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BELL SYSTEM TECHNICAL JOURNAL 



required to actuate the filament. The efficiency of oscillator circuits 

 ranges all the way from a few per cent, to as high as 90% or better. 

 The principal factors determining the efficiency are those which 

 determine the amount of energy dissipated upon the plate of the tube. 

 Inspection of the oscillogram, Fig. 55, shows that the sharper and 



Filament Current -Amps. 



Fig. 59 



narrower the plate current wave and the more nearly the plate voltage 

 approaches zero, the higher will be the efficiency. In an extreme 

 case such as the hypothetical one illustrated in Fig. 62 it is evident 

 that the efficiency would be very large indeed. The p of the tube 



lb Ic Id 



eo a e 



to 7 7 



60 6 6 



50 5 5 



101 1 



30 3 J 



?0 2 2 



rig. 60 



Fig. 61 



largely determines the sharpness of the plate current wave and ex- 

 perience shows that for efficiencies of about 50% and better, ju should 

 be at least ten; an increase above this value does not result in any 

 very large improvement. It is also generally true that for the highest 

 efficiencies the circuit constants should be so arranged that R is at 



