Re: Stepper motor as an encoder

Bob,

I'm OK with that and I hope my comments didn't give offense. I guess
I'm just looking at it from the point of view it has to work all the
way down to zero speed. It's a shame it can't do that.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "cncdxf" <cncdxf@a...> wrote:
> Mariss,
> I posted the links to show some people are using steppers
> as encoders and that they do work in some applications!
>
> Bob
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> > Bob,
> >
> > Nice circuit but it still doesn't get around the problem. The
> circuit
> > has a miniscule amount of hysterisis to latch the output to the
> last
> > signal peak, + or - . It would work down to 1/3 RPM as stated as
> long
> > as the detent torque is unloaded. The detent torque causes
> momentary
> > velocity to generate a voltage on the coils. A real world load
> would
> > swamp out this effect, rendering it useless at speeds below 1/2
> RPS.
> > It also cannot address sensitivity to vibration (microphonics) at
> > these very low speeds.
> >
> > To qoute from the listed page, note the honest caveat:
> >
> > "The problem with a stepper (or any other motor) used as a
> generator
> > is that at very slow speeds it gives virtually no output - so
there
> > is a problem with slow speeds. You have to make some sort of
trade
> > off between high speed and low speed performance. Proper encoders
> use
> > optical switches which work at any speed."
> >
> >
> >
> > Mariss
> >
> > --- In CAD_CAM_EDM_DRO@y..., "cncdxf" <cncdxf@a...> wrote:
> > > Hi,
> > > The link below sums it up.
> > >
> > >
> > > http://www.4qdtec.com/stpen.html
> > >
> > >
> > > Bob