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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
DO-IT-YOURSELF Here's the fun and easy way to start building circuits for your projects Have you ever wanted to build your own electronic device? Put together a thermostat or an in-line fuse, or repair a microphone cable? This is the book for you! Inside you'll find the tools and techniques you need to build circuits, with illustrated, step-by-step directions to help accomplish tasks and complete projects. As you accomplish the tasks throughout the book, you'll construct many projects while learning the key circuitbuilding principles and techniques. Find out about measuring and testing, maintenance and troubleshooting, cables, connectors, how to test your stuff, and more. Stuff You Need to Know * The tools you need and how to use them * How to make sense of schematics and printed circuit boards * Basic techniques for creating any circuit * How to make and repair cables and connectors * Testing and maintenance procedures
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Veröffentlichungsjahr: 2011
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Do-It-Yourself Circuitbuilding For Dummies®
Table of Contents
Circuitbuilding Do-It-Yourself For Dummies
by H. Ward Silver
Published byWiley Publishing, Inc.111 River StreetHoboken, NJ 07030-5774www.wiley.com
Copyright © 2008 by Wiley Publishing, Inc., Indianapolis, Indiana
Published by Wiley Publishing, Inc., Indianapolis, Indiana
Published simultaneously in Canada
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Library of Congress Control Number: 2007943806
ISBN: 978-0-470-17342-8
Manufactured in the United States of America
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About the Author
H. Ward Silver has the experience of a 20-year career as an electrical engineer developing instrumentation and medical electronics. He also spent 8 years in broadcasting, both programming and engineering. In 2000 he turned to teaching and writing as a second career. He is a contributing editor to the American Radio Relay League (ARRL) and author of the popular “Hands-On Radio” column in QST magazine every month. He is the author of the ARRL’s Amateur Radio license study guides and numerous other articles. He developed the ARRL’s online courses, “Antenna Design and Construction,” “Analog Electronics,” and “Digital Electronics.” Along with his comedic alter-ego, Dr Beldar, Ward is a sought-after speaker and lecturer among “hams.” When not in front of a computer screen, you will find Ward working on his mandolin technique and compositions.
Dedication
Circuitbuilding Do-It-Yourself For Dummies is dedicated to the many technical writers whose articles in QST, Popular Electronics, 73, CQ, Scientific American, among others, inspired me to cut and solder and tinker my way through high school. Getting an amateur radio license on the way, that practical experience led directly to my first career as an electrical engineer. Another dedication is due my students and readers that make my second career as a writer equally enjoyable. If I can do for you what they did for me, I’ll be very satisfied, indeed.
Author’s Acknowledgments
In the early days of electrical experimentation, before “electronics” was even a word, there was no choice but to build one’s own circuits. Back then, circuits were all about motors, lighting, and simple control systems. They were built with hammers, wrenches, screwdrivers, and, yes, soldering irons. Circuitbuilding was a full-body experience!
For a time not so long ago, it seemed that actually building one’s own circuits was an activity that would go the way of AC-DC motor and knife switch. Electronic gadgets had become so inexpensive and easy to use, why should anyone bother to build anything more complicated than plugging cables together? The Internet and personal computer took building out of the physical world and into the realms of the network and cyberspace.
That trend has reversed in recent years. People of all ages are rediscovering the thrill and satisfaction of learning-by-doing. They’ve found that “lifting the hood” is just as much fun for electronics and circuits as developing a Web site or hooking up the latest gadget from the store. Not only just building, but modifying or “hacking” equipment, is providing hours of enjoyment, too!
If you’re a budding circuitbuilder, welcome to the party! Join the thousands of ham radio operators, robotics enthusiasts, engineers, inventors, tinkerers, and hobbyists—people just like you. Heat up that soldering iron, turn on the voltmeter, and start building!
—H. Ward Silver
Publisher’s Acknowledgments
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Introduction
Perhaps you’ve never built anything electronic, and now you want to. Perhaps you have built something before, but now you want to do something different. Look no further. Circuitbuilding Do-It-Yourself For Dummies is the book for both kinds of readers. Primarily, this book is intended to act as an introduction and guide to someone just getting started with electronics and circuits. It covers basic tools and techniques. If you are somewhat experienced with electronics, you’ll find the book most useful as a workshop reference for specific kinds of tasks. The latter half of the book focuses on specific how-tos: cables, connectors, measurements, and maintenance.
There are so many circuits and applications of electronics that it is impossible to provide a detailed how-to guide for even a tiny fraction of the different types! The goal of this book is to show you the tools and techniques that circuitbuilders use, common to a wide variety of electronic construction needs.
This book presents basic techniques most useful to beginners. As such, you won’t find detailed discussions of advanced topics such as fabricating your own circuit boards or performing reflow soldering at home. Nevertheless, if you become familiar with the techniques in this book, it will be easier for you to move on to more sophisticated techniques. I’ll also give you pointers about where to find information on them.
This book is not a circuit design course or cookbook. I’ll be assuming that you already have a schematic from a book or magazine or maybe you’ve purchased a kit. This book shows you how to build it, not design it. The list of resources in Appendix A include quite a number of how-to-design books about electronics and even some online courses and tutorials.
