February 14, 2012
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If you've been a homebrewer for any significant amount of time (or over the course of a number of projects), you probably have considered taking the route of making your own pc boards. It is indeed a tempting prospect; and as you'll discover in this week's session, it is pretty straightforward and low risk. Having done more that 30 projects over the last 10-15 years with design buddy N2CX, I was pleasantly surprised by how one's technique and quality improves with experience. The main thing is to get started and "just do it", and the rest takes care of itself.
So this session is dedicated to the time-tested methods of taking that schematic from the back of a paper napkin stage, to that of a nice and reproducible page in electronic format, and then on to ultimately having a pc board fabricated and sitting in your hand.
What this session is NOT going to cover is the use of some super expensive or overly-complex, high-end schematic capture package. Most of us do not have the ability to invest that kind of money ($2,000 to $10,000) into such a tool.
We're also NOT going to cover the totally homebrew board fabrication process with photo resist, etchant, etc. There are some real nice approaches with this technique, and a number of good homebrewers successfully using the method, but it's not conducive to creating multiples of the project for kitting efforts with your club, for the Boy Scouts, etc.
Along the way you'll find that people's preferences for these schematic and pcb layout tools fall into the "religious preferences" category. That is, many guys find a tools they like and then stick with it, defend it and promote it over all others. This is surely the case with me, and it stems from a desire to not wanting to learn a new tool every time something new comes out. My theory is: "If you know it and it works well for you, there's no need to learn and use something else." (Sort of a derivative of "If it ain't broke, don't fix it."
So here in this session, we'll be overviewing some of the basic approaches, and will have clear examples and definitions based on the tool set that we use on a regular basis.
~George N2APB & Joe N2CX
Audio Recording ... (Listen to MP3 recording)
Text Log from this week's session ...
<20:03:34>"George - N2APB": Everyone: please pull up our
webpage for some updated notes that I'll reference during the talk this evening
<20:22:23>"Frank N3PUU": eagle free is size limited I believe
<20:36:12>"George - N9DXP": I have used eagle
<20:36:33>"John - KJ6CVB": Tape and decals!
<20:38:20>"Terry WB4JFI": AutoCad under CP/M
<21:04:21>"John - KJ6CVB": Does PPT file contain component templates?
<21:07:53>"Terry WB4JFI": There is a free, open software PCB tool out there, but I don't remember the name
<21:08:45>"Al - N8WQ": thanks George
<21:09:40>"Chris - w0anm": Thanks guys, as always... 73
<21:10:53>"George - N2APB": Regarding component templates, or libraries in PowerPoint ... none that I know of, but once you start with one circuit you can just keep on "borrowing" fromt he prveious design. Plus, you're welcome use any schematics that I've developed along the way: NUE-PSK modem, Micro908 Analyzer, SIC, etc.
<21:11:18>"Russ G3OTH": Thanks George and Joe, GM from England
<21:11:34>"George - N9DXP": Thank you very much. Very helpful information.
Session Notes ...
Hand-drawn (and scanned, photographed, copied)
PowerPoint ... an effective "micro-positioned and line overlay technique for drawing good schematics"
A real "schematic capture" program
Combined with a PCB layout
Good design practices, regardless of the tool
Number of layers
Test points & Design for Testability
Prototype vs. Production
Keeping good records of design changes
Silkscreen (colors, top and bottom,
N2APB's Schematic Capture:
CASE STUDY: The Sweeper Input Card (SIC)
The familiar "napkin design" starting point ...
And on to making a nice schematic using PowerPoint and the N2APB-patented "micro-adjustment" technique ...
Download "perfect" PDF file of SIC schematic -- Notice how all the micro-alignments are perfectly lined up.
Download PowerPoint version of SIC schematic -- Use this as the starting point for making your own project's schematic
Here's the Circad PCB layout results ...
And the parts layout view (just showing the silkscreen) ...
And of course the completed SIC card ...
Schematic Capture & PCB Layout:
Circard (Holophase) ... This is N2APB's preference .. and oldie but goodie
PCB Fab Shop References:
MyRO PCB ... My favorite for everything now
Alberta Printed Circuits ... Very satisfied for prototype runs
Bay Area Circuits ... Good (US-based) for larger production runs
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