> Linear Hall sensors seems to be good-enough solution.
> But, as I recall from my student years (I've done about
> a hundred lab jobs on phisics with real research apparatus)
> Hall effect gves relatively small voltage, so thermo-stability
> of amplification may arise into serious issue,

Prescript:

            Note that GMR is sensitive to ANGLE of field NOT
            amplitude - it is much closer ideal for angle sensing
applications.

Also look at GMR (Giant Magneto Resistive?) which for practical purposes may
be crudely considered as super output Hall sensors. Infineon (nee Siemens)
are the kings of GMR. I posted a large ref to GMR on list some months ago
but Google would probably be as quick (eg www.platan.ru/pdf/00130.pdf  &
www.infineon.com/designlink/3347/)
Also see Honeywell.

Here is Infineon's MR & GMR page


http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/prod_cat.jsp?oid=-9382



        RM

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