# AC Circuits

Chad Davis, University of Oklahoma

Copyright Year: 2017

Publisher: University of Oklahoma Libraries

Language: English

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## Reviews

The book seems to be mostly a collection of formulas that are illustrated via examples that make use of the circuit simulation software Multisim. Important equations and definitions are simply presented as facts to be accepted with little to no... read more

The book seems to be mostly a collection of formulas that are illustrated via examples that make use of the circuit simulation software Multisim. Important equations and definitions are simply presented as facts to be accepted with little to no accompanying foundational explanations. Almost every example is a “plug and chug” problem, implying that engineering is merely the act of finding the appropriate formula and then substituting values into it to obtain a numerical answer. Nowhere is the reader asked to manipulate variables to arrive at a symbolic expression or to gain insight. The level of analytical sophistication is extremely low. There are almost no proofs or derivations of any of the equations or definitions given in the book. This is a major shortcoming, since engineering students need to practice this skill, and the first place they should see it is in their textbooks. One example of this shortcoming is the discussion of phasors in Module 2. Many good examples are presented with regard to rectangular-to-polar form conversion (and vice versa), addition, subtraction, multiplication, division, and reduction of the phase angle to a value between -pi and +pi. However, the fundamental reason for using phasors and their theoretical foundation are not presented at all. The reader is simply told, without justification, that phasors represent sinusoidal functions. Thus, they remain a mystery. As another example, in Sec. 3.4 (AC Power Calculations), the concept of power factor is abruptly defined as the cosine of the impedance phase angle. There is no introductory discussion regarding its significance or how its use came about historically. Moreover, the significance of the power triangle and its use by power engineers is completely ignored. At the end of Sec. 3.4 there are finally a few sentences that explain that power companies try to bring the power factor value close to 1, but there is no explanation of why. A glaring example of the lack of rigor appears in Sec. 6.4 (Rectifiers). The formula relating ripple voltage to the filter capacitor value is presented completely without derivation. This misses a great opportunity to develop some intuition about how filter capacitors really work. There is no discussion of transient analysis; the focus is totally on sinusoidal steady-state analysis. There is no index.

The book is mostly accurate, but there are several items that are at least misleading or in some cases completely untrue. The large number of them is in itself problematic. There are several appearances of the statement (or some variation of it) “It is a good idea to think of a DC signal as one that can be obtained by freezing time in an AC signal and looking at the instantaneous voltage or current values at that specified time.” This is misleading and, in some cases, incorrect. It’s certainly not true in the case of an inductor or capacitor. On p. 10, the phrase “power spectrum density” appears; it should be “power spectral density.” Also, PSD is *not* a plot of “frequency versus time.” In Example 3.9 (starting on p. 48), the reader is erroneously asked to add a component to “eliminate the apparent power and produce a power factor of 1.” Adding a capacitor eliminates the reactive power, not the apparent power. Hopefully, this is merely a careless mistake and not a true misunderstanding of apparent power. On p. 52, the claim that “Power transmission and distribution systems is [sic] the most important application of RLC circuits” is dubious at best and probably demonstrably wrong. There is a partial correction in the first sentence of Module 4 (“filtering is a close second” – but it’s probably #1), but the statement completely ignores the widespread use of RLC circuits in wireless devices and its foundational use in the theory of transmission lines. On p. 53, there is an implication that active filters are made only with operational amplifiers. They can be made with discrete transistors as well. In Module 6, silicon diodes are often incorrectly referred to as “silicone.” The diode equation is not presented at all, and all diodes are assumed to operate under the constant voltage model. On a positive note, Sec. 6.3 provides a cursory description of protection diodes used with inductive loads. It’s not very comprehensive, but at least it is present; many textbooks do not include this important application.

The book covers material that will safely remain mostly unchanged but nevertheless vitally important for electrical and computer engineers to know for decades to come. That being said, the book has one major and one minor departure from commonly accepted standards. One of the most serious shortcomings of the book is its use of the sine convention ([for example, v(t) = 170 sin(w*t + theta)] for expressing sinusoidal voltages and currents instead of the cosine convention. The latter convention is the IEEE standard and is used by almost every other current textbook on circuit theory. This issue alone would probably keep me from using this book in one of my courses or recommending it to others. Another departure from standards is the form of the equations for inductive and capacitive reactance. The book uses the formulas L*w and -1/C*w (where “w” is the radian frequency) instead of the standard w*L and -1/w*C, respectively. This is a minor nit, but it is a possible source of confusion to readers new to the material who might be consulting other references that present these formulas in standard form.

