Electronics For Dummies^®

Introduction

Are you curious to know what makes your iPod tick? How about your mobile phone, laptop, stereo system, digital camera, plasma TV – or, well, just about every piece of electronics you use for work or play, in the office, at home or on the move?

Perhaps you’ve even thought that you could design and build your own little electronic circuit or gadget to do something you want it to do?

If you’ve ever wondered how transistors, capacitors and other building blocks of electronics work, or if you’ve been tempted to try building your own electronic devices, you’ve come to the right place!

Electronics For Dummies is your entry into the electrifying world of modern electronics. No dry, boring or incomprehensible tome, this; what you hold in your hands is the book that enables you to understand, create and troubleshoot your own electronic devices. We’re getting excited already!

Why Buy This Book?

All too often, electronics seems like a mystery, because it involves controlling something you can’t see – electric current – which you’ve been warned repeatedly not to touch. That’s enough to scare most people away. But as you continue to experience the benefits of electronics on a daily basis, you may begin to wonder how so many incredible things can happen in such tight spaces.

This book is designed to explain electronics in ways you can relate to. It gives you a basic understanding of exactly what electronics is, provides down-to-earth explanations of how major electronic components work and gives you just what you need to build and test working electronic circuits and projects. Although this book doesn’t pretend to answer all your questions about electronics, it does give you a good grounding in the essentials.

We hope that when you’re done with this book, you’ll realise that electronics isn’t as complicated as you may have thought. And we want to arm you with the knowledge and confidence you need to go deeper into the exciting world of electronics.

Why Electronics?

Electronics is everywhere. You find electronics in your phones, audio and video systems, and kitchen appliances. Electronic systems control traffic lights, Internet commerce, medical devices – even many toys. You can’t see most of them, but electronic systems also proliferate throughout your car. Try for just one minute to imagine your life without electronics; you may as well be living in the Dark Ages!

So what does all this mean to you as you peruse this book? After all, you don’t expect to be able to design satellite communication systems after a sit-down session with this humble For Dummies book.

Remember though that even the most complicated electronics systems consist of no more than a handful of different electronic component types governed by the same set of rules that make simple circuits work. So if you want to understand complex electronic systems, you start with the basics – just like the designers of those systems did when they started out.

More importantly, understanding the basics of electronics can enable you to create some really useful, albeit somewhat simple, electronic devices. You can build circuits that flash lights at just the right time, sound a buzzer upon sensing an intruder or even move an object around the room. And when you know how to use integrated circuit (IC) chips, which are populated with easy-to-use fully functioning circuits, you can create some rather clever designs for just a few well-spent pounds.

Technology development being what it is – lightning fast, smaller and cheaper year after year – you can now hold the ingredients for very advanced electronic systems in the palm of your hand. With a little knowledge and a willingness to experiment, you can build a unique musical birthday card, fantastic flashing decorations or an alarm that senses someone trying to get into your bedroom or biscuit tin.

Also, you may have another hobby that can be enriched by electronics. If you’re into model railways, you can build your own automated switching points. If your hobby is racing radio-controlled cars, electronics know-how may enable you to improve the performance of your car and win the next championship. Knowing more about electronics can really enhance your hobbies.

Last but not least, electronics is fun. Finding out about and messing with electronics is its own reward.

Foolish Assumptions

This book assumes that you’re curious about electronics, but you really don’t know much, if anything, about its inner workings. You chose this book, rather than a book consisting exclusively of recipes for electronic circuits, and therefore we assume that you want to discover more about how parts such as resistors, capacitors and transistors actually work.

So we take the time (and more than half the book) to explain the basics to you, distilling fairly technical information down into easy-to-understand concepts. You don’t need to be well-versed in physics or mathematics to benefit from reading this book, although a little bit of school algebra is helpful (but we do our best to refresh that possibly painful memory).

We assume you may want to jump around this book a bit, diving deep into a topic or two that holds special interest for you, and possibly skimming through other topics. For this reason, we provide loads of chapter cross-references to point you to information that can fill in any gaps or refresh your memory on a topic. And although the first half of the book is devoted to how electronic circuits and individual parts work, we include cross-references to simple circuits and projects that appear later in the book. That way, as soon as you find out about a component, you can jump ahead, if you like, and build a circuit that uses that very component.

