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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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PCBs: Everybody's doing it (But will they do it for you?)
There is no shortage of companies that manufacture PCBs; the tricky part comes when you have to find ones that take orders for anywhere from one to a handful of boards from a hobbyist for a reasonable price.
We point out some manufacturers that fit this criterion, but we suggest that you compare prices among manufacturers when you’re ready to buy. You can do a search using Google or your favorite search engine for “printed circuit board manufacturer” and compare prices by visiting the Web sites that the search engine finds for you.
As of this writing, we recommend that you take a look at these three manufacturers:
Olimex: To obtain a board at a low cost, try Olimex (www.olimex.com). The only drawback to Olimex is that they have longer shipping times than other manufacturers because they’re not-so-conveniently located in Bulgaria.
AP Circuits: If you can’t wait the few weeks it takes to ship products from Europe, try AP Circuits (www.apcircuits.com). Although their prices aren’t quite as low as Olimex, they’re reasonable. And if you’re in the US or Canada, you’re looking at a much shorter shipping time.
^ Advanced Circuits: If you’re a college student, you may want to check out Advanced Circuits (www.4pcb.com). They waive their minimum order requirement for college students, allowing you to order one board for the same price per board that the rest of us pay when ordering three boards. Who says education doesn’t pay off?
TERM LinG - Live, informative, Non-cost and Genuine !
274 Part V: A Plethora of Projects
Using CAD to Make Artwork
You use Computer Aided Design programs to make layout art for PCB boards. These programs contain libraries of symbols for common components and templates, and they include tools for creating drawings. They provide several features that help turn your ideas into polished drawings.
You can buy sophisticated CAD programs for hundreds or thousands of dollars (and you may have to be a rocket scientist to use some of them); or, you can download freeware or shareware CAD programs. Some of these are pretty simple to use. Do a Google search for “CAD software for PCB design,” and you can find several software packages.
The program that we recommend is Eagle Light from CadSoft. You can download this program for free at www.cadsoft.de.
What you can do with Eagle Light CAD
Of course, you pay a price for getting things free: The free Eagle Light CAD program has a few limitations. You can’t use it to draw a board larger than 4 inches by 3.2 inches or one containing more than two layers. If you need to make a board that exceeds these limitations or are making boards for a profit, go ahead and fork over the money for the full version of the software (about $200 for the standard version and $400 for the professional version at the time of this writing).
You can use Eagle Light software to produce board layout drawings and data files. These Gerber files contain the data that PCB manufacturers need to make your custom board. You can also print out the layout drawing and use it to make the PCB yourself with one of the methods that we cover in the earlier sections in this chapter.
Getting to work designing a board
We suggest that you read the tutorial for Eagle Light on the CadSoft Web site (www.cadsoft.de) and then do the low-tech thing: Print out the page of the tutorial that gives you the tool button functions and tape it next to your computer monitor. The tutorial, along with the demonstration schematics and layout drawings they include with the download, give you enough to get started generating your own PCB layout drawings and files.
TERM LinG - Live, informative, Non-cost and Genuine !
Chapter 12: Building Your Own Printed Circuit Boards 275
Figure 12-8:
A schematic drawn in Eagle Light.
We won’t kid you: You may have to stumble around a bit the first few times that you use the software before you get it right. But stick with it, and you can soon become an Eagle Light master.
To give you an idea of what you can do with a CAD program, we outline the major steps for using Eagle Light here:
1. Enter your circuit into the CAD software.
Entering your circuit into the software involves steps such as placing symbols for all the components from your circuit into your onscreen layout and then drawing lines that represent the wires between the appropriate pins, placing junctions in the appropriate places, and attaching +V and ground symbols to the appropriate pins.
2. Next, you run an automated electrical rule check (ERC) by clicking the ERC tool button.
This check catches problems that you may have missed, such as failing to attach ground to the correct pin of an IC.
3. Correct any errors and run the ERC again.
Figure 12-8 shows a schematic drawn in Eagle Light. (Credit where it’s due: The drawings in this section come from a barometer project constructed by Philip Gladstone.)
F1 2 Schematic C:\Program Files\EAGLE-4.13Vprojects\New_Project_1\Pressure-v2-final\pressure.sch - EAGLE 4.... [L |ff X |
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