File:The practical telephone handbook and guide to the telephonic exchange (1906) (14756161545).jpg

Identifier: practicaltelepho00pool (find matches)
Title: The practical telephone handbook and guide to the telephonic exchange
Year: 1906 (1900s)
Authors: Poole, Joseph
Subjects: Telephone
Publisher: New York, Macmillan Co.
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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Text Appearing Before Image:
ard sub-station arrangement is, however, gener-ally associated with the Hayes C.B. system, and the othersub-station systems with the Stone C.B. system in America,but in this country the Standard sub-station arrangementis generally used even when the Stone system of current supplyis used, as will be seen in connection with the Post Officeexchanges. CHAPTER XVII COMMON BATTERY MULTIPLE SWITCH-BOARDS Practical Details of C.B. Systems. (1) Electrical Con-nections.—Having given a short history of the more importantC.B. systems, it now becomes necessary to describe how theyare worked in actual practice. Western Electric Co.s System.—This system, which is thestandard in this country, is used in the most important ex-changes here and in America. It is a development of theHayes system, with the Standard sub-station arrangement,and represents the latest C.B. practice. Line Connections.—Fig. 240 is a sketch of the line connectionssomewhat simplified, showing one only of the multiple-jacks,
Text Appearing After Image:
Fig. 240.—C.B. Line Connections simplified which are all connected in parallel with the one shown. Thepositive pole of the 11-cell storage battery (24 volts) is shownconnected to earth, the negative pole being connected throughthe line relay and a contact of the double cut-off relay, tothe b wire of the line. The a wire is connected through thesecond contact of the cut-off relay, to the positive pole of thebattery. As shown in the figure, there is a break in the- linecircuit at the sub-station instrument until the receiver is lifted,when the circuit is completed. The current then passes, and215 2l6 PRACTICAL TELEPHONE HANDBOOK operates the line relay, which in its turn closes a local circuitincluding the calling lamp and battery, when the lamp glows,and attracts attention. Note.—In some of the older C.B. exchanges the line relayis connected in the A wire circuit and a 60-ohm resistancelamp is included in the B wire circuit. These were used toenable current to be fed through subscr

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