ARMSTRONG, OPERATING FEATURES OF THE AUDION 219 



of energy as aii amplifier when the grid potential is adjusted to this 

 point. Fig. 6 shows the oscillogram of the action as an amplifier. The 

 result bears out the explanation already given. 



The action of the audion as a detector of high-frequency oscillations 

 is quite different from its action as an amplifier. Since the incoming 



B.# ^^ 



Fig. 10 



oscillations are of too high a frequency to affect directly the telephone 

 receiver, the audion must be so connected and adjusted that the cumula- 

 tive effect of a group of oscillations in the grid circuit is translated into 

 a single low-frequency pulse or variation in the telephone current. This 

 may be done in two ways, one depending on the non-linear form of the 



(^riei jaoTen/i'a/ 



V/m^ CiJtrrs^nf 



Te/ephoriB- otrrnrnt 



Fig. 11 



operating characteristic of the audion and the other depending on the so- 

 called "valve" action between hot and cold electrodes at low pressures. 



Fig. 7 shows the connection used for operating in the first-named man- 

 ner. The potentiometer F is employed for the purpose of adjusting the 

 potential of the grid to point M on the characteristic curve of Fig. 1. 

 The action is much the same as in one of Professor Fleming's methods 



