but seem to get similar results. I have a 15A atx supply powering the peripheral power to the H-bridges so there must be enough available current and it may be a long shot but I was wondering if anybody has any suggestions?

The only thing I've noticed is there only seems to be 0.3A on each of the H-bridge outputs, where the steppers are rated at 0.6A per channel. As only two of the four outputs are simultainiously energised throughout the sequence, does this mean the two energised outputs should equal 0.6A?

I know its a bit vauge, but any suggestions would be great...




Joined Apr 16, 2010
Some steppers require a pause between steps; otherwise they just buzz.

I found that one motor I was working with required at least 1 msec between step commands. In addition, I found that the pauses must be at least 4 msecs in order to avoid the motor missing pulses. At 3 msec, the motor would occasionally miss pulses which caused inaccurate stepping. Note that this problem surfaced after the addition of counter EMF diodes (1N4001) on the MOSFET outputs.
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Thread Starter


Joined Nov 20, 2007
Theres a 10ms pause between pulses, and like I said the steppers worked well on breadboards, and the H-bridges output the correct sequence when I hook up LED's. When the steppers are connected to the outputs, 300mA @4.8v is drawn through each channel so it seems the only thing it could really be is either buggered steppers (unlikley) or the channels are not in the right order (Although IU've tried each configuration). I would post everything but I'm not currently with my files. I'll try again tomorrow. Cheers for getting back to me


Joined Jul 17, 2007
You have to determine what you did differently on the breadboard from what you did on the PCB's. There is obviously SOMEthing different, or they would be working.