Electrical Engineering 101 Pdf Free Download

Cover image

Front Matter

Copyright

Preface

About the Author

Chapter 0. What Is Electricity Really?

Chapter 1. Three Things They Should Have Taught in Engineering 101

Chapter 2. Basic Theory

Chapter 3. Pieces Parts

Chapter 4. The Real World

Chapter 5. Tools

Chapter 6. Troubleshooting

Chapter 7. Touchy-Feely Stuff

Glossary

Index

Front Matter

Electrical Engineering 101

Third Edition

Electrical Engineering 101

Everything You Should Have Learned in School… but Probably Didn't

Third Edition

Darren Ashby

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Copyright

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Library of Congress Cataloging-in-Publication Data

Ashby, Darren.

Electrical engineering 101 : everything you should have learned in school – but probably didn't / Darren Ashby. – 3rd ed.

p. cm.

ISBN 978-0-12-386001-9 (pbk.)

1. Electrical engineering. I. Title. II. Title: Electrical engineering one hundred one. III. Title: Electrical engineering one hundred and one.

TK146.A75 2011

621.3–dc23 2011020171

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

For information on all Newnes publications visit our website at www.elsevierdirect.com

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Printed in the United States of America

Preface

The First Word

In my day job I have been lucky enough to work with one of the greatest corporate success stories in the technical field ever. For a sparky tech nut just going to the Google™ campus was a bit like traipsing to mecca. I remember my first tour there, and getting a free lunch. Our corporate contact made a comment. He said, They've created some kind of engineers' paradise over here. I kind of wondered about that comment. Over the last couple of years I have pondered it quite a bit. I learned a lot more about what this paradise was in subsequent dealings with the king of search. They had the free food and all these other perks but the thing that stood out most to me from the first time I heard it was 20% time. A quick Google search will tell you the details of 20% time. The principle is simple: You are given 20% of your time to work on a pet project. The project is your choice. The only caveat is that if you come up with something cool Google gets to use it to make more money. In talking to contacts there I found out that time is sacrosanct; your management cannot demand you give up that time for your main goals. You can volunteer it if you want to but it is up to you. In general planning, however, you and your boss plan four days a week on your main assigned tasks and one day every week is yours.

Build Intrepreneurs

I learned a new term recently that I think is very relevant in corporate growth and success, intrepreneur. The intrepreneur is the baby brother to the entrepreneur. This is the guy who has that big idea and wants to change the world; he has the mentality to do so but doesn't have the resources. Resources, in fact, is the only way in which they differ. The entrepreneur finds a way to resource his idea, but whether due to motivation or circumstance, the intrepreneur can't quite get over that issue. Often times these are the shooting stars in your organization. The trick is to enable these guys to make things happen. Give them the resources and turn them loose. The 20% time mentioned above is a great way of finding these individuals. The successful intrepreneur will gather others and use their 20% time to make something cool. What engineer do you know that wouldn't consider that paradise?

Engineers = Success

Why are engineers so important to America's success? Here is an interesting fact or two: Google hires 50% engineers and 50% everyone else. Twice as many start-up businesses are from new MIT grads than from Harvard Business School graduates (and the schools are practically right next to each other). I haven't met an engineer who doesn't like to make cool things; it is in their mindset; it is in their nature; great engineers usually make pretty good money relative to the average Joe in America, simply because their skill set is so valued. Thing is, they aren't always the top-paid people, even though their contributions are often much more critical to success than that of all the management above them. I think this is because they get so much satisfaction out of making stuff that, as long as they feel like they are making ends meet, things are good. This type of person is a huge asset to the American economy. Greed doesn't drive them, invention does, and invention leads to an improved economy more than anything else. Invention of new technology improves the standard of living for everyone. It is the only thing that does.

Google went from nothing to the top in 11 years; they themselves credit this to hiring great engineers and cutting them loose to change the world. We need more of this. We humans have a built-in engineering gene; we love to build and make stuff. Every kid plays with blocks, creates things, and imagines things. So why aren't there more engineers? Is it really that hard to become one? Should it be? I hope that somebody out there reads this book and thinks, Screw all those guys who think I'm not smart enough—I'm gonna change the world anyway!

