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Want to hook up your home theater system?
Want to fix it so your garage band rocks the neighborhood?
Want to solder the faulty wire on your old phonograph so you can play those 60s albums you?ve kept all this time?
Whether you?re a do-it-yourselfer , hobbyist, or student , this book will turn you on to real-world electronics. It quickly ...
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Want to hook up your home theater system?
Want to fix it so your garage band rocks the neighborhood?
Want to solder the faulty wire on your old phonograph so you can play those 60s albums you’ve kept all this time?
Whether you’re a do-it-yourselfer , hobbyist, or student , this book will turn you on to real-world electronics. It quickly covers the essentials, and then focuses on the how-to instead of theory. It covers:
Author Gordon McComb has more than a million copies of his books in print, including his bestselling Robot Builder’s Bonanza and VCRs and Camcorders For Dummies. He really connects with readers! With lots of photos and step-by-step explanations, this book will have you connecting electronic components in no time! In fact, it includes fun ideas for great projects you can build in 30 minutes or less. You’ll be amazed! Then you can tackle cool robot projects that will amaze your friends! (The book gives you lots to choose from.)
Students will find this a great reference and supplement to the typical dry, dull textbook. So whether you just want to bone up on electronics or want to get things hooked up, souped up, or fixed up,…whether you’re interested in fixing old electronic equipment, understanding guitar fuzz amps, ortinkering with robots, Electronics For Dummies is your quick connection to the stuff you need to know.
In This Chapter
* Understanding the role of electrons, conductors, and voltage
* Looking at how electricity is generated
* Exploring some electronic components
* Connecting components together in circuits
* Introducing a few tools of the electronics trade
* Breaking it all down into units
* Understanding Ohm's Law
When you plug in the coffee maker in the morning, you're using electricity. When you flip on the TV to watch a rerun of Sex in the City, you're using electricity again (for better or worse).
You use electricity and electronics devices all the time, and you've finally worked up enough curiosity to want to tinker with electronic gadgets yourself. That's great. But before you can jump into playing with wires and batteries, it helps to understand what puts the elec in electricity and electronics.
In this chapter, you discover all about how electrons make electricity and how harnessing that electricity is the basis of electronics. You also get an introduction to some of the tools and parts that you can play with in the electronics projects in Chapters 14 and 15.
Just What Is Electricity?
Like most things in life, electricity is more complex than you may think. A lot of conditions have to come together to make that little spark when you touch a doorknob orprovide the power to run a supercomputer. To understand how electricity works, it helps to break it down into its parts.
First, you take an electron
Electrons are one of the building blocks of nature. Electrons are buddies with another of nature's building blocks, protons. Electrons and protons are very small and are contained in ... well, everything. A speck of dust contains millions and millions of electrons and protons, so you can imagine how many there are in your average sumo wrestler.
Electrons and protons have equal and opposite electric charges, with electrons having the negative charge and protons the positive. Opposite charges are attracted to each other. You can visualize a similar type of attraction by putting the ends of two magnets together. If the ends of the magnets are opposite poles, the magnets cozy right up to each other and stick together. If the ends of the magnets are the same pole, the magnets will move apart like two politicians in a heated debate. In a similar way, because electrons and protons have opposite charges, they are attracted to each other just as you can see opposite magnetic poles attracting. The attraction between electrons and protons acts like glue on a microscopic scale, holding matter together.
Although protons stay reasonably static, electrons are adventurous little fellows who don't like to just sit around at home. They can, and often do, move from one object to another. Walk across a carpet on a dry day and touch a doorknob; electrons traveling between your finger and the doorknob cause the spark that you feel and sometimes see. Lightning is another example of electrons traveling between two things - in this case, between a cloud and the ground. These examples both show electricity in an unharnessed state.
Moving electrons around through conductors
What do electrons use to travel from one place to another? The answer to that question gives you the next piece of the electricity puzzle. Although you may use your old Chevy to get around, electrons use something called a conductor. Electricity is simply the movement of electrons through a conductor.
A lot of materials can act as conductors, but some are much better at it than others. Electrons can move more easily through metal than through plastic. In plastic, even though all the electrons are moving around their proton buddies, they pretty much stay in their own backyard. But in metal, the electrons are free to move all over the place. Free electrons in metal act like marbles thrown on an ice-skating rink. The electrons glide through the metal like the marbles slide across the ice. Plastic, an insulator, is more like sand. Marbles don't go much of anywhere if you throw them into a sandbox, and neither do electrons in an insulator.
So which materials are good conductors and which are good insulators? Most folks use copper and aluminum as conductors. In fact, electronics projects often use copper wire conductors. Plastic and glass are commonly used insulators.
Resistance is the measurement of the ability of electrons to move through a material. A copper wire with a large diameter has lower resistance to the flow of electrons than a copper wire with a small diameter. You need to understand resistance because almost every electronics project you do involves a resistor. Resistors have controlled amounts of resistance, which allows you to control the flow of electrons in a circuit.
