Bill, thanks for the complement. One of my mentors, Dr. Tom Van Doren, of the University Missouri - Rolla, would say “the more different “ground” symbols he saw in a schematic, the more business he knew he would get”.
Ken _______________________ I'm here to help you succeed! Feel free to call or email with any questions related to EMC or EMI troubleshooting - at no obligation. I'm always happy to help! Kenneth Wyatt Wyatt Technical Services LLC 56 Aspen Dr. Woodland Park, CO 80863 Phone: (719) 310-5418 Email Me! <mailto:[email protected]> | Web Site <http://www.emc-seminars.com/> | Blog <http://design-4-emc.com/> The EMC Blog (EDN) <http://www.edn.com/blog/The-EMC-Blog> Subscribe to Newsletter <http://www.emc-seminars.com/Newsletter/Newsletter.html> Connect with me on LinkedIn <http://www.linkedin.com/in/kennethwyatt> > On Jun 28, 2017, at 1:57 PM, Bill Stumpf <[email protected]> wrote: > > Truly outstanding analogies Ken, Ralph & Bill. I too cringe every time I > hear the term "ground" bandied about in EMI circles. It's a widely > misunderstood term that the non-initiated envision as some sort of EMI black > hole that's by some means able to soak up all that excess RF energy. I'm > sure we all could tell some stories from the lab. > > > Bill > > > From: Ken Wyatt [mailto:[email protected]] > Sent: Wednesday, June 28, 2017 1:29 PM > To: [email protected] > Subject: Re: [PSES] USB dongle connector shield filtered grounding > > Like they say in some movies…”follow the money”. In the case of EMC issues, > it’s usually “follow the current”. Both differential and common mode currents > want to return to their sources in the most expedient (low-impedance) route. > If designers fail to define a return path, invariably, some of that RF > current radiates. Once the noise source(s) are identified, then what’s the > return path? There will always be a return path…just not always the one you > want. > > Cheers, Ken > > _______________________ > > I'm here to help you succeed! Feel free to call or email with any questions > related to EMC or EMI troubleshooting - at no obligation. I'm always happy to > help! > > Kenneth Wyatt > Wyatt Technical Services LLC > 56 Aspen Dr. > Woodland Park, CO 80863 > > Phone: (719) 310-5418 > > Email Me! <mailto:[email protected]> | Web Site > <http://www.emc-seminars.com/> | Blog <http://design-4-emc.com/> > The EMC Blog (EDN) <http://www.edn.com/blog/The-EMC-Blog> > Subscribe to Newsletter > <http://www.emc-seminars.com/Newsletter/Newsletter.html> > Connect with me on LinkedIn <http://www.linkedin.com/in/kennethwyatt> > > On Jun 28, 2017, at 11:35 AM, Ralph McDiarmid > <[email protected] > <mailto:[email protected]>> wrote: > > Rather than 'ground', perhaps 'RF return' or 'counterpoise' might be better > terms? > > I think the thing that makes EMC mysterious is that the complete RF circuit > is unseen and difficult to accurately define, given all the parasitic > elements. The experience of 'inside' verses 'outside' the chassis envelope a > prime example, something I encountered some years ago, but never fully > understood. > > Ralph McDiarmid > Product Compliance > Engineering > Solar Business > Schneider Electric > > > -----Original Message----- > From: Bill Owsley [mailto:[email protected] > <mailto:[email protected]>] > Sent: Saturday, June 24, 2017 8:33 PM > To: [email protected] <mailto:[email protected]> > Subject: Re: [PSES] USB dongle connector shield filtered grounding > > Ancient EMC mythology, well proven to be wrong and so abandoned decades ago. > And still it pops on occasion and often with new twists to revive the > mythology.So it gets ignored as those new to the stories, such that they > cannot figure it out, will need the lessons of 'on the job training'. > ps. the proper terminology needed to clearly enunciate the concepts is not > settled. > The physics is plain and simple but to describe it takes a lot words due to a > lack of commonly understood terminology. > For example 'ground' serves as the catchall term, for shielding, signal > return, power return, zero reference, analog return, digital return, chassis, > circuit, logic, cable, AND for Safety as in earth ground. > Now Maxwell's law's (made up by a mad Scotman back in the 1800's) dictate > that a so-called signal must be accompanied by its return signal, and further > more that return signal will couple as close as possible to the original > so-called signal. The two parts are inextricably intertwined and cannot be > considered separately, without great risk to ones grasp of reality. Just as > the alleged E-field and H-field are two aspects of the same thing, which > conveniently might be called the Poynting Vector, and are related by the > Impedance, the ratio of the two fields, which in free space, well away from > any conducting structures, is approximately 377 ohms. > > Now conducting structures, ones like a circuit 'ground', a chassis 'ground', > a shielding 'ground' and signal returns often called 'ground' and the concept > of 'inside' verses 'outside' which seems to ignore Maxwell, are all going to > make for a rich realm of mythology which is not well defined and so, all > sorts of imaginings are created to fill all the constructed voids from using > all these artificial concepts, when one simple concept is necessary and > sufficient to complete the structure. > > Aside: If that secret, the simple one, was to be 'leaked' to common > knowledge, we all would be out of a job in managing EMC since even the simple > digital guys could understand it. So we keep it under-wraps and obscure by > using mysterious language so that the neophytes and uninitiated think that > they understand and/or have no clue as to what is going on. > > Always the correct answer: "It depends!"- Bill > > > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > ______________________________________________________________________ > > - > ---------------------------------------------------------------- > 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 > <[email protected] <mailto:[email protected]>> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > <http://www.ieee-pses.org/emc-pstc.html> > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ > <http://product-compliance.oc.ieee.org/> can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html > <http://www.ieee-pses.org/list.html> (including how to unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > <http://www.ieee-pses.org/listrules.html> > > For help, send mail to the list administrators: > Scott Douglas <[email protected] <mailto:[email protected]>> > Mike Cantwell <[email protected] <mailto:[email protected]>> > > For policy questions, send mail to: > Jim Bacher: <[email protected] <mailto:[email protected]>> > David Heald: <[email protected] <mailto:[email protected]>> > > - > ---------------------------------------------------------------- > 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 > <[email protected] <mailto:[email protected]>> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > <http://www.ieee-pses.org/emc-pstc.html> > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ > <http://product-compliance.oc.ieee.org/>can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > <http://www.ieee-pses.org/listrules.html> > For help, send mail to the list administrators: > Scott Douglas <[email protected] <mailto:[email protected]>> > Mike Cantwell <[email protected] <mailto:[email protected]>> > > For policy questions, send mail to: > Jim Bacher <[email protected] <mailto:[email protected]>> > David Heald <[email protected] <mailto:[email protected]>> > > - > ---------------------------------------------------------------- > 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 > <[email protected] <mailto:[email protected]>> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > <http://www.ieee-pses.org/emc-pstc.html> > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ > <http://product-compliance.oc.ieee.org/>can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > <http://www.ieee-pses.org/listrules.html> > For help, send mail to the list administrators: > Scott Douglas <[email protected] <mailto:[email protected]>> > Mike Cantwell <[email protected] <mailto:[email protected]>> > > For policy questions, send mail to: > Jim Bacher <[email protected] <mailto:[email protected]>> > David Heald <[email protected] <mailto:[email protected]>> > - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
