RE: Filtered D-Types.
Filtered D-subs can be purchased from Conec, Spectrum Control and Amphenol (maybe not any more). A rubber insert with filter caps can be purchased from Metatech. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | -Original Message- From: David Sproul [SMTP:david.spr...@alexanderlynn.co.uk] Sent: Saturday, October 12, 2002 7:39 AM To: EMC-PSTC Subject: Filtered D-Types. Hello Group, does anyone knee where I can get either filtered D-type connectors or filter cards that be inserted inside the shell to filter the signals? I was at a seminar where these were shown being used in a Japanese video, (with English voice over) and I was asked if I could source them. Can anyone help? Best regards, David Sproul, --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Ground potential differences
I read in !emc-pstc that Bailey, Jeff jbai...@mysst.com wrote (in B115DFA26896D511BAB600105AA3493275EA3F@SSTMAIL) about 'Ground potential differences' on Fri, 11 Oct 2002: I am interested to know what the actual magnitude of ground differences may be from one end of a plant to another as well as where the numbers come from. It depends on what sort of equipment is present. Some things have very high leakage current, putting a lot of amps in total into ground conductors. Then, in old plants, there may be bad ground wiring that doesn't show up as a fault. Have they been calculated or actually measured? Both. Usually after the problem has been discovered by chance. I've measured 9 V over a distance of 20 m, but there are reports of much higher voltages. If shields are connected directly to chassis at each node of a network will there be an effect of equalizing the ground levels through the network or will enough current flow to melt the shield of the cable? Both are possible. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Ethernet Radiated Emissions
I read in !emc-pstc that neve...@attbi.com wrote (in 20021011040337.NIT V4193.rwcrmhc51.attbi.com@rwcrwbc69) about 'Ethernet Radiated Emissions' on Fri, 11 Oct 2002: Second, I recommend refraining from sarcastic comments in this forum, since that doesn't seem it was about naivety. No sarcastic comment. I really meant 'naive'. I knew next to nothing about Ethernet before I asked, and now I know a little more. I could not believe that a 100 Mbps system used such long pulses, even for setting up a link. Thank you. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: David Sproul...UL creepage limits ;~)
I thought that I might weigh in on this one: As someone mentioned previously, the big hazard involved in jump starting an automobile is the risk of a spark igniting hydrogen gas vapors from the battery. This causes the battery to explode, which sends dilute sulfuric acid and pieces of the battery case flying everywhere. A local service garage still has holes in the plaster ceiling from one such event. Whenever working around an automobile battery EYE PROTECTION SHOULD BE WORN! Many service centers now require technicians to wear full face shields around batteries. Service manuals advise connecting positive leads first, and then making the final negative connection (at the jumped vehicle) to a good ground AWAY from the battery. Any heavy bracket bolted to the engine should do. This is the last connection made and the first to be removed. There is always some sparking when jumping a battery and the idea is to keep it away from those vapors. There is a second hazard with modern vehicles. Suddenly breaking the connection may cause the voltage to spike which can damage electronics. This is because solid- state regulators have a much faster loop response than the older mechanical ones, especially when mounted on the alternator. A wise precaution is to place some loads such as headlamps on high beam before removing the jumper cables. I have done it this way many times without problems. The sulfuric acid in batteries is dilute enough that getting splashed will not cause immediate harm EXCEPT TO THE EYES. When gotten on the skin the first symptom is an itching sensation that quickly gets worse. The skin starts to redden as it begins to hurt. Rinsing with water will prevent injury. Any water, even from a mud puddle, is better than letting the acid remain. Even spit may be resorted to if nothing else is available. Creepage does exist around automobile batteries. There are three major sources: 1) Intentional low current circuits such as clocks, etc. These draw some current even when the vehicle is not running. 2) Dirt and conductive salts on the battery case. If not cleaned periodically they can drain a battery over time. 3) Faulty wiring or defective circuitry. These can cause huge current drains and may be the cause of some accidents when jump starting a vehicle. I always like to connect a test light in series with the last connection when the cause of the dead battery is unknown. If it glows brightly the load is too severe to take the risk. I apologize for being so wordy but I hope that sharing my experience may save fellow listmembers from vehicle damage or serious injury. Scott Lacey ORIGINAL MESSAGE This is because when you double the voltage the power is proportional to a quarter of the current Very high voltage circuits hardly creep at all whereas low voltages creep the most. That is why you should never join the two negative terminals when you jump start a car, the car battery charging circuits have so much creepage they can melt the battery. I though everybody knew that... --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Filtered D-Types.
