I also have a copy of those waveforms and a paper Michael King wrote on one of
my older Macs, can likely find it if needed.
I was lucky to have been mentored by Michael King when I was younger. He is a
great scientist/engineer and had a great effect on me.
I was fortunate to have four great ment
/2018 12:06 PM, Douglas Smith wrote:
> I did that experiment a long time ago, almost 30 years ago, when
> developing this experiment, which is described in my book.
>
> Reducing ground lead length to near zero eliminates the effect almost
> completely with no other changes in the experime
One common cause of nuisance tripping is EMI line filters whose input
capacitance to ground biases GFCIs near the tripping point. I would never power
up a computer on a GFCI circuit, asking for trouble. No high voltage pulses
needed.
Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 7
argument/experiment would be to show
that by eliminating the suspect element, the signal pickup goes away.
Regards,
Istvan Novak
Oracle
On 1/29/2018 10:55 PM, Douglas Smith wrote:
Hi Istvan, If I connect the oscillator directly to the scope chassis, I get
similar readings at different
Hi Istvan, If I connect the oscillator directly to the scope chassis, I get
similar readings at different frequencies. I generally get less amplitude
as well.
The small capacitance between the scope and oscillator is capable of tuning
the whole system to a low input impedance on the probe end. I
I am looking to contact Jeffery as I think his Facebook Messenger account
has been compromised in a really bad way. Can anyone give me his real
contact info?
Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108
Email: d...@dsmith.org Website: http://dsmith.org
-
-
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
Not sure what the problem is. Maybe a Windoz setup problem?
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 13:48, Lyndell Asbenson
wrote:
Doug,
Thanks for your YouTube videos, a problem that I
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
Great quote! It pretty much describes much of medical research in my opinion.
The great thing about engineering is the field is “grounded” (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 medici
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 wrot
Actually, inductive coupling (Faraday's law) can generate thousand of Volts
near ESD events, enough to breakdown insulation barriers!
Just get a di/dt of 40 Amps/ns (a 10kV or somewhat less contact discharge) near
a loop and see what you get for 50 nH of inductance (not much)
E = 40A/ns * 50 nH =
and so on J Then, of
course, there may be attempted legal action – which, is, I guess, a minefield
against which to defend if you are the manufacturer /supplier!
John E Allen
W.London, UK.
From: Douglas Smith [mailto:d...@emcesd.com]
Sent: 06 January 2018 18:28
To: EMC-PSTC@LISTSERV.IEEE.ORG
a new experiment at your workshops. ;-)
Cheers, Adam in Atlanta
On Sat, Jan 6, 2018 at 2:48 AM, Douglas Smith < d...@emcesd.com
[d...@emcesd.com] > wrote:
Thus is a common occurrence. The iPhone was not actually connected to you so
the large E field induced a different charge on you th
BTW, indoor humidity is constant in Boulder City, NV as the dewpoint does not
change much summer to winter. It is often 10 degrees F almost any time of year,
and conventional air conditioning actually increases indoor relative humidity
as they do not remove water (dewpoint too low) but cool the
Thus is a common occurrence. The iPhone was not actually connected to you so
the large E field induced a different charge on you than on the phone and hence
the discharge through your ear (the lowest breakdown between the iPhond and you.
Such discharges have led to claims of injury that ended up
I recently replied to another post and mentioned uncertainty in ESD
testing. I thought it would be good to post it separately to start a wider
discussion, so here we go:
In ESD testing, the poor specification of the simulator in standards, like
IEC 61000-4-2 [tel:61000-4-2] , leads to uncertaint
How would you relate the tolerance of placement of system components like
cables or PCs (in cm) to measurement uncertainty? Just setting up for the
next test can make a few dB difference. In a large system, it may even
affect antenna placement in the chamber to get the right distance to the
EUT
Hi Ken and the group,
The LED bulbs I have, mostly Cree and high quality, take about a second to
extinguish completely after power is removed, about the same as an incandescent
bulb, obviously there is energy storage in the bulb.
