Inc. Web: http://www.pearl-hifi.com E-mail: ♦ Verso Filler Page ♦ ELECTRONIC TRANSFORMERS AND CIRC IT U S Reuhen Lee Advisory Engineer Westinghouse Electric Corporation SECOND EDITION NEW YORK LONDON . JOHN WILEY & SONS, INC. CHAPMAN & HALL, LIMITED COPYRIGHT © 1947, 1955 BY JOHN WILF;Y & SONS, INC. All Rights Reserved This book or any part thereof must not be reproduced in any form without the written permission of the publisher. Library of Congress Catalog Card Number: 55-10001 PRINTED IN THE UNITED STATES OF AMERICA PREFACE TO SECOND EDITION In the years since the first edition of this book was published, several new developments have taken place. This second edition encompasses such new material as will afford acquaintance with advances in the art. Some old topics �which were inadequately presented have received fuller treatment. Several sections, especially those on electronic amplifiers and wave filters, have been deleted because more thorough treatments of these subjects are available in current literature. Thus the original obj ectives of a useful book on electronic transformers and related devices, with a minimum of unnecessary material, have been pursued in the second edition. Wherever the old material appeared adequate, it has been left unchanged, and the general arrangement is still the same, except for the addition of new Chapters 9 and 1 1 . More information in chart form, but few mathematical proofs, are included. In a book of general coverage, there is room only for a brief treatment of any phase of the subject. Thus the new chapter on magnetic amplifiers is a condensed outline of the more common components and circuits of this rapidly growing field. It is hoped that this chapter will be helpful as a general introduction to circuit and transformer designers alike. Recent circuit developments are reported in the AIEE Transactions. In response to inquiry it should be stated that, where a mathematical basis is given, graphical performance is always calculated. There has been good general correspondence between the graphs and experimental tests. This correspondence is quite close in all cases except pulse transformers ; for these, the graphs presented in this book predict wave shape with fair accuracy, but to predict exactly all the superposed ripples would be impracticable. This is pointed out in Chapter 10. Although technical words usually have the same meaning as in the first edition, there are several new magnetic terms in the second edition. These terms conform with ASTM Standard A127-48. Pascal said that an author should always use the word "our" rather than "my" in referring to his work, because there is in it usually more of other people ' s than his own. Never was this more true than of the present volume. Acknowledgment is due many vVestinghouse engineers, especially R. M. Baker, L. F . Deise, H. L. Jessup, J. W. Ogden, G. F . Pittman, R. A. Ramey, T. F . Saffold, and D . S . Stephens, all of whom v VI PREFACE TO SECOND EDITION assisted immeasurably by their constructive comments on the manuscript. D. G. Little ' s continued interest was most encouraging. Helpful comment has been received from men outside Westinghouse. Mr. P. Fenoglio of the General Electric Co. kindly pointed out an omission in the first edition. Output wave shapes given for the front or leading edge of a pulse transformer were accurate for a hard-tube modulator, but not for a line-type modulator. The missing information is included in the second edition. Finally, to my wife Margaret, my heartfelt thanks not only for her understanding of the long disruption of normal social life but also for her patience in checking proofs. REUBEN LEE Baltimore, Maryland August, 1955 ACKNOWLEDGMENTS Figures 23 and 24 were furnished through the courtesy of the Armco Steel Corp. Figures 50, 51, 52, 53, and 86 first appeared in a paper by O. H. Schade, Proc. I.R.E., July, 1943, p . 341 . Figure 150 is reprinted from Proc. I.R.E., April, 1945. Figure 63 first appeared in the I.R.E. Transactions on Component Parts, April, 1955. Figure 71 is reprinted from Electronics, March, 1955. Figures 89, 90, and 9 1 are reprinted from, and Section 52 (p. 123) is based on, "Solving a Rectifier Problem," Electronics, April, 1938. Figures 100 and 101 are reprinted from Electronics for September, 1949. Figure 180 and Section 97 (p. 232) are based on "A Study of R-F Chokes," which appeared in Electronics in April, 1934. Sections 123, 124, 125, and 127 (p. 294 et seq) are based on "Iron-Core Components in Pulse Amplifiers," Electronics, August, 1943. Figures 73, 258, and 259 are reprinted from this article. Figure 88 is reprinted from Tele-Tech and Electronic Industries, October, 1953 (copyright Caldwell-Clements, 480 Lexington Avenue, New York) . Figures 1 07 and 1 10, and part of Section 67 (p. 153), first appeared in Radio Engineering, June, 1937. Figure 142 is reprinted from the General Radio Experimenter, I\ ovember, 1936. Figures 163, 1 64, and 165 are reprinted from "Magnetic Ferrites­ Core Materials for High Frequencies," by C. L. Snyder, E. Albers­ Schoenberg, and H. A. Goldsmith, Electrical Manufacturing, December, 1949. Figure 191 is reprinted from Electrical Manufacturing for September, 1 954. The magnetic amplifier analysis on p. 276 is based on an unpublished paper by D . Lebell and B. Bussell, presented at the I.R.E. Convention, New York, March, 1952. Figures 235, 252, 254, and 255, Proc. I.R.E., August, 1 954. and Table XVII, are reprinted from Vll PREFACE TO FIRST EDITION The purpose of this book is twofold: first, to provide a reference book on the design of transformers for electronic apparatus and, second, to furnish electronic equipment engineers with an understanding of the effects of transformer characteristics on electronic circuits. Familiarity with basic circuit theory and transformer principles is assumed. Conventional transformer design is treated adequately in existing books, so only such phases of it as are pertinent to electronic transformers are included here. The same can be said of circuit theory ; only that which is necessary to an understanding of transformer operation is given. It is intended that in this way the book will be encumbered with a minimum of unnecessary material. Mathematical proofs as such are kept to a minimum, but the bases for quantitative results are indicated. The A.I.E.E. "American Standard Definitions of Electrical Terms" gives the meaning of technical words used. Circuit symbols conform to A.S.A. Standards Z32.5�1944 and Z32.1O�1944. Chapter headings, except for the first two, are related to general types of apparatus. This arrangement should make the book more useful. Design data are included which would make tedious reading if grouped together. For instance, the design of an inductor depends on whether it is for power or wave filter work, and the factors peculiar to each are best studied in connection with their respective apparatus. Parts of the book are based on material already published in the Proceedings of the Institute of Radio Engineers, Electronics, and Communications. Much of it leans heavily upon work done by fellow engineers of the Westinghouse Electric Corporation, the warmth of whose friendship I am privileged to enjoy. To list all their names would be a difficult and inadequate expression of gratitude, but I should be guilty of a gross omission if I did not mention the encouragement given me by Mr. D. G. Little, at whose suggestion this book was written. R. L. July 1947 IX