The author often forgets that the reader is not intimately familiar with the material. Two cases in point are the references to sampling on p. 10 and the confusing caption for Fig. 1.10 on p. 14. In the caption, it is not immediately clear that phrase “top to bottom” refers to the labels on the right side of the oscilloscope screen image. Although an experienced reader should figure it out fairly quickly, I suspect that a new student would be completely confused. On p. 19 (and in many other places), the author acknowledges that the Multisim probe feature sometimes produces minor errors but does not explain why or, more importantly, whether this calls into question the appropriateness of using Multisim as the basis for examples. These kinds of unexplained errors can only sow confusion with readers new to the material. In the discussion of Fig. 3.3 (p. 35), the author refers to the “current clamp” feature of Multisim. Again, the current clamp is not fully explained.

The text is generally consistent, except for a few issues already discussed above.

The book is clearly divided into seven modules, and each module has clearly indicated subsections.

The numerous references to Multisim and its features presuppose familiarity with the author’s DC Circuits e-book or at least with Multisim. Although the author states this in the preface, it nevertheless limits the utility of the book for students who used a different textbook when studying DC circuits and/or who have not used or do not have access to Multisim. Equations are often not presented in standard format. For example, multiplication is indicated using the center dot symbol. The accepted current practice is simply to write variables and functions adjacent to each other to indicate multiplication. The center dot could be confused with the vector dot product. Many basic rules for preparing professional-quality figures and captions are not followed. For example, in Fig. 1.6 (p. 11), no units are given for the frequency axis, and the captions for Fig. 1.17 (p. 20) and Figs. 1.18 and 1.19 (p. 21) incorrectly use title capitalization. Units are missing in the final answers of many examples. I found the use of colored fonts to emphasize terms, step-by-step instructions, and other items to be fatiguing and a little condescending. It’s a cheap way to attempt to spice up tech-heavy text. However, I suppose some readers might find it helpful to locate important items.

The copious use of links to different parts of the book is generally helpful, but in some cases is excessive, especially for equations and figures that are on the same page as the reference (or on the next page). This is somewhat distracting because the links are indicated using colored font. Each page is pock-marked with links, which results in a busy appearance. I found the book fatiguing to read for this reason. There are many instances where figures and diagrams have text that is too small to read. It is necessary to zoom up to 200% in many cases. Examples of this are Fig. 1.2 (p. 6) and the screen shot accompanying Example 1.5 (p. 20). There are also many pages that have too many images, diagrams, boxed and/or colored text, and other items crammed into one place. Many items are so reduced in size that their features and text cannot be read without zooming. The crowding is often so severe that it becomes ridiculous. I can imagine a new reader being overwhelmed by this type of presentation. Examples of this issue include Fig. 1.14 (p. 18), all of p. 42, and all of p. 47. In the last case (p. 47), the columns of numbers that dominate the left half of the page are barely explained in the caption. I doubt most readers new to the material would be able to make sense of it. On p. 32, the link to the Appendix leads to Sec. 7.3 instead.

The book exhibits a large number of grammatical issues that reveal either little to no effort to proofread or perhaps that the author was simply unaware of them. Many readers might not notice them or be bothered by them, but with the increasing awareness of the need for engineers to communicate effectively, textbooks should serve as good examples. Some issues that appear in multiple places include: 1. Words inexplicably capitalized when they should not be. 2. Confusion regarding the use of the words “continuously” versus “continually.” 3. The phrase “solve the circuit” (or similar) appears in many places. “Circuits” are not solved; equations and/or problems are. 4. Quantities that are presented as digits instead of being spelled out (e.g., on p.5, “5” should be “five”). 5. Improper verb tenses.

There are no cultural references at all. This is actually a shortcoming. The addition of discussions of real-life applications greatly improves any textbook.

The appendix is poorly organized in that there are no headings for the Bode plot examples. There is also no introductory paragraph that explains the appendix’s structure. The book suffers from the lack of any real-world examples. Like too many other textbooks, many of the examples use unrealistically large or small component values.

The textbook is well written covering most of the topics on ac circuits discussed in standard textbooks. Numerical examples solved throughout the textbook were also verified using multisim/matlab software. This is a very important addition for the... read more

The textbook is well written covering most of the topics on ac circuits discussed in standard textbooks. Numerical examples solved throughout the textbook were also verified using multisim/matlab software. This is a very important addition for the students to hone their circuit analysis skills. Oscilloscope outputs and multimeter readings included in the textbook provides the practical understanding required in ac circuits laboratory experiments. The weblinks provided in all the chapters will serve as a useful resource for deeper understanding of the concepts. One issue I have with the book is that it does not cover three-phase circuits which is a very important topic for the students to understand in ac circuits. Also, multisim software is a must if one decides to adopt this textbook. Care has to be taken to update the weblinks if there are any changes in the future. Other than the above issues, I find the textbook to be a valuable resource for ac circuits class and laboratory. I am confident that students will improve their ac circuit theory skills by reading the textbook thoroughly, practicing all the examples in multsim and simultaneously referring the weblinks provided.

Based on my review the technical content presented in the book is accurate and free from errors.

