Re: Driving unmarked steppers

Hugh,

You are on the right track. What I do is use a precision (1%) 100mA /
1A current source I built up to measure very low resistances
accurately with a voltmeter.

Your technique will work very nicely if you make one change. Use a
12VDC power supply and put a 10 to 20 ohm, 10W resistor in series
with your DC ammeter. This resistor will limit current to a 0.5A to
1A maximum into a short circuit.

Mariss

--- In CAD_CAM_EDM_DRO@y..., Hugh Currin <currinh@O...> wrote:
> Paul, et al:
>
> I know little of this so maybe Mariss or others with some
electrical
> background can straighten me out. But not to keep my foot out of
my mouth, I
> think you can get better information on low resistances by using
two meters,
> one mearsuring voltage and another measuring current. With these
two data
> points ohms law will give the resistance. It is my undertanding
that ohm
> meters are not too good at low resistances, at least quantitatively.
>
> FWIW. :-)
>
> Hugh Currin
> Klamath Falls, OR
>
> On Friday 15 February 2002 02:04 pm, you wrote:
> >
> > This is a really useful bit of info -And yes, I do have some
other unknown
> > motors of the newer square design. 4 wire size 23, about 75mm
(3") long.
> > Comparing the numbers with some data sheets, the wattages tally
pretty
> > closely. All I need to do now is to find a good milliohm
meter.....
> > A visit to the local store and ask for a demo on real world
components is
> > in order.....
> >