Re: [CAD_CAM_EDM_DRO] Encoders - Slightly O.T.

I was succesful in making an encoder for gasoline pumps back in the early 80's.

It passed the certification for CSA (Canada) at that time.

I used hall sensors and a multipole magnetic disk set up in a current loop with the current limited by the circuitry at the counter.

It was optoisolated as well - I think that made it easier to certify.

You are allowed a fair bit of current as long as there's no capacitance at the sensor. I think a regular optical head could be made
to work with some careful design.

You might try to see if the encoders used today in gasoline pumps would be suitable. At the time I was doing it, they were only
available as reed sensors at very low resolutions so I had to roll my own.

Ed Koffeman

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 19, 2002 12:54 AM
Subject: Re: [CAD_CAM_EDM_DRO] Encoders - Slightly O.T.


> Brian Walsh wrote:
>
> > Hi list,
> >
> > I'm looking for a source of shaft encoders (A + B O/P's), certified
> > intrinsically safe for use in a Zone 2 Hazardous Area. Any suggestions?
>
> Hmmm, intrinsically safe is not so easy for externally powered devices.
> Not only must the encoders be IntSafe, but the power source must
> also be rated IntSafe for use with the specific encoder, as well as
> the wiring, conduits, etc. I suspect you need to do serious research
> with Rockwell/Allen-Bradley, BEI, Heidenhain, or one of the other
> industrial encoder manufacturers. I'm sure they have all faced this
> at one time or another.
>
> Jon
>
>
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