[transfrank]

Hi,
I'm a n00b. I found I have a lot of vibration on my stepper motor. Is this common/normal?

I am using 'Full stepping' with two coils simultenously on as described in http://www.zaber.com/wiki/Tutorials/Microstepping on a bipolar stepper. I built the driver myself with a ULN2803 and a PIC controling it. The rotational speed I get from it is pretty bad: 5 rot/s.

Should I just go with a microstepped driven bipolar or can I continue with the unipolar somehow?
Thanks,
Frank

[H500]

Full stepping will vibrate too much on most systems. Most serious designs use microstepping.

[transfrank]

I tried half-stepping with the same unipolar stepper motor and ULN2803 and it is already better. In reality, it is not true half stepping, because I am not current limiting, so sometimes I give two windings both current I1 and sometimes I give only one widing I1. The sound went down and it looks smoother. The rotational speed is still much too slow, so I will have to replace this setup soon. The stepper motor is rated 12V with a 36 ohm coil and I drive it with 12V, no current limiting. From what I see, better motors have lower winding resistnace and are driven with 10x more voltage.

[H500]

Yes, the system you have is very low performance compared to one that use a proper high voltage driver. The latter can easily spin a motor at several thousand RPMs.