Re: rotary hand encoder wheels with detent

Alan,

No converter is needed! The stepper will output quadrature when it is
turned. (okay, 90 degree out of phase sine waves, but scmitt triggers
fixes that<G>). The issue is the varying voltage at which the quad
signals are produced; you need "boost" when turned slowly, and "clip"
when turned fast. One of the pop tronics type mags had a circuit for
this awhile back.

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> Hi Doug,
>
> Yeah, I gotta agree, The stepper gives it a nice feel (but ya can't
spin
> it)! I must have been imagining (wishful thinking) that my encoder
had
> some feel.
>
> Do I recall the last time we talked about using steppers for
encoders,
> that there was a circuit for a "pulse generator" or "quadrature
> generator" for a stepper? I haven't sat down to see if I can
figure one
> out, but it seems that a few opamp comp's, and perhaps a few F/F's
> should be able to generate quadrature signals. Anybody wanna give
it a
> try?
>
> I'm USING my brand new dual shaft steppers!
>
> Alan KM6VV
>
>
> Doug Fortune wrote:
> >
> > Alan Marconett KM6VV wrote:
> >
> > > Are you saying that the pulse generating hand wheels
> > > actually have some force feedback, or that you can
> > > feel the steps (detents?) of the encoder? So once
> > > zeroed, their scales remain accurate to position,
> > > just like a manual mill?
> >
> > How about just using a big knob connected to a small
> > dual shaft NEMA 17 or NEMA 23 stepper motor (to give
> > the quality 'feel' of detents), and add an encoder to
> > the back of the stepper for feedback to the computer.
> >
> > The stepper motor is not connected up, its just there
> > to add the 'feel'.....
> >
> > If the encoder has the same resolution as the steps
> > of the motor, so much the better.
> >
> > Here is an improvement: I just grabbed a slo-syn NEMA23
> > 200 step stepper off the the shelf (this one is dual stack)
> > to 'feel' it, and it does feel nice.. those little
> > detents just whip off...
> >
> > However, shorting some of the leads causes the motor to
> > be difficult to turn (this is no surprise), so much so
> > that individual steps can be felt and almost counted! ..
> > it is hard to turn it more than 10 or 15 steps/second....
> > so that it would be easy to rotate into a given particular
> > spot without overshooting it. Thus maybe a pushbutton
> > should be placed on the panel somewhere to put the
> > 'encoder wheel' into this mode for
> > 'sneaking up' to a precise position.
> >
> > Everybody try this at home with your spare steppers!
> >
> > Also note that the real cheap 7.5 degree or 15 degree
> > steppers could also be used, if you wanted 'big hops'
> > between steps, instead of little mini ones.
> >
> > Doug Fortune
> > http://www.cncKITS.com