508 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



fixed emitter current. These effects are shown to lead to two new elements in the 

 theoretical small-signal equivalent circuit. One, the collector conductance (g'c), 

 is proportional to emitter current and varies inversely with collector voltage. 

 This term is the dominant component of collector conductance in high-quality 

 junction transistors. The other element, the voltage feedback factor (fiec), is 

 independent of emitter current, but varies inversely with collector voltage. The 

 latter element is shown to modify the elements of the conventional equivalent 

 tee network. 



Four-Terminal p-n-p-n Transistors. J. J. Ebers^ I.R.E., Proc, 40, 

 pp. 1361-1364, Nov., 1952. 



The equivalent circuit of a p-n-p-n transistor is obtained. It is demonstrated 

 that a p-n-p transistor and an n-p-n transistor can be connected so that the com- 

 bination has the same equivalent circuit as the p-n-p-n structure. A simplified 

 circuit is obtained which can be used when the p-n-p-n transistor is connected as 

 a hook-collector transistor. A method of adjusting the current gain of p-n-p-n 

 transistors by external means is given as w^ell as experimental results. 



Dynamics of Transistor Negative-Resistance Circuits. B. G. Farley^ 

 LR.E., Proc, 40, pp. 1497-1508, Nov., 1952. 



A general method is presented for calculating approximately the behavior of 

 many nonlinear circuits by dividing the region of operation into subregions, 

 within each of which the circuit may be considered linear to a good approxima- 

 tion. The method is appHed to a high-speed transistor switching circuit as an il- 

 lustrative example. 



Regenerative Amplifier for Digital Computer Applications. J. H. 

 FelkerI. i^r^e., Proc, 40, pp. 1584-1596, Nov., 1952. 



A description of the negative-resistance properties of the point-contact transis- 

 tor is presented as an introduction to the description of a regenerative amphfier. 

 The choice of circuit parameters for the amplifier is discussed and a sample de- 

 sign presented. The illustrative amplifier regenerates digital information at a 

 megacycle rate and develops pulses with rise times of less than 0.05 /xsec. It op- 

 erates from supply voltages of +6 and —8 volts, with a battery drain of less 

 than 0.05 watt. A complete set of computer building blocks has been designed 

 around the amphfier. Their use is illustrated in two computer applications. 



Evidence for Domain Structure in Anti-ferromagnetic CoO From Elas- 

 ticity Measurements. M. E. Fine^ Letter to the Editor. Phys. Rev., 87, 

 p. 1143, Sept. 15, 1952. 



Optical Position Encoder and Digit Register. H. G. Follingstad^ J. N. 

 Shive^ and R. E. Yaeger^ LR.E., Proc, 40, pp. 1573-1583, Nov., 1952. 



The usefulness of transistors in systems has been given a feasibility proof 

 through the construction and operation of a six-digit position encoder and serial- 



1 Bell Telephone Laboratories. 



