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Old 22nd Jul 2021, 2:11 pm   #2
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Re: Shared Service (Party Line) emulation

I am sure others with more knowledge will chip in but my recolection is that the two wires were connected in parallel for the speech circuit so that if one party is talking the other could listen in by simply lifting the receiver.
The ringing was selective by sending the ac ring voltage between one wire and earth, each party had their bell connected from one of the wires to a local ground spike, each party used a different wire.

Which reminds me of the story, apocriphal I am sure, about the lady who claimed to have a psychic dog, it would howl just before the telephone rang.
Turns out she used to tie her dog to the local earth spike by a metal chain. The earth spike was in dry ground and a poor earth. When the ring voltage was sent the chain connected to the earth spike gave the dog a shock, who then howled and wet himself, the wee wet the ground and completed the earth and the telephone rang.

Peter
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