The practical telephone handbook and guide to the telephonic exchange (1906) (14755854662)

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:

Fig. 244.—Testing Connections simplifiedP 224 PRACTICAL TELEPHONE HANDBOOK

Text Appearing After Image:

mm i —^ of the calling side of a pair of cords when about to make anengaged test, and also shows two jacks of an unconnectedline with the cut-off relay,while Fig. 245 shows asimilar pair of jacks, onebeing connected to thethird conductor of a plugand cord. In the latter casethe engaged click would beobtained when the tip ofthe plug (Fig. 244) touchedthe socket of the unoc-cupied jack. This clickwould not be caused by adirect current passing fromthe battery through thereceiver, but by a partialdischarge current passingfrom the condenser, owingto the difference of poten-tial between the two coat-ings of the condenser beingreduced when a currentpasses through the tip con-ductor, the P.D. havingbeen previously equal to thefull voltage of the battery.Speaking Connections.—Fig. 246 shows the sim-plified speaking circuitwhen two sub-stations areconnected through a switch-board. It will be readilyunderstood without furtherdescription. Barnsbury Switch-Board.—In order to facilitate the d

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1906

Northeastern University, Snell Library

http://commons.wikimedia.org/

public domain