The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 289
(n) of which is, under normal conditions,kept deflected to the right by the 4-volt battery (4 v.).It will be noticed that at both ends of the trunk line, connec-tion is made to a 24-volt battery, in such a manner that eachbattery opposes the other. No current, therefore, passes untila connecting… … TRUNK-LINE EXCHANGES 263 equipotential method of working, which was described inthe preceding chapter, as used on both-way junction hues. Method of Working.—When London wishes to call the pro-vincial exchange a plug is inserted in the jack. This cuts offthe permanent battery. A ringing key (s in…
Telephone
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