Contents

Cover

Title Page

Copyright

Dedication

Preface

Acknowledgments

About the Author

About the Reviewers

Note to Instructors

ONE SEMESTER COURSE

ONE-QUARTER COURSE

1: How to Design Resistive Circuits

1.1 DESIGN OF A RESISTIVE THEVENIN SOURCE

1.2 DESIGN OF A COUPLING CIRCUIT

1.3 DESIGN OF A PI ATTENUATOR

PROBLEMS

REFERENCES

2: How to Prevent a Power Transistor From Overheating

2.1 ELECTRICAL MODEL FOR HEAT TRANSFER

2.2 USING MANUFACTURER’S DATA FOR THERMAL ANALYSIS

2.3 FORCED-AIR COOLING

2.4 DYNAMIC RESPONSE OF A THERMAL SYSTEM

PROBLEMS

REFERENCE

3: How to Analyze a Circuit

3.1 FREQUENCY RESPONSE OF A TRANSFER FUNCTION

3.2 FREQUENCY RESPONSE AND IMPEDANCE OF SIMPLE CIRCUITS

3.3 FREQUENCY RESPONSE FOR LADDER NETWORKS

3.4 GENERALIZED TECHNIQUE FOR DETERMINING FREQUENCY RESPONSE

PROBLEMS

REFERENCES

4: How to Use Statistics to Ensure a Manufacturable Design

4.1 INDEPENDENT COMPONENT FAILURES

4.2 USING THE GAUSSIAN DISTRIBUTION

4.3 SETTING A MANUFACTURING TEST LIMIT

4.4 PROCURING A CUSTOM COMPONENT

PROBLEMS

REFERENCES

5: How to Design a Feedback Control System

5.1 INTUITIVE DESCRIPTION OF A CONTROL SYSTEM

5.2 REVIEW OF CONTROL SYSTEM OPERATION

5.3 PERFORMANCE OF CONTROL SYSTEMS

5.4 FIRST-ORDER CONTROL SYSTEM DESIGN

5.5 SECOND-ORDER CONTROL SYSTEM DESIGN

5.6 CIRCUIT REALIZATION OF A SECOND-ORDER CONTROL SYSTEM

5.7 FIRST-ORDER DISCRETE CONTROL SYSTEM

PROBLEMS

REFERENCES

6: How to Work with OP-AMP Circuits

6.1 THE IDEAL OP-AMP

6.2 PRACTICAL OP-AMPS

PROBLEMS

REFERENCES

7: How to Design Analog Filters

7.1 PASSIVE VERSUS ACTIVE FILTERS

7.2 THE LOWPASS RC FILTER

7.3 FILTER RESPONSE CHARACTERISTICS

7.4 SPECIFICATION OF FILTER TYPE

7.5 GENERALIZED FILTER DESIGN PROCEDURE

7.6 DESIGN OF ACTIVE LOWPASS FILTERS

7.7 DESIGN OF PASSIVE RF FILTERS

PROBLEMS

REFERENCES

8: How to Design Digital Filters

8.1 REVIEW OF SAMPLING

8.2 USING THE Z-TRANSFORM TO DETERMINE THE TRANSFER FUNCTION AND FREQUENCY RESPONSE OF DIGITAL FILTERS

8.3 FIR AND IIR DIGITAL FILTERS

8.4 DESIGN OF SIMPLE AND PRACTICAL DIGITAL FILTERS

PROBLEMS

REFERENCES

9: How to Work with RF Signals

9.1 ENERGY TRANSFER

9.2 SIGNAL REFLECTIONS

9.3 EFFECT OF SIGNAL REFLECTIONS ON DIGITAL SIGNALS

9.4 EFFECT OF SIGNAL REFLECTIONS ON NARROWBAND SIGNALS

9.5 THE SMITH CHART

9.6 USING THE SMITH CHART TO DISPLAY IMPEDANCE VERSUS FREQUENCY

9.7 FINAL COMMENTS REGARDING THE SMITH CHART

PROBLEMS

REFERENCES

10: Getting a Job—Keeping a Job—Enjoying Your Work

10.1 GETTING A JOB

10.2 KEEPING A JOB

10.3 ENJOYING YOUR WORK

Afterword

Answers to Problems

Index

Copyright © 2014 by John Wiley & Sons, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.
Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permission.

