Introduction

Circuit analysis is often one of those weed-out classes in engineering schools. Either you pass the class to study engineering, or you don’t pass and start thinking about something else. Well, I don’t want you to get weeded out, because engineering is such a rewarding field. This book is here to help you make sense of circuit analysis concepts that may be puzzling you. Along the way, you explore a number of analytical tools that give you shortcuts and insight into circuit behavior.

You can take the tools you find here and apply them to whatever high-tech gizmo or craze is out there. And not only can you pass your class, but you can also take these concepts to the real world, enriching human lives with comfort and convenience and rewarding you with more time to do useful activities.

About This Book

Like all other For Dummies books, Circuit Analysis For Dummies isn’t a tutorial. Rather, it’s a reference book, which means you don’t have to read it from cover to cover, although you certainly can if that’s your preference. You can jump right to the topics or concepts you’re having trouble with. Either way, you’ll find helpful information along with some real-world examples of electrical concepts that may be hard to visualize otherwise.

Conventions Used in This Book

I use the following conventions throughout the text to make things consistent and easy to understand:

New terms appear in italics and are closely followed by an easy-to-understand definition. Variables likewise appear in italics.

Bold is used to highlight keywords in bulleted lists and the action parts of numbered steps. It also indicates vectors.

Lowercase variables indicate signals that change with time, and uppercase variables indicate signals that are constant. For example, v(t) and i(t) denote voltage and current signals that change with time. If, however V and I are capitalized, then those signals don’t vary in time.

What You’re Not to Read

Although it’d be great if you read every word, you’re welcome to skip the sidebars (the shaded boxes sprinkled throughout the book) and paragraphs flagged with a Technical Stuff icon.

Foolish Assumptions

I may be going out on a limb, but as I wrote this book, here’s what I assumed about you:

You’re currently taking an introductory circuit analysis course, and you need help with certain concepts and techniques. Or you’re planning to take a circuit analysis course in the next semester, and you want to be prepared with some supplementary material.

You have a good grasp of linear algebra and differential equations.

You’ve taken an introductory physics class, which exposed you to the concepts of power, positive and negative charges, voltage, and current.

How This Book Is Organized

Circuit analysis integrates a variety of topics from your math and physics courses, and it introduces a variety of techniques to solve for circuit behavior. To help you grasp the concepts in manageable bites, I’ve split the book into several parts, each consisting of chapters on related topics.

Part I: Getting Started with Circuit Analysis

This part gives you the engineering lingo, concepts, and techniques necessary for tackling circuit analysis. Here, I help you quickly grasp the main aspects of circuit analysis so you can analyze circuits, build things, and predict what’s going to happen. If you’re familiar with current, voltage, power, and Ohm’s and Kirchhoff’s laws, you can use this part as a refresher.

Part II: Applying Analytical Methods for Complex Circuits

This part looks at general analytical methods to use when dealing with more complicated circuits. When you have many simultaneous equations to solve or too many inputs, you can use various techniques to reduce the number of equations and simplify circuits to a manageable level.

Part III: Understanding Circuits with Transistors and Operational Amplifiers

This part deals with two devices that require power to make them work. You can use transistors as current amplifiers, and you can use operational amplifiers as voltage amplifiers.

Part IV: Applying Time-Varying Signals to First- and Second-Order Circuits

This part gets tougher because you’re dealing with changing signals and with circuits that have passive energy-storage devices such as inductors and capacitors. You also need to know differential equations in order to analyze circuit behavior for first- and second-order circuits.

Part V: Advanced Techniques and Applications in Circuit Analysis

This part takes the problems described in Part IV and changes a calculus-based problem into one requiring only algebra. You do this conversion by using phasor and Laplace techniques. You can gather additional insight into circuit behavior from the poles and zeros of an equation, which shape the frequency response of circuits called filters.

Part VI: The Part of Tens

Here you find out about ten applications and ten technologies that make circuits more interesting.

Icons Used in This Book

To make this book easier to read and simpler to use, I include some icons to help you find key information.

Anytime you see this icon, you know the information that follows will be worth recalling after you close this book — even if you don’t remember anything else you just read.

This icon appears next to information that’s interesting but not essential. Don’t be afraid to skip these paragraphs.

This bull’s-eye points out advice that can save you time when analyzing circuits.

This icon is here to prevent you from making fatal mistakes in your analysis.

Where to Go from Here

This book isn’t a novel — you can start at the beginning and read it through to the end, or you can jump right in the middle. If you like the calculus approach to solving circuits, head to the chapters on first- and second-order circuits. If calculus doesn’t suit your fancy or if you’re itching to find out what the Laplace transform is all about, flip straight to Chapter 16.

If you’re not sure where to start, or you don’t know enough about circuit analysis to even have a starting point in mind yet, no problem — that’s exactly what this book is for. Just hop right in and get your feet wet. I recommend starting with the chapters in Part I and moving forward from there.