The table of contents at the front of the book provides an excellent resource that you can use to find quickly exactly what you’re looking for. Finally, the good people at Wiley have thoughtfully provided a thorough index at the back of the book to help you find what you want fast.

Safety Is Number 1

Reading about electronics is pretty safe. About the worst that can happen is that your eyes get tired from too many late nights with this book. But actually building electronic projects is another matter. Lurking behind the fun of your electronics hobby are high voltages that can electrocute you, soldering irons that can burn you and little bits of wire that can fly into your eyes when you snip them off with sharp cutters. Aaaagh!

Safety comes first in electronics. It’s so important, in fact, that we devote a major section of Chapter 9 to it – and continually refer you to this section. If you’re brand new to electronics, please be sure to read this section thoroughly. Don’t skip over it, even if you think you’re the safest person on earth. Even if you’ve dabbled in electronics before, we still say you should read this bit as you may be surprised by some of the information. When you follow proper precautions, electronics is a very safe and sane hobby. Be sure to keep it that way!

Although we try to give you great advice about safety throughout, we can’t possibly give you every safety precaution in the world in one book. In addition to reading our advice, use your own common sense, read manufacturer’s instructions for parts and tools that you work with and always stay alert.

How This Book Is Organised

Electronics For Dummies is organised so that you can quickly find, read and understand the information that you want. Also, if you have some experience with electronics, or want to deepen your knowledge of one particular topic, you can skip around and focus on the chapters that interest you.

The chapters in this book are divided into parts to help you zero in on the information that you’re looking for quickly and easily.

Part I: Understanding the Fundamentals of Electronics

Turn to Part I if you want to get a thorough grounding in basic electronics theory. Chapter 1 gives you the big picture of exactly what electronics is and the amazing things it can do for you. You discover the fundamentals of electronic circuits and get introduced to voltage, current and sources of electrical energy in Chapter 2.

In Chapters 3–6, you dive deep into the heart of all the major electronic components, including resistors, capacitors, inductors, transformers, diodes and transistors. You find out how each component works, how it handles electric current and what role it plays in electronic circuits.

Chapter 7 introduces you to integrated circuits (ICs) and explains a bit about digital logic and how three popular ICs function. Chapter 8 covers sensors, speakers, buzzers, switches, wires and connectors.

Throughout Part I, we point you to introductory circuits you can build in Part III to see what each component does.

Part II: Getting Your Hands Dirty

Part II is all about tooling-up, constructing real circuits and probing around working (and non-working) circuits – without electrocuting yourself.

In Chapter 9, you find out how to set up an electronics workbench, what electronic components, tools and other supplies you need to build circuits, and how to protect yourself and your electronic components as you work on circuits. Chapter 10 explains how to interpret circuit diagrams (known as schematics) so that you know how to connect components together when you build a circuit.

You discover various methods of wiring up temporary and permanent circuits in Chapter 11, including how to solder. Finally, Chapter 12 explains how to use the most important testing tool in electronics – the multimeter – to explore and analyse your circuits. This chapter also introduces you very briefly to two other tools: the logic probe and oscilloscope.

Part III: Putting Theory into Practice

If you’re anxious to wire up some circuits and get your electronic juices flowing, Part III is the place to be.

Chapter 13 shows you some elementary circuits that you can build to demonstrate the principles of electronics and observe specific electronic components functioning as advertised. Turn to this chapter if you want to reinforce your theoretical knowledge of electronics or gain experience building simple circuits.

When you’re ready for more involved circuits, explore Chapter 14. Here, you find several projects that you can have fun building and exploring. You may even decide to put one or two of them to good use in your home or office.

Part IV: The Part of Tens

As you may expect, Part IV is where you can find further information laid out in top-ten list format.

Chapter 15 offers pointers to help you expand your electronics horizons. Here, you can find information on all-inclusive project kits and circuit simulation software, suggestions for additional testing tools and tips on how to get great deals on electronics supplies.

When you’re ready to shop for all things electronic, turn to Chapter 16 for a list of the top electronics suppliers in the UK and abroad.

Icons Used in This Book

We can’t place dozens of Post-it notes in each and every copy of Electronics For Dummies, so we use icons to draw your attention to critical information.

