Re: [PSES] Measurement Dilema - THE EXPLANATION!
OK Everyone, here is the explanation: The box is superfluous, it just hides what is actually going on. The box contains two heavy gauge wires. One shorts the two tips sig and gnd together and the other connects the center point of the first wire to the center pin of the BNC connector. This is equivalent to removing the box and putting a stiff wire into the BNC center pin on the generator and connecting both probe tips and both ground leads to this stiff wire. Doing so causes the generator to push a current out the prob e ground leads creating a voltage across the inductance of the leads that create a loop at the front of the probe. The current flowing through the ground leads creates magnetic fields that for the most part are captured by the loop formed by the ground leads and probe delivering the induced voltage to the probes. The probes only respond to voltage between their tips and ground lead attachment point, and the ground lead induced voltage is delivered to each probe by loop they form. Since the probes are lying apart from each other, one on the plastic table with a loop in its cable, and the other over a highly conducting (center layer) ESD mat, their common mode impedance will be different, varying at different frequencies. That results in different common mode currents on the probes and the ground lead induced voltages are therefore different and that is what is displayed on the scope. It is interesting that the current output of an HC240 Octal Inverting Buffer can induce volts across the ground leads when its output is only 5 V P_P, but entirely understandable if you calculate e = Ldi/dt = 100 nH*.040 A/2ns) as an approximation. For the generator to push a current onto the probe cables, it must form an image current somewhere and that is displacement current to the nearby scope chassis and some radiation from the oscillator itself into the "ether," although it is on the small side to radiate itself efficiently at 40 MHz. I suspect the total current being pushed onto the probes is about 40 mA, the short circuit current of the HC240 IC being used. At some frequencies, each probe cable will resonate with the capacitance back to the scope from the oscillator. By changing the frequency, I can make either probe register a larger signal than the other probe. I love experiments like this. I have been doing this one for over 20 years for my classes and have have tons more demos to challenge engineering minds. Most of my demos have an unexpected result and the discussion that follows elucidates some engineering principle or addresses a myth. Doug University of Oxford, Course Tutor Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- On Mon, 29 Jan 2018 14:40:17 -0800, "Tom Dagostino" wrote: Why is everybody looking for tricks or complex answers. This is really a very simple, basic issue. If you look closely you will see the difference. Tom Dagostino 971-279-5325 t...@teraspeedlabs.com Teraspeed Labs SW Wilshire Street Suite 102 Portland, OR 97225 -Original Message- From: si-list-bou...@freelists.org [mailto:si-list-bou...@freelists.org] On Behalf Of Austin Mack Sent: Monday, January 29, 2018 2:28 PM To: d...@emcesd.com; 'si-list' Subject: [SI-LIST] Re: ***UNCHECKED*** Measurement Dilema Hi All, It looks to me like the oscillator and its power pack (with very long leads) are in close proximity to the CH2 probe cable. Since the oscillator output is tied to GND at the probes, it and the floating power pack will be radiating like crazy at 40MHz and electromagnetically and capacitively coupling to the CH2 shield which BTW is close to a quarter wavelength. Austin -Original Message- From: si-list-bou...@freelists.org [mailto:si-list-bou...@freelists.org] On Behalf Of Doug Smith Sent: Friday, January 26, 2018 2:53 PM To: si-list Subject: [SI-LIST] ***UNCHECKED*** Measurement Dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY I do a lot of experiments in my classes that give surprising results. Each one addresses a design or troubleshooting problem that engineers do not realize their troubleshooting efforts. Next one:http://emcesd.com/bcsem_hfmeas.htm on March 13-16. Doug -
Re: [PSES] Measurement dilema
Not really. Full disclosure tomorrow when I get settled in the office. It is actually simpler than one might imagine, just will take me a fair amount of typing so need a real keyboard not an iPhone. Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: d...@dsmith.org Website: http://dsmith.org On Sun, Jan 28, 2018 at 4:54, Bart De Geeter wrote: Hi Doug, Could it be that there is just a piece of transmission line inside the box terminated with a certain impedance? You might be measuring in the middle of this transmission line. If the input impedance selected on channel A of your oscilloscope is f.e 50 ohm and the other input channel has 1Mohm input impedance selected, you will measure a different voltage at this particular point (as the measured signal is the sum of the direct wave+ reflected wave on this transmission). So far, my guess š Greetings, Bart Van: Doug Smith [mailto:d...