What You’re Not to Read
As you make your way through Circuitbuilding Do-It-Yourself For Dummies, feel free to skip around to where your interests and needs take you. You don’t have to read each chapter in order. Use the Table of Contents or the Index to find help on a specific topic, such as wiring up a particular cable. The extensive Glossary in the back of the book will help with unfamiliar terms. Sidebars contain material that’s interesting but not required reading.
Assumptions About You
The subject of electronics is big and broad and deep, but don’t panic! You only need tackle the small steps at first — be comfortable and progress at your own speed. This book doesn’t expect you to have an engineering degree or a complete shop. In fact, I deliberately performed all of the tasks myself with the simplest equipment and tools, just to be sure my readers could do them, too!
What I do assume about you, however, is that you’re curious and motivated to build on the basic skills in Circuitbuilding Do-It-Yourself For Dummies. Take a few minutes to investigate the online resources I note throughout the book. You’ll also find an extensive list of resources in Appendix A.
Finally, you don’t have to run out and buy all of the tools and components shown in the book. I’m sure your local electronics emporium would love it if you did, but take your time! Each task lists the tools and materials needed, and you will be just fine if you acquire them as you need them.
How This Book Is Organized
Circuitbuilding Do-It-Yourself For Dummies is composed of six parts. You’ll get started with some electronic construction basics, then move onto specific tasks that show how circuitbuilding is done. From there you can read about techniques that support circuitbuilding like taking measurements and maintenance. A Glossary and the famous Parts of Ten wrap up the book.
Part I: Working Basics for Electronic-ers
This book doesn’t neglect the basics — tools and techniques. You may have most of the tools, already! If you don’t, this introductory part will help you get the ones you need. Then it’s on to simple techniques for working with the materials you’ll encounter when building circuits. I’ll also help you read and make sense of electronic schematics, the language of circuitbuilders.
Part II: Building Circuits
This part of the book presents several ways of working with electronic components and materials to turn an idea into a living breathing circuit. By learning the basic techniques, you can build even the most complex circuits. Then learn how to install your circuit in a simple enclosure.
Part III: Cables and Connectors
Take a look at the back of any stack of electronic gadgets and what do you find? Cables and connectors! Lots of them! Yet the “how to” of making and repairing cables is rarely presented. That information doesn’t get left out of this book! I cover all kinds of cables and connectors so that when your circuit is finally built, you’ll be able to make the necessary connections to other equipment, too.
Part IV: Measuring and Testing
You can’t see, smell, or touch electricity in your circuits — unless something goes pretty wrong! Testing and evaluating your circuits, then, takes some special electronic eyes and ears. This part of the book shows you how to use basic test instruments as part of the circuitbuilding process and during troubleshooting.
Part V: Maintaining Electronic Equipment
Circuitbuilding isn’t just about soldering components together. Once you’ve built your circuit, what then? This part of the book covers installation and troubleshooting along with information on batteries and dealing with interference and noise. All of these topics are mighty handy out there in the Real World!
Part VI: The Part of Tens
Familiar to all For Dummies readers, these are condensed lists of helpful and (hopefully) memorable ideas. In this part, you’ll get the top ten secrets of the art of circuitbuilding, as well as indispensable information on circuit first aid and some supplies you should keep handy.
Glossary
As you go through the book, specific technical terms in italics will often be found in the Glossary. Keep a bookmark in the glossary and you won’t have to gloss over a term you don’t understand.
Bonus Chapters
The book was so chock-full of critical info, we had to leave a few things out. But have no fear because you can find two bonus chapters on the Web site (www.dummies.com/go/circuitbuildingdiyfd) covering resistor and capacitor types.
Conventions and Icons
To make the reading experience as clear and uncluttered as possible, a consistent presentation style is used:
Italics are used to note a new or important term.
Web site URLs (addresses) use a monospace font.
Additionally you’ll see the following icons used as markers for special types of information.
This icon alerts you to a hint that will help you understand a technical or operating topic. These are often referred to as “hints and kinks” by circuitbuilders.
This icon highlights a new term or concept that you’ll need to know about. Be sure to check the book’s Glossary, as well.
Whenever I could think of a common problem or “oops,” you’ll see this icon. Before you become experienced, it’s easy to get hung up on some of these little things.
This icon lets you know that there are safety, rules, or performance issues associated with the topic of discussion. Watch for this icon to avoid common gotchas.
These icons remind you of an important idea or fact that you should keep in mind.
Where to Go from Here
If you are just getting started with electronics, I recommend that you read Parts I and II thoroughly and try a few of the tools and techniques. Building a kit (Chapter 4) is a great way to turn your newfound knowledge into a gadget you can really use — a great confidence builder! Then try a couple of the other techniques before striking out on your own. The tasks in Part III can be performed whenever they arise as you build circuits. Study the techniques in Parts IV and V and give them a try.
If you’re more experienced with electronics and want to use this book as a reference and how-to guide, be sure to scan through the book first. I’ll bet there are a few sections or tips that might be an “Ah, hah!” for you. The Table of Contents can serve as your reference for workbench use.
