[sdiy] Aaron's first PCB layout

[Veronica Merryfield]

I would second this. For RF or digital, I would use a ground and power  
plane. For audio, I would use star ground track, run a ring of ground  
round the outer edge (habit more than anything) and use short runs for  
the power. Use ground guards round crucial areas and to isolate  
sections. I would not assume that both ground pins are wired either,  
tut tut :) Dividing a ground is not a good thing to do.

The two 2.2R (I assume) resistors work with the local decoupling  
capacitors to form a low pass filter on the incoming power lines and  
not fusing, although they will do that is something goes wrong. This  
was (still is?) a common technique in audio circuits to provide local  
filtering to the power lines. As such, the resistors should be nice  
'n' close to the pins and the 10uF caps should be close too.

Whilst I think you'll be ok, there are three caps that are very close  
to pin 3 of three ICs. I would move them away a little more.

i would include values and number. Whilst it is nice having values, it  
makes it harder to figure out where in the circuit you are at any  
point, like having to describe them by position above and when  
debugging.

If you are worried about capacitor foot print, you could add an extra  
pin hole 0.1" away from one of the pins.

Jumpers can be marked in the silk screen layer as a line between two  
holes or as 0R but no part number usually. I say usually in respect of  
this project but if you had an automated production facility, you  
might have links that are zero ohm resistors that a pick and place can  
use and that you want to appear in the BOM for ordering, in which case  
you would back propagate the link to the schematic assuming the  
schematic is the master data holder.


On 7-Jun-08, at 3:45 AM, Paul Perry wrote:

> I'm not a fan of ground planes, unless you are at UHF.
> If you have ground traces, at least you know exactly where the  
> currents are
> going. Plus, you can isolate stuff if you need to.
>
> paul perry Melbourne Asutralia
>
>
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