Friday, October 10, 2008

DCII 10.10.08

Digital Communications II starts today. I'm blogging links to sites about things I mention in passing.

Talking Telephone Numbers

Party Lines


voltage of ringing - as asked: 90v AC, frequency 20-25Hz.
(28 volt I mentioned is the pulse in the exchange to drive the rotary electro-mechanical relay, not the ringing - and was a UK analogue post office standard.

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