Re: Stepper Voltage and Current question

the stepper power rating is typically between 3 to a maximum of 25
times the rated voltage. (data from Marrissi's white paper.)

the higher the voltage, the more power you will be using to power
your motor. that said, you can use a PC power supply to test
everything at no real cost to you, even the current limiting
resistors are cheaper. Then when you need the power, you can just up
your power supply.

But, like Bob mentioned, unless you need to heat your shop, the
limiting resistors are best for tiny motors. Look into a chopper
circuit to build your own, or there are a few comercial drives, Gecko
being the one we talk about most because it seems to meet about 99%
of the needs on this list. and seems to be as sturdy as they come.

The Gecko can handle 70 volts, so if you got a 48 vac transformer and
cap, and rectifier, you can get about 68 vDC to drive. Of course,
anything less is fine and will work.

Dave

--- In CAD_CAM_EDM_DRO@y..., "Bob Stone" <spoothammer@h...> wrote:
> Hi,
>
> If the motors are 3 volts and 2 amps, that means the windings are
1.5 ohms.
> If you apply 25 volts to these coils you'll draw almost 17 amps
which will
> shut down your supply, toast your driver circuit, etc.
>
> To limit current, say at 25 volts, you'd need a approx. an 11 ohm
power
> resistor that could handle 110 watts. That would be nuts. You
better have a
> chopper drive and even then I'd go to a higher voltage motor with
that
> supply.
>
> bob
>
> >From: "starcast82" <rh@g...>
> >Reply-To: CAD_CAM_EDM_DRO@y...
> >To: CAD_CAM_EDM_DRO@y...
> >Subject: [CAD_CAM_EDM_DRO] Stepper Voltage and Current question
> >Date: Fri, 03 May 2002 05:10:07 -0000
> >
> >I am currently starting to design my stepper drive and wanted to
make
> >sure of a couple things. I hate to see smoke. First off I have 3
> >volt, 2 amp unipolar stepper motors.
> >
> >1. I plan on using 25 volt supply, is this enough or should I jump
up
> >to 50 volts ? I read I can go 20 times the rated voltage.
> >
> >2. As far as current limiting goes, since I have 2 amp motors, from
> >what little I found from reading, does this mean I can run 2 amps
> >through each of the 4 coils <what I read> or does this mean I can
> >run .5 amp through each coil ?
> >
> >Thanks for the help
> >If anyone is interested in what I come up with when I'm finished
I'll
> >be more than happy to post it.
> >
> >
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