Voltage, the driving force
The previous sections in this chapter explain how electrons move and that they move more freely in a conductor. But some kind of force has to pull the electrons from one place to another. This attractive force between positive and negative charges is an electromotive force called voltage. Negative electrons move toward a positive voltage by way of a conductor.
Remember Ben Franklin's adventure flying a kite in a storm? The spark he produced that night gave him an understanding of how an electric current moves. In Ben's case, electrons traveled down the wet string, which acted as a conductor. (This was at least in part because the string was wet. Try this same stunt with dry string and it doesn't work nearly as well). The voltage difference between the negatively charged clouds and the ground pulled the electrons down the wet string.
Don't try Franklin's experiment yourself! By flying a kite in a storm, you're basically playing with lightning - which can effectively turn you into toast.
An important combo: Electrons, conductors, and voltage
Say that you have a wire (a conductor), and you attach one of its ends to the positive terminal of a battery and the other end of the wire to the negative terminal of the battery. Electrons then flow through the wire from the negative to the positive terminal. This flow of electrons is referred to as an electric current. When you combine electrons, a conductor, and voltage you create an electric current in a form that you can use.
To help you picture how conductors and voltage affect the flow of electric current in a wire, think of how water pressure and pipe diameter affect the flow of water through a pipe. Here's how this analogy works:
Where Do You Get Electricity?
Electricity is created when voltage pulls an electric current through a conductor. But when you sit down and run a wire between a switch and a light, just where do you get the juice (the electricity) to power that light?
There are many different sources of electricity - everything from the old walking-across-a-carpet-and-touching-a-doorknob kind to solar power. But to make your life simple, this book takes a look at the three sources that you're likely to use for electronics projects: batteries, your wall outlet, and solar cells.
They just keep on going: Batteries
A battery uses a process called electrochemical reaction to produce a positive voltage at one terminal and a negative voltage at the other terminal. The battery creates these charges by placing two different metals in a certain type of chemical. Because this isn't a chemistry book, we don't get into the guts of a battery here - but trust us, this is essentially what goes on.
Batteries have two terminals (a terminal is just a fancy word for a piece of metal to which you can hook up wires). You often use batteries to supply electricity to devices that are portable, such as a flashlight. In a flashlight, the bulb has two wires running to the battery, one to each terminal. What happens next? Something like this:
Because the electrons move in only one direction, from the negative terminal through the wires to the positive terminal, the electric current generated by a battery is called direct current, or DC. This is in contrast to alternating current (AC) which is discussed in the following section, "Garden-Variety Electrical Outlets."
The wires on a battery must connect to both terminals. This setup allows electrons to flow from one terminal of the battery, through the bulb, and all the way to the other terminal. If the electrons can't complete this kind of loop between negative and positive, electrons don't flow.
Garden-variety electrical outlets
When you plug a light into an electrical outlet in your wall, you're using electricity that originated at a generating plant. That plant may be located at a dam or come from another power source, such as nuclear power. Or it may be fired by coal or natural gas. Because of the way electricity is generated at a power plant, the direction in which the electrons flow changes 120 times a second, making a complete turnaround 60 times a second. This change in electron flow is called alternating current, or AC.
When the change in electron flow makes a complete loop, it's called a cycle. The number of cycles per second in alternating current is measured in Hertz, abbreviated Hz. The example of a cycle in the previous paragraph is based on the fact that the United States uses a 60 Hertz standard frequency; some other countries use 50 Hertz as a standard, which means that the electrons change direction 100 times a second.
Electricity generated at a dam uses water to turn a coil of wire inside a huge magnet. One of the properties of magnets and wires is that when you move a wire near a magnet, a flow of electrons is induced in the wire. First, the magnet causes the electrons to flow in one direction, and then, when the wire loop rotates 180 degrees, the magnet pulls the electrons in the other direction. This rotation creates alternating current.
Just plugging a cord into a wall outlet sounds easy enough, but you need direct current for most projects, rather than alternating current. If you use wall outlets to supply electricity for your project, you have to convert the electricity from AC to DC. You can do this conversion with something called a power supply. For an example of a power supply, think of the charger that you use for your cell phone; this little device essentially converts AC power into DC power that the battery uses to charge itself back up. You can find out more about power supplies in Chapter 3.
Safety, safety, safety. It's an important issue for you to consider when deciding whether to use the AC electricity that you get from wall outlets. Using the electricity from a battery is like petting a house cat. Using the electricity from wall outlets is more like cozying up to a hungry lion. With a cute tabby, you may get your hand scratched; with the king of the jungle, you may be eaten alive. If you think that you need to use electricity from a wall outlet for a project, make sure that you know what you're doing first. See Chapter 2 for specific advice about safety.
Solar cells are a form of semiconductor. Like batteries, solar cells have wires attached to two terminals. Shining light on a solar cell causes an electric current to flow. (This reaction to light is a property of semiconductors and is discussed in the sidebar "Getting fancy with semiconductors," later in this chapter.) The current is then conducted through wires to devices, such as a calculator or a garden light beside the pathway to your front door.
