Bob Blick wrote:
> In supermarkets they use either "70 volt line" or "25 volt line"
> systems. At each speaker is a small transformer with many taps, and
> you
> select the speaker's impedance and how much relative power you want it
> to have, and connect to the big long speaker wire that runs through
> the store.

I can picture it now.  Howls, clicks, rasping noises, growls, and other
spooky sounds all around, then suddenly "Price check, register 5".


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