Overview

For Engineers

Granted, there are many good teachers out there and you might have gotten the basics, but time and too many status reports have dulled the finish on your basic knowledge set. If you are like me, you have found a few really good books that you often pull off the shelf in times of need. They usually have a well-written, easy-to-understand explanation of the particular topic you need to apply. I hope this will be one of those books for you.

You might also be a fish out of water, an ME thrown into the world of electrical engineering, who would really like a basic understanding to work with the EEs around you. If you get a really good understanding of these principles, I guarantee you will surprise at least some of the sparkies (as I like to call them) with your intuitive insights into the problems at hand.

For Students

I don't mean to knock the collegiate educational system, but it seems to me that too often we can pass a class in school with the assimilate and regurgitate method. You know what I mean: Go to class, soak up all the things the teacher wants you to know, take the test, say the right things at the right time, and leave the class without an ounce of applicable knowledge. I think many students are forced into this mode when teachers do not take the time to lay the groundwork for the subject they are covering. Students are so hard-pressed to simply keep up that they do not feel the light bulb go on over their heads or say, A-ha, now I get it! The reality is, if you leave the class with a fundamental understanding of the topic and you know that topic by heart, you will be eminently more successful at applying that basic knowledge than anything from the end of the syllabus for that class.

For Managers

The job of the engineering manager¹ really should have more to it than is depicted by the pointy-haired boss you see in Dilbert cartoons. One thing many managers do not know about engineers is that they welcome truly insightful takes on whatever they might be working on. Please notice I said truly insightful; you can't just spout off some acronym you heard in the lunchroom and expect engineers to pay attention. However, if you understand these basics, I am sure there will be times when you will be able to point your engineers in the right direction. You will be happy to keep the project moving forward, and they will gain a new respect for their boss. (They might even put away their pointy-haired doll!)

¹Suggested alternate title for this book from reader Travis Hayes: EE for Dummies and Those They Manage. I liked it, but I figured the pointy-haired types wouldn't get it.

For Teachers

Please don't get me wrong, I don't mean to say that all teachers are bad; in fact, most of my teachers (barring one or two) were really good instructors. However, sometimes I think the system is flawed. Given pressures from the dean to cover X, Y, and Z topics, sometimes the more fundamental X and Y are sacrificed just to get to topic Z.

I did get a chance to teach a semester at my own alma mater. Some of these chapters are directly from that class. My hope for teachers is to give you another tool that you can use to flip the switch on the a-ha light bulbs over your students' heads.

For Everyone

At the end of each topic discussed in this book are bullet points I like to call Thumb Rules. They are what they seem: those rule-of-thumb concepts that really good engineers seem to just know. These concepts are what always led them to the right conclusions and solutions to problems. If you get bored with a section, make sure to hit the Thumb Rules anyway. There you will get the distilled core concepts that you really should know.

About the Author

Darren Coy Ashby is a self-described techno geek with pointy hair. He considers himself a jack-of-all-trades, master of none. He figures his common sense came from his dad and his book sense from his mother. Raised on a farm and graduated from Utah State University seemingly ages ago, Darren has more than 20 years of experience in the real world as a technician, an engineer, and a manager. He has worked in diverse areas of compliance, production, testing, and his personal favorite, research and development.

Darren jumped at a chance some years back to teach a couple of semesters at his alma mater. For about two years, he wrote regularly for the online magazine Chipcenter.com. He is currently the director of electronics R&D at a billion-dollar consumer products company. His passions are boats, snowmobiles, motorcycles, and pretty much anything with a motor. When not at his day job, he spends most of his time with his family and a promising R&D consulting/manufacturing firm he started a couple of years ago.

Darren lives with his beautiful wife, four strapping boys, and cute little daughter next to the mountains in Richmond, Utah. He believes pyromania goes hand in hand with becoming a great engineer and has dedicated a Facebook™ page to that topic. You can email him with comments, complaints, and general ruminations at dashby@raddd.com; if all you want are tidbits of wisdom you can follow him on Twitter™ under sparkyguru.

Chapter 0. What Is Electricity Really?

This introductory chapter is a basic explanation of what electricity actually is, before moving on to the fundamental concepts of electrical engineering. It begins by describing the parts of the atom—the proton has a positive charge, the electron is negative, and the neutron has no charge. It explains that electricity is fundamentally charges, both positive and negative and that like charges repel and opposite charges attract. This is followed by a discussion of conductors and insulators. An analogy of an electron pump (a crank used to generate enough electricity to power a light bulb) is used to illustrate the following concepts: an accumulation of charges is called voltage, movement of charges is current or amperage, and energy is work; in a circuit the electromagnetic effects move energy from one point to another. The chapter concludes by drilling that knowing the basics leads to greater understanding of more advanced topics.