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Library of Congress Cataloging-in-Publication Data:

Dorr, Barry L., 1958-
   Ten essential skills for electrical engineers / Barry L. Dorr.
      pages cm
   Includes bibliographical references and index.
   ISBN 978-1-118-52742-9 (pbk.)
   1. Electrical engineering–Problems, exercises, etc. 2. Electrical engineering–Vocational
guidance. I. Title.
   TK169.D67 2014
   621.38–dc23

2013026573

This book is dedicated to my father, Roger Dorr, who shared with me his
love of all things mechanical, electrical, and musical.

It is dedicated to my wife, Judy, who brings joy to me and all whom
she touches.

PREFACE

This book and the companion website* will do two things for you: First, it will help you excel in your technical interviews so you can secure a great first job. Second, it will help you succeed in that job by showing you how to solve real-world problems using what you already know from your engineering courses.

There is often a disconnect between what you learned in school and the expectations of those interviewing you. On one hand, the engineering curriculum has taught you a tremendous amount of theoretical and practical material, but it is simply not possible to remember it all in an interview. On the other hand, the interviewing team will likely consist of your potential supervisor and coworkers, and they will be looking for someone with the skills to be an immediate contributor in their department. The interview will typically focus on what you can do instead of how much you know. This book bridges the gap by reviewing how to apply what you learned in school to practical engineering tasks.

Each chapter reviews design skills by relating them to fundamental concepts. Consider the skill of designing an averaging FIR digital filter. This is a valuable skill, but the best designers understand the basics of digital filters—they understand the practical use of z-transforms and how to work with any discrete-time structure. As a result, they can work with a wide variety of digital filters thereby enabling them to design the best filter for a given requirement. This text reviews digital filter design and many more commonly required design skills covering a wide variety of areas and relates them to the fundamentals. Chapters begin with the fundamentals and then present the skills.

As a workplace reference, this book will give you information you need to succeed at basic design tasks. For more in-depth problems, it will help direct you to manufacturer’s literature or the appropriate sections of your college textbooks. I hope it will merit valuable space on your bookshelf for many years.

Whether you are a recent graduate or an experienced engineer, your time is valuable. This book was written to help you—not challenge you. To this end, the mathematical derivations are kept simple, but not simplistic, and the examples presented show practical applications using practical skills that will help you in job interviews and during your first several years in the workplace. Each chapter in this book can be read in a matter of hours—not days.

Finally, I hope that you enjoy working through the examples and problems in this book, and I hope they motivate you to tackle and solve hundreds or thousands of problems over what should be a satisfying and rewarding career.

BARRY L. DORR, PE

Carlsbad, CA

May 2013

* www.blog.dorrengineering.com

ACKNOWLEDGMENTS

Shortly after obtaining my BSEE and moving to San Diego, I attended several signal processing lectures by Professor fred harris (capitalization omitted at his insistence) at San Diego State University. Professor harris had an uncanny ability to explain difficult signal processing techniques using basic concepts and simple drawings. Wanting to learn more, I pursued an MSEE at San Diego State and was fortunate to have him as part of my thesis committee. Professor harris has been teaching and inspiring students and working engineers in San Diego for over 45 years. I’m sure I speak for all my colleagues in San Diego when I thank him.

I was fortunate to have David Hull as a mentor at my first job. David guided me through many of my first design tasks with skill and patience. I would frequently take his lab books home to study at night and return in the morning with a list of questions which he would cheerfully answer despite his busy schedule.

I would also like to thank James Crawford who has been a mentor, a source of technical inspiration, and a valued friend for many years.

I would like to thank all of my current colleagues, especially my good friends Jeff Babb, John Huebner, Steven Chuwang, Leon Huynh, and Kim Do, who all provided excellent feedback and personal encouragement throughout the project. Working with this great group always left me with plenty of energy and enthusiasm to write late into the night. I would like to thank John Wiley and Sons for sharing my vision for this book and Ms Kari Capone for working as my liaison with Wiley. I would also like to thank Professor Dennis Derickson at Cal Poly San Luis Obispo for providing valuable feedback at the beginning of the project.

Good reviewers find mistakes and make suggestions. Excellent reviewers take great effort to understand the author’s purpose and vision, and then help the author succeed with that vision. I was fortunate to have the help of three of the best.

Any interaction with my nephew, Joshua Dorr, is always a pleasure, so I was thrilled to have him as a reviewer. He provided excellent feedback on accuracy of concepts, mathematical derivations, and correct use of the English language. I’ll always appreciate that Josh agreed to undertake this project during the completion of his PhD thesis.

