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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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IC sockets come in different shapes and sizes, to match the integrated circuits they're meant to work with. For example, if you have a 16-pin integrated circuit, choose a 16-pin socket.
Here are some good reasons for using sockets:
^ Soldering a circuit board can generate static. You can avoid ruining CMOS or other static-sensitive integrated circuits by soldering to the socket rather than the actual IC.
^ ICs are often one of the first things to go bad when you're experimenting with electronics. The ability to pull out a bad chip and replace it with a working one makes troubleshooting a whole lot easier.
^ You can share an expensive part, such as a microcontroller, among several circuits. Just pull the part out of one socket and plug it into another.
Sockets are available in all sizes to match the different pin arrangements of integrated circuits. They don't cost much — just a couple of pennies for each socket.
Getting Wrapped Up in Wire Wrapping
Wire wrapping is a point-to-point wiring system that uses a special tool and extra-fine 28- or 30-gauge wrapping wire. When you do it properly, wire-wrapped circuits are as sturdy as soldered circuits. And you have the added benefit of being able to make modifications and corrections without the hassle of desoldering and resoldering.
You have to limit wire wrapping to projects that use only low-voltage DC. It’s not for anything that requires a lot of current, because the wire you use isn’t large enough to carry much current.
To wire wrap, you need
Perf board: You attach the components to this board. You can use a bare (no copper) board or one that has component pads for soldering. We personally prefer the padded board.
Wire-wrap sockets for ICs and other parts: These sockets have extra-long metal posts. You wrap the wire around these posts.
Tie posts: These posts serve as common connection points for attaching components together.
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248 Part V: A Plethora of Projects
Wire-wrap wire: The wire comes pre-cut or in spools. We prefer pre-cut wire, but try both before you form an opinion.
^ Wire-wrapping tool: You only have to use this specific tool to wrap wire around a post and remove it. The tool also includes an insulation stripper; use this, not a regular wire stripper, to remove the insulation from wire-wrap wire.
Though you can wire wrap directly to resistor, capacitor, diode, and other component leads, most people prefer using wire-wrap sockets. The reason? Most components have round leads. A wire-wrap socket has square posts. The square shape helps to bite into the wire, keeping things in place. If you wrap directly to component leads, you may want to tack on a little bit of solder to keep the wire in place.
Here’s the basic process for wire wrapping:
1. Insert a socket into the perf board.
If the board has solder pads, touch a little solder between one of the pads and the post sticking through it. This dab of solder keeps the socket from coming out.
2. Repeat Step 1 to insert all the other sockets that you may need.
3. Use the wire-wrap tool to connect components together.
4. Plug the ICs and other components into their sockets.
A big advantage of wire wrapping is that you can make changes relatively easily. Simply unwrap the wire and re-route it to another post. If the wire gets cruddy, just replace it with a new one.
There’s more to wire wrapping than we can cover here. If it sounds like a method you think would be useful to you, do an Internet search on “wire wrapping techniques” (include the quotes for more specific results). You can find numerous Web sites that help you become an expert wire wrapper-upper, such
as or http://www.okindustries.eom/products/
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Chapter 12
Building Your Own Printed Circuit Boards
In This Chapter
^ Understanding what goes into a circuit board ^ Exploring how you make a circuit board ^ Choosing copper clad for your board ^ Cutting a circuit board to size ^ Using the magic of photography to make PCBs ^ Making circuit boards with the help of Mr. Copier ^ Creating your own circuit boards from scratch ^ Etching, final prep, and drilling ^ Sending your circuit designs to a PCB manufacturer
¦# ou’re well on your way to being an electronics guru when you make your first printed circuit board. Forget all the wires criss-crossing from one place to the next on a breadboard or components stretched out over a premade soldering board. You know that you’re playing with the big kids when you hold up your very own custom-made circuit board, and say “I made this!”
To begin with, in this chapter, you discover just what makes up a circuit board. The electronic construction technique of choice for many is the printed circuit board, or PCB. There are a number of ways to build a custom printed circuit board for your project. This chapter details several methods, including direct etch, photo transfer, and laser film transfer. We also give you tips about how to use a computer to speed up your work.
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