In article ,
Meat Plow wrote:

Something that traces phone wires or other electric wiring?

That's about what I would guess.

A friend of mine recently had to trace down a couple of short circuits
in some in-wall wiring... a house he partially built a couple of
decades ago, which passed electrical inspection and has since been
sitting empty and idle. He disconnected the mains, then rigged up an
audio oscillator and power amp and a current-limiting resistor, and
used the combination to put an audio tone into the wiring at the
breaker box between the two wires which were showing a shorted load.
He then used a home-made setup similar to what you're showing (a coil,
fed to an audio amplifier) to trace along the walls, using the audible
tone to figure out where the wires were running inside the drywall.

By noting where the tone suddenly disappeared, he was able to figure
out where the wires inside the Romex were shorted. In the first case,
it was due to a drywall screw that had bit into the Romex and shorted
hot to ground (the screwhead turned out to be within 1/16" of where he
marked the "lost the signal here" spot on the painted drywall). In
the second case, he lost the tone at an outlet/switch box, and found
that an overly-tight cable retaining clamp had caused "cold flow" in
the PVC insulation of the Romex and had punched a small pinhole
through to the hot wire.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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