. Practical wireless telegraphy; a complete text book for students of radio communication . ng tuner to prevent the soundin the head telephone from becoming of un-bearable intensity. Although various means have been devisedto shield crystalline detectors from the localtransmitting apparatus at a given station, nonehave as yet afforded the desired , it is generally necessary at the close ofa period of transmission to readjust the re-ceiving detector to its maximum degree ofsensitiveness. If the receiving tuner is fittedwith a test buzzer the detector can be quicklyreadjusted by
. Practical wireless telegraphy; a complete text book for students of radio communication . ng tuner to prevent the soundin the head telephone from becoming of un-bearable intensity. Although various means have been devisedto shield crystalline detectors from the localtransmitting apparatus at a given station, nonehave as yet afforded the desired , it is generally necessary at the close ofa period of transmission to readjust the re-ceiving detector to its maximum degree ofsensitiveness. If the receiving tuner is fittedwith a test buzzer the detector can be quicklyreadjusted by setting the buzzer into action andchanging the position of the opposing contacton the crystal until the loudest signals are ob-tained. The ordinary vibrating buzzer can beput to a variety of uses in radio telegraph systems, such as exciting the circuits of a j- ,■ , wavemeter or setting up oscillations in an aerial system for radio telegraph meas-urements. Such circuits will be described in the chapter following. 150. Receiving Telephones.—The flux generated by a given electromagnet. 194a—3,000-Ohm Head TelephoneReceiver. 168 PRACTICAL WIRELESS TELEGRAPHY. is determined by the product obtained in multiplying the strength of the currentby the number of turns, e. g., the ampere turns determine the magnetizing , if a feeble current only is available, a magnet wound with a large numberof turns of fine wire will generate the greatest magnetizing flux. Now the local circuit of the average telephone receiver, such as shown in Fig. 194a,is traversed by feeble currents, and therefore the magnets of the telephones shouldbe wound with a great number of turns of rather fine wire such as No. 36 or No. 40B. and S. Such a winding necessarily has considerable resistance, but a greater magnetizing force will result therefrom than would be ob-tained by a winding of a few turns of coarserwire. The resistance of the average telephonereceiver for reception of radio signals is 2,000t
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
