I'm amused. Boiled down to the basics, a metal detector is nothing but an induction machine. When conductive materials are brought within the detectors field, phase shift and frequency offset in the inductors are the primary results. The innards, detect these changes, and report to the user in a variety of ways. They can be an analog, digital, or a combination. They all do a fairly good job at what they were designed for, with some consideration as to sophistication and therefore price. Just as important is what they aren't!
While they operate from audio to low radio spectrum frequencies, and are susceptible to nearby electrical fields, they're not lighting rods any more than a golf club is. When you're out in a flat field with no trees (ala golf course), it is best not to be there when there is lightning about!
Damageable by nearby sources of electromagnet devices? Probably not, unless the electromagnetic field is strong enough to zap your body like standing in front of a radar!
It is clear to me, that not too many of my fellow detectorists, really know what goes on inside their chosen detector? Maybe, there should be a discussion forum to propagate factual information therein, and not wive's tales.
