Re: Rotary Pulse Generators ?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

>
>
> jimalb2309 wrote:
>
> >Hello to all;
> > These where advertised as 2 channel RPG's, with IR emitter and
> >photo logic detectors which output 5v logic level.
> >My question is what are they, and can they be used like encoders?
> >they have what looks like an encoder wheel inside. if i look

close

> >through the two holes in the case i can see the slots in the disk,
> >one set seems to be coarse and the other set seems to be fine,

theirs

> >a small circuit board with the transmitters and receivers with a
> >resister and capacitor and looks like maybe a couple of trimmer

pots,

> >(assume for adjusting the sensitivity), and four wires red, black,
> >orange and brown, assume red and black power and ground, and brown
> >and orange the two channels.
> >
> >
> MPGs (manual pulse generators) are very much like encoders. The

major

> differences is they are not necessarily designed to accept fast

movement,

> the bearings may be designed for a relatively low number of

revolutions,

> and they are almost always of low resolution, typically 25 or 100

cycles

> per revolution, so that they produce 100 ticks per rev to the CNC
> control. Given these limitations, you COULD use them as encoders
> in some circumstances.
>
> The coarse and fine tripes sounds quite odd. Generally, the two
> channels of an encoder or MPG are the same number of pulses per
> rev, but displaced by 90 degrees relative to the pitch of the

stripes.

> This allows the decoder to determine direction. If the two channels
> are actually different pulses per rev, I don;t think you'll be able
> to do much with these.
>
> Jon

Testing will offer just how sensitive they are. If they are
unsuitable for X or Y, my thought is spindle speed, but if they are
brass bearings they may not hold up over long hours of use.

The other thought that comes to ming is a DRO or some kind.

Dave