The practical telephone handbook and guide to the telephonic exchange (1906) (14569502619)

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

Text Appearing Before Image:

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Text Appearing After Image:

Fig. 21: Scale TV Fig. 213 which joins to the main exchange. For the working of thesupervisory and calling signals, and for supplying speakingcurrent to lines not connected through to the main, one ormore pairs of power leads are run between the main EXCHANGE SWITCH-BOARDS i87 and branch exchanges. The number of such pairs dependson the distance, the number of working lines, and the amountof traffic on the lines in the branch. Two sizes of copperwire are used for the leads—viz., Nos. 20 and 22 S.W.G. Asan example we may take a branch exchange at a distanceof 500 yards from the main. For this 1 pair of No. 20wires would be sufficient for a traffic equal to a maximum of5 connecting-cord circuits in use at the same time, and 2 pairsfor a maximum up to 10 cord circuits. These leads are con-nected to bus bars, as shown in Figs. 214 and 215. Line Connections.—Fig. 214 shows the line connections of Common Lzaos to Battery j/JNgj

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1906

Northeastern University, Snell Library

http://commons.wikimedia.org/

public domain