82 



AUSTIN! EXPERIMENTS WITH THE AUDION 



ment of apparatus was employed: The primary of an iron core 

 telephone transformer was placed in series with the telephones 

 and to its secondary a silicon detector in series with a sensitive 

 galvanometer was connected. The changes in current strength 

 which affect the telephones produce similar effects in the tele- 

 phone transformer and give rise to alternating currents in the 

 secondary which in turn are rectified in the silicon detector 

 and are thus made to affect the galvanometer. The galva- 

 nometer deflections have been shown to be proportional to the 

 square of the alternating currents in the detector 2 and there- 

 fore to the square of the telephone pulses in the main circuit. 

 When the audion was made to produce local oscillations these 

 were found to affect the detector slightly, but their influence 

 was entirely eliminated by placing a condenser of 0.1>f across the 

 detector. 



The strength of the high frequency oscillations which were 

 sent out from the sending wave meter was measured by means 

 of a thermoelement connected in the wave meter circuit. 



TABLE I 



Old Audion 



DAMPED EXCITATION 



The first experiment was intended to determine the law of 

 response of the circuit in old audion connection, the sending 

 wave meter being excited by a buzzer. The results are shown 

 in Table 1. Here I) represents the readings of the thermo- 



2 Bulletin I'ureau of Standards, 6: 530. 1911. 