Tips alert you to information that can really save you time, headaches or money (or all three!). If you use our tips, your electronics experience is that much more enjoyable.

When you tinker with electronics, you’re bound to encounter situations that call for extreme caution. Enter the Warning icon: a not-so-gentle reminder to take extra precautions to avoid personal injury or prevent damage to your tools, components, circuits – or your bank balance.

This icon reminds you of important ideas or facts that you really need to keep in mind. Occasionally, we use this icon to note where in the book an important concept is originally introduced, so that you can flick back to more detailed information for a refresher, if you need one.

Even though this entire book is about technical stuff, we flag up some mini topics to alert you to deeper techie info that may require a little more brain power to digest. Of course, if you choose to skip over this info, that’s absolutely fine; you can still follow along with no problem. Think of this techie stuff as extra material – a diversion off the main path, if you will – like bonus questions in a quiz.

Part I

Understanding the Fundamentals of Electronics

In this part . . .

Do you ever wonder what makes electronic devices tick? Are you ever curious to know how speakers speak, motors move and computers compute? Well, then, you’ve come to the right place!

In the chapters ahead, we explain exactly what electronics is, what it can (and does) do for you and how all sorts of electronic things work. But don’t worry. We don’t bore you with long essays involving physics and mathematics. We use analogies and down-to-earth examples to make understanding electronics easy – fun, even. And while you’re enjoying yourself, you’re discovering how electronic components work and combine forces to make amazing things happen.

Chapter 1

What Is Electronics and What Can It Do for You?

In This Chapter

Seeing electric current for what it really is

Recognising the power of electrons

Using conductors to go with the flow (of electrons)

Making the right connections with a circuit

Controlling the destiny of electrons with electronic components

Applying electrical energy to loads of things

If you’re like most people, you probably have some idea about what electronics is. You’ve been up close and personal with lots of so-called consumer electronics devices, such as iPods, stereo equipment, personal computers, digital cameras and televisions, but to you, they may seem like mysteriously magical boxes with buttons that respond to your every desire.

You know that underneath each sleek exterior nestles an amazing assortment of tiny components connected together in just the right way to make something happen. And now you want to understand how.

In this chapter, you discover that electrons moving in harmony constitute electric current, which is shaped by electronics. You take a look at what you need to keep the juice flowing, and you also get an overview of some of the things you can do with electronics.

Just What Is Electronics?

When you turn on a light in your home, you’re connecting a source of electrical energy (usually supplied by your power company) to a light bulb in a complete path, known as an electrical circuit. If you add a dimmer or a timer to the light bulb circuit, you can control the operation of the light bulb in a more interesting way than simply switching it on and off.

Electrical systems, like the circuits in your house, use a standard electric current to make things such as light bulbs work. Electronic systems take this a step further: they control the electrical current, changing its fluctuations, direction and timing in various ways in order to accomplish a variety of functions, from dimming a light bulb to communicating with satellites (take a look at Figure 1-1). This control is what distinguishes electronic systems from electrical systems.

To understand how electronics controls electricity, you need to first understand what electricity is and how it powers things like light bulbs.

Understanding Electric Current

Electric current is the flow of electrical charges carried by unbelievably small particles called electrons. So what on earth are electrical charges, where exactly do you find electrons and how do they move around? You find the answers by taking a peek inside the atom.

Getting a charge out of electrons

Atoms are the natural building blocks of everything. They’re so tiny that you can find millions of them in a single speck of dust – so you can imagine how many exist in your average sumo wrestler! Electrons are found in every single atom in the universe, outside the atom’s centre, or nucleus. All electrons have a negative electrical charge and are attracted to positively charged particles, known as protons, which exist inside the nucleus. Electrical charge is a kind of force within a particle, and the words ‘positive’ and ‘negative’ are somewhat arbitrary terms used to describe the two different forces that exhibit opposite effects. (We can call them ‘north’ and ‘south’ or ‘Tom’ and ‘Jerry’ instead, but those names are already taken.)

