The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 161
mbler bells being used in place of themagneto generators and bells. Extension without Secrecy.—Fig. 151 shows the connectionsof the National Telephone Co.s arrangement for working anexchange instrument or main with one or two extensioninstruments on the same line. There is no switch provided. 138… … •& * I \ \ f t. Fig. 151.—Connections for Exchange Line with 2 Extension Lines—Non Secrecy provided, which, by means of current derived from theexchange current supply, rings the ordinary trembler electric £XT. INST. 2
Telephone
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