What Is an Electronics Project, Anyway?
Obviously, an electronics project involves electronics, meaning that you use electricity to make something happen. However, overlaps exist among elec tronics, mechanics, and even programmable devices such as robots. Here’s what we mean when we say electronics projects
Electronics, mechanics, robotics: Huh?
Do you dream of building elaborate Erector Set-types of mechanical structures — perhaps a model of the Golden Gate Bridge with pulleys and levers moving objects around? Is your goal to create a robot butler with a programmed brain that enables it to serve your every whim? Well, those aren’t exactly what we categorize as electronics projects. Certainly, electronics projects are often combined with mechanical struc tures that use motors, and a robot has electronic components driven by microcontrollers and computer programs. In this book, though, we focus on projects that use simple electronics components to form a circuit that directs voltage to produce effects such as motion, sound, or light. By keeping to this simple approach, you can pick up all the basic skills and discover all the common components and tools that you need to work on a wide variety of projects for years to come. For these projects, you don’t have to become a mechanical or programming whiz. An electronic circuit might run a motor, light an LED display, or set off sounds through a speaker. It uses various components to regulate the voltage, such as capacitors and resistors. A circuit can also use integrated circuits (ICs), which are teeny, tiny circuits that provide a portion of your circuit in a very compact way. This saves you time micromanaging pieces of the project because somebody else has already done that job for you, such as building a timer chip that sets off a light intermittently
Programmable versus nonprogrammable
ICs are preprogrammed or programmable. And that brings us to our next distinction. Although we do use ICs in many of our projects — for example, in the form of a sound chip that’s preprogrammed with beeps and music — for the most part, we keep away from programmable electronics. In order to work with program mable electronics, you have to get your hands dirty with programming code and microcontrollers, and that’s not what we’re about here. Instead, we focus on building electronics gadgets that teach you about how electricity works and get your mind stirring with ideas about what you can do by using electronics, rather than computers. Don’t get us wrong: Microcontroller projects can be a lot of fun. After you get your hands dirty and pick up lots of basic skills doing the projects in this book, you might just go out and buy Microcontroller Projects For Dummies (if such a book existed).
Mixing and Matching Effects
The possibilities of what electronics projects can do are probably endless; on a basic level, the projects in this book use electricity to do a variety of things, from running a small cart around the room to setting off a sequence of lights or sounds.
Generally, most electronics projects consist of four types of elements
Input: This sets off the effect, such as a remote control device or a switch that you push. An event and a sensor, such as a motion or light detector, can also be used to activate an effect.
Power source: We typically use batteries in these projects.
Circuit: Components that control the voltage — such as transistors, capacitors, amplifiers, and resistors — are connected to each other and to the power source by wires and make up the circuit.
Output: This is what is powered by the circuit to produce an effect, such as speaker emitting sound, LED lights going off, or a motor that sets attached wheels spinning.
What Can You Do with Electronics Projects?
You get to explore a number of variations in the projects in this book. And sure, this stuff sounds like it might be cool, but what’s in it for you? Electronics projects offer three benefits (at least):
Fun
The thrill of making something work all by yourself
A boatload of useful knowledge
Just for the fun of it
One obvious benefit of tinkering with gadgets is that it’s just plain fun. If you’re the type who’s intrigued by how things work and what’s under the hood, you probably already know this. In fact, we have lost ourselves for hours figuring out circuits (this is the elec tronics equivalent of a jigsaw puzzle, which starts as a drawing, like the one shown in Figure 1-1), wiring the components, and refining the results. You can also, quite literally, amaze your friends with the things you build. And if you go in for electronic gizmos that you can race, scare people with, or use to entertain crowds at parties, you can share the fun with others. Don’t forget the social aspect: Electronics projects devotees comprise a friendly bunch of folks who like to help each other. You can get into discus sion groups online or join a local electronics club and find both interesting ideas and friendships at the same time. Chapter 16 provides ten great Web sites about electronics where you’ll find such online groups
Building things you can actually use
So why, when you can buy an AM radio for $7.95, would you decide to build one yourself with parts that cost $30? That’s a good question. The truth is just about everything you build in the projects included in this book — and most of the circuits floating around on the Internet — is something that you could probably buy in some form somewhere. But where would the challenge be in that?
Here’s why hundreds of thousands of electronics junkies build instead of buying: Because they can. They can make something that grabs music out of the airwaves or sets off a light display or sends a little cart wheeling around the room themselves. We guess this is why people knit sweaters instead of buying them or work on old cars instead of taking them to mechanics. It just feels good to master something on your own.