Under normal circumstances, an equal number of protons and electrons reside in each atom, and the atom is said to be electrically neutral. The attractive force between the protons and electrons, known as an electromagnetic force, acts like invisible glue, holding the atomic particles together, much as the gravitational force of the earth keeps the moon within sight. The electrons closest to the nucleus are held to the atom with a stronger force than the electrons farther from the nucleus, and some atoms hold on to their outer electrons with a vengeance whereas others are a bit more lax.

Moving electrons in conductors

Materials such as air and plastic, in which the electrons are all tightly bound to atoms, are insulators – they don’t like to let their electrons move and so they don’t easily carry an electric current. However, other materials, like the metal copper, are conductors because they have ‘free’ electrons wandering between the atoms, normally moving around at random. When you give these free electrons a push, they all tend to move in one direction and, hey presto, you have an electric current. This flow appears to be instantaneous because all those free electrons, including those at the ends, move at the same time.

A coulomb is defined as the charge carried by 6.24 x 1018 (that’s 624 followed by 16 zeros) electrons. If a coulomb of charge moves past a point within a second, we say that the strength of the electric current is one ampere, or one amp (abbreviated to 1 A). That’s a whole lot of electrons moving simultaneously, and much more than is typically found in electronic systems. You’re more likely to see current measured in milliamps (mA). A milliamp is one one-thousandth of an amp.

Harnessing Electricity to Do Work

Benjamin Franklin was one of the first people to observe and experiment with electricity, and he came up with many of the terms and concepts (for instance, current) that we know and love today. Contrary to popular belief, Franklin didn’t actually hold the key at the end of his kite during that storm in 1752. (If he had, he wouldn’t have been around for the American Revolution.) He may have performed that experiment, but not by holding the key.

Franklin knew that electricity was both dangerous and powerful, and his work got people wondering whether a way existed to use the power of electricity for practical applications. Scientists such as Michael Faraday, Thomas Edison and others took Franklin’s work a bit further and figured out ways to harness electricity and put it to good use.

Where Electrical Energy Comes From

In this section, we explore where electrical energy comes from and how you can apply that energy to make things work.

Tapping into electrical energy

An electric current flowing in a conductor moves energy from its source, such as a battery, to a place where it can do something useful. That place could be a light bulb, motor or loudspeaker, for example. These useful objects convert the electrical energy into another form of energy, such as light, heat or mechanical energy. In this way, you make the filament glow, the motor shaft rotate or the speaker diaphragm vibrate.

As you can’t see – and don’t necessarily want to touch – the masses of flowing electrons, try thinking about water to help make sense out of harnessing electricity. A single drop of water can’t do much to help (or hurt) anyone, but get a whole group of water drops to work in unison, funnel them through a conduit, direct the flow of water towards an object (for example, a waterwheel) and you can put the resulting water energy to good use. Just as millions of drops of water moving in the same direction constitute a current, so too millions of electrons moving in the same direction make an electric current. In fact, Benjamin Franklin came up with the idea that electricity acts like a fluid and has similar properties, like current and pressure (but he probably would have cautioned you against drinking it).

Giving electrons a nudge

The force that gets the free electrons in a conductor moving is known as voltage, which is measured in units called volts (abbreviated to V). Think of voltage as electric pressure. Much like water pressure pushes water through pipes and valves, voltage pushes electrons through wires and other circuit components. The higher the pressure, the stronger the push, and so the higher the voltage, the stronger the electric current that is pushed through a circuit.

You may also hear the terms potential difference, voltage potential, potential drop or voltage drop used. Try not to let these different terms confuse you. We discuss this a bit more in Chapter 2.

Using conductors to make the circuit

Electric currents don’t just flow anywhere. (If they did, you’d be getting shocked all the time.) Electrons only keep flowing if you provide a closed conductive path, or circuit, for them to move through and start that flow by applying a source of electrical energy such as a battery. Copper and other conductors are commonly formed into wire to provide a path for the flow of free electrons, so that you can direct electrical energy to a light bulb or other part that can use it. Just as with pipes and water, the wider the wire, the more freely the electrons flow.

