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Table of Contents
Introduction
About This Book
Foolish Assumptions
Staying Safe
Icons Used in This Book
Beyond the Book
Where to Go from Here
Book I: Getting Started with Electronics
Chapter 1: Entering the Exciting World of Electronics
What Is Electricity?
Introducing electricity: Common knowledge
Understanding electricity basics
Discovering the Difference Between Electrical and Electronic Devices
Using the Power of Electronics
Making some noise
Painting with light
Transmitting to the world
Computing
Looking Inside Electronic Devices
Chapter 2: Understanding Electricity
Wondering about the Nature of Electricity
Looking for electricity
Peering inside atoms
Examining the elements
Charging ahead
Conducting and Insulating Elements: Current, Voltage and Power
Keeping current
Pushing electrons around: Voltage
Comparing direct and alternating current
Working out with power
Chapter 3: Creating Your Own Mad-Scientist Lab
Setting up Your Lab
Equipping Your Lab
Acquiring basic hand tools
Seeing clearly with magnifying glasses
Getting a firm grip on third hands and hobby vices
Making connections with a soldering iron
Measuring with a multimeter
Using a solderless breadboard
Conducting electricity with wires
Supplying power with batteries
Stocking up on other useful items
Gathering Together the Basic Electronic Components
Curbing current with resistors
Keeping charged with capacitors
Depending on diodes to block or allow current
Producing light with LEDs
Controlling current with transistors
Chipping in with integrated circuits
Chapter 4: Staying Safe
Facing the Shocking Truth about Electrical Dangers
Heeding the warning: Household electrical current can kill you!
Understanding that even relatively small voltages can hurt you
Staying safe by staying dry
Realising that voltage can hide in unexpected places
Considering Other Ways to Stay Safe
Keeping Safety Equipment on Hand
Protecting Your Equipment from Static Discharges
Chapter 5: Reading Schematic Diagrams
Introducing Simple Schematic Diagrams
Laying out a circuit
Connecting or not connecting
Interpreting Symbols in Schematic Diagrams
Looking at commonly used symbols
Representing integrated circuits in a schematic diagram
Simplifying Ground and Power Connections
Labelling Components in a Schematic Diagram
Chapter 6: Building Your Own Electronic Projects
Building an Electronic Project in Five Steps
Envisioning Your Project
Designing Your Circuit
Prototyping Your Circuit on a Solderless Breadboard
Understanding how solderless breadboards work
Laying out your circuit
Assembling the coin-toss circuit on a solderless breadboard
Troubleshooting if your circuit fails to work
Constructing Your Circuit on a Printed Circuit Board (PCB)
Understanding how PCBs work
Using a preprinted circuit board
Building the coin-toss circuit on a PCB
Mounting Your Circuit
Finding a suitable enclosure for your circuit
Working with a project box
Chapter 7: Uncovering the Secrets of Successful Soldering
Understanding How Solder Works
Procuring What You Need to Solder
Buying a soldering iron
Stocking up on solder
Getting together the other goodies you need
Preparing to Solder
Soldering a Solid Solder Joint
Checking Your Work
Undoing Your Work: Desoldering
Chapter 8: Measuring Circuits with a Multimeter
Looking at Multimeters
Discovering What a Multimeter Measures
Keeping current with the ammeter
Calculating voltage with the voltmeter
Sensing resistance with the ohmmeter
Meeting some other measurements
Reading schematic symbols for meter functions
Using Your Multimeter
Building a circuit to measure
Measuring current
Measuring voltage
Measuring resistance
Chapter 9: Catching Waves with an Oscilloscope
Understanding Oscilloscopes
Examining Waveforms
Calibrating an Oscilloscope
Displaying Signals
Book II: Working with Basic Electronic Components
Chapter 1: Working with Basic Circuits
What Is a Circuit?
Using Batteries
Introducing the battery
Building a lamp circuit
Working with Switches
Moving switches in different ways
Making connections with poles and throws
Building a switched lamp circuit
Understanding Series and Parallel Circuits
Building a series lamp circuit
Building a parallel lamp circuit
Using Switches in Series and Parallel
Building a series switch circuit
Building a parallel switch circuit
Switching between two lamps
Building a three-way lamp switch
Reversing Polarity
Chapter 2: Working with Resistors
What Is Resistance?