Key Words

Electron; Proton; Atom; Charge; Energy; Insulator; Conductor; Current; Amperage; Voltage

Chicken vs. Egg

Which came first, the chicken or the egg? I was faced with just such a quandary when I set down to create the original edition of this book. The way that I found people got the most out of the topics was to get some basic ideas and concepts down first; however, those ideas were built on a presumption of a certain amount of knowledge. On the other hand, I realized that the knowledge that was to be presented would make more sense if you first understood these concepts—thus my chicken-versus-egg dilemma.

Suffice it to say that I jumped ahead to explaining the chicken (the chicken being all about using electricity to our benefit). I was essentially assuming that the reader knew what an egg was (the egg being a grasp on what electricity is). Truth be told, it was a bit of a cheat on my part, ¹ and on top of that I never expected the book to be such a runaway success. Turns out there are lots of people out there who want to know more about the magic of this ever-growing electronic world around us. So, for this new and improved edition of the book, I will digress and do my best to explain the egg. Skip ahead if you have an idea of what it's all about, ² or maybe stick around to see if this is an enlightening look at what electricity really is.

¹Do we all make compromises in the face of impossible deadlines? Are the deadlines only impossible because of our own procrastination? Those are both very heavy-duty questions, not unlike that of the chicken-versus-egg debate.☺

²Thus, the whole Chapter 0 idea; you can argue that 0 or 1 is the right number to start counting with, so pick whichever chapter you want to begin with of these two and have at it.

So What Is Electricity?

The electron—what is it? Well, we haven't ever seen one, but we have found ways to measure a bunch of them. Meters, oscilloscopes, and all sorts of detectors tell us how electrons move and what they do. We have also found ways to make them turn motors, light up light bulbs, power cell phones, computers, and thousands of other really cool things. The impact on our society is immeasurable, it goes to the very core, we even use the symbol of a light bulb turning on as an analogy to having a great idea. Not bad for something that only became part of the world at large a little over 100 years ago. Ironically it is this very light bulb I hope to metaphorically turn on for the readers of this book.

What is electricity though? Actually, that is a very good question. If you dig deep enough you can find RSPs³ all over the world who debate this very topic. I have no desire to that join that debate (having not attained RSP status yet). So I will tell you the way I see it and think about it so that it makes sense in my head. Since I am just a hick from a small town, I hope that my explanation will make it easier for you to understand as well.

³RSP = Really Smart Person. As you will soon learn, I do hope to get an acronym or two into everyday vernacular for the common engineer. BTW, I believe that many engineers are RSPs; it seems to be a common trait among people of that profession.

The Atom

We need to begin by learning about a very small particle that is referred to as an atom. A simple representation of one is shown in Figure 0.1.

Atoms⁴ are made up of three types of particles: protons, neutrons, and electrons. Only two of these particles have a feature that we call charge. The proton carries a positive charge and the electron carries a negative charge, whereas the neutron carries no charge at all. The individual protons and neutrons are much more massive than the wee little electron. Although they aren't the same size, the proton and the electron do carry equal amounts of opposite charge.

⁴The atom is really, really small. We can sort of see an atom these days with some pretty cool instruments, but it is kind of like the way a blind person sees Braille by feeling it.

Now, don't let the simple circles of my diagram lead you to believe that this is the path that electrons move in. They actually scoot around in a more energetic 3D motion that physicists refer to as a shell. There are many types and shapes of shells, but the specifics are beyond the scope of this text. You do need to understand that when you dump enough energy into an atom, you can get an electron to pop off and move fancy free. When this happens the rest of the atom has a net positive charge⁵ and the electron a net negative charge. ⁶ Actually, they have these charges when they are part of the atom. They simply cancel each other out so that when you look at the atom as a whole the net charge is zero.

⁵An atom with a net charge is also known as an ion.

⁶Often referred to as a free electron.

Now, atoms don't like having electrons missing from their shells, so as soon as another one comes along it will slip into the open slot in that atom's shell. The amount of energy or work it takes to pop one of these electrons loose depends on the type of atom we are dealing with. When the atom is a good insulator, such as rubber, these electrons are stuck hard in their shells. They aren't moving for anything. Take a look at the sketch in Figure 0.2.

