[sdiy] Aaron's first PCB layout

[Csaba Zvekan]

Hi Aaron,

I would Isolate a little bigger for your ground plane. Cause you might  
have problems etching and soldering that thing later. (unless you give  
it to PCB manufacturing place, then it's OK).Also check your clearance  
in NetClasses and DesignRules  .It looks to me that under the ground  
plane above the (2.2R?) resistor (what is 2.2R anyway , did you mean  
2.2K?) lays a hidden trace that Eagle finds to close to you next trace  
according to your DRU(DesignRules) settings.

Csaba
On Jun 7, 2008, at 9:55 AM, Aaron Lanterman wrote:

> After much cussing and fussing, I think I finally have come to an  
> understanding with Eagle. Wow, what an unintuitive program! But I  
> think I have the hang of it.
>
> Anyway, I've put together my very first PCB layout, and wanted to  
> show a picture of it the group so that people could tell me if  
> something that looks really wrong jumps out at them. I'm probably  
> making all sorts of neophyte PCB layout mistakes:
>
> http://users.ece.gatech.edu/~lanterma/aarons_first_board.png
>
> The board is 3.4" x 2.8".
>
> I did one that was smaller where I just plunked down the parts and  
> used the autorouter to make a two-sided board. But then I got  
> obsessed with doing a one-sided board, so I made one where I placed  
> the parts down a few at a time and hand routed as I went. I was all  
> proud of myself that I was able to do it without using any jumpers.
>
> I found I really like the style of Ken Stone's boards, where  
> resistors and caps are just given by their value, and you can just  
> plug parts in without having to look up "OK, what is R32 again?" So  
> I made a modified version of the capacitor symbol that doesn't  
> include the schematic-looking symbol on the PCB, and that puts the  
> value inside the box.
>
> One thing I need to go back and think about is the sizes of the  
> capacitors. I used all the same size in my initial layout; I need to  
> actually go look at some real caps and see what's realistic and  
> tweak accordingly.
>
> A few specific things I'm wondering about:
>
> 1) To avoid using jumpers, I run a signal line between the MOTM  
> style ground pins. So this requires that the user be sure to apply  
> ground to both pins. I'm not sure if that's good practice or not.
>
> 2) There's one big ground plane (well, two really, one coming out of  
> each ground pin). I also have a +15V plane (running along the top  
> half of the 5532 chips) and a -15V plane (running along the bottom  
> half of the 5532 chips). Is it a good idea to power things with a  
> "plane" like that? Or does that do something weird, so I should just  
> be using wide traces?
>
> 3) When I do the design rule check, eagle complains about clearance  
> at a specific spot on the board, but I can't figure out what it is  
> complaining about. You can see Eagle's complaint here:
>
> http://users.ece.gatech.edu/~lanterma/eagle_complaining.png
>
> If you look closely you can see hatch marks in the middle.
>
> I find I really enjoy the puzzle of laying out PCBs - it's like a  
> game of Tetris.
>
> If I get this working I'll make extra copies of the board available,  
> kind of like Ken and JH do, but at a more informal level, if people  
> are interested.
>
> - Aaron
>
> P.S. When people are hand routing in Eagle and want to put in a  
> jumper - is it a good idea to go back to the schematic and put it in  
> as a part somehow? Or maybe use a second layer to decide where you  
> want jumpers, but not send that to the PCB house? How do people  
> handle that?
>
> P.P.S. Any recommendations for places that make small-run single- 
> layer PCBs?
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