Electronics All-in-One For Dummies. Doug Lowe
Чтение книги онлайн.
Читать онлайн книгу Electronics All-in-One For Dummies - Doug Lowe страница 24
Название: Electronics All-in-One For Dummies
Автор: Doug Lowe
Издательство: John Wiley & Sons Limited
Жанр: Отраслевые издания
isbn: 9781119822134
isbn:
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 machines to machines that can beat humans at games we once thought humans were the masters of, such as chess, Jeopardy!, and Go.
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 learn plenty about digital electronics in Books 5 through 8.
Looking inside Electronic Devices
Have you ever taken apart an electronic device that no longer works, like an old clock radio or VHS tape player, just to see what it looks like on the inside?
I just took some hefty server computers to an e-waste recycler. You can bet that before I did, I opened them up to see what they looked like on the inside. And I removed a couple of the more interesting pieces to keep on my shelf. (Call me weird if you want. Some people collect teacups, some people collect spoons from around the world, and some people collect shot glasses. I collect old computer CPUs.)
Inside most electronic devices, you’ll find a circuit board (or circuit card; it’s all the same), which is a flat, thin board that has electronic gizmos mounted on it. In most cases, one side of the circuit board is populated with tiny devices that look like little buildings. These are the components that make up the electric circuit: the resistors, capacitors, diodes, transistors, and integrated circuits that do the work that the circuit is destined to do. The other side is painted with little lines of silver or copper that look like streets. These are the conductors that connect all the components so that they can work together.
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.
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 4 of this minibook before you begin disassembling anything!
Chapter 2
Understanding Electricity
IN THIS CHAPTER
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.
Pondering the Wonder of Electricity
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, СКАЧАТЬ