Creating resistance
Measuring resistance
Looking at Ohm’s Law
Introducing Resistors
Reading Resistor Colour Codes
Working out a resistor’s value
Understanding resistor tolerance
Heating Up: Resistor Power Ratings
Limiting Current with a Resistor
Building Resistance in Combination
Combining resistors in series
Combining resistors in parallel
Mixing series and parallel resistors
Assembling resistors in series and parallel
Dividing Voltage with Resistors
Varying Resistance with a Potentiometer
Chapter 3: Working with Capacitors
What Is a Capacitor?
Catching up with capacitors
Knowing the capacitor symbols
Counting Capacitance
Finding out about farads
Reading capacitor values
Sizing Up Capacitors
Calculating Time Constants for Resistor/Capacitor Networks
Looking at the calculations
Appreciating the RC time constant
Combining Capacitors
Combining capacitors in parallel
Connecting capacitors in series
Putting Capacitors to Work
Charging and discharging a capacitor
Blocking DC while passing AC
Chapter 4: Working with Inductors
What Is Magnetism?
Pointing to the north and south of magnetism
Pondering permanent magnets
Examining Electromagnets
Inducing Current
Resisting change: Inductance
Regarding henrys
Calculating RL Time Constants
Calculating Inductive Reactance
Combining Inductors
Putting Inductors to Work
Chapter 5: Working with Diodes and LEDs
What Is a Semiconductor?
Examining elements and atoms
Doping is really rather clever
Combining types into one-way junctions
Discovering Diodes
Boning up on bias
Moving voltage forward – or in reverse
Meeting the many types of diodes
Blocking reverse polarity with a diode
Putting Rectifiers to Work
Looking at rectifier circuits
Building rectifier circuits
Introducing Light-Emitting Diodes
Providing the necessary resistance
Detecting polarity with LEDs
Chapter 6: Working with Transistors
What’s the Big Deal About Transistors?
Peering inside a transistor
Examining transistor specifications
Amplifying Current with a Transistor
Switching with a Transistor
Exploring an NPN transistor switch
Building an LED driver circuit
Walking Through a NOT Gate
Looking at a simple NOT gate circuit
Building a NOT Gate
Oscillating with a Transistor
Inspecting an astable multivibrator
Building an LED flashing circuit
Book III: Working with Integrated Circuits
Chapter 1: Introducing Integrated Circuits
Investigating Integrated Circuits
Manufacturing integrated circuits
Packaging integrated circuits
Depicting ICs in schematic diagrams
Powering ICs
Avoiding Static and Heat Damage
Reading IC Data Sheets
Meeting the Family: Popular Integrated Circuits
555 timer
741 and LM324 Op-Amp
78xx voltage regulator
74xx logic family
Chapter 2: The Fabulous 555 Timer Chip
Examining how the 555 Works
Understanding 555 Modes
Using the 555 in monostable (one-shot) mode
Using the 555 in astable (oscillator) mode
Using the 555 in bistable (flip-flop) mode
Working with the 555 Timer Output
Doubling Up with the 556 Dual Timer
Constructing 555 Chip Projects
Making a one-shot timer
Brightening up with an LED flasher
Employing a set/reset switch
Building a beeper
Chapter 3: Working with Op Amps
Looking at Operational Amplifiers
Understanding Open Loop Amplifiers
Considering Closed Loop Amplifiers
Investigating inverting amplifiers
Reversing inputs: Noninverting amplifiers
Using an Op Amp as a Unity Gain Amplifier
Configuring a voltage follower
Configuring a unity inverter
Comparing Voltages with an Op Amp
Adding Voltages: Summing Amplifiers
Working with Op-Amp ICs
Book IV: Getting into Alternating Current
Chapter 1: Understanding Alternating Current
What Is Alternating Current?