@emcesd.com] Verzonden: vrijdag 26 januari 2018 23:50 Aan: EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY [https://youtu.be/qj-HBFMEJiY] Doug - 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 [emc-p...@ieee.org] > 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 < sdoug...@ieee.org [sdoug...@ieee.org] > Mike Cantwell < mcantw...@ieee.org [mcantw...@ieee.org] > For policy questions, send mail to: Jim Bacher < j.bac...@ieee.org [j.bac...@ieee.org] > David Heald < dhe...@gmail.com [dhe...@gmail.com] > - 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 [emc-p...@ieee.org] > 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 < sdoug...@ieee.org [sdoug...@ieee.org] > Mike Cantwell < mcantw...@ieee.org [mcantw...@ieee.org] > For policy questions, send mail to: Jim Bacher < j.bac...@ieee.org [j.bac...@ieee.org] > David Heald < dhe...@gmail.com [dhe...@gmail.com] > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Measurement dilema
I was thinking only that people who have had my course not reply because they should already know. Will post the answer discussion later tomorrow. I have really enjoyed the replies and learned from them. And you are right. Ground lead parasitic inductance plays a major part. Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: d...@dsmith.org Website: http://dsmith.org On Sun, Jan 28, 2018 at 18:42, Ken Javor wrote: Re: [PSES] Measurement dilema As long as weāre all chiming in here that was my guess as well (probe ground lead parasitics) but I thought the ground rule :-) was no group replies... Ken Javor Phone: (256) 650-5261 From: Dale Reid Reply-To: Dale Reid Date: Sun, 28 Jan 2018 20:38:56 -0500 To: Subject: Re: [PSES] Measurement dilema How about the different size loops the ground leads on your probes are making. Dale Reid Product Safety Engineer O +1 859 825 4733 re...@lexmark.com <http://www.lexmark.com/> [http://www.lexmark.com/] www.lexmark.com <http://www.lexmark.com> [http://www.lexmark.com] On Sun, Jan 28, 2018 at 7:54 AM, Bart De Geeter wrote: Hi Doug, Could it be that there is just a piece of transmission line inside the box terminated with a certain impedance? You might be measuring in the middle of this transmission line. If the input impedance selected on channel A of your oscilloscope is f.e 50 ohm and the other input channel has 1Mohm input impedance selected, you will measure a different voltage at this particular point (as the measured signal is the sum of the direct wave+ reflected wave on this transmission). So far, my guess š Greetings, Bart Van: Doug Smith [ mailto:d...@emcesd.com] [d...@emcesd.com]] Verzonden: vrijdag 26 januari 2018 23:50 Aan: EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug - 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 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) <http://www.ieee-pses.org/list.html> [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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald - 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://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) <http://www.ieee-pses.org/list.html> [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 <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - 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 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
Re: [PSES] Measurement dilema
So far Iāve been wrong on two private replys, so they wouldnāt have helped anybody anyway! ;-} Brent DeWitt, AB1LF Milford, MA From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Sunday, January 28, 2018 9:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Measurement dilema As long as weāre all chiming in here that was my guess as well (probe ground lead parasitics) but I thought the ground rule :-) was no group replies... Ken Javor Phone: (256) 650-5261 _ From: Dale Reid mailto:re...@lexmark.com> > Reply-To: Dale Reid mailto:re...@lexmark.com> > Date: Sun, 28 Jan 2018 20:38:56 -0500 To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG> > Subject: Re: [PSES] Measurement dilema How about the different size loops the ground leads on your probes are making. Dale Reid Product Safety Engineer O +1 859 825 4733 re...@lexmark.com <mailto:re...@lexmark.com> <http://www.lexmark.com/> <http://www.lexmark.com/> www.lexmark.com <http://www.lexmark.com> <http://www.lexmark.com> <http://www.lexmark.com> On Sun, Jan 28, 2018 at 7:54 AM, Bart De Geeter mailto:bart.de.gee...@telenet.be> > wrote: Hi Doug, Could it be that there is just a piece of transmission line inside the box terminated with a certain impedance? You might be measuring in the middle of this transmission line. If the input impedance selected on channel A of your oscilloscope is f.e 50 ohm and the other input channel has 1Mohm input impedance selected, you will measure a different voltage at this particular point (as the measured signal is the sum of the direct wave+ reflected wave on this transmission). So far, my guess š Greetings, Bart Van: Doug Smith [mailto:d...@emcesd.com] Verzonden: vrijdag 26 januari 2018 23:50 Aan: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Onderwerp: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug - 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 mailto:emc-p...@ieee.org> > 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) <http://www.ieee-pses.org/list.html> <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org> > Mike Cantwell mailto:mcantw...@ieee.org> > For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org> > David Heald mailto:dhe...@gmail.com> > - 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://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) <http://www.ieee-pses.org/list.html> <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - 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 mailto:emc-p...@ieee.org> > 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 Co
