[sdiy] Dual ground planes

[Harry Bissell]

my opinion: (ymmv)

Ground planes on the 'bottom' of the board are only useful if there are sensitive
through-hole components on the other side. Unconnected grounds probably make things worse
(imho) as they increase capacitive coupling and don't have any benefits.

Large ground areas on the bottom could make a circuit work better to some extent. Small
areas are not worth the trouble imho.

H^) harry

----- Original Message -----
From: David G. Dixon <dixon at interchange.ubc.ca>
To: 'Tim Ressel' <madhun2001 at yahoo.com>, 'David Ingebretsen' <dingebre at 3dphysics.net>, synth-diy at dropmix.xs4all.nl
Sent: Tue, 03 Aug 2010 14:51:48 -0400 (EDT)
Subject: Re: [sdiy] Dual ground planes

All this talk about ground planes has got me to wondering...

I lay out one-sided boards in Excel (it's antediluvian, but it suits my
cockeyed sensibilities) with lots of jumpers.  I always fill in the empty
spaces with "ground" as I can, or just leave islands of unconnected copper.
My boards are usually pretty densely populated, and the end result almost
looks like a machined board.

What I'm wondering is this: does this make any difference whatsoever, or
would I be just as well off simply having ground traces, with no islands of
unetched copper (grounded or not)?


> Are you talking 2-layer here? I'll assume you are. Also I'll assume you're
> not
> going for EMC compliance here. Mostly dual ground planes give you better
> ground
> paths (obviously). This becomes an issue if there are lots of traces
> cutting
> across the board. Also if you have mixed signal (analog&digital) having
> planes
> on both sides can make splitting the ground planes easier.
> 
> Given all of that, ground planes are not critical to the basic design. But
> as
> performance requirements go up the use of ground planes become necessary.
> As an
> example, I just added a quantizer to my Muse thingie. It is all hand-wired
> with
> no ground planes. The signals are okay, but I can see little wiggles when
> I poke
> around the circuit. Most likely from inferior grounds. The circuit works,
> but
> could be better.

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-- 
Harry Bissell & Nora Abdullah 4eva