[SI-LIST] PCB to PCB or chassis resonances can cause problems

From: Doug Smith <doug@xxxxxxxxxx>
To: Si-List <si-list@xxxxxxxxxxxxx>
Date: Tue, 06 Sep 2011 16:56:38 -0700
 Hi All,
Just posted my new Technical Tidbit for the month:

Technical Tidbit - September 2011
PCB-Chassis Ground Connections - Avoiding Pitfalls Due to Unintended System
Resonances 
This month's Technical Tidbit describes how unintended system resonances
formed by PCBs and chassis ground can cause system problems. 
Abstract: PCB to chassis ground connections are often needed in electronic
equipment, but if care is not taken, the PCB and the chassis ground
structurecan become a hi-Q resonant circuit that may cause problems.
Background information is given and techniques to avoid problems in designs
are discussed.

The article is at: http://emcesd.com/tt2011/tt090611.htm[1]

Also, on September 19th-21st, I am holding a seminar in Newport Beach, CA.
Details at http://emcesd.com/#Newport[2]

A significant part of the class covers design techniques and troubleshooting
methods I have developed myself and are not available in the published
literature. I use these methods and techniques in my work and share them in
my classes.

For those of you who have been on vacation, you may have missed my Technical
Tidbit for August:

Technical Tidbit - August 2011
Power Over Ethernet Injectors Can Affect Ethernet Radiated Emissions
(High Frequency Measurement of 1000Base-T Ethernet Common Mode Currents)

Abstract: Power Over Ethernet (POE) has become widespread over the last few
years and with that popularity a need has developed to add POE features to
older Ethernet hardware. As a result, POE injectors have become available
which inject DC power into an Ethernet connection. Some POE injectors
significantly unbalance the Ethernet connection which results in common mode
current on unshielded twisted pair (UTP) media. The resulting emissions from
the UTP Ethernet cable can be significant. Three POE injectors were measured
for their ability to generate common mode currents compared to a simple
coupler. The experimental method used and results obtained are reported and
contain a surprising result.

The URL for the article is: http://emcesd.com/tt2011/tt080111.htm[3]

Doug -- ------------------------------------------------------- ___ _ Doug
Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _
TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 |
q-----() | o | Email: doug@xxxxxxxxxx[4] \ _ / ] \ _ / Website:
http://www.dsmith.org[5]
------------------------------------------------------- 

--- Links ---
   1 http://emcesd.com/tt2011/tt090611.htm
   2 http://emcesd.com/#Newport
   3 http://emcesd.com/tt2011/tt080111.htm
   4 mailto:doug@xxxxxxxxxx
   5 http://www.dsmith.org
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[SI-LIST] PCB to PCB or chassis resonances can cause problems

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