The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 300
ified by the additionof inductance coils and condensers that some of the bellsonly respond to a weak and high frequency current, and othersonly to a stronger and lower frequency current. (7) The Wheatstone Bridge method, in which a rheostator adjustable resistance at the exchange enables the… … Fig. 278 have proved the most promising in practice, and a short de-scription will now be given of two or three arrangementswhich have proved specially promising. The Hibbard System.—This, which is extensively used inAmerica, is based on Nos. 4 and 5 methods. Biassedpolarised bells are used. This…
Telephone
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