Measuring Alternating Current
Understanding Alternators
Meeting up with Motors
Thinking about Transformers
Coiling up to create energy
Producing huge power efficiently with AC
Chapter 2: Working with Mains Voltage
Adapting the Mains Supply for Use in Your Projects
Staying safe with mains voltage
Understanding live, neutral and earth
Working Safely with Mains Voltage
Wiring and connecting
Protecting mains-voltage circuits with fuses
Controlling mains-voltage circuits using relays
Chapter 3: Supplying Power for Your Electronics Projects
Powering up from Your Electrical Outlet
Using Power Adapters
Understanding the Power Supply
Transforming voltage
Turning AC into DC
Filtering rectified current
Regulating voltage
Book V: Working with Radio and Infrared
Chapter 1: Tuning in to Radio
Rolling with Radio Waves
Transmitting and Receiving Radio Waves
Making waves with radio transmitters
Catching the waves: Radio receivers
Approaching AM Radio
Finding out about FM Radio
Chapter 2: Building a Crystal Radio
Looking at a Simple Crystal Radio Circuit
Gathering Together Your Parts
Creating the Coil
Assembling the Circuit
Stringing up an Antenna
Connecting to Ground
Using Your Crystal Radio
Chapter 3: Working with Infrared
Introducing Infrared Light
Detecting Infrared Light
Creating Infrared Light
Constructing Proximity Detectors
Building a common-emitter proximity detector
Building a common-collector proximity detector
Book VI: Doing Digital Electronics
Chapter 1: Understanding Digital Electronics
Distinguishing Analogue and Digital Electronics
Understanding Binary
Knowing your number systems
Counting by ones
Doing the logic thing
Using Switches to Build Gates
Chapter 2: Getting Logical
Introducing Boolean Logic and Logic Gates
Entering Through the Different Types of Logic Gates
Noting NOT gates
Appraising AND gates
Observing OR gates
Looking at NAND gates
Checking out NOR gates
Going over XOR and XNOR gates
Diving into De Marvellous De Morgan’s Theorem
Understanding that All You Need is NAND (or NOR)
Using universal NAND gates
Combining universal NOR gates
Playing with Gates in Software
Noting Notations
Chapter 3: Putting Logic Circuits to Work
Creating Logic Gates with Transistors
Discovering a transistor NOT gate circuit
Going high with a transistor AND gate circuit
Staying low with a transistor NAND gate circuit
Looking at a transistor OR gate circuit
Knowing about transistor NOR gate circuits
Introducing Integrated Circuit Logic Gates
Making use of the versatile 4000-series logic gates
Building projects with the 4011 Quad Two-Input NAND Gate
Chapter 4: Interfacing to Your Computer’s Parallel Port
Understanding the Parallel Port
Peering into the makeup of a parallel port
Connecting with the DB25 connector and its pins
Pinning your hopes on the pinout assignments
Designing a parallel-port circuit
Working with DB25 connectors
Controlling Parallel-Port Output from an MS-DOS Prompt: Programming from a PC
Using the RELAY command
Creating a command script
Seeing why timing is everything: DELAY and WAITFOR
Building a parallel-port LED flasher
Sussing out Seven-Segment Displays
Introducing the seven-segment display
Building a seven-segment display countdown timer
Driving up the Current
Using Darlington arrays forhigh-current outputs
Building a motor driver
Chapter 5: Getting the Hang of Flip-Flops
Looking at Latches
Going Over Gated Latches
Introducing Flip-Flops
Building flip-flop projects
Debouncing a clock input
Book VII: Working with BASIC Stamp Processors
Chapter 1: Introducing Microcontrollers and the BASIC Stamp
Meeting the Mighty Microcontroller
Working with the BASIC Stamp
Introducing the BASIC Stamp 2 Module
Buying a BASIC Stamp
Working with the BASIC Stamp HomeWork board
Choosing the Board of Education
Connecting to BASIC Stamp I/O pins
Installing the BASIC Stamp Windows Editor
Connecting to a BASIC Stamp
Writing Your First PBASIC Programs
Discovering programming basics
Saying ‘Hello World’
Running the Hello World program
Flashing an LED with a BASIC Stamp
Chapter 2: Programming in PBASIC
Introducing and Using the PBASIC Language
Building a test circuit for the programs
Flashing the LEDs
Commenting to Clarify Your Code
Creating Names in your Programs
Employing Constants as Substitute Values
Assigning Names to I/O Pins
Creating Variables to Use RAM Memory
Carrying out Maths Functions
Making use of IF Statements
Pressing DO Loops into Service
Keeping Count with FOR Loops
Chapter 3: Discovering More PBASIC Programming Tricks
Pushing Buttons with a BASIC Stamp
Checking the Status of a Switch in PBASIC
