Doug Lowe - Electronics All-in-One For Dummies

6 Chapter 6: Building Projects Looking at the Process of Building an Electronic Project Envisioning Your Project Designing Your Circuit Prototyping Your Circuit on a Solderless Breadboard Constructing Your Circuit on a Printed Circuit Board (PCB) Finding an Enclosure for Your Circuit

7 Chapter 7: The Secrets of Successful Soldering Understanding How Solder Works Procuring What You Need to Solder Preparing to Solder Soldering a Solid Solder Joint Checking Your Work Desoldering

8 Chapter 8: Measuring Circuits with a Multimeter Looking at Multimeters What a Multimeter Measures Using Your Multimeter

9 Chapter 9: Catching Waves with an Oscilloscope Understanding Oscilloscopes Examining Waveforms Calibrating an Oscilloscope Displaying Signals

Chapter 1

IN THIS CHAPTER

Understanding electricity

Defining the difference between electrical and electronic circuits

Perusing the most common uses for electronics

Looking at a typical electronic circuit board

I thought it would be fun to start this book with a story, so please bear with me. In January of 1880, Thomas Edison filed a patent for a new type of device that created light by passing an electric current through a carbon-coated filament contained in a sealed glass tube. In other words, Edison invented the light bulb. (Students of history will tell you that Edison didn’t really invent the light bulb; he just improved on previous ideas. But that’s not the point of the story.)

Edison’s light bulb patent was approved, but he still had a lot of work to do before he could begin manufacturing a commercially viable light bulb. The biggest problem with his design was that the lamps dimmed the more you used them. This was because when the carbon-coated filament inside the bulb got hot, it shed little particles of carbon, which stuck to the inside of the glass. These particles resulted in a black coating on the inside of the bulb, which obstructed the light.

Edison and his team of engineers tried desperately to discover a way to prevent this shedding of carbon. One day, someone on his team noticed that the black carbon came off of just one end of the filament, not both ends. The team thought that maybe some type of electric charge was coming out of the filament. To test this theory, they introduced a third wire into the lamp to see if it could catch some of this electric charge.

It did. They soon discovered that an electric current flowed from the heated filament to this third wire, and that the hotter the filament got, the more electric current flowed. This discovery, which came to be known as the Edison Effect, marks the beginning of technology known as electronics. The device, which Edison patented on November 15, 1883, is the world’s first electronic device.

When Edison patented his device in 1883, he had no idea what it would lead to. Now, nearly 140 years later, it’s hard to imagine a world without electronics. Electronic devices are everywhere. There are more television sets in the United States than there are people. No one uses film to take pictures anymore; cameras have become electronic devices. And you rarely see a teenager anymore without headphones in their ears.

Without electronics, life would be very different.

Have you ever wondered what makes these electronic devices tick? In this chapter, I lay some important groundwork that will help the rest of this book make sense. I 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 of electronics: electricity.

I promise I won’t bore you too much with tedious or complicated physics concepts, but I must warn you from the start: In order to learn how electronics works at a level that will let you begin to design and build your own electronic devices, you need to have at least a basic idea of what electricity is. Not just what it does, but what it actually is. So put on your thinking cap and get started.

Before you can understand even the simplest concepts of electronics, you must first understand what electricity is. After all, the whole purpose of electronics is to get electricity to do useful and interesting things.

The concept of electricity is both familiar and mysterious. We all know what electricity is or at least have a rough idea based on practical experience. In particular, consider these points:

We are very familiar with the electricity that flows through wires like water flows through a pipe. That electricity comes from power plants that burn coal, catch the wind, absorb sunlight, or harness nuclear reactions. It travels from the power plants to our houses in big cables hung high in the air or buried in the ground. Once it gets to our houses, it travels through wires through the walls until it gets to electrical outlets. From there, we plug in power cords to get the electricity into the electrical devices we depend on every day, such as ovens and toasters and vacuum cleaners.

We know, because the electric company bills us for it every month, that electricity isn’t free. If we don’t pay the bill, the electric company turns off our electricity. Thus, we know that electricity is valuable.

We know that 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.

We know that some kinds of batteries, like the ones in our cellphones, are rechargeable , which means that when they’ve been drained of all their electricity, more electricity can be put back into them by plugging them into a charger, which transfers electricity from an electrical outlet into the battery. Rechargeable batteries can be filled and drained over and over again, but eventually they lose their ability to be recharged — and you have to replace them with new batteries. (Or, in the case of your iPhone, you have to buy a whole new phone.)

We also know that electricity is the stuff that makes lightning strike in a thunderstorm. In grade school, we were taught that Ben Franklin discovered this by conducting an experiment involving a kite and a key, which we should not attempt to repeat at home.

We know that electricity can be measured in volts. Household electricity is 120 volts (abbreviated 120 V). Flashlight batteries are 1.5 volts. Car batteries are 12 volts.

We also know that electricity can be measured in watts. Traditional incandescent light bulbs are typically 60, 75, or 100 watts (abbreviated 100 W). Microwave ovens and hair dryers are 1,000 or 1,200 watts. The more watts, the brighter the light or the faster your pizza reheats and your hair dries.

Except that we also know that some technologies do more work for a given wattage. Thus, a 20-watt CFL bulb and a 12-watt LED bulb both produce as much light as a 75-watt incandescent bulb.

We also may know that there’s a third way to measure electricity, called amps. A typical household electrical outlet is 15 amps (abbreviated 15 A).

The truth is, most of us don’t really know the difference between volts, watts, and amps. (Don’t worry; by the time you finish Chapter 2of this minibook, you will!)