The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 344
nical strain upon them, a startingswitch is used. This, by inserting a resistance in serieswith the machine, and then gradually cutting it out as themotor gets up speed, gives a gradual increase of E.M.F., andtherefore current, to the coils. Generator-Field Rheostat.—The generators used are usually… … 3i6 PRACTICAL TELEPHONE HANDBOOK as desired, and the E.M.F. generated in the machine can beraised or lowered at will. Double-Pole Switches.—These are heavy switches, used toconnect the generators to the battery when the machine hasattained the proper speed for charging—viz. so as to givean E.M.F.…
Telephone
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