Randomising Your Programs
Reading a Value from a Potentiometer
Using Subroutines and the GOSUB Command
Chapter 4: Adding Sound and Motion to Your BASIC Stamp Projects
Creating Sound with a Piezo Speaker and a BASIC Stamp
Freaking out with the FREQOUT command
Testing the piezo speaker
Playing with sound effects
Moving by Degrees with a Servo and a BASIC Stamp
Connecting a servo to a BASIC Stamp
Programming a servo in PBASIC
Building a servo project
Book VIII: Having Fun with Special Effects
Chapter 1: Synchronising Sight and Sound with a Colour-Organ Circuit
Considering the Colour-Organ Project
Understanding how the colour organ works
Getting your equipment together
Building the Colour Organ Project
Assembling your colour organ
Thinking inside the (project) box
Wiring up your circuit
Putting Your Colour Organ to Work
Chapter 2: Unearthing Hidden Treasure with a Handy Metal Detector
Uncovering the Big Picture: Project Overview
Scoping out the schematic
Sticking to adhesive precautions
Perusing the parts
Taking Construction Step by Step
Assembling your metal detector circuit
Building the box to house the circuit
Putting it all together
Handling the handle
Trying Out Your Detector
Chapter 3: Making Light Dance to the Music
Illuminating the Big Picture: Project Overview
Scoping out the schematic
Following some wiring tips
Perusing the parts
Taking Construction Step by Step
Building the circuit
Using LEDs to create the lights
Adding the rest of the gubbins
Trying Out Your Dance to the Music Display
Chapter 4: Hacking a Toy to Make a Talking Puppet
Talking about the Big Picture: Project Overview
Scoping out the schematic
Noting some construction issues
Perusing the parts
Taking Construction Step by Step
Creating your puppet’s circuit
Making the box puppet-friendly
Programming fun sounds
Hooking up your puppet
Playing with Your Puppet
About the Authors
Cheat Sheet
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Electronics All-in-One For Dummies®
Published by: John Wiley & Sons, Ltd., The Atrium, Southern Gate, Chichester, www.wiley.com
This edition first published 2014
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A catalogue record for this book is available from the British Library.
ISBN 978-1-118-58973-1 (pbk); ISBN 978-1-118-58970-0 (ebk); ISBN 978-1-118-58971-7 (ebk)
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10 9 8 7 6 5 4 3 2 1
Introduction
Electronics changed the world during the 20th century, from radios, telephones and cinema to modern computing and the so-called Information Age. This revolution may turn out to be as important as the Industrial Revolution. The Internet was recently voted the greatest invention of all time – and yet it’s not even 25 years old. Each new electronic gadget is adopted quicker than the last (you may be reading this book on an e-reader or tablet computer) and mobile phones now outnumber people on the planet.
Yet despite using electronics every day, many people have virtually no understanding of what’s going on under their thumbs and behind those screens; the process may just as well be magic to them. Fortunately, you don’t have to understand completely the inner workings of every component, even if you want to design an amazing new electronic gizmo.
This book is for people who’ve always been fascinated by electronics but didn’t make a career out of it. In these pages, you find clear and concise explanations of the most important concepts that form the basis of all electronic devices, such as the nature of electricity (if you think you know what it is, you’re kidding yourself); the difference between voltage, amperage and wattage; how basic components such as resistors, capacitors, diodes and transistors work; and how you can use some super-complex components such as integrated circuits to realise your own dream project.
You not only gain an appreciation of the electronic devices that are part of everyday life, but also discover how to build simple circuits that impress your friends, are great fun and may even be the prototype for the invention that makes your fortune!
About This Book
Electronics All-in-One For Dummies is a practical reference containing the most important topics you need to know when you dabble in building your own electronic circuits. It’s a big book made up of eight smaller ones, which we call minibooks. Each of these minibooks covers the basics of one key topic for working with electronics, such as circuit-building techniques, how electronic components work or using integrated circuits.