Bruno Paillard is living proof that there are wonderful and special people at the other end of the Internet—he lives over 3000 miles away, and we have met in person only once. But our common interest in things technical has turned into a special friendship over the years. Bruno is a practical, hands-on engineer with a comprehensive theoretical background. In addition to his technical review, his insightful comments on what was and was not relevant to engineers were invaluable in determining the scope of the book.

Jon Bernardi’s background is chemical engineering, but after reading several of his excellent magazine articles, I asked him to be a reviewer. Jon’s teaching and travel schedule keep him extremely busy, so he reviewed the chapters and wrote his feedback mostly from airline seats and hotel rooms. He exemplifies the saying “If you want something done, give it to a busy person.” Jon masterfully removed the tension from many poorly worded sentences and also provided expert guidance on consistency throughout the project.

The reviewers are special people and special friends. Their fingerprints are all over the pages of this book.

B. L. D.

ABOUT THE AUTHOR

Barry L. Dorr, PE has designed signal processing algorithms and circuitry in San Diego for nearly 30 years. He holds a BSEE from California Polytechnic State University in San Luis Obispo and an MSEE from San Diego State University.

Mr Dorr’s interest in electronics began when, as a high-school freshman, he purchased a worn-out 1949 Ford pickup truck from a Southern California orange grower. As the boy disassembled and rebuilt the truck, his father, an engineer, saw an opportunity to improve his son’s less-than-satisfactory math grades by artfully explaining how each system worked, how it could be described mathematically, and how it might be improved. The old truck became a rolling laboratory for numerous high-school and college projects involving electronics, heat transfer, engine control, and troubleshooting. Working on the truck left him with a lifelong fascination with all things electrical, mechanical, and mathematical.

Mr. Dorr has worked at several small and large electronic firms in San Diego and owned and operated a small consulting firm for 11 years. He currently designs DSP and RF systems for Datron World Communications. He holds eight patents for various communication and signal processing techniques. Outside of work, he enjoys bicycling, working on cars and motorcycles, and playing trombone as a freelance studio musician.

ABOUT THE REVIEWERS

Jon Bernardi

Jon Bernardi (BS Chem Eng., University of Illinois; MBA, Bellarmine University) spent 36 years with the BFGoodrich/Lubrizol organization in a variety of roles: process engineering, project engineering, quality systems, information systems, process improvement, Six Sigma black belt improvement projects, and safety systems. This was an even split between manufacturing level and corporate responsibilities. He would be given a job and told “Work your way out of this, and we will find something else for you to do.” It really worked out that way and he enjoyed a great ride. In his last corporate role he served as the Lubrizol process safety manager. He had the opportunity to work with and travel to the various company sites around the world. In conjunction with his regular job duties, he was also the in-house trainer for Cause Mapping® (ThinkReliability), a root cause analysis methodology. Now, semi-retired, he works as an instructor for ThinkReliability, teaching a wide range of companies root cause analysis for incident/accident investigation. When not in the air, he is on the road playing with his old car, seeking out new architectural sites or just relaxing with a good book.

Joshua Dorr

Joshua Dorr is a PhD candidate in physics at Harvard University. Though a physicist by trade, his interest in circuits has grown from the deep connection between electronics and measuring fundamental properties of the real world. He is currently working on measuring single cyclotron excitations of a single trapped positron at 100 mK—a project that has led him to use many of the techniques covered throughout this book. When he’s not designing and building scientific apparatus, he enjoys hiking, climbing, bird watching, or any other activity that combines learning, adventure, and the outdoors.

Bruno Paillard

Bruno Paillard initially trained as a technician at IUT-Le Creusot (France), then as an engineer at INSA Lyon (France), he then went on to complete his PhD in digital signal processing from Université de Sherbrooke (Canada). His dissertation focused on the fields of auditory modeling and perceptual coding of music. From 1993 to 2003 he was a professor of electrical and computer engineering at Université de Sherbrooke, where he taught classes in embedded systems and did advanced research on adaptive filtering and active control of acoustical and vibrational processes. His research work led to several groundbreaking applications and technology transfers, including the world’s first multi-channel active noise cancellation system in an industrial exhaust stack. In 1998, while still working at Université de Sherbrooke, he began consulting for D-BOX Technologies (Canada), who were developing the world’s first motion simulation system for home theater applications. He was Director of Research and Development for D-BOX from 2004 to 2008 and while there developed their unique vibro-kinetic technologies. In particular, he was responsible for the hardware and software designs of the DSP systems, including breakthrough designs for the proprietary electro-mechanical motion actuators and computer-based motion controllers. His work at D-BOX contributed greatly to them being awarded over half a dozen patents for motion simulation systems and technologies. In 2008, he co-founded Convergence Instruments where he is senior designer and is responsible for all the leading-edge product designs.