In an insulator, these electron charges are stuck in place, orbiting the nucleus of the atom—similar to water frozen in a pipe. ⁷ Do take note that there are just as many positive charges as there are negative charges.

⁷I like the frozen water analogy; just don't take it too far and think you just need to melt them to get them to move!

With a good conductor though, such as copper, the electrons in the outer shells of the atoms will pop off at the slightest touch; in metal elements these electrons bounce around from atom to atom so easily that we refer to them as an electron sea, or you might hear them referred to as free electrons. More visuals of this idea are shown in Figure 0.3.

You should note that there are still just as many positive charges as there are negative charges. The difference now is not the number of charges; it is the fact that they can move easily. This time they are like water in the pipe that isn't frozen but liquid—albeit a pipe that is already full of water, so to speak. Getting the electrons to move just requires a little push and away they go. ⁸ One effect of all these loose electrons is the silvery-shiny appearance that metals have. No wonder the element that we call silver is one of the best conductors there is.

⁸Analogies are a great way to understand something, but you have to take care not to take them too far. In this case, take note that you can't simply tip your wire up and get the electrons to fall out, so it isn't exactly like water in a pipe.

One more thing: A very fundamental property of charge is that like charges repel and opposite charges attract. ⁹ If you bring a free electron next to another free electron, it will tend to push the other electron away from it. Getting the positively charged atoms to move is much more difficult; they are stuck in place in virtually all solid materials, but the same thing applies to positive charges as well. ¹⁰

⁹It strikes me that this is somewhat fundamental to human relationships. Good girls are often attracted to bad boys, and many other analogies that come to mind.

¹⁰There are definitely cases where you can move positive charges around. (In fact, it often happens when you feel a shock.) It's just that most of the types of materials, circuits, and so on that we deal with in electronics are about moving the tiny, super-small, commonly easy-to-move electron. For that other cool stuff, I suggest you find a good book on electromagnetic physics.

Thumb Rules

■ Electricity is fundamentally charges, both positive and negative.

■ Energy is work.

■ There are just as many positive as negative charges in both a conductor and an insulator.

■ In a good conductor, the electrons move easily, like liquid water.

■ In a good insulator, the electrons are stuck in place, like frozen water (but not exactly; they don't melt).

■ Like charges repel and opposite charges attract.

Now What?

So now we have an idea of what insulators and conductors are and how they relate to electrons and atoms. What is this information good for, and why do we care? Let's focus on these charges and see what happens when we get them to move around.

First, let's get these charges to move to a place and stay there. To do this we'll take advantage of the cool effect that these charges have on each other, which we discussed earlier. Remember, opposite charges attract, whereas the same charges repel. There is a cool, mysterious, magical field around these charges. We call it the electrostatic field. This is the very same field that creates everything from static cling to lightning bolts. Have you ever rubbed a balloon on your head and stuck it on the wall? If so, you have seen a demonstration of an electrostatic field. If you took that a little further and waved the balloon closely over the hair on your arm, you might notice how the hairs would track the movement of the balloon. The action of rubbing the balloon caused your head to end up with a net total charge on it and the opposite charge on the balloon. The act of rubbing these materials together¹¹ caused some electrons to move from one surface to the other, charging both your head and the balloon.

¹¹Fun side note: Google this balloon-rubbing experiment and see what charge is where. Also research the fact that this happens more readily with certain materials than others.

This electrostatic field can exert a force on other things with charges. Think about it for a moment: If we could figure out a way to put some charges on one end of our conductor, that would push the like charges away and in so doing cause those charges to move.

Figure 0.4 shows a hypothetical device that separates these charges. I will call it an electron pump and hook it up to our copper conductor we mentioned previously.

In our electron pump, when you turn the crank, one side gets a surplus of electrons, or a negative charge, and on the other side the atoms are missing said electrons, resulting in a positive charge. ¹²

¹²There is actually a device that does this. It is called a Van de Graaff generator, so it really isn't hypothetical, but I really like the word hypothetical. Just saying it seems to raise my IQ!

