The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 178
S POIWT BREAK JACK Fig. 169.—Scale \ SWITCH-BOARD APPARATUS 153 When a plug is inserted in a jack the two outer springsare pressed away from the two shorter inner springs, and thusbreak contact. Fig. 170 gives a view of a strip of ten 4-point jacks con- ajfU Mi … Fig. 170 structed in a somewhat similar manner to those shown inFig. 169. Fig. 171 shows part of a strip of 7-point jacks. These aresimilar to the 5-point jacks, but the spring connection to thesockets is not permanentlyconnected, being pressed awayfrom contact (when a plug isinserted) by an…
Telephone
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