Re: [PSES] [SI-LIST] Re: need some advice on cancellation policy for a seminar

[Doug Smith]

Hi Doug,
All my classes include lodging, breakfast, and lunch each day so their only 
additional cost would be a couple of Uber rides and dinner each day (about $15 
for dinner around here for a good meal, less for fast food). So the amount at 
issue is only $260 for airfare round trip. (Michigan to Las Vegas McCarran).


Doug SmithSent from my iPhoneIPhone:  408-858-4528Office:
702-570-6108Email: doug@dsmith.orgWebsite: http://dsmith.org







On Sat, Sep 15, 2018 at 11:44 AM -0700, "Doug Brooks" 
 wrote:










I agree with Istvan. But with regards to your idea of giving them 
tickets, are you forgetting hotel room costs. That is often the larger 
cost of travel.

Your problem stems from not having a policy stated up front. That will 
solve this issue next time. This time, if your offer doesn't work, you 
may just have to "eat" the cost.

Doug






Doug Smith wrote:
>
>   
>   
>   
>   
>   Someone on the list had a great idea. I can buy round trip 
> tickets for $260 so I may offer that. That should work and be a good 
> compromise if that is the real reason. I am suspicious of the manager’s 
> intentions here but will find out on Monday when I make the offer.
> What should I do if the offer to buy the airline tickets (their reason for 
> cancellation in the first place) is rejected?
> Also an engineer from the list is intending to register which would replace 
> one of the other two. So things are working out. Will have a written policy 
> after this. If the person had a personal issue like sickness or a family 
> emergency, even at the last minute, I would refund the whole amount.
>   
>   
>
>   Doug SmithSent from my iPhoneIPhone:  408-858-4528Office:
> 702-570-6108Email: doug@dsmith.orgWebsite: http://dsmith.org
>
>   
>
>
>
>
> On Sat, Sep 15, 2018 at 7:29 AM -0700, "Istvan Novak"  wrote:
>
>
>
>
>
>
>
>
>
>
> Hi Doug,
>
> Arguing with a no travel policy may not help, because those are usually
> across the board measures in companies, allowing few or no exceptions.
>
> I think the straightforward approach is to make clear at the time of
> registration that there is a cancellation policy with a deadline beyond
> which there is reduced or no refund.  If you want to be fair and
> accommodating, you can give a refund (minus a cancellation fee to cover
> the extra administration) IF the two seats are filled by other applicants.
>
> Regards,
>
> Istvan
>
>
> On 9/14/2018 4:51 PM, Doug Smith wrote:
>>  
>>
>>
>> Hi Everyone,
>>
>> I need some advice on a pair of cancelled registrations for a class I am 
>> holding next month. Two people from the same company registered and the 
>> company paid the registration fees. At that point the seminar was full (I 
>> limit it six people for a good experience) so I stopped marketing activities 
>> for the last week and a half. Then a manager higher up decided there will be 
>> no travel and now they want a refund. At this point, it is not likely, 
>> although possible, that two people additional people will register as time 
>> is short to get the required approvals. I have about an hour of work on each 
>> registration invested at this point for a total of two hours plus that much 
>> time to register and arrange for two different people if the register. Part 
>> of my time is making hotel reservations as the hotel and most meals are 
>> covered in the registration fee. Issuing a refund is a fair amount paperwork 
>> and record keeping, probably about an hour total for both. Basically, to 
>> save a few hund
>>red doll
>>ars this company wants to cost me almost 10X that if I cannot fill the 
>> two seats (of six).
>>
>> The problem is the no travel policy. I use Las Vegas McCarrann airport which 
>> must be the cheapest airport in the world because of being a vacation 
>> destination. I can fly to California for less than the cost of gas to drive 
>> there in a car ($49 ticket on SouthWest). The cost of their tickets should 
>> be about $300 or less per person round trip from their location compared to 
>> about $2000 per person already paid.
>>
>> What do others do for a cancellation policy? In the past, I let someone come 
>> to a future delivery for no extra charge. In that case, the person had a 
>> personal reason for not being able to come. I try to be good to people as 
>> with the person just described plus I le

Re: [PSES] [SI-LIST] need some advice on cancellation policy for a seminar

[Doug Smith]

Someone on the list had a great idea. I can buy round trip 
tickets for $260 so I may offer that. That should work and be a good compromise 
if that is the real reason. I am suspicious of the manager’s intentions here 
but will find out on Monday when I make the offer.
What should I do if the offer to buy the airline tickets (their reason for 
cancellation in the first place) is rejected?
Also an engineer from the list is intending to register which would replace one 
of the other two. So things are working out. Will have a written policy after 
this. If the person had a personal issue like sickness or a family emergency, 
even at the last minute, I would refund the whole amount.



Doug SmithSent from my iPhoneIPhone:  408-858-4528Office:
702-570-6108Email: doug@dsmith.orgWebsite: http://dsmith.org






On Sat, Sep 15, 2018 at 7:29 AM -0700, "Istvan Novak" 
 wrote:










Hi Doug,

Arguing with a no travel policy may not help, because those are usually 
across the board measures in companies, allowing few or no exceptions.