Throughout these minibooks, we include dozens of simple, practical projects which you can build to demonstrate the operation of typical circuits. For example, in the chapter on transistors (Book II, Chapter 6), you find several simple projects that demonstrate common uses for transistors, such as driving an LED, inverting an input and creating an oscillator.
Reading about electronics circuits is one thing, but to understand how a circuit works, you need to build it and see it in operation. Most of the projects are simple enough that you can build them in 20–30 minutes, assuming you have the parts on hand.
This book doesn’t pretend to be a comprehensive reference for every detail on every possible topic related to electronics. Instead, it shows you how to get up and running quickly so that you have more time to do the things you really want to do. Designed using the easy-to-follow For Dummies format, this book helps you get the information you need without labouring to find it.
To make its use as easy as possible, we design this book with multiple access points to help you find what you want. At the beginning of the book is a detailed table of contents that covers the entire book. Plus, each minibook begins with a minitable of contents that shows you at a mini-glance what chapters are included in that minibook. Useful running heads appear at the top of each page to point out the topic we discuss on that page, and handy thumb-tabs run down the side of the pages to help you find each minibook quickly. At the back, a comprehensive index lets you find information anywhere in the entire book.
This book isn’t the kind you pick up and read from start to finish, as if it were a novel. If we see you reading it like this at the beach, we’ll kick sand in your face. Beaches are for reading romance novels or murder mysteries, not electronics books. Although you can read this book straight through from start to finish, it’s designed for you to pick up, open to just about any page and start reading.
You don’t have to memorise anything in this book. It’s a ‘need-to-know’ book: you pick it up when you need to know something. Want a reminder on how to calculate the correct load resistor for an LED circuit? Pick up the book. Can’t remember the pinouts for a 555 timer IC? Pick up the book. After you find what you need, put the book down and get on with your life.
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.
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.
Staying Safe
Most of the electronic circuits we describe in this book are perfectly safe: they run from common AAA or 9 V batteries and therefore don’t work with voltages large enough to hurt you.
Occasionally, however, you come across circuits that work with higher voltages, which can be dangerous. You need to consider any project involving mains voltage (that you plug into an electrical outlet) as potentially dangerous and handle it with the utmost care. In addition, even battery-powered circuits that use large capacitors can build up charges that can deliver a potentially painful shock.
When you work with electronics, you also encounter dangers other than those posed by electricity. Soldering irons are hot and can burn you. Wire cutters are sharp and can cut you. Plus, plenty of the small parts you use can fall on the floor and find themselves in the mouths of children or pets.
Safety is such an important topic that we devote a whole chapter to it. We strongly urge you to read Book I, Chapter 4 before you build anything.
Icons Used in This Book
Like all For Dummies books, this one is chock-full of helpful icons that draw your attention to items of particular importance. You find the following icons throughout this book.
Beyond the Book
As you walk your journey of discovery into the world of electronics, you can augment what you read here by checking out some of the access-anywhere extra goodies that we’ve hosted for you online.
You can find the book's e-cheat sheet online, at www.dummies.com/cheatsheet/electronicsaiouk
. The at-a-glance, essential info that we serve up in this cheat sheet can be very handy sources of reference when printed out and pinned up near your workspace.
Additionally, you can also find a variety of great bonus content online, at www.dummies.com/extras/electronicsaiouk
.
Where to Go from Here
This book works like a reference source. To discover the basics of electronics, peruse Book I. If you have a topic in mind that you want to find out about, look for it in the table of contents (which is detailed enough to find most topics) or turn to the index, where you can find even more detail.
The book is loaded with information and you can stay swimming in the shallow end or dive as deep as you desire. If you want to take a brief dip into a topic, you’re more than welcome. If you want to know the big picture on digital electronics, for instance, read Book VI, Chapter 1. If you want to learn about logic gates, read Chapter 2 in Book VI. Or if you want to focus in on XOR gates, use the index to find the specific section in Book VI, Chapter 2.
Whatever your needs, with this book in hand you’re ready to immerse yourself in the exciting hobby of electronics. Browse through the table of contents and decide where you want to start. Be bold! Be courageous! Be adventurous! Be careful! But above all, have fun!
