1210 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1952 



the problem is multiplied due to the lack of a long background of experi- 

 ence. 



It has been assumed that negative resistance is a common thread 

 among "trigger circuits" and oscillators regardless of the device em- 

 ployed — electron tube, gas tube, transistor, mechanical structures, etc. 

 This is not a new or novel idea and there is no intent to present it as 

 such.* Rather, it is used as a pattern upon which a certain degree of 

 transistor analysis may be based, leading to simple understanding. The 

 analysis assumes that the negative resistance characteristic can be broken 

 into three regions; each region is then considered on a linear basis. 



Section I will deal with simple circuit properties; Section II with 

 analysis and Section III with device properties. 



I — Simple Circuit Properties 



The common property ascribable to switching functions is that of 

 definiteness of state. The condition of the function is either "off" or 

 "on". Switches are either open or closed; relays are operated or not; tubes 

 are in cutoff or overload; doors are open or closed and so on. This is 

 common regardless of the phenomena being exploited. 



There is an intermediate region between these two conditions usually 

 characterized by a time which is related to how fast the function may 

 go from one state to another. Functionally the times of closing and 

 opening are taken to be zero; practically, they are of determining im- 

 portance. Relays replace hand-operated switches and electronic devices 

 replace relays as speed becomes important. Obviously, no function or 

 system can be faster than its state-devices. 



All such state-devices will have separate attendant properties such 

 as the degree of reverse coupling between the controlling signal and the 

 controlled signal. Separated into families, however, there are those 

 which are passive and those which are active. The latter are threshold 

 devices in which a small amount of signal or control energy causes the 

 translation of a relatively larger amount of stored energy into dynamic 

 energy which consummates the change in state. As long as the control 



* See for example "Negative Resistances, Their Characteristics and Effects. 

 Sinusoids, Relaxation Oscillations and Relaxation Discontinuities", Walter 

 Reichardt, Elektrische Nachtrichen-Technik, 20, pp. 76-87, March, 1943; "Uniform 

 Relationship Between Sinusoids, Relaxation Vibrations and Discontinuities", 

 Walter Reichardt; Elektrische Nachtrichten-Technik, 20, pp. 213-225, Sept., 1943. 

 For transistors: "Counter Circuits Using Transistors", E. Eberhard, R. O. 

 Endres and R. P. Moore, RCA Review, pp. 459-476, Dec. 1949; "A Transistor 

 Trigger Circuit", H. J. Reich and Ungvary, Rev. Sci. Instr., 20, p. 8, p. 586, Aug., 

 1949; and "Some Transistor Trigger Circuits", Proc. Inst. Radio Engrs., 39, pp. 

 627-632, June, 1951, P. M. Schultheiss and H. J. Reich. 



