Abstracts of Technical Articles by Bell System Authors 



The Transistor — A New Semiconductor Amplifier} J. A. Becker and 

 J. N. Shri\t. This article describes the construction, characteristics, and 

 behavior of the newly discovered device, the transistor. Used as a semicon- 

 ductor amplifier, it works on an entirely different principle and is capable of 

 performing the same tasks now done by the vacuum tube triode. 



A Review of Magnetic Materials? R. A. Chegwidden. Significant advances 

 have been made within recent years in the development of new and better 

 magnetic materials, and in the theories of magnetism. High permeability 

 materials that may be classed as non-conductors, materials with greatly 

 improved initial permeabilities, and permanent magnet alloys capable of 

 storing four or five times as much energy as those obtainable ten years ago 

 are now available. Descriptions of some of these developments are given. 

 The paper gives compilations of data and curve sheets showing some of the 

 typical characteristics of many of these materials. 



Ratio of Frequency Swing to Phase Swing in Phase- and Frequency-Modula- 

 tion Systems Transmitting Speech} D. K. Gannett and W. R. Young. 

 Computed and measured data are presented bearing on the relation be- 

 tween the phase and the frequency swing in phase- and frequency-modula- 

 tion systems when transmitting speech. The results were found to vary with 

 different voices, with the microphone and circuit characteristics, and with 

 the kind of volume regulation used. With a particular carbon microphone, 

 it was found that a phase deviation of 10 radians corresponds to a frequency 

 deviation of between 11 and 15 kc in a phase-modulation system, and be- 

 tween 6 and 12 kc in a frequency-modulation system, depending on condi- 

 tions. 



Design and Performance of Ethylene Diamine Tartrate Crystal Units.'^ 

 J. P. Griffin and E. S. Pennell. A research program on synthetic crystals 

 has resulted in the development and adoption of EDT for carrier telephone 

 filters. Some unusual physical properties of the crystalline material give 

 rise to novelty in the processing methods and mechanical design of the units. 

 These properties include anisotropic expansion coetlicients, fragility, natural 

 cleavages and water solubility. The electrical properties of EDT result in 

 filters with wider pass bands and lower impedance levels than commerically 

 obtainable with quartz. 



^Electrical Engineering, v. 68, pp. 215-221, March 1949. 



2 Metal Progress, November 1948. 



» Froc. I. R. E., V. 37, pp. 258-263, March 1949. 



* A. I. E. E. Transactions, v. 67, pt. 1, pp. 557-561, 1948. 



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