Hello Group, does anyone knee where I can get either filtered D-type connectors or filter cards that be inserted inside the shell to filter the signals? I was at a seminar where these were shown being used in a Japanese video, (with English voice over) and I was asked if I could source them. Can anyone help? Best regards, David Sproul,
RE: Creepage
Peter Tarver and all, Yes I know that these aren't harmonised standards. My original query I guess was why independent bodies should decide upon such varying creepage distance requirements. I had naively thought that these distances would have been determined by some universally recognised formula, that would have given the same results for the same circumstances wherever in the world it was applied. It has now be made clear to me (thanks to all who helped me understand) that this wasn't the case, and that throughout the world some very different methods are used to determine appropriate creepage distances. Perhaps one day there will be method accepted by all disciplines of product design around the world, like everyone using IEC 60664 for instance. But until that day comes I now at least have an answer for our customers when they ask about the different requirements. Thanks you all again. Best regards, David Sproul. -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Peter L. Tarver Sent: 11 October 2002 17:27 To: EMC-PSTC Subject: RE: Creepage David - These are not harmonized standards. UL 891 bases it's spacings on US electrical distribution standards, while EN60439-1 most likely relies on IEC60664. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com -Original Message- From: David Sproul Sent: Friday, October 11, 2002 6:15 AM Sorry Brian, I missed your response until now. The standards I was using was EN 60439-1 for Europe and UL 891 in America. These were the standards recommended by the customers association and UL. Best regards, David Sproul. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Ferrites for GND
Dan, It is a lossy material and most commercially available ferrite beads are 'tuned' to peak around the 100 MHz (VHF band II ?). I suppose there must be lots of exception but I have not use any outside this region. Most of them have different Q to describe their individual characteristics. Obviously, there are lots of RFI from many FM radio stations making it a necessity for many design. The material's 'lossy' property are subjected to saturation etc... Here is how I suppose it works :-) or fail to work often..., the presence of a ferrite bead in the ground path increases the inductance of the return path at some frequencies, it also introduces a form of RF losses that can be modelled as an ac resistance. Hence, it is a differential mode filter of sorts, it will not work against CM interference if the bead is only in the path of the return lead (signal ground). There is always other grounds that RF breakthrough can come around. However, so much being said, pay careful attention to the layout (installation and placement) because in general reference designs often do not provide reference 'photographs' for best layout practices. Some do provide PCB layout but very often in the interest to avoid verbosity, the all important 'notes' are absent. Inter-conductor capacitance can ruin the performance of the ferrite bead. Just my 2 ยข cheerio... Tim Foo Dan Pierce dpie...@openglobe.net To: emc-p...@majordomo.ieee.org cc: (bcc: Wan Juang Foo/ece/staff/npnet) Sent by: Subject: Ferrites for GND owner-emc-pstc@majordo mo.ieee.org 10/12/02 03:01 AM Please respond to Dan Pierce I have always been reluctant to place ferrite beads in the ground path, but I see them frequently in reference designs for USB and Analog Audio. What kind material should this be and what characteristics would this type of ferrite have. I am assuming this ferrite would not have 600 Ohm impedance @ 100MHz Thanks in advance, Daniel J. Pierce Sr. Design Engineer OpenGlobe, Inc. (An Escient Technologies Affiliate) 6325 Digital Way Indianapolis, IN 46278 mailto:dpie...@openglobe.net P: (317) 616.6587 F: (317) 616.6587 (See attached file: Dan Pierce.vcf) bindN572fe2aR.bin Description: Binary data