NOTE TO INSTRUCTORS

Recent graduates have always been valued for their enthusiasm and creativity, and in better economic times were often seen as the future of the company. As a result, they were given some time to acclimate to their new job before being expected to do critical engineering tasks. But the combination of today’s result-oriented workplace and the fact that most recent graduates will switch jobs after a few years results in companies expecting new graduates to enter the workplace with demonstrable design skills.

This presents a dilemma for academia. It must give the students the breadth, depth, and critical thinking skills they need to be engineers, but in order to get hired after graduation they will often have to compete with the practical design skills of experienced engineers. Most engineering curriculums include practical design skills, but in nearly 30 years of interviewing students, the author has found that they frequently can’t demonstrate those skills in an interview.

This book addresses this dilemma. It consists of nine chapters of purely technical review followed by a chapter on interviewing strategies and thriving in the workplace. When the students read the chapters and work the problems they will get an infusion of practical skills and a strong reminder that the fundamentals of the EE curriculum can be used to solve nearly any problem they’ll encounter in the workplace. The text was written to be easily readable and the problems are straightforward, so the material will help the students rather than challenge them.

This book can be integrated into the EE curriculum starting in the sophomore year. As the students approach the end of individual courses, the relevant chapters can be assigned and they’ll find the material quite easy. As they progress through the curriculum, they will complete the entire book. As graduation approaches they will recall that these chapters provide a practical review and revisit them as they prepare for their technical interviews. As they prepare for interviews they are encouraged to visit the companion website www.blog.dorrengineering.com where they will find a large collection of interview practice problems and additional practical skills.

The book can also be used as a supplement to a one-quarter or semester senior seminar course. The material is not overly difficult, so the instructor can use class time to focus on other aspects of the course and have the students review this material as self or group study. The schedule outlined below will require about 4–6 hours per week of the student’s time.

ONE SEMESTER COURSE

Week 1: How to Design Resistive Circuits

Week 2: How to Prevent a Power Transistor from Overheating

Week 3: How to Analyze a Circuit

Week 4: How to Use Statistics to Insure a Manufacturable Design

Weeks 5, 6: How to Design a Feedback Control System

Week 7: How to Work with Op-Amp Circuits

Weeks 8, 9: How to Design Analog Filters

Weeks 10–12: How to Design Digital Filters

Weeks 13, 14: How to Work with RF Signals

Week 15: Getting a Job—Keeping a Job—Enjoying Your Work

ONE-QUARTER COURSE

Week 1: How to Design Resistive Circuits

Week 2: How to Prevent a Power Transistor from Overheating

Week 3: How to Analyze a Circuit

Week 4: How to Use Statistics to Insure a Manufacturable Design

Week 5: How to Work with Op-Amp Circuits

Weeks 6–9: Let the students choose between remaining chapters based on individual interest

Week 10: Getting a Job—Keeping a Job—Enjoying Your Work

Students will need MATLAB® for many of the examples in this book. If it is not available through the university they can contact MathWorks to obtain a student edition or a trial edition.

If you or your students have comments or questions about the book or if you find errors please send e-mail to

Finally, graduation time can be a stressful time for students. In addition to completing their course requirements, they are facing many other changes in their lives. It would have been impossible to write this book without sharing my own enjoyment of being an electrical engineer. Working through these examples and problems will remind graduating seniors that they have a fascinating, exciting, and enjoyable career awaiting them.

1

HOW TO DESIGN RESISTIVE CIRCUITS

Chances are good that every schematic diagram you’ve seen contained at least a few resistors. This component is an electrical workhorse, commonly used for establishing bias voltages, programming gain, summing signals, attenuating signals, and numerous other functions. Ideal resistors dutifully follow Ohm’s law, which has no frequency dependence, so it is easy to believe that designing with resistors is a simple task. This is probably the most common reason candidates are caught off guard and fail when asked to design simple resistive networks in interviews. This chapter will show you how to design and analyze practical resistive networks that solve problems you’ll encounter in interviews and in the workplace.

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!