Appendix A lists many references and provides some bonus material about electronic components, too. Bookmark the sites you find most interesting or useful and you’ll have an instant electronic reference library! The print references listed in Appendix A are those that I’ve found to have a long useful life — many can be found in used bookstores or online at a fraction of their new cost. Even older texts will provide excellent information about how circuits work.
I couldn’t be more pleased to welcome all of you readers to the world of electronics and circuitbuilding. You’ll be able to use these tools and techniques for a long time. Learning them launched me into a lifetime of professional electronics that I’ve found to be both rewarding and enjoyable. I hope it’s the same for you!
Circuitbuilding Do-It-Yourself For Dummies
Introduction
Circuitbuilding Do-It-Yourself For Dummies
Part I
Working Basics for Electronic-ers
In this part . . .
Are you ready to roll up your sleeves and get started? Well, the handiest place to begin is a tour of the toolbox and a review of a few techniques that every circuitbuilder must master. The better you are equipped and the more experience you have in building, the better you will be at this craft.
This part begins with a chapter that covers the physical tools that you’ll need to create the circuits. Along with the hardware, you’ll be introduced to some low-cost, easy-to-use software that makes circuitbuilding (and designing!) much easier.
And what book on electronics would be complete without a discussion of soldering? The second of these chapters introduces you to the fine art of melting solder. There’s also some information about how to install your circuits in enclosures and on working with metal and plastics. Finally, get a handle on reading schematic diagrams — your roadmaps to understanding circuits everywhere!
Chapter 1
The Toolbox
Tasks Performed in This Chapter
Basic tools for electronic construction
The solderless breadboard
Keeping a notebook
Software tools and utilities
To build anything, large or small, using the right tools makes a huge improvement in the quality of the finished product. The right tools will also speed up the process of building, minimize wasted materials, and reduce operator fatigue and stress. Sounds pretty important to have the right tools, doesn’t it? You’re right! This chapter shows you which, out of the zillions of tools, are the ones to use for building electronic circuits.
Basic Tools for Building Circuits
You’ll be pleasantly surprised to find that you don’t need a giant set of fancy tools to do excellent work! In fact, you may have most of them already and a couple of additional acquisitions are all that’s needed.
Mechanically speaking, you’ll need squeezers, cutters, turners, pokers, holders, and hole makers. That’s pretty simple, isn’t it? Of course, there is an incredible variety of available tools. I’ll list the basic items you really need, ways to upgrade them, and some optional tools that are handy but not necessities. Then you go shopping!
Buy the best tools you can afford — always! Then take care of them — always! With care, tools will last a literal lifetime. The author’s toolbox has perfectly functional and often-used tools that are 40 years old or more. Avoid bargain-bucket and no-name tools. An all-in-one tool is handy at times, but is no match for a single-purpose tool. Buy from a store with a no-questions-asked return policy that stands behind their tools.
The selection of tools listed in this section has been made with electronics in mind, not robot assembly, plumbing installation, or home wiring. Tools for those jobs are often inappropriate for the smaller scale of electronics. Conversely, electronic tools are often overmatched for beefier work. There is no one-size-fits-all tool selection!
The Klein Company has specialized in tools for electrical and electronic work for decades. They have an excellent selection of tools designed for every possible use at the electronics workbench. Their online catalog (www.kleintools.com/ToolCatalog/index.html) is a great reference. Klein is my favorite, but there are many other fine tool companies. Ace Hardware has a comprehensive introduction to many common types of tools on their Web site at www.acehardware.com. Click ProjectsÍSolutionsÍLearning Guides to access the directory of informative pages.
Safety and visibility
Before you head off to the hardware store with a big list, be sure that right at the top you include some basic safety equipment — goggles (or safety glasses), workspace ventilation (for soldering smoke or solvent fumes), and first aid. Electronics may sound tame, but the first time you snip a wire and hear the sharp end “ping” off your safety glasses or take them off and find a small solder “splat” right in front of your eye, you’ll be glad you had them on!
It sounds trite, but you really do need to be able to see what you’re doing! There are two paths to seeing your electronics clearly; lighting and magnification. Your workspace simply has to be brightly lit, preferably from more than one angle to minimize shadows. Inexpensive swing-arm laps with floodlight bulbs are good choices because they can be moved to put light where you need it.
Head-mounted magnifiers are inexpensive and lightweight. The Carson MV-23 dual-power magnifier (www.carsonoptical.com/Magnifiers/Hands%20Free) is widely available and provides both x2 and x3 magnification. Swing-arm magnifiers, such as the Alvin ML100 (www.alvinco.com), can be positioned in front of your face and provide additional illumination, too. Magnifiers are often found at craft and sewing stores for considerably less cost than at office or technical-supply stores.
Pliers and tweezers
In the “squeezer” category are pliers and tweezers. The largest electronic thing you are likely to have to grab with pliers is a half-inch nut; the smallest will be tiny set screws. Pliers and tweezers that fit things in that range are good to have in your toolkit. Figure 1-1 shows a few examples of the pliers and tweezers that I use a lot.
