Re: TC77b Rewrite of 61000-4-2 and 61000-4-4

HI Eric and the group, The main difference in the ESD test is in how the waveform is specified. The waveform is not being changed, just a better specification and calibration procedure for the simulator. Some ESD simulators may need little or no change while others will need a redesign.

Re: GR-78 Circuit pack ESD test.

Hi Gary, Can you give us more details? If I remember correctly from my Bell Lab days, the circuit pack ESD test I remember was useless as it assumed boards were always held by the edges and zapped on a predetermined grid. If the waveform is slower than IEC 61000-4-2 (801-2 was replaced by

pwb coupling to surroundings (continued)

Hi All, I have posted at http://emcesd.com the latest Technical Tidbit (picture link at bottom of page). In April and May, the Technical Tidbit articles discussed the coupling between a circuit board and a nearby metal plane. This month, Printed Wiring Board Coupling to a Nearby Metal Plane,

Kirchoff and Faraday voltage measurements

Hi All, Well, I have been writing again. This month my article is on voltage measurements. Voltage measurements can give misleading results with some measurements yielding a result that appears nowhere in the circuit of interest! This month's Technical Tidbit at http://emcesd.com is titled

active probe issues

Hi All, Most of us use active probes because we believe they have a high input impedance. However this is not usually the case in the upper octave of their stated frequency range. My Technical Tidbit article for August, 2002 (http://emcesd.com) presents measured data on a popular active probe

EMC test equipment - Cheap!

Hi All, Occasionally, test equipment designed for one use has another use quite distinct from the intended one, but in another field. Such equipment is often very inexpensive and yields useful results. In the July Technical Tidbit at http://www.dsmith.org (or http://emcesd.com), an example is

Re: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels

Not to mention the vastly different current risetimes. Low voltage discharges actually have higher di/dt values than high voltage ones (and therefore higher interference potential). Doug don_borow...@selinc.com wrote: Let me add a bit on the air discharge side. You will want to do the

Mutual inductance as a troubleshooting tool

Hi All, Mutual inductance can be a powerful debugging tool for problem circuits. It can also be either a friend or foe in the designs themselves. This month's Technical Tidbit at http://www.dsmith.org relates direct measurement of Ldi/dt voltage drop with Mdi/dt of the same voltage. Often

immunity of a pwb as a function of grounding

Hi All, I have been busy again setting up experiments and taking data on a circuit board that indicates a design rule for ESD that I have heard from many sources does not work. I knew this was the case, but thought some data was in order. This month, the Technical Tidbit at http://emcesd.com

Re: A very nice game

Robert, You do not have to open the attachment on this one at all if you have IE! Just preview or open the message. During virus outbreaks, like this one, I use a great webmail reader mail2web.com to preview my mail before downloading it. Doug Robert Wilson wrote: In spite of the attachment

Re: A very nice game

Hi Chris and the Gang, It was probably a particularly nasty one called W32/Klez.h@MM which I have received through other channels several times lately. It is bad enough that if you actually get infected (McAfee will prevent this if your DAT files are reasonably new) you have to go into DOS and

Re: Suitable CDN for IEC61000-4-6 ethernet 10/100

Hi All, Just a word of caution about test equipment used to measure EUT performance, such as a LAN-analyzer or similar equipment that counts errors. My experience has been that some of this equipment is itself very susceptible to EMI. In a recent case, I had to move a bit-error tester to the

Capacitive coupling to cables

Hi All, I have posted the latest article on my website at http://emcesd.com: Cable Effects Pt 3: Capacitive Pickup by Cables in a System Last month the Technical Tidbit on http://emcesd.com explored inductive coupling to cables. The article for March discusses capacitive coupling to cables in a

coupling to cables

Hi All, Well a new month and my typing fingers get restless. After an afternoon doing experiments, I have come up with some information on coupling from devices to cables in a system. Local fields emanating from devices in a system that would normally not be a problem can induce currents in

[SI-LIST] job postings

Hi All, I have a page on my website where I post both positions available and persons looking for positions. I do this as a service (no charge for the posting). Three new positions have been added in the last few days, one this evening from Maryland. The direct URL of the page is:

cable discharge measurements

Hi All, I have seen some postings recently on the technical lists on cable discharge so I decided to do a few measurements using a simple test setup. Cable discharge happens when a cable becomes statically charged and then is connected to equipment. This can happen by dragging a cable on the

