Ronald van Aalst wrote:
>
> It might. I do know that recently a VLF receiver was proposed in the
> hobby mag "elector" that consisted of nothing more than a large coil stuck
> in your pc soundcard.

> > Can a battery-powered device with no AC line connection sense a power
> failure
> > by noticing the LACK of any 60Hz pickup?  Given sufficient care in battery
> > life preservation, that would make possible "stick up" emergency lighting
> > that didn't need to be connected to anything, which would be quite a neat
> > idea, IMHO...


It's an interesting idea and sounds do-able. :o)
The trick will be to do it WITHOUT having to use
a large heavy and expensive coil to pick up the
60Hz.

I have a telephone extender amplifier, cheap little
thing that came with a cheap pick up coil. The coil
is about 1" and has a rubber suction cup. These are
avaliable separately. It picked up mains hum ok,
especially the higher freq harmonics but needed to
be close to the wires.

For stick-up emergency lighting I would use one
cheap transmitter on the lighing circuit, and
multiple receiver lights. This keeps it all wiring-
free as you required and has little cost difference.
-Roman

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