AndyS wrote:
Andy writes:

I remember from 50 or so years ago reading a copy of POP
electronics, or
maybe ELEC illustrated, which featured a couple of young boys named
Carl
and Jerry and the stuff they messed about with each month. Kind of
like
a "Mr Wizard" story.....

One of the articles was winding a coil of wire around a plastic
bottle of
water and exciting it , then watching the output from the coil as "the
water
molecules oscillated"...... I don't remember the details, but they
called
the affair a "differential proton magnetometer", and used it to
measure
magnetic fields....

Do


Other references exist, but you probably want to take a look at
Scientific American, "The Amateur Scientist", "How to make a sensitive
magnetometer" February 1968, page 124. Used discrete transistors and LC
filters on pot cores. I suspect one can do much better today with opamps
and microcontrollers, and I'm sure someone has done it if you google around.

See also
http://www.gellerlabs.com/PMAGThoughts.htm for an update..