If you want to carry forward the water analogy, think of this as a pump hooked up to a pipe full of water and sealed at both ends. As you turn the pump, you build up pressure in the pipe—positive pressure on one side of the pump and negative pressure on the other. In the same way, as you turn the crank you build up charges on either side of the pump, and then these charges push out into the wire and sit there because they have no place to go. If you hook up a meter to either end you would measure a potential (think difference in charge) between the two wires. That potential is what we call voltage.

Note

It's important to realize that it is by the nature of the location of these charges that you measure a voltage. Note that I said location, not movement. Movement of these charges is what we call current (more on that later.) For now what you need to take away from this discussion is that it is an accumulation of charges that we refer to as voltage. The more like charges you get in one location, the stronger the electrostatic field you create. ¹³

¹³There isn't a good water analogy for this field. You simply need to know it is there; it is important to understand that this field exists. If you still don't grasp this field, get a balloon and play with it 'til you do. Remember, even the best analogies can break down. The point is to use the analogy to help you begin to grasp the topic, then experiment until you understand all the details.

Okay, it's later now. We find that another very cool thing happens when we move these charges. Let's go back to our pump and stick a light bulb on the ends of our wires, as shown in Figure 0.5.

Remember that opposite charges attract? When you hook up the bulb, on one side you have positive charges, on the other negative. These charges push through the light bulb, and as they do they heat up the filament and make it light up. If you stop turning the electron pump, this potential across the light bulb disappears and the charges stop moving. Start turning the pump and they start moving again. The movement of these charges is called current. ¹⁴ The really cool thing that happens is that we get another invisible field that is created when these charges move; it is called the electromagnetic field. If you have ever played with a magnet and some iron filings, you have seen the effects of this field. ¹⁵

¹⁴Current is coulombs per second, a measure of flow that has units of amperes, or amps.

¹⁵In a permanent magnet, all the electrons in the material are scooting around their respective atoms in the same direction; it is the movement of these charges that creates the magnetic field.

So, to recap, if we have a bunch of charges hanging out, we call it voltage, and when we keep these charges in motion we call that current. Some typical water analogies look at voltage as pressure and current as flow. These are helpful to grasp the concept, but keep in mind that a key thing with these charges and their movements is the seemingly magical fields they produce. Voltage generates an electrostatic field (it is this field repelling or attracting other charges that creates the voltage pressure in the conductor). Current or flow or movement of the charges generates a magnetic field around the conductor. It is very important to grasp these concepts to enhance your understanding of what is going on. When you get down to it, it is these fields that actually move the work or energy from one end of a circuit to another.

Let's go back to our pump and light bulb for a minute, as shown in Figure 0.6.

Turn the pump, and the bulb lights up. Stop turning and it goes out. Start turning and it immediately lights up again. This happens even if the wires are long! We see the effect immediately. Think of the circuit as a pair of pulleys and a belt. The charges are moving around the circuit, transferring power from one location to another—see Figure 0.7. ¹⁶

¹⁶This diagram is a simplified version of a scalar wave diagram. I won't go into scalar diagrams in depth here, to limit the amount of information you need to absorb. However, I do recommend that you learn about these when you feel ready.

Fundamentally, we can think of the concept as shown in the drawing in Figure 0.8.

Even if the movement of the belt is slow, ¹⁷ we see the effects on the pulley immediately, at the moment the crank is turned. It is the same way with the light bulb. However, the belt is replaced by the circuit, and it is actually the electromagnetic¹⁸ fields pushing charges around that transmit the work to the bulb. Without the effects of both of these fields, we couldn't move the energy input at the crank to be output at the light bulb. It just wouldn't happen.

¹⁷The charges in the wire are moving much more slowly than one might think. In fact, DC current moves at about 8 CM per hour. (In a typical wire that is, the exact speed depends on several factors, but it is much slower than you might think.) AC doesn't even keep flowing, it just kind of bounces back and forth over a very small distance. If you think about it, you might wonder how flipping a switch can get a light to turn on so quickly. Thus the motor and belt analogy; it is the fact that the wire pipe is filled (in the same way the belt is connected to the pulley) with these charges that creates the instantaneous effect of a light turning on.

¹⁸When I use the term electromagnetic, it is referring to the effects of both the electrostatic field and the magnetic field that we have been talking about.

Like the belt on the pulleys, the charges move around in a loop. But the work that is being done at the crank moves out to the light bulb, where it is used up making the light shine. Charges weren't

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