. Practical wireless telegraphy; a complete text book for students of radio communication . ephone current by curve B, C. The peakof the dotted curve is thepoint at which a positivealternation is interruptedat the peak, and, asshown by the peak B, theaudio-frequent current isnegative and at a maxi-mum. The peak D is the, . .. , „ point where a negative 298b-Showmg Superposed Current. alternation is interrupted at the peak and the telephone current, as shown by peak C, is seen to be positive and at amaximum. At all other points on the curve, the strength of the periodic tele
. Practical wireless telegraphy; a complete text book for students of radio communication . ephone current by curve B, C. The peakof the dotted curve is thepoint at which a positivealternation is interruptedat the peak, and, asshown by the peak B, theaudio-frequent current isnegative and at a maxi-mum. The peak D is the, . .. , „ point where a negative 298b-Showmg Superposed Current. alternation is interrupted at the peak and the telephone current, as shown by peak C, is seen to be positive and at amaximum. At all other points on the curve, the strength of the periodic telephone currentwill be less varying as the relative amounts of positive and negative current admitted tothe telephone by the tone wheel. To produce a note of audio-frequency from the Tuckerton transmitter at its present wavelength, a toothed wheel interrupter having 800 contact segments revolving approximately at3,000 revolutions per minute would be required. This would interrupt the receiver circuit39,450 times per second, which would give a note equal to the pitch of 1,000 per 286 PRACTICAL WIRELESS TELEGRAPHY. The tone wheel is frequently termed a frequency transformer because it converts me-chanically the oscillations of radio-frequency into current of audio-frequency. It is superiorto the ordinary tikker, first, because it produces a musical pitch so highly desirable foraurul reception, and, second, it converts more energy of the incoming oscillations into usefulsound than does the tikker. A photograph of the Goldschmidt tone wheel appears in Fig. 299. The commutator discof this detector is driven at speeds approximating 4,000 revolutions per minute.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
