[SI-LIST] Re: Book

Someone recommended Henry Ott's book "noise reduction techniques in
Electronic Systems" and I have this book and didn't find it very useful for
chassis grounding (it's very old). He actually recommends separating chassis
and digital ground. I think this is based on how systems in the past often
had shielded cables going from one chassis to another. Often the ground
potentials are different in those systems and large currents can flow in the
shield and thus in the chassis. The large currents in the chassis can cause
noise and or the ground reference to change if the digital ground is part of
the chassis. Most telecomm systems I work with today don't have any shielded
cables or for that matter any ground connections between chassis. Also, all
of the telecom companies I have worked at have tied digital ground to the
chassis (also PC's are made this way).

My thoughts are that it probably wouldn't matter much either way for the
type of system I described, but isolating the ground may be difficult and if
you're going to tie them together you might as well do it at as many points
as you can. Also, for high power systems (I have seen systems with 12+
boards each consuming 100 watts of power) it beefs up the DC current return
path.

Any thoughts are welcome.

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Alex Horvath
Sent: Thursday, June 21, 2001 9:45 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Book



Anyone have "Grounding for the control of EMI" by Hugh Denny?

Any good or any other recommendations?

--------------------------------------------
Alex Horvath
Agile Storage
130 Knowles Dr. Suite B
Los Gatos, CA 95032
408-963-2419
--------------------------------------------
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