Stepper motor current

[alanhunt]

Hi
I am trying to determine the maximum current for my stepper motors. The original controller is no more and I have built a new one (L297/L298) based on my own design. Unfortuanatly I do not know what the vref voltage and hence the current limiter was set to.

The motors are marked Nanotek - Munich and have a resistence of 3.2ohm/phase and are 17 size. I am pushing a peak of 1A through them at the moment but torque seems to be lacking and motors do not get even barely warm.
I have checked the o/p of the sense resistors with a scope, and I'm getting what I think is ok- voltage of 0.5v (0.5ohm resistors) but only on for 5-30% of the time. There are though pos and neg spikes (noise?)

Any advice would be appreciated

alan

[limbo]

I would expect them to be around 1.4A/phase. My astrosyns are 3.4V/1.4A too. Nanotec has several steppers around 3.2Ohm, and they seem to be 1.4A for 17 and 23 size. Check out www.nanotec.de

greetings,
John

[limbo]

Sorry, I made a mistake.

Just looked it up. My astrosyns are 23 size, 3.5V,1.4A, so that makes them 2.5Ohm. Can't compare them to yours.

I looked in the astrosyn datasheets to find a comparable one and found this example:
17 size, 3.1Ohm, 3.7V, 1.2A.

In the nanotec datasheets I can't find your type exactly, but comparable ones are also around 1.2Amps, assuming its a 4lead bipolar type. Sorry for the mixup.

greetings,
John

[alanhunt]

Hi John
many thanks for your help, did try finding nanotec's web site before but with their name ending as 'tek' nor tec!

I emailed them with the exact number on my motor and just recieved a reply telling me that 1.4A/phase is what I should be using- so far everything is ok again
thanks again

alan