Actually I want to do different typr of coils, i need something to compare
strenght. So i do not really need the absolute value, but just an
indication what works best.
ken
I have quit doing it now but, I have been building a little Guass
meter for several years that slotcar (remember those?) racers use to
test and match the little magnets in their motors. Yeah, a lot of
those guys are very serious about their racing. Anyway, I was able to
wholesale it for $150 so you should have no problem building one
yourself on the cheap. The units I made used a ratiometric sensor
similar to the ones that have been recommended. My earliest versions
used opamps to shift and scale the sensor output that fed a panel
meter module. The last ones I made used a sigma delta A/D and a PIC
driving a standard LCD. Either works just fine. All have used the same
sensor built into a traverse probe. The sensor cost me about $13 ea
and were never in stock so I always ordered 25 at a time. Whatever
sensor you use, make sure it stays linear throughout the range of the
field you expect to encounter. Most of those sensors will run out at
anywhere from +- 100-2500 Gauss. I don't know if repeatability is all
that important to you, but keep an eye on the temperature specs for
sensitivity, offset, and linearity.
Mike