At 14.40 2010.12.30, RussellMc wrote:
>> Gray code encoders, if cheap enough, usually are rotary (I never saw=20
>one linear
>> at least). Pretty expensive anyway.
>
>Gray code encoder can be optical or use other sensors
>Gray code can be a SINGLE track with multiple sensors spaced along it
>in such a way that they between them "see" a gray code. Mathematicians
>used to say it was impossible. Nowadays its done. I don't know how
>hard it is to get 6 or 7 bits.
>BUT if you can use and end of track detector then you need simply two
>detectors in quadrature on a single track. Very standard. cf eg
>mechanical wheeled mouse. Each axis ha one "track" and two sensors.
>
>36mm / 6 bits is about 0.5 mm/bit. Somewhat fine.
>
>An optical "window" with width affected by position would probably be
>easy enough. read light level shining through "window" to get
>position.

Dammit Russel.. this is too simple and effective to be true!!

What do you neozelandeses eat? A lot of Omega-3 fish I guess. I gotta
eat more too. :-)

Thanks, I'll invent something along the lines of a single light source
getting proportionally dimmed by something displacement related. Easy
and effective, and probably much more precision than I'll ever need.

A+!


>
>
>     Russell
>
>
>
>>
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