The textbook covers all the standard topics expected for a class on ac circuits. Some of the topics included in standard textbooks have been left out but weblinks have been provided. Additon of a chapter on three-phase circuits will make the book more relevant. Based on how the textbook has been written it does not require much effort to add an additional chapter.

The content written by the author is very easy to understand. There are minor sentence formation mistakes and errors with regards to figure referencing.

The textbook is consistent with the terminology adopted for all the chapters.

The textbook is well organized and it is divided into several modules and submodules based on the topic. Addition of subtopics is fairly easy and it would not disturb the flow of the textbook

The book is well organized and the topics have been presented in a logical manner.

The book is free from interface issues and it is easy to navigate with the help of bookmarks provided.

There are minor grammatical mistakes and sentence formation errors but they are not a major cause for concern.

The book is not culturally insensitive or offensive in any way.

I am sure the weblinks provided throughout the textbook will definitely help the students to understand the concepts clearly. Providing links to online videos (ex. youtube) depicting the practical applications of ac circuits will be an added asset.

This book (or ebook, as it refers to itself) discusses all major topics related to AC circuits and what is typically covered in a second circuits course (e.g., OpAmps and filters). In particular, the book provides a comprehensive account of... read more

This book (or ebook, as it refers to itself) discusses all major topics related to AC circuits and what is typically covered in a second circuits course (e.g., OpAmps and filters). In particular, the book provides a comprehensive account of sinusoidal signals and RLC circuits. The treatment of transformers and some of the more advanced topics, as also mentioned in the book, is not very comprehensive and the book refers the readers to other online material (links are provided). The book does provide the basics needed for the understanding of the AC circuits and does it in a very lean way (which is in sharp contrast to many traditional textbooks). Simultaneously, this also means some application examples are left out. I understand this is by design as the book explicitly mentions it has elected to not go on “tangents” and rather provide internet links for noncentral topics. The text uses Multisim extensively as an educational tool. The book can also be used as a handbook for a quick refresher.

This is an engineering book so there is little that can be “biased.” The content is accurate and examples seem to be error free.

The book discusses the fundamental concepts of AC circuits in electrical engineering. Naturally, it is not expected that the content ever becomes obsolete. The book uses Multisim extensively as an educational aid and Multisim, as a software tool, naturally does not have the same longevity as physical concepts, but the usage is quite transferable to other software tools.

The text is clear and easy to follow. The author refers to the reader as “you,” which while a bit unconventional, in fact, helps with the flow of the text. The text is in general concise and to the point.

The book is consistent, even in the font color it uses to refer to inductors (blue) and capacitors (red).

The book is very modular. Naturally most chapters draw on the content of previous ones, but this is within reason. Some later chapters (e.g., OpAmp) can be independent of others.

The book is very well organized as also mentioned regarding the modularity of the book.

The book is provided as a PDF. I did not experience any issues. Both internal and external links in the book work fine. The book has a certain color scheme that is designed to distinguish different sections/types of material. While I personally might have chosen another color scheme (which is purely a cosmetic change), the helps with navigating the book.

No grammatical errors. The book refers to the reader in second-person, which while unusual for engineering texts, helps with the flow of the text.

The book is not culturally insensitive or offensive.

## Table of Contents

Preface

- Module 1 – AC Signal Overview
- Module 2 – AC Circuits Math Background
- Module 3 – RLC Circuit Analysis with AC Sources
- Module 4 – Passive Filters
- Module 5 – Transformers
- Module 6 – Diodes and AC to DC Conversion
- Module 7 –Operational Amplifiers (OpAmps)

References and Links

## About the Book

This eBook was written as the sequel to the eBook titled DC Circuits, which was written in 2016 by Chad Davis. This eBook covers Alternating Current (AC) circuit theory as well as a brief introduction of electronics. It is broken up into seven modules. Module 1 covers the basic theory of AC signals. Since only DC sources are used in the first eBook, details of AC signals such as sinusoidal waveforms (or sine waves), square waves, and triangle waves are provided. Module 2, titled AC Circuits Math Background, covers the mathematics background needed for solving AC circuit problems. The background material in Modules 1 and 2 are combined in Module 3 to solve circuits with AC sources that include resistors, inductors, and capacitors (RLC circuits).

## About the Contributors

### Author

**Chad Davis **received his PhD from the University of Oklahoma in 2007. Since 2008 he has been a full-time member of the ECE faculty at OU. He holds a dual discipline (electrical & mechanical) professional engineering license in the state of Oklahoma. Prior to joining the OU-ECE faculty he worked in industry at Uponor, McElroy Manufacturing, Lucent, and Celestica. His work experience ranges from electromechanical system design to automation of manufacturing and test processes. Dr. Davis is a licensed private pilot and performs research primarily in areas related to aviation. His current research at OU involves the design and development of a new GPS Ground Based Augmentation System utilizing feedback control and the design of instrumentation and data acquisition for navigational systems. Additionally, he serves as the ECE recruiting coordinator and one of the primary academic advisors for ECE students.