Re: [CAD_CAM_EDM_DRO] stepper pulser, and RE: Stepper driver question (slightly O.T.)

Why not just use a mechanical DC motorized actuator with two limits. Some simple circuitry with the optical/photo sensors to trigger. Latch two relays through a stop NC limit both directions? Can't imagine a stepper holding something for 12 hours at a time. Just went way off topic..sorry

Ron

Alan Marconett <KM6VV@...> wrote:
HI Dave, Marv,

You're right! The 555 timer circuit posted in the files could ramp a
stepper up. Add comparators, and you might have it.

But just changing directions may not be enough. Some hysteresis may be
required, so that the device does not "hunt". How wide would the "dead
band" (area between limits where no motor activity is desired) be? I
suppose if a "limit" (photo detector, what type?) was reached, one could
simply move 1/2 the distance across the dead band.

Contact Dave or I off list if you're interested in a PIC solution. Dave and
I are currently working on a "stepper pulser" that runs a stepper with
proper acceleration/deceleration in either direction when a switch or push
button is actuated. Your project doesn't sound like a big leap from ours.

A stepper driver would be required; an LMD18245 stepper driver would work,
or you could order a single axis Xylotex board. The ELS board (ELS list)
would be a candidate; it has a driver on board. Also has an LCD display,
which may or may not be desired.

Our stepper pulser board is smaller, and may be used with or without an LCD.


Alan KM6VV

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of turbulatordude
> Sent: Sunday, January 29, 2006 8:25 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: Stepper driver question (slightly O.T.)
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Marv Frankel"
> wrote:
> >
> > Guys,
> > I have an industrial application that requires only one stepper
> > motor, and two photocells. When one photocell goes dark, the stepper
> > motor cranks clockwise. When the other photocell goes dark, the
> > stepper motor cranks counterclockwise. I'm looking for a fairly simple
> > driver. Any suggestions?
> >
> > Marv Frankel
> > Los Angeles
>
>
> It sounds like your machine has an ON/OFF setting. no signal at all
> and it is OFF.
>
> any signal and it is ON.
>
> ONE of the signals ALSO changes state of the DIR pin.
>
> Very simple to do, but the logic and electronics may not be on topic
> for the list.
>
> the motor and driver parts seem pretty close though.
>
> What size motor ? how much power do you need ? (have?)
>
> It sounds somewhat similar to Mel Bartels's telescope stuff (CNC to
> move a telescope)
>
> Alan is correct that a PIC could handle this, but so could a 555 and a
> comparitor.
>
> The comparitor would report when either input went high. and also
> report when that one went high so as to necessitate a DIR change.
>
> With the signal, the 555 would just start pulsing away.
>
> If you were running TurboCNC or some such, you could feed those
> signals into inputs and run G-Code to make the thing move.
>
> Dave
>
>
>
>
>
>
>
>
>
>
>
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