Elusive Glitch - Part 3

The Elusive Glitch - Part 3 This month on http://www.dsmith.org, the Technical Tidbit is the final Part 3 of the Elusive Glitch story. The first two articles in October and November talked about how ESD and other impulsive events can disrupt measurements on digital circuits. Also covered were

Re: Impedance Stabilization Network

Hi All, I suspect that Fischer Custom Communications should have them. Their website is: http://www.fischercc.com/ Doug Heffken, Jan wrote: Does anybody know of a source of ISN's as required for Telecom Port conducted emissions in CISPR 22? Jan Heffken Compliance Test Engineer

more glitches

The Elusive Glitch - Part 2 Hi All, This month, I describe in my Technical Tidbit article (www.dsmith.org) a way to accurately pinpoint the source of a waveform glitch. It takes last month's article one step further than just determining if a glitch is likely coming from an external source

Re: EFT Failures..Help!

Hi Alex and the group, Often, one is very lucky to be able to fix such a problem while at the lab. Time there is best spent collecting data on the failure. Things like the actual failure voltage, cable positioning effects, and the such are important data that will make your device easier to

wasted engineering effort

Hi All, It seems we spend quite a bit of time tracking down glitches on logic signals. Once a glitch has been found that appears to be causing a system to hang-up, reset, or otherwise not perform as expected..Now what? All may not be as it appears and if not, a great deal of engineering

Re: ESD Immunity Testing

. Possibly David Pommerenke can fill you in on the latest as I had to miss the committee meeting a few weeks ago in Quebec City due to my heavy involvement with the EOS/ESD Symposium in Portland, OR. Doug John Woodgate wrote: I read in !emc-pstc that Douglas C. Smith d...@emcesd.com wrote

Re: ESD Immunity Testing

Hi Richard and the group, There are lots of problems with existing standards that would take to long to describe here. In general, the limits of instrumention and time constraints I think are the main reason for existing shortcomings. IEC 61000-4-2 is being rewritten and the current draft

paper posted

Hi All, I have posted the paper I just delivered at the EOS/ESD Symposium in Portland, OR titled The EMI/ESD Environment of Large Server Installations. If you work a server company, supplier to such, or in an organization that maintains servers, you may be interested in this paper. It is posted

FET probe caution

Hi All, Did you know that a common accessory for FET probes can, in some cases, cause a significant error in the measurement? My September Technical Tidbit at: http://www.dsmith.org describes the problem. The accessory in question is a probe tip with a small ground spring or pin on a hinge

Re: STP vs FTP Ethernet cables

Hi Paolo, I worked for a few years in the part of Bell Labs that was involved with networking cable systems several years ago. I am suspicious of foil shielded cables as it is difficult to properly terminate the foil shield (360 degrees). I have had a foil shield crack and split if the cable is

Re: ESD Testing

Richard, With today's faster circuits low voltage evernts may be more likely a problem than high voltage ones. Low voltage air discharges have much higher di/dt (and therefore interference potential) than high voltage events. A device that passes 15kV may easily fail at 1 kV because the di/di at

[SI-LIST] Immunity troubleshooting technique

Hi All, Well, its that time of the month when I get an itch to write something. So here goes Troubleshooting intermittent design problems can be a real time and resource burner in the development lab. Sometimes intermittent problems can be caused by lack of system immunity to noise on

Re: SONET ESD performance

Hi Scott and the group, Just a thought... If the equipment you are testing responds unfavorably to something the environment, it does not matter that you pass GR-1089. And, I have seen lots of stuff that affected lightwave equipment not covered under 1089 that got the operating companies pretty

cable shielding effectiveness

Hi All, What do an AM radio, a copper tape spark gap, two paper cups, and a cable have in common? Together they can be used as a quick way to evaluate the relative shielding effectiveness of a shielded cable. This month's Technical Tidbit at http://www.dsmith.org uses the copper foil spark gap

Static to dynamic field converter

Hi All, It is amazing what can be accomplished with simple, inexpensive test fixtures when it comes to debugging designs. The Technical Tidbit this month on www.dsmith.org describes a simple structure that generates repeatable, intense EMI useful for finding weaknesses in system designs. It also

Re: EMC Courses in Europe

Hi Gunter and the group, The following link will take you to the Oxford University that has several short courses you may find interesting: http://www.conted.ox.ac.uk/ousep/ Doug gunter_j_ma...@embraco.com.br wrote: Colleagues I am looking for short

