> -----Original Message-----
> From: Reinaldo Alvares [SMTP:reinaldoalvares@TELIA.COM]
> Sent: Wednesday, April 30, 2003 9:22 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [PIC]: Frequency multiplier?
> No is not an x-y plotter.The encoder is on a moving cart with a scanning
> system on it. The pulses are used to trigger one scan per pulse. The
> encoder
> is connected to the shaft of one of the wheels. I used magnets placed on
> the
> wheel to trigger an Allegro hall effect sensor with quadrature output.
> Because of the size of the wheel I could not mount more magnets on it. I
> used the smallest ones I could found 1mm diameter. The magnets were used
> because this equipment goes into water, dust and many other tough
> conditions, where optical systems are difficult to implement. So the end
> was
> to get an E4 encoder from USdigital and get a rugged case for it. The
> whole
> construction is a cylinder 120mm long and 29mm diameter and solved all the
> problems. I spent quite a while trying to do the trick with a micro,
> that's
> why I was interested in some opinions regarding this. I guess from the
> beginning it was a doomed project. Anyway, I always try to listen to other
> people because one can never learn to much.
> Thanks a lot for your time.
>
Perhaps consider a reluctance sensor, as used on engine managment systems
for engine position sensing?  This way all you need on the rotating part is
a ferrous toothed wheel which should give you considerably better
resolution.  You can use two reluctance sensors to give a quadrature output
if needed.

Regards

Mike


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