The most common type of pliers are slip-joint pliers (8”) which have jaws that can be adjusted to grip large or small things. A small pair of locking pliers (6”) (optional) — also known as Vise-Grips™, come in very handy when working with connectors and can be used as an impromptu clamp or vise.
Needle-nose pliers (a generic term that covers many different styles of pliers) with serrated jaws are a necessity. You’ll need a heavy pair of combination long-nose pliers (8”–9”, with or without a side cutter) for bending and holding. Smaller needle-nose pliers (5”–6”) will be used for positioning and holding delicate components. Additional pliers with extra-fine jaws (or bent-nose pliers) are nice to have in the toolbox, but not required.
Figure 1-1: This set of pliers and tweezers will grab anything you’re likely to encounter in electronics.
Tweezers are absolutely necessary when working with surface-mount devices (see Chapter 4) and small mechanical assemblies. They should be made of stainless steel; you’ll need a pair with a blunt nose and a pair with pointed tips. Do not use regular bathroom or cosmetic tweezers — they’re not really designed for electronics jobs.
Cutters and knives
Two pairs of wire cutters will suffice. For heavy wire, coaxial, and data cable, you’ll need a pair of heavy-duty diagonal cutters (6”) like those in Figure 1-2. Get a pair with comfortable handles so that when you squeeze really hard you won’t hurt your hand. For small wires, such as component leads, a 5” pair of flush-cutting, pointed-nose or blunt-nose cutters is appropriate.
As you use your cutters day in and day out, they’ll naturally lose their fine edge — although they may still cut wire just fine. For trimming very small wires, such as coaxial cable braid, you’ll want a pair of very sharp cutters. It’s a good idea to have one pair of “everyday” cutters and another pair used only for fine jobs — a miniature pair of pointed-nose cutters is good — and make sure those stay sharp.
A sharp knife is a must. For electronics-size jobs, a utility knife with a retractable segmented blade is a good choice. As the tip or edge dulls, you snap off the knife blade segment to expose new, sharp cutting edges.
Heavy scissors are used frequently and can even cut the lighter thicknesses of printed-circuit (PC) board. They will also be used to cut lighter gauges of sheet metal, such as aluminum and brass.
Figure 1-2: The essential cutters and knives.
Screwdrivers and wrenches
Your toolbox should include both Phillips and flat-blade screwdrivers in sizes #0, #1, and #2. An optional long-shaft (8” or longer) screwdriver is useful for getting at long cabinet-mounting screws in recessed locations. The many different types of screwdriver blades are explained and illustrated at www.acehardware.com/sm-learn-about-screwdrivers--bg-1266832.html.
A miniature flat-blade screwdriver with a 3/32” blade will come in very handy as a general-purpose poker, pusher, and stirrer. It is particularly useful for mixing and applying epoxy! (Just don’t let epoxy harden on the blade.)
Jeweler screwdrivers are handy, but not required. You’ll use them mostly for attaching knobs to control shafts. If you do buy a set, make sure the shafts don’t slip in their handles and that the blades are of good-quality steel. A lot of torque is applied to jeweler’s screwdrivers; it’s easy to twist off a blade or ruin an irreplaceable miniature screw if the blade isn’t tough enough.
Obtain a set of nutdrivers for nuts from 1/4” through 1/2”. These fit the nuts for screw sizes from #4 through 5/16”. The larger nutdrivers also fit switch- and control-mounting nuts. They will tighten the nuts without scratching a front panel and can be used on congested panels where a regular wrench can’t be used.
Another optional tool is a miniature Crescent® wrench smaller than 6 inches long. Most mechanical fasteners used in electronics are too small for wrenches, but enough are large enough for the Crescent wrench to be a welcome sight in the toolbox.
A set of Allen wrenches is optional, but when you really need them (mostly for set screws), they have no substitutes. If you have a choice of buying a set of individual wrenches or a set mounted on a handle, the individual tools are somewhat easier to use (and lose). In addition, the ball-end wrenches can be used at an angle to the screw — which is sometimes necessary in tight quarters. Figure 1-3 shows several examples of screwdrivers, nutdrivers, and wrenches.
It is common for adjustable devices to come with an Allen wrench that fits their mounting set screws. When you’re done installing the device, put the wrench in a locking plastic bag and label it with a permanent marker. You’ll be able to find it much easier when the adjustment or mounting has to be redone later.
Drills and drill bits
To build electronic stuff, you’ll need a small electric drill. A cordless model makes working on a car (or in the field) much easier, but cordless is not required. A 3/8” chuck is big enough for electronic needs. A hand drill can be used on plastics, but is not recommended for general use. If you plan on installing your circuit in cabinets or project boxes with knobs or switches — especially with front panels that need to look good — invest in a small bench-mount drill press. It gives you dramatically improved ease of use and finished quality compared to what you get with a hand-held drill.
Figure 1-3: An assortment of screwdrivers is complemented by a set of nutdrivers. The miniature Crescent wrench and Allen wrenches round out the collection.
For delicate jobs, enlarging small holes, or just cleaning out a pre-drilled hole, a replacement drill chuck can make a fine hand-held holder for a drill bit. The machined metal chuck fits well in the hand and works like a handle for the bit; its size allows reasonable control of the bit.
