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Frank,
I queried Digikey's literature stating the magnetic
membrane potentiometers used batteries,
with the manufacturer Spectrasymbol. Heres the
reply....
No
batteries are required and the MagnetoPots should be able to handle 12 volts
(that?s what they were all qualified with). The only restriction is that
we do have a 1W, at 100mA, specification.
So it looks good.
Have been thinking these units could be easy to
make.
Inside the acrylic housing that we need to make to pressure proof
the pots; you first glue a layer of "fridge magnet material"
Then add a flexible resistant wire or tape, then a gap of
about 1mm, then a copper trace wich is glued to the underside
of the lid of the acrylic housing. As a larger magnet runs along
the outside of the housing it pulls the resistance wire/tape
up off the fridge magnet material & on to the copper
trace shortening its length & resistance
through its travel.
The problem being finding a flexible, suitable resistance material
that attracts to a magnet. Nicrone wire in a fine coil may
work,
it attracts to magnets. Will see what old electrical appliances I
can pul to bits.
Alan
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