stepper as encoder wasRe: How can you test a stepper ?

Hello,

Motors of different specs (hi-inductance vs. lo inductance, for ex.)
are going to respond differently. Which may be why yours does not
work. Try turning slower or faster...

The principle used here was described in a recent?(last few years)
article in poptronics or similar mag. It was about using a stepper as
an encoder. Basically the curcuit just limited thew voltage developed
by the stepper.

The problem, as you have found, and Jan mentions, is that slow
movement will not generate enough electricity to reliably be used as
outputs.

If you have an application where the encoder/motor will always be
turning "fast enough", then this might be worth looking into. And
although encoder prices have fallen in recent years, a #11 or 17 size
hybrid stepper could be a pretty cheap "encoder" if the above
conditions are met.

Also could be okay for a "jog wheel", as long as you don't expect 1:1
ALL the time.

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:
> In a message dated 2/21/2003 8:04:24 PM Central Standard Time,
> hllrsr@c... writes:
>
> > Tried this trick today, (O.K. I was bored..) and couldn't get it
to work.
> > What's the trick?
>
> Iain: I did this ONLY with a couple of Size-23, single-stack
motors I have
> "loose", and it doesn't work "well". Works better if the shafts
are
> "pointing upward". Less radial friction? Also, if you spin one
motor with
> the fingers rather abruptly. Slow-turning, and it won't do much.
Do NOT
> expect "synchronous" operation! I suspect some multi-stack and/or
Size-34
> and larger motors might work better for this, as ONE has
to "generate" pulses
> adequate to jog the other motor, and that might not work very well
on the
> smaller motors. No, I have NO interest in doing further research
on this!
> Have fun!
>
> Best test is to MEASURE the resistances, to see if the windings are
within
> 10% of "published values", and that there is "infinite" resistance
between
> the windings, and between them and the case, etc.!
>
> Lotsa luck! Jan Rowland
>
>
> [Non-text portions of this message have been removed]