You’ll need an assortment of drill bits from 1/16” to 3/8”. It’s not necessary to have dozens of sizes and standard twist bits will suffice. A complete discussion of drill bit types and applications is available on the Ace Hardware Web site (www.acehardware.com). Add an optional countersink bit to your collection of drilling tools to smooth the edges of holes.
While drilling small panels and enclosures, you should use a vise. For temporary and portable use, purchase a small machinist’s vise or a small bench vise that clamps to the work surface. Trying to hold the material being drilled by hand often results in damage to your enclosure or panel — and if the material is seized by the drill bit, you can be injured. Examples of both can be viewed at www.lexic.us/definition-of/machinist’s_vise.
It’s important to mark a hole’s center before drilling to prevent “walking” or wandering by the drill bit before the hole is deep enough to control the drill’s position. A center set punch is tapped with a hammer, leaving a small dimple that can be placed precisely where the hole is to be drilled. Or you can use a nail, saving a bit of dough at the cost of a tiny bit of precision.
A scratch awl is handy for a number of punching and poking tasks. It can do the job of a center set in soft metal, plastic, and other soft materials. It makes holes in all sorts of flexible coverings. In wood, it can make a deep enough hole for a wood screw to be inserted.
A 1⁄2” hand reamer is used to enlarge a small hole. Using a reamer is often easier than drilling a large hole, especially in brittle plastics. An example showing how a reamer is used can be found in Chapter 5. Needle files come in a set including round, half-round, triangular, square, and other cross-sections (see Figure 1-4). They are used to smooth holes or file them into custom shapes.
Figure 1-4: A set of drill bits and simple tools are all that is needed for basic electronic construction.
The toolkits made by Kronus and Belkin include good, reasonable-quality starter tools. They are available from many electronics and tool retailers, including RadioShack, Sears, CompUSA, and others. You can replace individual tools with higher-quality selections as is convenient.
A somewhat odd, certainly optional, but very handy tool for circuitbuilders is the nibbling tool. All holes are not round! You may find that a display needs a rectangular cutout in a panel or that an elongated connector needs a rounded slot. Instead of drilling a lot of holes and then filing away (that works, but it takes a while), the nibbling tool shown at http://adelnibbler.com/index.html takes small bites out of sheet metal (and other thin material) in just about any shape you need!
Special electronic tools
As you put your circuitbuilding projects together, you’ll find that you need a few specialized tools. You’ll need some kind of wire stripper to remove insulation. A number of tools include wire-stripping capability, but they don’t work as well (or as conveniently) as a tool made specifically for that purpose. The stripper should have individual positions for different sizes of wire, such as the Kronus 64-2980 available from RadioShack (www.radioshack.com). An automatic stripper (Kronus 64-2981) doesn’t require pulling on the wire and is bulkier than the plier-like stripper — but it is fun to watch as it works!
Working on circuit boards and small devices is a lot easier if they are held firmly and at a convenient angle. The Panavise 301 vise shown in Figure 1-5 (www.panaviseonline.com/index.php) is made specifically for electronic and other detail work. The head of the vise swivels and turns 360 degrees. The PC board vise head has extra-wide jaws that can open wide for big boards.
Figure 1-5: The Panavise family of benchtop vises is designed for working with electronics and other small projects.
Some of the tasks later in this book require specific tools that do something unique — for example, the crimping tools used to install connectors (as shown in Part III of this book). Soldering equipment is covered in Chapter 2.
Measuring sticks
A small, metal mechanic’s rule is a must-have in the electronics toolbox. Most are 6” long with one side marked in metric units (mm and cm) and the other in English units (inches and fractions of inches). Because it’s made of metal, it doubles as a conveniently firm straight-edge for marking or cutting. A short tape measure is also useful.
Stop giving me static!
As you peruse tool catalogs and Web sites, you’ll see a number of accessories that dissipate static from people and tools. Why is this important? Well, if you’ve ever walked across a room and gotten a shock when you touched a doorknob, imagine that same amount of energy applied to a defenseless little transistor or IC! Suddenly, ESD (Electrical Static Discharge) protection starts to make sense!
A thorough introduction to ESD (www.esda.org/basics/part1.cfm) is published by the ESD Association, an electronics industry group that researches ESD protection. You can learn all about the different tools and techniques that prevent roasting your electronic components with a spark.
If you live in an area that is very dry on occasion, the best way to add ESD protection to your workspace is a static-dissipating mat and a personal grounding clip. Both of these connect to a safety ground and conduct excess charge away from sensitive electronics.
A permanent ruler is an option if your workspace allows. Use a yardstick to make permanent markings directly on the work surface. If you have a broken or cut tape measure, tack a length of the tape to the work surface. Being able to measure a cable or wire or other material without having to get out a new tool saves a lot of time!
Optionally, you may want to pick up a set of calipers to measure inside and outside widths and diameters, thicknesses, and even depths. Excellent quality calipers are available for a few dollars if you learn to read a vernier scale as instructed at www.marylandmetrics.com/tech/calipuse.pdf.