Book I
Getting Started with Electronics
Contents at a Glance
Chapter 1: Entering the Exciting World of Electronics
Chapter 2: Understanding Electricity
Chapter 3: Creating Your Own Mad-Scientist Lab
Chapter 4: Staying Safe
Chapter 5: Reading Schematic Diagrams
Chapter 6: Building Your Own Electronic Projects
Chapter 7: Uncovering the Secrets of Successful Soldering
Chapter 8: Measuring Circuits with a Multimeter
Chapter 9: Catching Waves with an Oscilloscope
Chapter 1
Entering the Exciting World of Electronics
In This Chapter
Understanding electricity
Distinguishing between electrical and electronic devices
Outlining the most common uses for electronics
Looking at a typical electronic circuit board
Electronic devices are everywhere: for example (and incredibly), the number of mobile phones on the planet exceeds the number of people. Plus, no one uses film to take photos anymore because cameras have become electronic devices, and at any given moment young people in particular are engrossed in sending text messages while simultaneously listening to music on their smartphones.
Without electronics, life today would be extremely different.
If you’ve ever wondered what makes these electronic devices tick, this chapter’s for you. Here we lay some important groundwork that helps the rest of this book to make sense. We examine the bits and pieces that make up the most common types of electronic devices, and take a look at the basic concept that underlies all electronics: electricity.
What Is Electricity?
We promise not to bore you with loads of tedious or complicated physics concepts, but in order to discover how electronics works at a level that lets you design and build your own electronic devices, you need to have a basic idea of what electricity is. After all, the whole purpose of electronics is to get electricity to do useful and interesting things.
Introducing electricity: Common knowledge
The concept of electricity is an odd one, familiar and mysterious. Here are a few of the familiar facts about electricity, based on practical experience:
Electricity comes from power plants that burn coal, catch the wind or harness nuclear reactions. It travels from the power plants to people’s houses in big cables hung high in the air or buried in the ground. At your home, it flows through wires in the walls (like water flows through a pipe) until it gets to electrical outlets. You plug in power cords to get the electricity into the electrical devices you depend on, such as ovens, toasters and vacuum cleaners.
Electricity is valuable and not free. You know this because a power company asks for payment for it every month, and if you don’t pay the bill it turns off your electricity.
Electricity can be stored in batteries, which contain a limited amount of electricity that can be used up. When the batteries die, all their electricity is gone.
Certain kinds of batteries, like the ones in mobile phones, are rechargeable: when drained of all their electricity, you can put more electricity back into them by plugging them into a charger, which transfers electricity from an electrical outlet into the battery. You can fill rechargeable batteries repeatedly, but eventually they lose their ability to be recharged – and then you have to replace them.
Electricity is the stuff that makes lightning strike in a thunderstorm. Perhaps you were taught about Ben Franklin’s experiment involving a kite and a key, and why you shouldn’t try it at home!
Electricity can be measured in three ways:
• Volts (abbreviated V): Household electricity in the UK is 230 V. Portable batteries are 1.5 V and car batteries are 12 V.
• Watts (abbreviated W): Traditional incandescent light bulbs are typically 60, 75 or 100 W. Modern compact fluorescent lights have somewhat smaller wattage ratings. Microwave ovens and hair dryers can be 1,000 W or more. The more watts, the brighter the light or the faster your pizza reheats and your hair dries. (Just to be clear, we don’t recommend drying your hair in a microwave – it’s not a good look!)
• Amps (abbreviated A): A typical household electrical outlet is 13 A.
Most people don’t really know the difference between volts, watts and amps, but you can find out by reading Chapter 2 of this minibook.
Static electricity is a special kind of electricity, which seems to sort of hang around in the air. You can transfer it to yourself by dragging your feet on a carpet, rubbing a balloon against your arms or forgetting to put an antistatic sheet in the tumble dryer.
Electricity can be very dangerous. So dangerous in fact that it has been used to administer the death penalty in America for well over a century.
Understanding electricity basics
We devote Chapter 2 of this minibook to a deeper look at the nature of electricity, but here we introduce you to three very basic concepts of electricity: electric charge, electric current and electric circuit.