Picking up lots of cool stuff along the way
One of the great things about electronics is that it teaches you about all kinds of things you can use in your life. For example, you discover
How electricity works and how to stay safe when working with it
How to read an electronic circuit and build it on a breadboard
How to use a variety of tools to solder, build, and customize casings to hold your gadgets
How to work with integrated circuits
A bit about wiring (which can give you a head start when you decide to learn how to add an outlet to your kitchen someday)
Safety First
We won’t kid you: Electricity deserves your respect. It can shock you, burn you, and even kill you. In this book, we stick with projects that work with AA batteries to limit the potential for serious damage. Still, anytime you work with electronics, there is potential for danger. If these projects get you excited about electronics so that you move on to projects that use bigger jolts of electricity, now is the time to learn the proper respect for electricity and the proper safety precautions when working with electronics projects. In this chapter, you discover what electricity is capable of — and how to keep yourself, electrical components, tools, and those near and dear to you safe. This is the one must-read chapter in this book. Humor us, and read it from top to bottom, okay?
Avoiding Shocks Like the Plague
Your body is a delicate machine. Electric shocks, depending on certain conditions, can be fatal, even at relatively low voltages. What comes out of your wall outlet is deadly if you play around with it. Even electrical gadgets working off batteries can cause you serious damage.
How voltage and current can get you
Your body is like a big resistor. Usually, your body’s resistance is high enough to prevent damage when you’re exposed to low voltages. However, certain conditions can lower your body’s resistance, lowering the amount of voltage needed to cause you serious damage, such as giving you a nasty burn. Those conditions might include handling electronics with sweaty palms or trying to change your 12 volt (V) car battery on a rainy day — either can turn a slight tingle into a fatal event.
Both AC (alternating current, such as the power from your wall outlet) and DC (direct current, such as from a battery) voltage can damage you in different ways:
AC voltage: This type of voltage regularly reverses direction. This can cause your heart to shift its regular beating pattern in a condition known as ventricular fibrillation. If this happens, your heart muscles go out of whack in a way that causes blood to stop pumping. In this situation, even if you cut the current, your heart might not be able to find its proper rhythm, and you could die
DC voltage: This type of voltage is on constantly and causes your muscles to contract and seize up quickly (including your heart muscle). If you grab an electrical device in conditions that cause your body to conduct DC voltage, your hands could become frozen (unable to let go of the device), and your heart could stop. If someone cuts the current quickly, though, your heart might begin to beat again (and you’ll be able to attend that Rotary luncheon next week).
Short of killing you, electric shock can cause burns as the current dissipates across your body’s natural resistance (that is, your skin).
How much is too much?
Most resistance in your body is in your skin. If your skin is wet or damp, that resistance is lowered. If you handle an electrical device with damp hands, even voltages under 20V or so (not enough to even light a low-wattage lamp) might be sufficient to do you serious damage. The 120V coming out of your electrical outlet has a lot of punch: more than enough to kill you.
Four AA batteries in series — which is what we use in the projects in this book — generate only about 6V. We did that on purpose to keep you relatively safe.
Just because AA batteries don’t have a high voltage output, don’t think that they can’t hurt you. If you short them out, all the electrons will flow quickly from the negative to the positive poles and generate a lot of heat — enough heat, in some cases, to destroy the battery and possibly burn you. If you feel heat coming from your circuit or the batteries, you might have a short-circuit or a component inserted the wrong way. Turn it off and let things cool down; then check to see what’s causing the problem.
The resistance in your body can vary greatly. For example, if you have sweaty hands and touch a live wire with one hand while the other hand rests on a metal table, this is a very dangerous situation. Because you have moisture on your hands — which lowers your contact resistance — a higher current will flow through your body for a given voltage. If you have dry hands — one hand touching a live wire, the other hand in your pocket — and your feet on a dry, rubber mat, there’s far less danger from the same amount of voltage because your resistance is higher. However, if a higher voltage comes your way, even with the higher resistance, you could die. Bottom line: There is no iron clad rule as to what level of voltage will kill or seriously injure a person because of all the variables.
Common sense: Protecting yourself from getting shocked
Although you should always use care working with electricity, we want to let you know some common situations to avoid that could turn your body into a super conductor. You know you shouldn’t stick your finger into an electrical outlet (we hope!), but you should also get into some other good habits. Read on
Rings are out
Metal is a dandy conductor. Wearing rings or other metal jewelry around electricity is a lousy idea. For example, when the skin on your finger is surrounded by a ring (a terrific contact point) and you touch a voltage source, your body’s resistance can be very low. In that state, even a lower voltage jolt could do you serious damage. Leave jewelry somewhere else. (Tell your spouse or fiancée that we said it’s okay for you to take off your wedding ring when working with electricity.)
Another good reason to avoid jewelry is that it can snag on things. Imagine working on a breadboard filled with wires and tiny components, only to have your ring or necklace catch on something and yank it out. At the least, you have to put the component back in place; at the worst, you could damage the component and have to replace it.
Beware of water!
Don’t work in a wet environment (say, outdoors on a rainy day, or while standing on a damp garage floor). This prevention might seem obvious, but consider that cup of coffee on your workbench. What would happen if you knocked it over while working with electricity? You need to become super careful about anything wet or moist in or near your work area. This includes you: If you just came in out of the rain or from a run, dry off before working on electrical equipment.
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