Using a calculator containing a solar cell, you can demonstrate that the calculator depends on the light shining on the solar cell for its power. Turn the calculator on and punch some numbers into the screen (choose a nice big number, like your income tax). Now, use your thumb to cover the solar cell. (The solar cell is probably near the top of the calculator in a rectangular area with a clear plastic cover.) After you've covered up the solar cell for a moment, the numbers fade away. Take your thumb off the solar cell, and the numbers reappear. Things powered by solar cells need light to work.
Where Do Electrical Components Fit In?
Electrical components are parts you use in electronics projects. Simple enough, right? You use some electrical components to control the flow of electricity, such as a dimmer switch that adjusts the brightness of a light. Electricity simply powers other electrical components, such as speakers blasting out sound. Still other electronic components, called sensors, detect something (such as light or heat) and then generate a current to do something in response, such as set off an alarm.
In this section, you meet some basic electrical components. Chapters 4 and 5 provide much more detail about components.
Electrical components, or parts, can control electricity. For example, a switch connects a light bulb to electric current. To disconnect the light bulb and make it go dark, the switch simply makes a break in the circuit.
Some other parts that control electricity are resistors, capacitors, diodes, and transistors. You can find more information on these parts in Chapter 4.
Controlling electricity even better (ICs)
Integrated circuits, or ICs, are components that contain a whole bunch of miniature components (such as resistors, transistors, or diodes, which you hear about in Chapter 4) in one device that may not be much bigger than an individual component. Because each IC contains many components, one little IC can do the same job as several individual parts.
An audio amplifier is one example of an IC. You can use audio amps to increase the power of an audio signal. For example, if you have a microphone, its small output signal is fed through an audio amplifier to make a strong enough signal to power a speaker.
Another type of IC used in electronics projects is a microcontroller, a type of integrated circuit that you can actually program to control cool gadgets like robots. We discuss microcontrollers in more detail in Chapter 13.
Sensing with sensors
Certain electrical components generate a current when you expose them to light or sound. You can use the current generated, together with a few of the components listed in the previous sections that control electricity, to turn on or off electronic devices, such as light bulbs or speakers.
Motion detectors, light sensors, microphones, and temperature sensors all generate an electrical signal in response to a stimulus (motion, light, sound, or temperature, respectively). These signals can then be used to turn other things on or off. A high signal level might turn something on and a low signal level turn something off. For example, when a salesperson walks up to your house, a motion detector can turn on a light (or better yet, sound a general alarm).
These signals take different forms, depending on the component supplying them. For example, a microphone supplies an AC signal, and a temperature sensor supplies a DC signal.
Figure 1-1 shows diagrams of a few signals that you run into often when working with electronics. These signals include
You can find out more about various types of sensors in Chapter 5.
Excerpted from Electronics For Dummies by Gordon McComb Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Part I: Getting Started in Electronics.
Chapter 1: From Electrons to Electronics.
Chapter 2: Keeping Humans and Gadgets Safe.
Part II: Aisle 5, Component Shack: Stocking Up.
Chapter 3: Outfitting Your Electronics Bench.
Chapter 4: Getting to Know You: The Most Common Electronic Components.
Chapter 5: Filling Out Your Parts Bin.
Part III: Putting It on Paper.
Chapter 6: Reading a Schematic.
Chapter 7: Understanding the Basics of Electronics Circuits.
Part IV: Getting Your Hands Dirty.
Chapter 8: Everything You Need to Know about Soldering.
Chapter 9: Making Friends with Your Multimeter.
Chapter 10: Getting Down with Logic Probes and Oscilloscopes.
Part V: A Plethora of Projects.
Chapter 11: Creating Your Own Breadboard Circuit.
Chapter 12: Building Your Own Printed Circuit Boards.
Chapter 13: The Exciting World of Microcontrollers.
Chapter 14: Great Projects You Can Build in 30 Minutes or Less.
Chapter 15: Cool Robot Projects to Amaze Your Friends and Family.
Part VI: The Part of Tens.
Chapter 16: Ten (Or So) Cool Electronics Testing Tool Tips.
Chapter 17: Ten Great Electronics Parts Sources.
Chapter 18: Ten Electronics Formulas You Should Know.
Appendix: Internet Resources.
Posted October 22, 2006
As an electrical engineering student going to school for my bachelor's this book is very handy. As a student you learn a lot of the mathematical background of Electrical and Electronic equipment, including simple circuits, amplifiers, microcontrollers, electric motors, and programming in VHDL. What schools lack, or what my school lacked, was giving the student a good experience with hands on lab work. I do a decent job solving transfer functions, determining which components to use for amplifiers and frequency filters, design some circuitry using some fancy software and a bit of Calculus, but do crap when it comes to hands on stuff. This book, this Electronics for Dummies book, saved me from feeling like too much of a idiot, and helped me finish up my senior design by creating a working security system for a house. Thank you dummies.
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Posted December 4, 2008
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