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.

Electric charge is one of the basic forces of nature that hold the universe together. Positive and negative charges are irresistibly attracted to each other. Thus, the attraction of negatively-charged electrons to positively-charged protons holds atoms together.

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.

Atoms don’t really ‘look’ for anything. They don’t have eyes and they don’t have minds that are troubled when they’re short an electron or have a few too many. But the natural attraction of negative to positive charges causes atoms that are short an electron to be attracted to atoms that are long an electron. When they find each other, something almost magical happens. The atom with the extra electron gives its electron to the atom that’s missing an electron. Thus, the charge represented by the electron moves from one atom to another, which brings us to the second important concept: current.

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.

The insulator serves two purposes:

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.

However complex they are, all circuits have to obey the basic principle of a closed loop that provides a complete path from the source of voltage (in this case, the battery) through the various components that make up the circuit (here the light bulb) and back to the source (the battery).

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.

The distinction between electrical and electronic devices is a bit blurry. These days, simple electrical devices often include some electronic components. For example, your toaster may contain an electronic thermostat that attempts to keep the heat at just the right temperature to make perfect toast, and your washing machine has electronics so that you can choose the right programme to wash your clothes. And even the most complicated electronic devices have simple electrical components in them. For example, although your TV set’s remote control is a pretty complicated little electronic device it contains batteries, which are simple electrical devices.

---

---

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.

LED stands for light-emitting diode. We don’t test you on that in this chapter, but it’s central to Book II, Chapter 5, where you work with LEDs.

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.

Don’t under any circumstances plunge carelessly into the disassembly of old electronic circuits until you’re certain you know what you’re doing.

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!