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 structure can 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 Also 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 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: d...@dsmith.org \ _ / ] \ _ / Website: http://www.dsmith.org ------------------------------------------------------- - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
