. Practical wireless telegraphy; a complete text book for students of radio communication . than 3 volts the flow ofcurrent (in microamperes) through the local circuit is relatively weak. The result of thisis seen to be a series of positive maxima of gradually decreasing amplitude to whichthe telephone diaphragm cannot respond individually but which produce an average effectin the receiver. The average current in the case of Fig. 157a may be considered for mereillustration to be 9 microamperes and the difference between the normal current 6 micro-amperes and the average current 9 microamperes
. Practical wireless telegraphy; a complete text book for students of radio communication . than 3 volts the flow ofcurrent (in microamperes) through the local circuit is relatively weak. The result of thisis seen to be a series of positive maxima of gradually decreasing amplitude to whichthe telephone diaphragm cannot respond individually but which produce an average effectin the receiver. The average current in the case of Fig. 157a may be considered for mereillustration to be 9 microamperes and the difference between the normal current 6 micro-amperes and the average current 9 microamperes (or nficroamperes) is the current ~ l« % i 14 1 1 .nl? 1 S / a 10 < j f?« 1 u J ^ / / 4 / 4 / ? y ^ ^ ^ K^ * r Fig. 157- 12 3 4 VOLT& -Characteristic Curve of Carborundum Rectifier. RECEIVING CIRCUITS, DETECTORS, TUNING APPARATUS. 139 which produces audible sound in the receiving telephone. We may state the foregoing inanother way by saying that the added voltage due to the oscillating E. M. F. being im- C-0 APPROXlMATt AVEaAfiE TELEPHONE CURRENTA-B NORMAL BATTERY CURRENT,. BALL JOIHT Fig. 157a.—Curves Showing the Fluctuations of the Local Battery Current flowingthrough the Carborundum Rectifier during the Reception of Signals. pressed upon the crystal is greater than the subtracted voltage and that the final effect ofthis is an increase of current through the head telephone circuit over the duration of onewave train. From the foregoing explanationit is apparent that when an operatorat a given receiving station adjuststhe position of the sliding contacton the potentiometer for maximumsignals, he adjusts the flow of cur-rent through the crystal and headtelephone to correspond to thecritical point on the characteristiccurve, or, in other words, to thatpoint on the curve where the super-position of a slight antenna E. upon the local E. M. F. causes arelatively large change in thestrength of the local battery cur-rent. And it also follows that thesteeper the charact
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
