The Bell System Technical Journal 



Vol. XXIV January, ig4f; No. i 



Intermittent Behavior in Oscillators 



By W. A. EDSON 



Oscillators of all sorts ma\', for certain values of the parameters, show low- 

 frequency disturbances. Usuall>- the disturbance takes the form of a low-fre- 

 quenc>- interruption of the desired oscillation. By the method here i)resented 

 it is possible to determine whether or not such intermittent behavior will occur 

 in a given oscillator and what circuit modifications are required to promote 

 stability. The intentional generation of a modulated wave by control of the low 

 frequency behavior of an oscillator is also considered. Oscillators of the nega- 

 tive resistance type are not considered. 



I. Introduction 



TT has been known for a long time that all kinds of oscillators are subject 

 -*• to the trouble variously referred to as intermittent oscillation, motor 

 boating, or squegging. In conventional circuits such as the Hartley the 

 phenomenon is most likely to be observed if the grid leak and grid condenser 

 are abnormally large. It is found that the time constant of this combina- 

 tion must be reduced as the frequency is raised and as the Q of the resonant 

 circuit is decreased. At frequencies above a few hundred megacycles the 

 problem of producing a practical circuit with suitable margin of stability 

 is quite difficult. 



With the advent of the oscillator having automatic output control the 

 problem assumed a new aspect.^- - By application of an amplified control 

 circuit a high degree of constancy of output together with low harmonic 

 output is obtained. Satisfactory operation is secured, however, only when 

 suitable attention is given to .the characteristics of the control circuit. 



The intentional generation of pulses by means of intermittent oscillations 

 of relatively high frequency has been studied to some extent, and circuits 

 of this kind are employed in some television systems. Usually the high- 

 frequency oscillation is limited to a small portion of the low-frequency C3'cle, 

 the charge stored during this period being allowed to dissipate itself relative^ 

 slowly during the remainder of the cycle. 



In all of these circuits satisfactory performance depends upon a proper 

 proportioning of elements not directly associated with the operating fre- 



1 L. B. Argimbau, "An Oscillator Having a Linear Operating Characteristic," Proc. 

 I.R.E., Vol. 21, p. 14, Jan. 1933. 



2 J. Groszkowski, "Oscillators with Automatic Control of the Threshold of Regenera- 

 tion," Proc. I.R.E., Vol. 22, p. 145, Feb. 1934. 



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