[SI-LIST] : Multi-GHz EMI from a static (DC) field

Hi All, It is a new month and here is my latest article. Doug Hidden Threats to Electronic Equipment Sometimes the connection between equipment malfunction and its cause can be difficult to make. This month's Technical Tidbit at http://www.dsmith.org covers a hidden form of ESD

Re: ESD generators max Contact discharge level

Hi Glyn, Here is one way to approach 30kV. First, slide out of your car seat, the Ford Taurus is great for this effect. This puts a charge on your behind. As you get out of the car (everything is plastic so you remain charged with respect to the car) your voltage rises because Q=CV. Q stays the

Re: ESD generators max Contact discharge level

be used where contact discharge cannot be applied. What conditions would make it such that contact discharge could not be applied? Thanks in advance. Dan Kinney Horner APG -Original Message- From: Douglas C. Smith [SMTP:d...@emcesd.com] Sent: Friday, April 20, 2001 2:54 PM

Re: ESD generators max Contact discharge level

Hi Terry and the group, Besides the question of finding a generator that can reach the level you mention, I am not aware of any natural ESD event that approaches the interference potential of even an 8 kV contact discharge. The problem comes in that high voltage air discharges have relatively

Looking for alumni

Hi All, Not sure if this the right place to inquire about this, but here goes... I make electronic updates of my course notes available at no charge to people who have been students at one of my seminars. I have a good list of those that have attended my public seminars but my list from private

Unusual sources of signal corruption

Hi All, My Technical Tidbit article (http://www.dsmith.org) for this month deals with signal corruption of digital and analog signals by magnetic fields emanating from switching power supplies in a system. Because this is an unlikely source of corruption, it is often overlooked at great expense.

It's just a wire, isn't it?

Hi All, After a few weeks of holiday rush, I managed to write my technical article for January. And when is a wire, not just a wire?. After a few month's of articles on measurement techniques, this month's Technical Tidbit article on www.dsmith.org is more along the lines of design

Probe construction

Hi All, For those of you who like to tinker in the lab (and sometimes we have to when the right equipment is not available), this month's Technical Tidbit (at http://www.dsmith.org near bottom of index page) describes how to make a shielded magnetic probe out of common materials (no semi-rigid

Resistor design and ESD Symposium pictures

Hi All, The EOS/ESD (electrical overstress/electrostatic discharge) Symposium was last week in Anaheim, CA, USA. I focused on the system level effects of ESD, as a source of EMI, as opposed to controlling static charge. 18 representative pictures are now posted at www.dsmith.org under

Re: compactPCI bus

Hi Bill, I missed your original posting (get hundreds of emails daily). Got to www.cpcibackplanes.com. You may find help there. That URL is the site of International Product Design, a local company here in Los Gatos, CA, USA. Shawn Arnold is one of the principles and I expect he can help. Doug

Data Transmission System paper

Hi All, In response to several requests from members of these lists, I have posted a paper I authored titled EMC Performance Comparison of Shielded and Unshielded Data Transmission Systems presented at EMC'Roma 94. Both emissions and immunity (corruption or lack thereof of the data) results are

Re: SAR

Hi Ron, I believe Elliott Labs in Sunnyvale, CA does such testing and have a very good customer focus. Doug ron_cher...@densolabs.com wrote: I am trying to get a list of labs that can perform SAR testing on the West Coast, (CA). Thanks, Ron DENSO

Re: Conducted Emissions on Telecom Ports

Hi All, I could not resist adding my two cents worth. In the last several years I spent at Bell Labs in NJ (moved to CA 4 1/2 years ago), part of my funding came from a group that was responsible for UTP (Cat 5) and associated hardware. On immunity performance, we were not able to find a

An interesting source for copper foil tape

...and what do slugs and snails have to do with circuit prototyping, debugging, or EMC work? Have you ever had a need for copper foil tape on short notice for circuit prototyping, debugging, or EMC work? This month's technical tidbit is on a source of such material, the local hardware store.

