. Practical wireless telegraphy; a complete text book for students of radio communication . rmanent magnets it undergoes a cyclic changein magnetism and is extremely sensitive to an impressed external magnetic field such asthat generated by a radio-frequent current flowing through the winding G. When electrical oscillations induced in a receiver aerial by a distant transmitter passthrough the winding P, one complete group of oscillations sets up an alternating magneticfield which causes a single movement or a change in the position of the flux in the ironband. S being in the path of
. Practical wireless telegraphy; a complete text book for students of radio communication . rmanent magnets it undergoes a cyclic changein magnetism and is extremely sensitive to an impressed external magnetic field such asthat generated by a radio-frequent current flowing through the winding G. When electrical oscillations induced in a receiver aerial by a distant transmitter passthrough the winding P, one complete group of oscillations sets up an alternating magneticfield which causes a single movement or a change in the position of the flux in the ironband. S being in the path of the flux, it is acted upon inductively, a currentbeing induced in the windings which flows through the head telephone creating a singlesound for each group of incoming oscillations. The note of the transmitter is faithfullyreproduced, because each group of oscillations radiated by the transmitter has a cumulativeeffect on the change of flux in the iron band, which causes a single movement of the tele-phone diaphragm. Although the magnetic detector lacks the sensitiveness of the crystal. RECEIVING CIRCUITS, DETECTORS, TUNING APPARATUS. 149 detector throughout the shorter range of wave lengths, as between 300 and 600 meters,for _ waves around 2,500 meters, it compares favorably with the jnost sensitive crystalrectifiers. The magnetic detector may be connected directly in series with the aerial system, but it func-tions best in ^ thecircuits of the Mar-coni Multiple Tun-er (English Mar-coni Company) inFigs. 168 and general, thecircuits of thistuner appear simi-lar to that of thevalve tuner, but thesecondary windingfor the magneticr ^ , . , detector has very tew turns as compared with the secondary of the valve tuner. The magneticdetector has low resistance compared with crystal detectors and, in consequence,the stopping condenser of the usual detector circuit becomes an active element ofthe closed oscillation circuit and must therefore be of variable capacity. In fact,plac
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
