. The Bell System technical journal . rds, when a gi\en amount of energy flows into the ampli-fier across the junction B. it must be transmitted annmd the regener-ative loop and returned to this junction unchanged in amount. Thesecond condition is that the phase displacement of the wave trans-mitted from A to B through the frequency control unit must be equalin amount and opposite in sign to the phase displacement of thewave transmitted fiom .6 to ^ through the amplifier. That is, awa\e which enters the amplifier at the junction B must be trans-mitted through the regenerative system and return
. The Bell System technical journal . rds, when a gi\en amount of energy flows into the ampli-fier across the junction B. it must be transmitted annmd the regener-ative loop and returned to this junction unchanged in amount. Thesecond condition is that the phase displacement of the wave trans-mitted from A to B through the frequency control unit must be equalin amount and opposite in sign to the phase displacement of thewave transmitted fiom .6 to ^ through the amplifier. That is, awa\e which enters the amplifier at the junction B must be trans-mitted through the regenerative system and returned to this junctionwith no resultant phase displacement. The individual character-istics of the amplifier and of the frequency control unit which permitthese two conditions to be satisfied fix the operating point of the the reasoning to be used in the succeeding paragraphsmay, in general, be applicfi to any oscillatory system, it will be easierto follow if descriijcd in terms of familiar electrical circuits. In Fig. 2. Fig. 2—Circiiil of :iTi \ the ami)lilier and associati-d liatteries are shown in the lorni of anelementary \acuum tube cirruii. It is necessary to use a two-stagecircuit if the voltages at ,1 and at B are to ha\e the same sign. Thisis because the grid voltage, which is obtained as a potential drop dueto current from an external source flowing through a resistance con-nected between the grid and the filament of the vacuum tube, reducesthe current flowing from the filament of the tube to the plate, througha second external resistance, as the current flowing from the grid to thefilament is reduced. That is, a change in the \oltage drop across This condition for stable equililuiuin will ,ilsi) Inshift around the loop is cfiiial to 2ir»; wlurc ii In- .ii ^.itislicil il llu- niinihcr. rcnii (\ 511 ilii- )i\k\ circuit resistiinci- causts a change f opposite si^n in theNoltagc drop across the p
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