I am surprised the Brits are affected by 100 Hz flicker. I could no
Hi Rich,
I am familiar with those concepts, but there is apparently quite a bit the
measurement companies do not understand about their own probes, at least they
do not publically cover some important issues. The fact they could have added a
whole octave of usable frequency response for essentia
Here is a bit of suspence for Friday, free webinar on this topic (joining
details available shortly).the addition of a simple change to the probe
significantly improves, almost eliminates, frequency response problems due to
the ground lead and circuit impedance. Can you guess what it is? Got
I agree with John. Also a search for FMEA produces a lot of references to some
music organizations and others.
Only if directed to a very narrow audience (not this group!) where everyone
knows what is being referenced, should one expect others to spend a total of
hours looking up acronyms that u
Pretty much everything by Gert looks incorrect or possibly a some typos.
More
turns on the core gives you less output over most of the frequency range
but
more output at the very low end of the frequency.
Zt = M/L * Zo in the flat region of the frequency response where Zo is the
50
Ohm load on
Dan is correct, but first make sure the lab did the test correctly, most do not
in my experience leading to often a 6 dB over test. When I have pointed this out
to test labs during testing, they always correct their testing when shown the
paragraph about the current limit.
After the test is run cor
How much did it fail by? You need to know this.
This test is often done in error by test labs resulting in a 6 dB over test.
Make sure they are applying the current limit loophole that is allowed for many
cases, often for Ethernet cables.
Be sure the failure is in your equipment not the aux equipme
Your option #2 may kill the Ethernet signal unless the beads are 4 or more
terminal common mode ones.
Doug Smith Sent from my iPhone IPhone: 408-858-4528 [tel:408-858-4528] Office:
702-570-6108 [tel:702-570-6108] Email: d...@dsmith.org Website:
http://dsmith.org
On Thu, Dec 10, 2015 at 01:26, A
Hi All,
I will be doing a repeat session on my EMC Test Lab Errors presentation
for those who missed the first one, next Wednesday, 27th June at 0930
PDT. Here is the description:
Measurement and procedural errors at EMC (and other) test labs can cost
your company a lot! Some of the errors a
Hi All,
Measurement and procedural errors at EMC (and other) test labs can cost
your company a lot! Some of the errors are egregious and others (more
common ones) are worth a few dB to 6 dB typically. These are easy to
spot by anyone viewing the test (no special training needed) so I wonder
w
Hi All,
Over the weekend I uploaded a lot of technical podcasts and some videos
to my website. The link is:
http://emcesd.com/#Podcasts
Some of the videos will not play on Mozilla products but work on IE,
Safari, and Opera. You can also right click and save on your computer to
play with any
Hi All,
I have added many technical podcasts to my site http://emcesd.com. The
description and link to the podcasts is just below the University of
Oxford material on the site or you can use this link to go directly to
that part of the page:
http://emcesd.com/#Podcasts
There are many podcas
Hi Ken,
I suspect that the health impact of the microwave popcorn far exceed
the leakage from the oven. This stuff is bad, not fit for human
consumption.
Doug
Douglas C. Smith
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire
Hi Rich and the group,
Even DC power internal busses in equipment are likely to have 1000
Volt transients if hot plug of power supplies and/or loads are
allowed. Outside transients are not necessary to have this happen.
I have personally observed these EFT
Hi Ed and the Group,
Ed said: "Did you create a write-up
on what those errors specifically were, and how it happened
that you noticed them in time to control them?"
I have not specifically written them up although I do tell them as
war
--
On 10/9/14 8:48 PM, Douglas Smith wrote:
Hi Everyone,
I am going to try sending short "tweets" on electronic design and
troubleshooting you may be interested in. If you want to see them,
look at: @dougcsmith_ee on Twitter. It
Hi Everyone,
I am going to try sending short "tweets" on electronic design and
troubleshooting you may be interested in. If you want to see them,
look at: @dougcsmith_ee on Twitter. It it proves useful to people I
may permanently keep doing it.
