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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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Chapter 11: Creating Your Own Breadboard Circuit 239
Table 11-1 Pre-Stripped Wire Lengths and Quantities
Length Quantity
% inch 10
1 inch 20
1% inch 25
I1/ inch 25
2 inch 10
2X inch 10
3 inch 10
4 inch 5
6 inch 5
You may find that you need more wires of some lengths than you get in the assortment, so buy two. But the odds are that one day you will be missing one length of prestripped wire, and youíll have to strip a wire or two. You can actually cut your own lengths, and then use a wire stripper to do the job. Itís best to use a stripper that has a dial adjustment. Set the dial for the gauge of wire that youíre using, say 20 or 22. This setting prevents the stripper from nicking the wire; nicks weaken the wire. A weak wire can get stuck inside a breadboard hole, which can ruin your whole day.
To make your own breadboard wire, follow these steps:
1. Cut the wire to length.
2. Strip off about J4- to /3-inch of insulation from both ends.
While stripping the insulation, insert one end of the wire into the stripping tool and hold the other end with a pair of needle-nosed pliers. If you have an automatic wire-stripper/cutter tool (available at some hardware stores; check the electrical parts section), you can cut the wire and strip the insulation in one easy step.
3. After stripping the insulation, use a pair of needle-nosed pliers to bend the exposed ends of the wire at a 90-degree angle, as you can see in Figure 11-4.
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240 Part V: A Plethora of Projects
Figure 11-4:
You strip and bend the ends of breadboard wire to insert them into the board.
Breadboarding techniques
Over the years, through trial and error, weíve discovered some tips for using solderless breadboards. To save you the painful learning curve, here are some of our favorites:
Use a chip inserter/extractor (most stores that sell electronics stuff sell these; they are about the shape of a ballpoint pen) to implant and remove ICs (integrated circuits). This nifty tool reduces the chances that you damage the IC while handling it. If youíre working with CMOS chips, which are especially sensitive to static electricity, ground the inserter/ extractor tool to eliminate stray static electricity. (If you need a refresher on integrated circuits, both the CMOS and TTL varieties, take a look at Chapter 4.)
When youíre using CMOS chips, build the rest of the circuit first. If you need to, use a dummy TTL IC to make sure that you wired everything properly. TTL chips arenít nearly as sensitive to static as the CMOS variety. Be sure to provide connections for the positive and negative power supply and that you connect all inputs (tie those inputs that youíre not
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Chapter 11: Creating Your Own Breadboard Circuit 241
using to the positive or negative supply rail). When youíre ready to test the circuit, remove the dummy chip and replace it with the CMOS IC.
^ When inserting wire, use a pair of small needle-nosed pliers to plug the end of the wire into the contact hole. If the wire is too short, use the pliers to gently pull it out of the hole when youíre done with the breadboard.
^ Never expose a breadboard to heat, because you can permanently damage the plastic. ICs and other components that become very hot (because of a short circuit or excess current, for example) may melt the plastic underneath them. Touch all the components while you have the circuit under power to check for overheating.
^ Solderless breadboards are designed for low-voltage DC experiments. Theyíre not designed for, nor are they safe, carrying 117 VAC house current.
^ You wonít always be able to finish and test a circuit in one sitting. If you have to put your breadboard circuit aside for a while, put it out of the reach of children, animals, and the overly curious ó you know the type, people who seem to always poke their fingers where they donít belong.
Neatness counts
You can easily build a birdís nest on your breadboard by routing connection wires carelessly. Neatness and tidiness are the keys to success when using a solderless breadboard. Messy wiring makes it harder to debug the circuit, and a tangle of wires greatly increases the chance of mistakes. Wires pull out when you donít want them to. Worse, the tangle of wires can cause the circuit to malfunction altogether. Chaos ensues.
Carefully plan and construct your breadboard circuits. This planning requires more time and patience on your part, but after you build a few projects, you find that the extra effort is well worth it. If you follow the advice in the next three sections, youíll greatly improve the neatness factor of the circuits that you build on your solderless breadboard.
Avoiding the crowd
Give yourself enough room to move around. If your circuit uses integrated circuits, start with those and provide at least three to five columns of holes between each IC. Go for ten empty columns between each IC if you can. Then add the other components.
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