If a break exists in the path (an open circuit), the electrons get stuck in a dead end. Picture water flowing through an open pipe. The water flows for a short time, but then stops when all the water exits the pipe. If you pump water through a closed pipe system, the water continues to flow as long as you keep forcing it to move.To keep the electric current flowing, you need to connect everything together into one big happy electrical circuit. As shown in Figure 1-2, every circuit needs at least three basic things to ensure that electrons get energised and deliver their energy to something that needs work done:

A source of electricity (or electrical energy): The source provides the force that nudges the electrons in the chain reaction. You may also hear the terms electrical source, power source, voltage source and energy source used to describe a source of electricity. We discuss sources of electricity in Chapter 2.

A load: The load is the thing that uses the energy in a circuit (for instance, a light bulb or a speaker). Think of the load as the destination for the electrical energy.

A path: A conductive path provides a conduit for electric current to flow between the source and the load.

An electric current starts with a push from the energy source and flows through the wire path to the load, where energy is released to make something happen, for instance, emitting light.

Oh, the Things Electrons Can Do!

Imagine applying an electric current to a pair of speakers without using anything to control or shape the current. What would you hear? It certainly wouldn’t be music! By using the proper combination of electronics assembled in just the right way, you can control the way each speaker diaphragm vibrates, producing recognisable sounds, like speech or music (well, certain music anyway). And you can do so much more with electric current when you know how to control the flow of electrons.

Electronics is all about using specialised devices, known as electronic components (for example, resistors, capacitors, inductors and transistors, which we discuss in Chapters 3, 4, 5 and 6 respectively) to control current (also known as the flow of electrons) in such a way that it performs a specific function.

Simple electronic devices use a few components to control current flow. The dimmer switch that controls current flowing into a light bulb is one such example. But most electronic systems are a lot more complicated than that; they connect lots of individual components together in one or more circuits to achieve their ultimate goal. The great thing is that when you understand how a few individual electronic components work and find out how to apply some basic principles, you can begin to understand and build interesting electronic circuits.

This section provides just a sampling of the sorts of things you can do by controlling electrons with electronic circuits.

Creating good vibrations

Electronic components in your iPod, car stereo and other audio systems convert electrical energy into sound energy. In each case, the system’s speakers are the load, or destination, for electrical energy, and the job of the electronic components within the system is to shape the current flowing to the speakers so that the diaphragm within each speaker moves in such a way as to reproduce the original sound.

Seeing is believing

In visual systems, electronic components control the timing and intensity of light emissions. Many remote control devices, such as the one wedged down the back of your sofa, emit invisible infrared light when you press a button, and the specific pattern of the emitted light acts as a sort of code to the device you’re controlling, telling it what to do.

Cathode ray tube (CRT) TV sets (the sort we all used before flat-panel sets) are coated with phosphors that glow when struck by electron beams within the tube. The electronic circuits within the TV set control the direction and intensity of the electron beams, thus controlling the pattern painted across the TV screen, which is the image you see. Enlightening, isn’t it?

Sensing and alarming

Electronics can also be used to make something happen in response to a specific level of light, heat, sound or motion. Electronic sensors generate or change an electrical current in response to a stimulus. Microphones, motion detectors, temperature sensors and light sensors can be used to trigger other electronic components to perform some action, such as activating an automatic door opener or sounding an alarm.

Controlling motion

A common use of electronics is to control the on/off activity and speed of motors. By attaching various objects, from wheels to aeroplane flaps, to motors, you can use electronics to control their motion. Such electronics can be found in robotic systems, aircraft, spacecraft, elevators and lots of other places.

Solving problems (aka computing)

Much as the ancients (those living thousands of years ago, not your great-grandparents) used the abacus to perform arithmetic operations, so you use electronic calculators and computers to perform computations. With the abacus, beads were used to represent numbers and calculations were performed by manipulating those beads. In computing systems, different electrical signals are used to represent numbers, letters and other information, and computations are performed by manipulating those patterns using electronic components. Of course, the worker-bee electrons inside have no idea they’re crunching numbers!

Communicating with each other

Electronic circuits in your mobile phone work together to convert the sound of your voice into an electrical pattern, manipulate the pattern (to compress and encode it for transmission), convert it into a radio signal and send it out through the air to a communication tower. Other electronic circuits in your handset detect incoming messages from the tower, decode the messages and convert an electrical pattern within the message into the sound of your friend’s voice (via a speaker).

Data communication systems, which you use every time you shop online, use electronics to convert your materialistic desires into shopping orders – and extract money from your bank account.