Re: +/- 10 V To Step/Dir Converter Circuit

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@...> wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, cnc002@ wrote:
> >
> >
> > In a message dated 3/12/2007 5:03:03 A.M. Eastern Daylight Time,
> > riet91@ writes:
> >
> > Hi All,
> >
> > Does anyone know about such circuit or IC which
> > converts analog +/-10 V into Step and Dir Signals?
> >
> > regards
> >
> > Babar
>
>
> It would be a simple circuit to make up.
>
> is the +10 and -10v a floating value ? like would the motor move
> slowly at 5volts and faster at 10 volts ?
>
> or, would it be either 10V or zero or -10v ? and nothing in-between ?
>
> Using a comparitor to look for anything over say 9 volts and if it
> were over 9 volts, it would then send out a pulse train.
>
> everything between +9v and -9v would be zero and not move. as -9v the
> same thing would happen, but also the DIR would change.
>
> Pretty easy circuit if that is all you need.
>
> What is misses is any ramping or accel or decel, and it also misses
> any speed controls at all.
>
> I think one would benifit from knowing what the voltage signal came
> from as a means to better design a circuit.
>
> Dave
>

Basicly a VtoF converter with direction sensing. I built a manual one
5 years ago. The frequecy output is linear to the voltage. It is
composed of three distinct circuits:

The absolute voltage circuit. The DC output is linear regardless of
the polarity. It becomes the control voltage for your VCO (voltage
controlled oscillator)

The polarity sensor (Simple comparator circuit) that swtiches
direction signals based of it the input control voltage is postive or
negative. It only has to sense a few milivolts in either polarity to
set direction

The VCO section. I used a CD4046 PLL CMOS chip that has an internal
VCO tha goes from sub-audible to 1 mhz. It is linear and the range
can be set with one resistor value with about a 1000:1 VCO span.
Since the freq is a direct function of the applied DC voltage you can
introduce an RC filter that gives a ramp frequency (accel & Decel) to
the output of the Absolute circuit.

All of this begs the question: Where do you need to convert from +-10
to step and dir? Usually it's the other way. The solution is the
Pixie card or the Rutex for S&D to +-10.

Tom Caudle
www.Candcnc.com