The Solderless Breadboard
One of the keys to learning about electronics is convenience. That is, learning and experimenting and testing should be as easy as possible. One way to make it easy is to use tools and techniques that reduce expense and bother. An excellent example of such a tool is the solderless breadboard. Using a breadboard is one of the basic starting points for the design of many types of circuits and projects. Also known as a plugboard or prototyping board, this miniature workbench allows you to whip up a circuit or try a new design in just minutes!
Using a breadboard
Figure 1-6 shows two examples of breadboards available from electronics parts and tool vendors. You can probably pick one up at your local RadioShack store. Models are available from postage stamp-sizes used for trying small circuits inside equipment all the way to foot-square models on which entire complex circuits can be built. A small one will do just fine as you start out, but it’s a good idea to buy one size bigger than you think you need. You’ll find yourself quickly outgrowing it, otherwise.
Figure 1-6: Two examples of solderless breadboards available from electronic retailers.
A solderless breadboard consists of plastic strips with small holes into which the leads of electronic components are inserted. (Figure 1-7 is a simplified drawing of a breadboard.) Brass strips under the holes connect each short row of openings together. Any two leads inserted into the same row of holes will be connected together electrically. The plastic body keeps adjacent strips from shorting together.
Up to four leads can be connected together in this way. If more common connections are required, a short piece of wire can be used to connect two (or more) rows together, creating a common electrical contact between all the holes in those rows. The slot between halves of the plastic strip is an insulating gap between the two sides so that integrated circuits with a DIP (Dual In-line Package) can be inserted with one row of pins on each side of the strip.
Figure 1-7: Typical organization of breadboard connections. Check the manual or use a voltmeter to see how your contacts are organized.
Most breadboards have areas for point-to-point circuit wiring and areas for distributing power and ground. These are called rails and run the length of the breadboard’s plastic strips. For analog circuits, these are generally used for positive and negative power supplies, plus a common ground or return to the power supply. Builders of digital circuits that operate from a single voltage find it easier to “double up” and use the extra rail for a duplicate power-supply connection. Breadboards with more than one strip, each with its own set of rails, are easy to use for circuits that have both analog and digital circuitry.
If you are just getting started, you might consider purchasing a breadboard that comes with its own power supplies and possibly even some limited test capabilities, such as the Jameco 1537264 (www.jameco.com). More expensive models even have test meters and test signal generators.
While separate power supplies and test equipment might be more flexible and have additional features, the convenience of always having the test equipment connected and ready (remember?) will be appreciated.
Figure 1-8 shows some typical components inserted into the breadboard, ready to be “wired up.” While circuits can be easier to build and troubleshoot with all the components laid horizontally, this generally isn’t required. Here short pieces of solid wire make the connections from point to point around the circuit. Don’t use stranded wire; the strands will move apart and cause hard-to-find short circuits.
Figure 1-8: Component leads are inserted into the breadboard holes. Strips of contacts under the holes allow other components to be connected at the same point.
What is a breadboard anyway?
Back in the old days, breadboards were literally just that — a wooden board on which loaves of bread were cut. Early electronics experimenters knew that these breadboards didn’t conduct electricity (much), wouldn’t catch fire (usually), and were cheap (definitely). That made breadboards just the right base for building a circuit — which in that era meant vacuum tubes: relatively high voltages and rather large components. Many a wireless set or amplifier was constructed with sockets and terminal strips screwed to the soft wood of the kitchen breadboard! Although it’s unlikely that you’ll be slicing any loaves on modern breadboards, the name has stuck. In fact, the term breadboarding has come to mean the “roughing out” or “prototype” stage of designing and building electronic devices.
Breadboard materials
In keeping with the theme of convenience, breadboards hardly need any special materials to use! You’ll need some test equipment to power and measure your circuits, certainly, but aside from the components themselves, little is needed. Here is a list of things you’ll need:
Insulated jumpers(20- to 24-gauge solid, insulated wire in various colors): It doesn’t have to be tinned (coated with solder); bare copper is fine. A good source of suitable wire is scrap lengths of 4-conductor telephone wiring cable using for wiring the wall jacks (not the flat cable used to connect phones and wall sockets).
Bare jumpers (20- to 24-gauge solid bare wire): This is used to connect adjacent rows of contacts, to create connection points for external equipment, or make leads for items that don’t have suitable leads for insertion into the breadboard sockets. Save the clipped-off pieces of component leads to create a bountiful supply!
Leaded components: It’s very difficult, if not impossible, to use surface-mount technology (SMT) components with a breadboard. Make the task easier by purchasing and stocking only leaded components.
That’s it! No special tools other than needle-nose pliers and a small pair of wire cutters are needed. You may also want to augment your eyesight by purchasing a pair of head-mounted magnifier glasses from a local craft store for a few dollars.
Limitations of breadboards
The breadboard sounds like a perfect way to build circuits, doesn’t it? There are limits, however — and you should keep them in mind.