Shielding Effectiveness - or when a dB is not a dB

Hi All, Shielding effectiveness is normally measured using plane waves (relatively far from the source). This method of measurement for shielding effectivenes does not always correspond to the way a shielding material is used. It is especially true when shielding material is incorporated into

[SI-LIST] : Hot ground noise probe

Hi All, I though some of you might enjoy my latest Technical Tidbit article. There are many techniques designers have used over the years to make quiet grounds on circuit boards and in systems. Sometimes it is done to reduce radiated emissions, other times to keep noise out of sensitive

Probe ground leads

Hi All, Here is some light reading if you are looking for a way to pass a hot day (it is 109 degrees here in Los Gatos today!) Often, a probe ground lead is thought of as a source of error in a measurement. But, the ground lead can also increase measurement accuracy. I have posted a

Re: Current Limitation for Single-Phase Power in the US and Canada

Hi All, 200 Amp single phase service is fairly common in the US (my present and last house has this service) so I know at least that much is possible. Separately, I posted sources for a couple of 180 degree combiners useful for differential probes at www.dsmith.org as this month's article. Last

Unusual System Glitchs

Hi All, We discussed at some length jingling change ESD and its relation to system operation some time ago. Along that line of unusual sources of system upset is multiple (up to hundreds) of ESD events in cushions of office chairs in the minute after a person rises from some chairs. The energy

50 Ohm Termination

Hi All, This month's technical tidbit article on www.dsmith.org is an easier way to construct a 50 Ohm termination good to 1 GHz or higher. Unlike my previous method, it is not necessary to try to solder surfact mount resistors to the rim of a BNC barrel adapter. The termination is useful by

1996 IEEE Paper on EFT

Hi Again, I forgot to mention that I also posted my 1996 IEEE paper on an investigation of the IEC 61000-4-4 Capacitive Clamp. It is under Technical Information for Download. It covers measurement error and also data that suggests that the capacitive clamp couples much more EMI onto I/O leads

Displaying measurement error and EFT testing

Hi All, I recently posted this month's article on my website www.dsmith.org. It shows how to display measurement error of a current measurement simulataneous to the measurement itself. This method catches almost all of the possible ways error can work its way into the measurement. The data I

Re: 50/75 Ohm pads

Hi Jim, Barth Electronics of Boulder City, NV (702-293-1576) has some of the highest quality pads on the market with flat frequency response to 20 GHz and some with the ability to take hundreds or thousands of volt pulses (he designs for a specific voltage coefficient of resistance by making his

Ferrites can increase emissions?

Hi All, I have noticed (like I expect many of you) that sometimes adding a ferrite on a cable to suppress common mode current caused emissions actually increases emissions at some frequencies. After thinking about this and trying an experiment to confirm one mechanism, I wrote up an article

Re: Ferrites can increase emissions?

sale) - Original Message - From: Douglas C. Smith d...@dsmith.org To: emc-pstc emc-p...@majordomo.ieee.org Sent: Wednesday, December 01, 1999 9:46 PM Subject: Ferrites can increase emissions? Hi All, I have noticed (like I expect many of you) that sometimes adding a ferrite

ESD data

Hi All, I have posted on my website the November article. It is related to the recent ESD and grounding threads on the Si-List and emc-pstc lists. Go to http://www.dsmith.org or http://emcesd.com and click on the picture at the bottom of the index page (after trying to guess the answers to the

Re: Home-Made RF probes.

Hi Kyle, It is important that the gap in the shield be exactly on the opposite side of the loop (as I believe you cite in your construction details). The loops with the gap at the end of the coax that is bent around do not actually have much electric field shielding. The details are in my paper

Re: Printed Circuit Board Grounding

Hi Don, Each situation should be evaluated on its own merits. I am going to list some general rules of thumb below, but there may be exceptions. I have done lots of ESD current measurements in different configurations and base my opinions on these measurments and personal experience with

1999 paper posted

Hi All, I decided to post my 1999 IEEE EMC Symposium paper on magnetic field probes, Signal and Noise Measurement Techniques Using Magnetic Field Probes, as well as the current probe paper. The 1999 paper provides background for last month's Technical Tidbit on the paperclip probe. The 1999

measuring voltage drop with a current probe

Hi All, I thought some of you might find my technical article of the month interesting. It is on making voltage measurements with a current probe. Over much of the useful frequency range of a current probe, its output is not the current in the wire but rather the voltage drop along the wire per

Re: Immunity Problems ??

Hi All, ESD or EFT could be the culprit. I would suggest putting a current probe around one of the instrument cables and connect to a digital scope and see if you can trigger on a noise event. If you are lucky, the instrument with the current probe will be the one that goes down. Alternatively,

1 GHz probe theory

Hi All, I have added a theory of operation section to the 1 GHz probe plans on my site at: http://emcesd.com The section discusses why the foil is needed and the underlying limitation on the useful frequency range of the probe. Also added is the ability to click on the probe pictures to blow