The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 293
tgoing end of * |250w Fig. 271 junctions to C.B. and magneto exchanges respectively. Thelines for the latter, it will be observed, have a cut-off relayfor disconnecting the earthed battery, which is connectedwhen the line is not in use. The connections of the junctions Fig. 272 at the incoming… … Fig. 273 than five trunk junctions are provided. The connectionsof one of these lines are shown in Fig. 273. They are multipledthroughout the sections, and in addition are provided with anengaged test, which takes the form of a small press button TRUNK-LINE EXCHANGES 267 having relay and lamp…
Telephone
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