The Artwork of Electronics

At long last I've managed to create a circuit board using the EAGLE CAD program. Rich had the (mostly) working board at the meeting Tuesday night (June 10, 2008).

Rich has done most of the work. Laying out the PCB was a lesson for me. I'm now a Rho-certified PCB layout guy ready to resume work on the GeekBoy.

Here are Rich's original sketches:


I put this (along with some updates) into EAGLE using its schematic capture:

Actually, before making the pretty schematic, I looked up all the parts on Digi-Key's and Mouser's websites and got copies of their data sheets. That information was used to create a project library. Each part in the library consists of a schematic symbol and a "footprint" that describes its copper pad layout and its image on the silkscreen.

I learned the hard way that it's not a good idea to blindly use parts from existing libraries. First of all, many of the parts you want won't be there; and secondly, if they are there, they probably aren't what you really want. For instance, there are many variations on pad sizes. If you're hand soldering (as opposed to wave or reflow soldering) it's a good idea to use larger pads. It seems that everyone has a different opinion on what size pads should be.

After you've entered the schematic into EAGLE, you click on a button and presto! A pile of parts appear. The parts are connected by "air wires" (rubber bands) that show how they connect.


All you need to do then is arrange them on the board (shown on the right), click another button, and presto! The autorouter makes your traces.


A few more clicks converts the board into Gerber files. These you email to Advanced Circuits, who (presto!) converts them into actual boards and ships them to you within two days. I was able to get 20 boards for about $90 with their Bare Bones special (no solder mask and no silkscreen). Here's a link to my files at Advanced Circuits: https://www.freedfm.com/freedfm/0011672802027086/results/plots.htm

Lest I sound like an EAGLE salesman let me clarify that things didn't go nearly as smoothly as described. In fact I found EAGLE to be rather tedious. It was originally written as a UNIX program and retrofitted for Windows. Consequently it doesn't have the feel of a normal Windows program. I needed to do much experimenting to relearn basic operations such as cut and paste. Another learning hurdle was realizing that many of the defaults were just plain wrong. This was with version 4.1. There is now a version 5.0, which apparently is more Windows-friendly. Oh yeah, I downright lied about the autorouter.

Here's a link to a tutorial that I wish I saw before trying to read the manual: http://www.cadsoftusa.com/Tour/tour01.htm

Of course after you get your boards and parts you need to solder them. A clunky old fashioned iron just won't do for the tiny surface mount parts, so here's what else I got: Aoyue 2900 Lead Free Soldering Station .

Here's the board Rich put together:


And here it is up and running:


-Loren

Last updated 12-Jun-2008