Re: [PSES] Measurement dilema
As long as weāre all chiming in here that was my guess as well (probe ground lead parasitics) but I thought the ground rule :-) was no group replies... Ken Javor Phone: (256) 650-5261 From: Dale Reid Reply-To: Dale Reid Date: Sun, 28 Jan 2018 20:38:56 -0500 To: Subject: Re: [PSES] Measurement dilema How about the different size loops the ground leads on your probes are making.Ā Ā Ā Dale Reid Product Safety Engineer OĀ Ā +1 859 825 4733 re...@lexmark.com <http://www.lexmark.com/> www.lexmark.com <http://www.lexmark.com> On Sun, Jan 28, 2018 at 7:54 AM, Bart De Geeter wrote: > Hi Doug, > Ā > Ā Ā Could it be that there is just a piece of transmission line > inside the box terminated with a certain impedance?Ā You might be measuring in > the middle of this transmission line. > If the input impedance selected on channel A of your oscilloscope is f.eĀ 50 > ohmĀ and the other input channel has 1Mohm input impedance selected, you will > measure a different voltage at this particular point (as the measured signal > is the sum of the direct wave+ reflected wave on this transmission). > Ā > So far, my guess š > Ā > Greetings, > Bart > Ā > > Van: Doug Smith [mailto:d...@emcesd.com] > Verzonden: vrijdag 26 januari 2018 23:50 > Aan: EMC-PSTC@LISTSERV.IEEE.ORG > Onderwerp: [PSES] Measurement dilema > Ā > > Hi All, > > Can you explain the result in this video I just made? Scope plots of the same > two nodes are completely different. Probes and scope are operating normally, > no problem with the equipment itself. > > If you have been to my seminars you know the answer, please do not post the > answer unless you have not seen this experiment until now. > > Hint 1: There are no EM fields radiating from the shielded box affecting the > probes. > Hint 2: There are no active components inside the box. > > https://youtu.be/qj-HBFMEJiY > > Doug > > > - > > 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 > > > 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) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas > Mike Cantwell > > For policy questions, send mail to: > Jim Bacher > David Heald > > - > > > 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://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) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <dhe...@gmail.com> - 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 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) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald - -
Re: [PSES] Measurement dilema
How about the different size loops the ground leads on your probes are making. *Dale Reid* Product Safety Engineer *O* +1 859 825 4733 re...@lexmark.com <http://www.lexmark.com/> www.lexmark.com On Sun, Jan 28, 2018 at 7:54 AM, Bart De Geeter wrote: > Hi Doug, > > > >Could it be that there is just a piece of transmission line > inside the box terminated with a certain impedance? You might be measuring > in the middle of this transmission line. > > If the input impedance selected on channel A of your oscilloscope is f.e > 50 ohm and the other input channel has 1Mohm input impedance selected, you > will measure a different voltage at this particular point (as the measured > signal is the sum of the direct wave+ reflected wave on this transmission). > > > > So far, my guess š > > > > Greetings, > > Bart > > > > *Van:* Doug Smith [mailto:d...@emcesd.com] > *Verzonden:* vrijdag 26 januari 2018 23:50 > *Aan:* EMC-PSTC@LISTSERV.IEEE.ORG > *Onderwerp:* [PSES] Measurement dilema > > > > Hi All, > > Can you explain the result in this video I just made? Scope plots of the > same two nodes are completely different. Probes and scope are operating > normally, no problem with the equipment itself. > > If you have been to my seminars you know the answer, please do not post > the answer unless you have not seen this experiment until now. > > Hint 1: There are no EM fields radiating from the shielded box affecting > the probes. > Hint 2: There are no active components inside the box. > > https://youtu.be/qj-HBFMEJiY > > Doug > > - > > > 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://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) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas > Mike Cantwell > > For policy questions, send mail to: > Jim Bacher > David Heald > - > > > 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://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) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <dhe...@gmail.com> > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Measurement dilema
