Doug Lowe - Electronics All-in-One For Dummies

An electronic circuit board looks like a little city! For example, have a look at the typical circuit board pictured in Figure 1-3. The top of the card is shown on the top; it has a variety of common electronic components. The underbelly of the circuit card is shown on the bottom; it has the typical silver streaks of conductors that connect the components topside so that they can perform useful work.

FIGURE 1-3:A typical electronic circuit board.

Here’s the essence of what’s going on with these two sides of the circuit card:

The component side of the card — the 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.

The circuit side of the card — the side with the roads — 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 coordinated way.

Okay, I couldn’t even get through the first chapter of this book without having to give you the first of many warnings about the dangers of working with electronics. So here it goes: Do not under any circumstances plunge carelessly into the disassembly of old electronic circuits until you’re certain that you know what you’re doing.

The little components on a circuit card, such as the one shown in Figure 1-3 can be dangerous, even when they are unplugged. In fact, the two tall cylindrical components near the back edge of this circuit card 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 see Chapter 4of this minibook before you begin disassembling anything!

Chapter 2

IN THIS CHAPTER

Unraveling the deep mysteries of the matter and energy (well, only a little bit)

Learning about three important aspects of electric circuits: current, voltage, and power

Looking at the difference between direct and alternating current

Learning your first electrical equation (don’t worry; it’s simple)

Frankly, the title of this chapter is a bit ambitious. Before you can do much that’s very interesting with electronics, you need to have a basic understanding of what electricity is and how it works, but unfortunately, understanding electricity is a tall order. Don’t let this discourage or dissuade you: Even the smartest physicists in the world don’t really understand it.

At the start of this chapter, you examine the very nature of electricity: what it is and what causes it. This first part of the chapter will remind you of a seventh- or eighth-grade science class, as you delve into the insides of atoms and learn about protons, neutrons, and electrons.

The second part of this chapter introduces you to three things you have to know about electricity if you want to design and build circuits: current, voltage, and power — the Manny, Moe, and Jack of electricity. Or if you prefer, the Huey, Dewey, and Louie, or the bacon, lettuce, and tomato, or the — you get the idea.

The exact nature of electricity is one of the core mysteries of the universe. Although we don’t really know exactly what electricity is, we do know a lot about what it does and how it behaves.

Strange as it may sound, your understanding of electricity will improve right away if you avoid using the term electricity to describe it. That’s because the term electricity isn’t very precise. We use the word electricity to refer to any of several different but related things. Each has a more precise name, such as electric charge, electric current, electric energy, electric field, and so on. All these things are commonly called electricity.

Electricity isn’t so much a specific thing, but a phenomenon that has many different faces. So to avoid confusion, I try to avoid the word electricity in the rest of this book. Instead, I use more precise terms such as charge or current.

I really hate to use the word phenomenon here because it sounds so scientific. I feel like I should wear a bow tie whenever I say the word phenomenon. I consulted my thesaurus to see if there was a simpler word I could use instead. None of the suggestions really seemed to fit, but the one that came closest was wonder .

Do you remember the movie Jurassic Park , where scientists discovered the DNA of dinosaurs locked inside bits of amber? Amber is fossilized tree resin, and it played a key role in the history of our knowledge about electricity.

Since the days of the ancient Greeks, people have known that if you rubbed sticks of amber with fur, the amber could then be used to raise the hair on your head and that lightweight objects like feathers would stick to it. They had no idea why this happened, but they knew that it did happen.

The Greek word for amber is elektron . The Latin version of the word was electricus.

At the beginning of the seventeenth century, an English scientist named William Gilbert began to study electricity. He used these ancient words to describe the phenomena he was investigating, including the Latin term electricus. The influence of Gilbert’s book, which was written in Latin, led to the word electricity in the English language.

Wonder isn’t a bad substitute. When it comes down to it, the phenomenon we call electricity is pretty amazing. It really does qualify as one of the great wonders of the universe.

Remember the so-called “Seven Wonders of the Ancient World,” which included the Great Pyramid of Giza, the Hanging Gardens of Babylon, the Temple of Artemis at Ephesus, the Statue of Zeus at Olympia, the Mausoleum of Halicarnassus, the Colossus of Rhodes, and the Lighthouse of Alexandria? If we were to make a list called “The Seven Wonders of the Universe,” I suppose it would have to include Matter, Gravity, Time, Light, Life, Pizza, and Electricity.