Re: faster steppers

Hi Henrik,

I found your previous post, I think,

" I have noticed, when running
the motors with my function generator, that it makes allot of difference
how
fast I 'accelerate' - to fast OR to slow makes the motor stall. So I
can't
say I can run 10000 half steps/sec reliable."

I've ran a few steppers with a function/rate generator in my time! Even
with a few 555 timers! One circuit we had used a cap to generate an
acceleration/deceleration ramp. I still have the little board, built
into a small box, with switches for direction and two push buttons. I
used it to run my robot! Er.., the water phantom for nuclear
instrumentation on the company's medical linear accelerator. Yah,
that's it!

Thanks for the URL. The counter program looks quite useful! And I
thought of but haven't tried yet (not for steppers, just Amateur Radio
receivers), but Spectrogram could also be useful for watching stepper
motors!

http://www.monumental.com/rshorne/gram.html

Alan KM6VV
Yeah! P.S. Several ideas from these threads!


Henrik Olsson wrote:

>
> Alan,
> Well, I didn't really measure the maximum steprate. I just turned the
> frequency up (squarewave 50& dutycycle) 'till the motor stalls and then
> looked at the scale on knob. Easy, but not really exact values.
> There are a lot of programs available to measure frequency on the PC - most
> for soundcard 'tho. Have a look at, for example:
> http://w3.pca.net/~cpclark/SBTESTEQU.html
> And you are right about the acceleration/deceleration ramps, see my previous
> post.
>
> /Henrik.
>
> Alan wrote:
> > How were you using a rate generator to MEASURE the maximum steprate?
> > Just by feeding the driver with a square wave? I've been trying to use
> > a Frequency counter designed for Amateur Radio (StarCraft?). Works part
> > of the time, but I suspect that the pulses (20us) may be too short for
> > higher speeds. I can read the frequency relatively well with an Interro
> > "lab scope" made for automotive testing ;>) I've also read pulse
> > repetitions with a 100mhz HP 'scope.
> >
> > Actually, as we have a good digital signal, one should be able to count
> > the frequency with a program running on the PC, and using the parallel
> > port as an input.
> >
> > You will need proper acceleration/deceleration ramps to get the maximum
> > speeds. AND high P.S. to coil voltage ratios (for full current) for
> > good "chopping".
>
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