Telegraph engineering : a manual for practicing telegraph engineers and engineering students (1922)
Hausmann, Erich, 1886- · New York : D. Van Nostrand Company · leaf 39
y by electric motors which re-ceive either direct or alternating current from servicemains. For the operation of telegraph circuits of all typesdifferent voltages are required from about 25 to 400 volts. The voltages now considered standard for main-hne 24 TELEGRAPH ENGINEERING operation are 80,… … Fig. 15. with the latter company. The generators for the two highervoltages are generally duplicated so as to permit of re-versal of potential, as necessary in duplex and quadruplexservice (see Chapters II and III). With printing tele-graph systems no volts are generally used.
Telegraph
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