Hi Doug, Could it be that there is just a piece of transmission line inside the box terminated with a certain impedance? You might be measuring in the middle of this transmission line. If the input impedance selected on channel A of your oscilloscope is f.e 50 ohm and the other input channel has 1Mohm input impedance selected, you will measure a different voltage at this particular point (as the measured signal is the sum of the direct wave+ reflected wave on this transmission). So far, my guess š Greetings, Bart Van: Doug Smith [mailto:d...@emcesd.com] Verzonden: vrijdag 26 januari 2018 23:50 Aan: EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug <https://hostingemail.xo.com/api/storage/d...@emcesd.com/signatures/images/2476c205-f457-4395-87cc-7aa199c734f2> - 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 mailto:emc-p...@ieee.org> > 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) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org> > Mike Cantwell mailto:mcantw...@ieee.org> > For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org> > David Heald mailto:dhe...@gmail.com> > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Measurement dilema
Pareto principle/distribution? Methinks it may be that way with all life sciences. After having read over 200 PhD and master's papers in agriculture/agronomy/botany, have come to the conclusion that their ilk's intellectual toolbox are simply not equipped with adequate mathematical tools, nor educational rigor. Agree that there is too much fiscal and political motivation in medical research, but to make a corollary, do not ascribe to mal intent what is incompetence. Or human 'entropy'. As for the different signals, would have to know more about the analog front end to the scope and whether multiple channels share ADCs (have not read that model's manual). Had somewhat similar affects in my box where the mux and ADC were triggered by external events, not the microcontroller. Would need to see a frequency-domain of both channels to know if this is an artifact of 'differential' sampling. Perhaps companding would do that, dunno. But probably just interference from space aliens. Brian From: John Woodgate [mailto:j...@woodjohn.uk] Sent: Saturday, January 27, 2018 11:44 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Measurement dilema It's probably another case of the 80/20 rule. Even with peer-reviewed papers, the long-term opinion may be that 20% at most were of value. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-01-27 19:27, Douglas Smith wrote: Great quote! It pretty much describes much of medical research in my opinion. The great thing about engineering is the field is āgroundedā (pun intended) in fundamentals. No so much in medicine where money and politics matter as much as science. My hobby when I am not doing engineering is medicine and I read tons of medical studies. Many are either junk (poorly done) or fraud! Some are great. Doug Smith Sent from my iPhone IPhone: Ā 408-858-4528 Office: Ā Ā 702-570-6108 Email: Ā Ā Ā d...@dsmith.org Website:Ā http://dsmith.org On Fri, Jan 26, 2018 at 17:34, Richard Nute wrote: Ā Hi Doug: Ā While I donāt yet have the answer (and may never have the answer), I ran across this quote from Luigi Galvani which I think applies here: Ā āFor it is easy in experimentation to be deceived, and to think one has seen and discovered what we desire to see and discover.ā Ā Best regards, Rich Ā Ā From: Doug Smith [mailto:d...@emcesd.com] Sent: Friday, January 26, 2018 2:50 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Measurement dilema Ā Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Measurement dilema
It's probably another case of the 80/20 rule. Even with peer-reviewed papers, the long-term opinion may be that 20% at most were of value. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-01-27 19:27, Douglas Smith wrote: Great quote! It pretty much describes much of medical research in my opinion. The great thing about engineering is the field is āgroundedā (pun intended) in fundamentals. No so much in medicine where money and politics matter as much as science. My hobby when I am not doing engineering is medicine and I read tons of medical studies. Many are either junk (poorly done) or fraud! Some are great. Doug Smith Sent from my iPhone IPhone: Ā 408-858-4528 Office: Ā Ā 702-570-6108 Email: Ā Ā Ā d...@dsmith.org Website:Ā http://dsmith.org On Fri, Jan 26, 2018 at 17:34, Richard Nute wrote: Hi Doug: While I donāt yet have the answer (and may never have the answer), I ran across this quote from Luigi Galvani which I think applies here: āFor it is easy in experimentation to be deceived, and to think one has seen and discovered what we desire to see and discover.ā Best regards, Rich *From:* Doug Smith [mailto:d...@emcesd.com] *Sent:* Friday, January 26, 2018 2:50 PM *To:* EMC-PSTC@LISTSERV.IEEE.ORG *Subject:* [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug - 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.