Current and voltage limits
The small contacts in a breadboard mean that they can only handle so much current before they are damaged by heating. Check the manufacturer’s specification on how much current is safe. Higher currents can also melt the plastic strips. High voltage is often a problem, too, since the plastic insulation is only so thick. Arcing can also damage a breadboard. Whether from excessive voltage or current, damaged breadboard contacts can’t be used reliably — and can’t be repaired. A good rule of thumb is to limit breadboards to circuits that use a maximum of 100 mA and 50 V. If your circuit uses higher currents and voltages, it’s a good idea to change your building methods or construct a separate circuit that only makes low-current connections to the breadboard circuit.
Frequency limit
The convenience of having lots of contacts and connections made of small wires has a drawback in poor performance for high-frequency signals. At high frequencies, the wires start to look like small inductors, upsetting circuit performance. Further, the many rows of closely spaced contacts act like small capacitors. Both the inductors and capacitors affect circuit performance in unpredictable ways. It’s also harder to create a good, solid ground connection for a circuit of any complexity that’s built on a breadboard. Another good general rule is to limit your circuit’s highest frequencies to about 500 kHz. For digital circuits, the clock-speed limit is 1 MHz. Above those frequencies, your circuit won’t be behaving the same way it will in a final version built with better techniques.
Contact wear-out
If you are a frequent builder, you’ll probably start wearing out the breadboard’s contacts. For example, some of the contacts will loosen, weakening their grip on a lead or wire. This is hard to detect — and can lead to intermittent problems that are difficult to assess and fix. If a contact has been overheated or has an oversized wire stuffed into it, its grip on smaller wires is relaxed. The connection points at one end of a power rail are particularly prone to this problem. Since you can’t repair those contacts, it’s best to mark which ones are bad and not use them again.
Your Notebook
The most important tool isn’t one that lives in your toolbox, it’s the one between your ears! The sharpening and lubricating for this tool comes from a notebook. Almost any old notebook will do — even one with cartoon characters on the cover. While a notebook filled with graph paper is the best, regular old lined or blank paper is fine. The important thing is to have a handy place to write down information as you work on projects.
Your notebook can be a record for design ideas, construction and installation notes, test results, project ideas — anything that you think goes in the notebook should go in the notebook. Believe me, you’ll be a believer when you can go back into a years-old notebook and quickly find just the right circuit or look up the color code of a control cable you installed way back when!
Make a habit of opening the notebook before you even start work!
Software Tools
Can software be a tool for building electronics? Sure it can! If you can draw it on paper or calculate it, there is a software tool to help with the job. The only thing software can’t do (yet) is fire up the iron and melt solder on that PC board. That’s still your job, but by using the appropriate software, what you build will be finished faster and work more like what you expected.
There are far too many programs to try or even list, so only a few are mentioned here. More software is available all the time. If you do an Internet search for “free electronic design software” you’ll be directed to Web sites such as the University of Nebraska’s Electrical Engineering Shop page (eeshop.unl.edu/cad.html) or Technology Systems (www.tech-systems-labs.com/freesoftware.htm). They list many, many programs for you to try. Experiment and choose the ones you like!
Schematic and PC board layout
The actual term for the software with which you draw schematics is schematic capture. Software you can use to lay out your own circuit boards is PCB layout. The following packages listed here include both functions. While professional packages can cost thousands of dollars, there are some capable packages available for free or at very low cost. Free versions are usually limited in how many pins (meaning IC pins) can be used — and the designs may not be used for commercial purposes. For a beginner in circuitbuilding, these versions are just fine! Here are a few:
Easy PC (www.numberone.com)
Dip Trace (www.diptrace.com)
Eagle (www.cadsoft.de; click Freeware)
Designworks Lite (www.capilano.com/dwlite.html)
There are also low-cost PC board fabricators that provide schematic-capture and layout software (Express PCB, www.expresspcb.com) but they are usually proprietary packages that don’t let you interface to other fabrication services. Nevertheless, this might not be a problem if such a package suits your purposes.
If you are familiar with PowerPoint software and only want to draw schematics that look good without any advanced features, a free package of schematic symbols developed by the author is available from the American Radio Relay League’s Technical Information Service at www.arrl.org/tis/info/HTML/Hands-On-Radio.
Electronic simulators
The power of the PC is really put to work in electronic circuit simulators that can predict how your circuit will work. With a simulator, it is possible to do almost all your developmental work at the computer — and only turn on the soldering iron for the final version. To be sure, there are many subtle factors in circuit design that a computer doesn’t know about or can’t handle well, but these are well beyond what a beginning circuitbuilder worries about.
Simulators are powerful programs; they have a steep learning curve when you get beyond simple simulations. Nevertheless, there’s no time like the present to try them out! These two packages are evaluation versions of professional-level circuit simulators:
Micro Cap (www.spectrum-soft.com/index.shtm)
Intusoft ICAP (www.intusoft.com)
The Linear Technology software, LTSPICE, is a capable version of the public-domain circuit-simulator program, SPICE. It’s completely free from www.linear.com/designtools/software/index.jsp and also includes a switching power-supply design package.
Mechanical drawing software
It’s also important to be able to make accurate drawings of panel layouts and other mechanical parts that are part of your project. Software that does mechanical drawings is called CAD for Computer-Aided Drafting. There are many inexpensive or free software packages (enter “cad drawing freeware” into an Internet search engine) for the downloading. Here are some general purpose drawing packages to try:
Vector Engineer (www.vectorengineer.com)
CadSted (www.cadstd.com)
There are also software packages for specialized drawing applications:
Scale (http://stiftsbogtrykkeriet.dk/~mcs/Scale.html) is a Web application to design meter scales and control dials. You enter the data for your scale and it sends you a graphic file you can edit or print.
Dial and Panel (http://hfradio.org/wb8rcr) are simple programs to make dial scales and design front panels.
Gpaper (http://pharm.kuleuven.be/pharbio/gpaper.htm) draws any kind of graph paper you can think of!
Utilities and calculators
Literally thousands of utility software packages are available on the Internet. If you need one for a specific purpose, just type the purpose plus “design utility” into an Internet search engine — for example, “555 timer design utility” or “555 timer design calculator” — and dozens of programs and Web sites pop up. Caveat emptor (or, in this case, browser), of course; you don’t know the pedigree of these programs. There is also a nice listing of electronic calculator programs at 101science.com/Radio.htm#Calculators.
As you collect the URLs for online calculators, set up a folder in your browser’s Favorites list specifically for calculators. That way they’ll always be easy to find.
You don’t have to download every calculator individually as there are some very nice packaged sets. Here are two of my favorites, both free:
Hamcalc(www.cq-amateur-radio.com/HamCalcem.html) has dozens of routines for all sorts of electronic design tasks.
Convert(http://joshmadison.com/software/convert) is a terrific little utility that I leave on my PC desktop for whenever I have to convert a value between units of measure — say, barrels to pecks. Seriously, this is one of those tools that occasionally saves a whole lot of time.
Chapter 2
Basic Techniques
Topics and tasks in this chapter
Metalworking
Making a practice panel
Learning to solder
Desoldering
Reading and drawing schematics
The mechanical part of electronic construction is usually quite straightforward. Circuits and their operating controls and connectors need to be mounted in a protective enclosure or housing and the circuits themselves need to be constructed properly. In this chapter, you’ll be introduced to the basics of working on enclosures and panels made of sheet metal and plastic.
Soldering is a fundamental skill to the electronic technician. If you’ve never soldered, now is the time to learn. It’s not hard and this chapter will get you started.
Finally, it’s hard to work with electronics if you don’t know the lingo of schematic diagrams. This chapter introduces the basics of schematics, both reading them and drawing them for others to read.
Basic Metalworking
Metalworking — it sounds so . . . so . . . industrial! Can’t you just see the red-hot metal and sparks and anvils? Well, you don’t have to heft a 16-pound blacksmith’s hammer to do the kind of metalworking required for electronics. Most of the metal you’ll encounter is light sheet metal, easily worked with hand tools no more complicated than a drill. You are actually more likely to work with plastic than metals. The same techniques apply to both materials.
Nearly all of the mechanical building for electronics that you’ll do as a beginner will involve mounting components on an enclosure or a panel for an enclosure. For example, connectors, controls, indicators, and switches all need mounting holes. Good-looking panels can be made with common hand tools and patient attention to detail.
To show you how easy making a panel can be, the following task shows you how to make a practice panel. The material that you use can be just about any scrap piece of sheet; aluminum, or plastic, even PC board material. Metal should be no thicker than 16-gauge and plastic no thicker than 1⁄8”.
Making a Practice Panel
Stuff You Need to Know
Toolbox:
• Drawing software, center-set or scratch awl or nail, electric drill, 1⁄8” drill bit, 1⁄2” reamer, round needle file
Materials:
• Panel-mount variable resistor with 3⁄8” bushing (including mounting nut and lock washer)
• Miniature toggle switch (SW) with 1⁄4” bushing
• T 1-3⁄4 (5mm) LED
• Scrap or metal or plastic sheet, 2” × 4”
Time Needed:
Less than half a day
The key to getting your finished product to look good is to start with a carefully measured and marked layout. Rather than work directly on the panel, it’s a lot easier to use software to lay out the controls and use a printed paper picture as a template. You can then mark the location of each hole or cut on the panel, using the template as a guide. The small amount of extra work at the beginning leads to higher-quality results and fewer mistakes.
1. Use a drawing program (perhaps the program named “Panel” referenced in Chapter 1 or even PowerPoint). If you don’t have drawing software, use graph paper and do an accurate job by hand. Place the corner mounting holes symmetrically at each corner. Locate and place the three holes on the horizontal center-line (the C with the L drawn through it is the symbol that denotes center-line). Locate and place the array of six 1⁄4” holes (marked “1⁄4 × 6”) symmetrically around the vertical center-line. (Absolutely exact spacing isn’t important on this practice panel.)
2. Print out a full-scale layout that is the actual size (4” × 2”) of the panel. Place the finished layout upside down on a flat surface.
3. With the surface of the panel that you want to be the front facing down, place the panel on the back of the printed layout. Align the panel to fit between the corner marks. Use two or three strips of tape to hold the panel to the back of the layout.
4.
