Re: determining stepper motor current

RichD,

Actually a battery powered multimeter set to DC Amps at very low
speeds (< 1 step per sec) or AC Amps at higher speeds (>240 full
steps per sec) is a terrific and very accurate way to measure step
motor phase current directly. Mind that the current will be Amps RMS
for the AC setting.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, RichD <cmsteam@s...> wrote:
> Alan,
> Meter??
> I hope you know that you can't use an ampmeter to measure motor
current.
> It's chopping at ~20kHz.
> The best way is to calculate based on the sense resistor value as
given
> before and set the VRef pot accordingly to needs.
> I don't understand the 1.2 vs 3.4 diff unless your ohmeter is ??? or
> the diff is that the higher reading is across a center tapped coil.
> RichD
>
>
> alanhunt2001 wrote:
> >
> > Hi Rich
> > Thanks for your help - will try upping the peak current.
> > Although the label says 1.2ohm, each coil actually measures 3.2ohm
> > so I think this will give about 2watts? But my meter shows that
I'm
> > sending 0.2A (is this the average current through coils??) at 32v.
> >
> > so 0.2A x 3.2ohm =.64v and 0.13watt I think its a question of
> > using either peak current or average current in the equation.
> >
> > I wish I had measured vref on the old board before removing all
> > components from it and as the board contained a multitude of
> > components for changing vref through software I can'nt even
> > reconstruct the schematic easily!!
> >
> > Thanks again
> > Alan