Electric charge
Electric charge refers to a fundamental property of matter still being discussed by the cleverest of physicists. Although a huge simplification, in essence two of the tiny particles that make up atoms – protons and electrons – are the bearers of electric charge. Two types of charge exist: positive and negative. Protons have positive charge and electrons have negative charge.
If an atom has the same number of protons as it has electrons, the positive charge of the protons balances out the negative charge of the electrons, and the atom itself has no overall charge.
If an atom loses one of its electrons, however, the atom has an extra proton, which gives the atom a net positive charge. When an atom has a net positive charge, it ‘goes looking’ for an electron to restore its balanced charge.
Similarly, if an atom somehow picks up an extra electron, the atom has a net negative charge. When this happens, the atom ‘goes looking’ for a way to get rid of the extra electron to restore balance.
Electric current
Electric current refers to the flow of the electric charge carried by electrons as they move between the atoms. The concept is very familiar: when you turn on a light switch, electric current flows from the switch through the wire to the light and the room is instantly illuminated.
Electric current flows more easily in some types of materials than in others:
Conductors: Materials that let current flow easily.
Insulators: Materials that don’t let current flow easily.
Electrical wires are made of conductors and insulators, as illustrated in Figure 1-1. Inside the wire is a conductor, such as copper or aluminium. The conductor provides a channel for the electric current to flow through. Surrounding the conductor is an outer layer of insulator, such as plastic or rubber.
Figure 1-1: An electric wire consists of a conductor surrounded by an insulator.
It prevents you from touching the wire when current is flowing, stopping you from receiving a nasty shock.
It prevents the conductor inside the wire from touching the conductor inside a nearby wire. If the conductors touch, the result is a short circuit, which brings us to the third important concept.
Electric circuit
An electric circuit is a closed loop made of conductors and other electrical elements through which electric current can flow. For example, Figure 1-2 shows a simple electrical circuit that consists of three elements: a battery, a light bulb and an electrical wire that connects the two.
Figure 1-2: A simple electrical circuit consisting of a battery, a light bulb and some wire.
Circuits can get much more complex that this very simple one, consisting of dozens, hundreds, thousands or even millions of separate components, all connected with conductors in precisely orchestrated ways so that each component can do its bit to contribute to the overall purpose of the circuit.
If you’re not certain what the term voltage means, flip to Chapter 2 of this minibook to find out.
Discovering the Difference Between Electrical and Electronic Devices
Electrical devices are common pieces of equipment, such as light bulbs, vacuum cleaners and toasters. But what exactly is the difference between electrical devices and electronic devices?
The answer lies in how devices manipulate electricity to do their work:
Electrical devices: Take the energy of electric current and transform it in simple ways into some other form of energy – most likely light, heat or motion. For example, light bulbs turn electrical energy into light so that you can stay up late at night reading this book. The heating elements in a toaster turn electrical energy into heat so that you can burn your toast. And the motor in your vacuum cleaner turns electrical energy into motion that drives a pump that sucks the burnt toast crumbs out of your carpet.
Electronic devices: Do much more that just convert electrical energy into heat, light or motion. They manipulate the electrical current itself to coax it into doing interesting and useful things.
One of the most common things that electronic devices do is manipulate electric current in a way that adds meaningful information to the current. For example, audio electronic devices add sound information to an electric current so that you can listen to music or talk on a mobile phone. And video devices add images to an electric current so you can watch films such as Monty Python’s Life of Brian, Airplane! or This is Spinal Tap over and over again until you know every line by heart.
Using the Power of Electronics
The amazing thing about electronics is that it’s being used today to do things that weren’t even imaginable just a few years ago. And of course, in another few years you’ll be using electronic devices that haven’t even been thought up yet.
The following sections provide a very brief overview of some of the basic things you can do with electronics.
Making some noise
One of the most common applications for electronics is making noise, often in the form of music though the distinction between noise and music is often debatable. Electronic devices that make noise are often referred to as audio devices. These devices convert sound waves to electrical current, store, amplify and otherwise manipulate the current, and eventually convert the current back to sound waves you can hear.
