Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 372
ll supply ringingcurrent to the various switchboard sections in succession, and not berequired to furnish the ringing current needed throughout the entireswitchboard at one time. In addition to the ringing springs these motorgenerator outfits carry busy, dial tone and howler attachments. Some-times… … Fig. 280.—Power switchboard and charging machine. commercial source of power supply for a few hours will not disable thetelephone plant. The reserve ringing apparatus, in the plant in whichthe photograph reproduced in Fig. 279 was taken, is a harmonic-con-verter outfit; in fact, two…
Telephone
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