Re: Going home / more stepper speed!

Hi Jon,

I'll have to give a look. I suppose you can also see the back EMF
spikes that can trash the output transistors if not dampened with
diodes. Measure with a current probe (AC current probe??) or a standard
10:1 signal probe?

Alan KM6VV

Jon Elson wrote:

>
> Alan Marconett KM6VV wrote:
>
> > Ballendo,
> >
> > One of your previous post's to Ian (a keeper!) was Re: "faster stepper"
> > (snip below), and had an EXCELLENT description of stepper resonance
> > effects. However I'm a little curious about being able to see the
> > STEPPER "ringing" (overshoot, resonance's..) you describe on a SCOPE?
> > The "ringing bell" is exactly what I'd expect to see in a resonant
> > circuit all right. Are you talking about actually seeing these
> > waveforms on the drive currents to the coils?
>
> You can, indeed! The motors have a magnet moving past a coil of
> wire, so any movement of that magnet will induce a voltage (or current)
> in the coils.
>
> The current pulses from the stepper driver will swamp these smaller signals,
> but with proper triggering techniques on the scope, you can see these ringing
> waveforms. You can probably evaluate damping techniques and find the
> resonance peaks this way, too.
>
> Jon