Just did a te
Hi All,
Got an error message from my last post so not sure who may have received
it, so here is a retry:
I just uploaded my latest video to YouTube on PCB design troubleshooting
and finding possible radiated immunity problems using direct RF
injection. Here is the link to the video. The seco
Hi All,
Not sure how the link got changed to youtu.be in my last post although
it seems to work. The intended link is:
https://www.youtube.com/watch?v=4LzLbOUYT-I
Doug
--
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
--
Hi All,
A few days ago I posted a link to my new video on my website. I have
also posted it to youtube. The data rate is better from youtube. The
subject is comparing the intensity of ESD directly from human skin to
ESD from a piece of metal held in a hand as seen in the EMI generated by
the
Hi Everyone,
I just posted my September Technical Tidbit titled:
Human Metal Model ESD Compared to Direct Skin Discharge (Human Body
Model) ESD
(Revisited in Video Format)
This article is really a video of the live experiment, my first video
Technical Tidbit. The video is in flash but if any
Hi Everyone,
I just posted my latest Technical Tidbit a few hours ago using a
class D stereo amplifier to illustrate a potential problem whereby
emission test standards may understate the emissions from a digital
device. Here goes:
Abstract: Radiated emissio
Hi Everyone,
I seem to have a continuing experience with UPS equipment overheating
the batteries. Most all of my UPSs have done this at one time or
another. Here is an example:
At the office, I was to be away for a week and if the power went out,
some of my UPSs sound an alarm which can anno
Hi Ken and the group,
Sounds like a very nice generator. I wish it could be controlled
from a web browser for a universal interface, like many scopes
these days. My productivity is so much higher on a Mac compared to
Windows, that a Windows machine is to ex
I don't think 1 or 2 MOhms will make
much difference for one second application of ESD pulses.
Tc = RC = 10**6 x 100*10**-12 = 10**-4 seconds (100 pF estimated,
not calculated between HCP and GRP. Even 10X that capacitance
would still yield a Tc of 1 ms, or
I can vouch for Don. He is a great engineer and is very
knowledgeable. Very good background in engineering fundamentals and
inquisitive mind. I have had the pleasure of having him attend one
of my seminars.
Doug
On 11/15/12 6:07 AM, Don MacArthur
wrote
Hi Everyone,
This month my Technical Tidbit is written by Tim Maloney of Intel for
publication on my site. He has devised a very good transmission line
equivalent circuit than makes it easy to understand transmission line
impedance behavior as a function of line length and termination
impedan
Hi All,
My Technical Tidbit article for this month discusses avoiding ESD events
when system modules or connectors make contact by using static
dissipative materials in plastic parts, a technique normally used to
reduce static charge in factory environments.
Minimizing ESD Events Involving El
Date: Wed, 04 Jun 2008 19:39:59 -0700
From: Douglas Smith <mailto:d...@emcesd.com>
Reply-To: d...@dsmith.org
Organization: D. C. Smith Consultants
To: emc-pstc <mailto:emc-p...@ieee.org> , SI-List
<mailto:si-l...@freelists.org>
Hi Everyone,
Hi Everyone,
I have posted the latest Technical Tidbit on my website http://www.dsmith.org
. It should be interesting to EMC folks who use magnetic field probes and to
SI people as well since magnetic loops are very useful at finding board layout
issues by signal injection thorough mutual inducta
Hi Lisa and the group,
I am on a business trip at the moment, but lucky enough to be at a
hotel with high speed internet service.
Lisa, I guess you could start with my website at http://emcesd.com
where I have posted about 60 papers and articles, many of them on
fixing EMI problems. There a
Hi David (and the group),
Take a look at the Technical Tidbits section of my site at
http://emcesd.com where you will find some experimental evidence for
your viewpoint. This month's article (at the bottom of the main page)
presents some data and links to two other articles.
Doug
On Friday
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