346 R. Whiddington, The self-oscillations of a Thermionic Valve 



The self -oscillations of a Thermionic Valve. By R. Whid- 

 dington, M.A., St John's College. 



[Read 19 May 1919.] 



(Abstract.) 



It lias been found possible to produce oscillations of almost any 

 frequency from a three electrode vacuum valve, without employing 

 the usual capacity-induction circuits. Thus a. valve with two 

 suitable batteries, one in the anode circuit, another in the grid 

 circuit, will produce quite powerful oscillations, whose frequency 

 will be determined by the value of the grid potential. 



The phenomenon can be explained by supposing that the oscil- 

 lations are due to surges of mercury ions closing in on the filament 

 from the grid with a frequency given by the approximate formula 



2 2^ T/ 



n = . V 



md^ ' 



e • 

 where — is the usual charge to mass ratio, d is the radial distance 



m o ^ 



filament to grid and V is the positive grid voltage. 



Experiments conducted so far indicate that the monatomic 

 Hg ion with one live charge is mainly responsible. 