Most audio devices contain these three parts:
Source: The input into the system. The source can be a microphone, which converts sound waves into an electrical signal. The subtle fluctuations in the sound waves are translated into subtle fluctuations in the electrical signal. Thus, the electrical signal that comes from the source contains audio information.
The source may also be a recorded form of the sound, such as sound recorded on a CD or in an MP3.
Amplifier: Converts the small electrical signal that comes from the source into a much larger electrical signal that you can listen to, when sent to speakers or headphones.
Some amplifiers are small, because they need to boost the signal only enough to be heard by a single listener wearing headphones. Other amplifiers are large, because they need to boost the signal enough so that thousands of people can hear, for example, the opening ceremony of the London 2012 Olympics.
Speakers: Convert electrical current into sound you can hear. They can huge or small enough to fit in your ear.
Painting with light
Another common use of electronics is to produce light. The simplest electronic light circuits are LEDs, which are the electronic equivalent of a light bulb.
Video electronic devices are designed to create not just simple points of light, but complete images you can look at. The most obvious examples are television sets.
Some types of electronic devices work with light that you can’t see. The most common are TV remote controls, which send infrared light to your television set whenever you push a button (assuming you can find the remote). The electronics inside the remote control manipulate the infrared light in a way that sends information from the remote control to the TV, telling it to turn up the volume, change channels or go to standby.
Transmitting to the world
Radio refers to the transmission of information without wires. Originally, radio was used as a wireless form of telegraph, broadcasting nothing more than audible clicks. Next, radio transmitted sound. In fact, to this day the term is usually associated with audio-only transmissions, such as music stations. However, the transmission of video information – in other words, television – is also a form of radio, as are wireless networking and cordless and mobile phones.
You can find out much more about radio electronics in Book V.
Computing
One of the most important applications of electronics in the last 50 years has been the development of computer technology. In just a few short decades, computers have gone from simple calculating devices to machines that have changed lives at work and home.
Computers are the most advanced form of a whole field of electronics known as digital electronics, which is concerned with manipulating data in the binary language of zeros and ones. You can discover digital electronics in Books VI and VII.
Looking Inside Electronic Devices
If you’ve ever taken apart an electronic device that no longer works, such as an old clock radio or VHS tape player, you know that inside is usually a circuit board (or circuit card): a flat, thin board with electronic gizmos mounted on it.
One or both sides of the circuit board are populated with tiny devices that look like little buildings. These components make up the electric circuit – the resistors, capacitors, diodes, transistors and integrated circuits that do the work the circuit is destined to do. (We discuss the first four of these components in Book II, Chapters 2, 3, 5 and 6, respectively, and cover integrated circuits in Book III.) In between those components the circuit board is painted with little lines of copper that look like streets. These conductors connect all the components so that they can work together.
An electronic circuit board looks like a city in miniature! For example, have a look at the circuit board pictured in Figure 1-3, which happens to be a board with components on only one side. The top of the board is shown, logically enough, at the top; it’s populated with a variety of common electronic components. The underbelly of the circuit board is shown at the bottom of the figure; it has the typical shiny streaks of conductors that connect the components topside so that they can perform useful work.
Here’s the essence of what’s going on with these two sides of the circuit board:
Component side, with the little ‘buildings’: Holds a collection of electronic components whose sole purpose in life is to bend, turn and twist electric current to get it to do interesting and useful things. Some of those components restrict the flow of current, like speed bumps on a road. Others make the current stronger. Some work like one-way street signs that allow current to flow in only one direction. Still others try to smooth out any ripples or variations in the current, resulting in smoother traffic flow.
Circuit side, with the shiny lines: Provides the conductive pathways for the electric current to flow from one component to the other in a certain order.
The whole trick of designing and building electronic circuits is to connect all the components together in just the right way so that the current that flows out of one component is passed on to the next component. The circuit side of the board is what lets the components work together in a co-ordinated way.
Figure 1-3: A typical electronic circuit board.
The little components on a circuit board such as the one shown in Figure 1-3 can be dangerous, even when they’re unplugged. In fact, the two tall cylindrical components near the back edge of this circuit board are called capacitors. They can contain stored electrical energy that can deliver a powerful – even fatal – shock long after you’ve unplugged the power cord. Please read Chapter 4 of this minibook before you begin disassembling anything!