The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 79
, then in a 1000-ohm circuit we should have a variation of -gV^hj or 2 per cent.,which is twenty times as great. This latter is the principlefollowed when a common battery is used for exchange working,the current for working the subscribers transmitters beingsent from the exchange. By maldng use of… … Fig. 40 wire, the currents induced in it by the variations in the primarycoil will have a high E.M.F., and will be able to overcomemuch resistance in the line and instruments at the other endwith comparatively little loss of strength. Microphones.—The next step in the direction of improve-ment was…
Telephone
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