The Determination of the Audibility Current of a Telephone Receiver with the Aid of the Wheatstone Bridge

A method of determining the audibility current of a telephone receiver, using a Wheatstone bridge with the telephone as indicator is described practically and theoretically. The method differs from the usual shunted telephone method which determines an audibility voltage. A method is given whereby a desired percentage accuracy can be secured even if the telephone resistance and impedance are only very approximately known.