Re: [PSES] Measurement dilema
Great quote! It pretty much describes much of medical research in my opinion. The great thing about engineering is the field is āgroundedā (pun intended) in fundamentals. No so much in medicine where money and politics matter as much as science. My hobby when I am not doing engineering is medicine and I read tons of medical studies. Many are either junk (poorly done) or fraud! Some are great. Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: d...@dsmith.org Website: http://dsmith.org On Fri, Jan 26, 2018 at 17:34, Richard Nute wrote: Hi Doug: While I donāt yet have the answer (and may never have the answer), I ran across this quote from Luigi Galvani which I think applies here: āFor it is easy in experimentation to be deceived, and to think one has seen and discovered what we desire to see and discover.ā Best regards, Rich From: Doug Smith [mailto:d...@emcesd.com] Sent: Friday, January 26, 2018 2:50 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY [https://youtu.be/qj-HBFMEJiY] Doug - 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 [emc-p...@ieee.org] > 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 < sdoug...@ieee.org [sdoug...@ieee.org] > Mike Cantwell < mcantw...@ieee.org [mcantw...@ieee.org] > For policy questions, send mail to: Jim Bacher < j.bac...@ieee.org [j.bac...@ieee.org] > David Heald < dhe...@gmail.com [dhe...@gmail.com] > - 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 [emc-p...@ieee.org] > 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 < sdoug...@ieee.org [sdoug...@ieee.org] > Mike Cantwell < mcantw...@ieee.org [mcantw...@ieee.org] > For policy questions, send mail to: Jim Bacher < j.bac...@ieee.org [j.bac...@ieee.org] > David Heald < dhe...@gmail.com [dhe...@gmail.com] > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Measurement dilema
That is certainly true, but the problem here is there is an error one is not aware of, although this is an extreme example. Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: d...@dsmith.org Website: http://dsmith.org On Fri, Jan 26, 2018 at 17:34, Richard Nute wrote: Hi Doug: While I donāt yet have the answer (and may never have the answer), I ran across this quote from Luigi Galvani which I think applies here: āFor it is easy in experimentation to be deceived, and to think one has seen and discovered what we desire to see and discover.ā Best regards, Rich From: Doug Smith [mailto:d...@emcesd.com] Sent: Friday, January 26, 2018 2:50 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY [https://youtu.be/qj-HBFMEJiY] Doug - 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 [emc-p...@ieee.org] > 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 < sdoug...@ieee.org [sdoug...@ieee.org] > Mike Cantwell < mcantw...@ieee.org [mcantw...@ieee.org] > For policy questions, send mail to: Jim Bacher < j.bac...@ieee.org [j.bac...@ieee.org] > David Heald < dhe...@gmail.com [dhe...@gmail.com] > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Measurement dilema
Hi Doug: While I donāt yet have the answer (and may never have the answer), I ran across this quote from Luigi Galvani which I think applies here: āFor it is easy in experimentation to be deceived, and to think one has seen and discovered what we desire to see and discover.ā Best regards, Rich From: Doug Smith [mailto:d...@emcesd.com] Sent: Friday, January 26, 2018 2:50 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Measurement dilema Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug <https://hostingemail.xo.com/api/storage/d...@emcesd.com/signatures/images/2476c205-f457-4395-87cc-7aa199c734f2> - 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 mailto:emc-p...@ieee.org> > 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) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org> > Mike Cantwell mailto:mcantw...@ieee.org> > For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org> > David Heald mailto:dhe...@gmail.com> > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
[PSES] Measurement dilema
Hi All, Can you explain the result in this video I just made? Scope plots of the same two nodes are completely different. Probes and scope are operating normally, no problem with the equipment itself. If you have been to my seminars you know the answer, please do not post the answer unless you have not seen this experiment until now. Hint 1: There are no EM fields radiating from the shielded box affecting the probes. Hint 2: There are no active components inside the box. https://youtu.be/qj-HBFMEJiY Doug - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: