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Electronics for dummies - McComb G.

McComb G., Boes E. Electronics for dummies - Wiley publishing, 2005. - 433 p.
ISBN: 0-7645-7660-7
Download (direct link): electronicsfordummies2005.pdf
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¦# ou may think that you’d get funny looks if you ask for a “breadboard” at your local super-duper electronics-parts mart. After all, what does bread have to do with electronic gizmos? But no, you can expect to get a smile of appreciation for your do-it-yourself spirit, and the friendly sales staff will point you to the make-your-own-circuits aisle. In that aisle, you find a bunch of funny-looking white square or rectangular plastic thingies with more holes than Swiss cheese.
These little critters are circuit breadboards, and you use them to experiment with all kinds of electronic ideas without having to warm up your soldering iron. You use them to create a sort of rough draft of a circuit board that you can play with before you go to the trouble of creating a finished, printed circuit board. It’s easy to fix mistakes at the breadboarding stage.
In this chapter, we tell you all about circuit breadboards and how to use them. They’re pretty simple, actually. You don’t need a degree in engineering to use them, but we do have some tips and suggestions that you don’t want to miss.
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234 Part V: A Plethora of Projects
We also include a couple of circuit board construction techniques in this chapter, including point-to-point wiring and something called wire wrapping. You can use these techniques when you’re ready to make a permanent circuit.
For now, though, you just play!
Taking a Look at Solderless Breadboards
Circuit breadboards, also called prototyping boards or solderless breadboards come in all shapes, styles, and sizes, but they all serve the same function: They have columns of holes that little slivers of metal connect electrically. You plug in components — resistors, capacitors, diodes, transistors, integrated circuits . . . you name it — and then string the wires to build your circuit. When you’re confident that the circuit works, you can use one of the many construction techniques available to you. (We talk about some of your construction options in Chapter 12.)
Don’t skip the step of first testing all the circuits that you plan to build on a solderless breadboard. Often, you can improve on the performance of the circuit just by tweaking a few component values. You can easily do these changes by simply removing one component on the breadboard — without having to unsolder and resolder — and exchanging it for another.
The following sections tell you everything you ever wanted to know about solderless breadboards.
Solderless breadboards, inside and out
A solderless breadboard, like the basic model in Figure 11-1, consists of a series of square holes, and inside the holes are rows and rows of metal strips. The metal strips, which are made of a flexible material, have been bent to make a channel. You slide wire into the holes and securely connect it inside the metal channel.
You call the metal channels inside the breadboard contacts. Each column in each row connects electrically. Each column connects together five holes, all also electrically joined. With this setup, you can connect components and wires just by plugging them into the right holes on the board. See Figure 11-2 for a visual representation of how the columns in a breadboard connect electrically.
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Chapter 11: Creating Your Own Breadboard Circuit 235
Figure 11-1:
A basic solderless breadboard.
Figure 11-2:
Breadboards consist of columns that connect electrically inside.
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236 Part V: A Plethora of Projects
Note also the long rows of contacts at the very top and bottom of the solder-less breadboard. These rows help you make convenient connections to power and ground. Most boards have two rows at the top and bottom. In some boards, the two rows connect electrically, but on others, each row is electrically isolated from the other. Don’t assume! Use your multimeter to check by sticking a jumper wire in each hole and then touching one probe to one wire and another probe to the other wire. If you get a low ohm reading, the two rows are connected together. If you get an infinite ohms reading, they’re not connected. See Chaper 9 for more about testing things with your multimeter.
The holes are spaced Xo of an inch apart (0.100 inch), a size just right for integrated circuits, most transistors, and discrete components, such as capacitors and resistors. You just plug in ICs, resistors, capacitors, transistors, and 20- or 22-gauge wire in the proper contact holes to create your circuit.
Solderless breadboards are cheap . . . er, inexpensive
Author Gordon McComb here to relate a little personal story: For years, and I mean years, I got by with a single solderless breadboard. Every time I wanted to try a new circuit, I had to disassemble the old one to make room for my latest and greatest idea. Sometimes I wasn't completely finished with the old circuit, so I had to rebuild it from scratch. That meant taking apart my new circuit and reconstructing the old one. Needless to say, this process was very time consuming (and more than a little annoying).
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