I think the straightforward approach is to make clear at the time of 
registration that there is a cancellation policy with a deadline beyond 
which there is reduced or no refund.  If you want to be fair and 
accommodating, you can give a refund (minus a cancellation fee to cover 
the extra administration) IF the two seats are filled by other applicants.

Regards,

Istvan


On 9/14/2018 4:51 PM, Doug Smith wrote:
>   
>
>
> Hi Everyone,
>
> I need some advice on a pair of cancelled registrations for a class I am 
> holding next month. Two people from the same company registered and the 
> company paid the registration fees. At that point the seminar was full (I 
> limit it six people for a good experience) so I stopped marketing activities 
> for the last week and a half. Then a manager higher up decided there will be 
> no travel and now they want a refund. At this point, it is not likely, 
> although possible, that two people additional people will register as time is 
> short to get the required approvals. I have about an hour of work on each 
> registration invested at this point for a total of two hours plus that much 
> time to register and arrange for two different people if the register. Part 
> of my time is making hotel reservations as the hotel and most meals are 
> covered in the registration fee. Issuing a refund is a fair amount paperwork 
> and record keeping, probably about an hour total for both. Basically, to save 
> a few hund
>   red doll
>   ars this company wants to cost me almost 10X that if I cannot fill the two 
> seats (of six).
>
> The problem is the no travel policy. I use Las Vegas McCarrann airport which 
> must be the cheapest airport in the world because of being a vacation 
> destination. I can fly to California for less than the cost of gas to drive 
> there in a car ($49 ticket on SouthWest). The cost of their tickets should be 
> about $300 or less per person round trip from their location compared to 
> about $2000 per person already paid.
>
> What do others do for a cancellation policy? In the past, I let someone come 
> to a future delivery for no extra charge. In that case, the person had a 
> personal reason for not being able to come. I try to be good to people as 
> with the person just described plus I let unemployed engineers come at about 
> to my cost if I have empty seats.
>
> What would you do? I could use some advice.
>
> Doug
>
>
>
>
>
>
>
>
>
> --
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>
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>









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Re: [PSES] need some advice on cancellation policy for a seminar

[Doug Smith]

John,

If they were a customer I would just refund the amount. I would normally just 
let them come to the next or any event (even though it would cost me two of six 
registrations for the future event). But they do not want to do that.

I have classrooms available to me at no cost of 6, 20, and 100 people but I 
choose to do small seminars. Large ones are not nearly as useful to the 
attendees as small ones. If this were a group of 20, I would just refund.

So, I will just start marketing the next few weeks and see what happens. If two 
more sign up I will just refund. I will probably not allow the company that 
cancelled to come to my events in the future without special arrangements 
compared to others.

Doug








On Fri, 14 Sep 2018 22:50:03 +0100, John Woodgate  wrote:


I guess you don't have a cancellation policy in your TCs. No doubt you 
will fix that, as a result of this experience. If you don't want to lose the 
customer, and maybe get bad music on social media, let them come to a future 
event at no extra charge. 

John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK

On 2018-09-14 21:51, Doug Smith wrote:







Hi Everyone,

I need some advice on a pair of cancelled registrations for a class I am 
holding next month. Two people from the same company registered and the company 
paid the registration fees. At that point the seminar was full (I limit it six 
people for a good experience) so I stopped marketing activities for the last 
week and a half. Then a manager higher up decided there will be no travel and 
now they want a refund. At this point, it is not likely, although possible, 
that two people additional people will register as time is short to get the 
required approvals. I have about an hour of work on each registration invested 
at this point for a total of two hours plus that much time to register and 
arrange for two different people if the register. Part of my time is making 
hotel reservations as the hotel and most meals are covered in the registration 
fee. Issuing a refund is a fair amount paperwork and record keeping, probably 
about an hour total for both.Basically, to save a few hundred dollars 
this company wants to cost me almost 10X that if I cannot fill the two seats 
(of six).

The problem is the no travel policy. I use Las Vegas McCarrann airport which 
must be the cheapest airport in the world because of being a vacation 
destination. I can fly to California for less than the cost of gas to drive 
there in a car ($49 ticket on SouthWest). The cost of their tickets should be 
about $300 or less per person round trip from their location compared to about 
$2000 per person already paid.

What do others do for a cancellation policy? In the past, I let someone come to 
a future delivery for no extra charge. In that case, the person had a personal 
reason for not being able to come. I try to be good to people as with the 
person just described plus I let unemployed engineers come at about to my cost 
if I have empty seats.

What would you do? I could use some advice.

Doug


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This message

[PSES] need some advice on cancellation policy for a seminar

[Doug Smith]

Hi Everyone,

I need some advice on a pair of cancelled registrations for a class I am 
holding next month. Two people from the same company registered and the company 
paid the registration fees. At that point the seminar was full (I limit it six 
people for a good experience) so I stopped marketing activities for the last 
week and a half. Then a manager higher up decided there will be no travel and 
now they want a refund. At this point, it is not likely, although possible, 
that two people additional people will register as time is short to get the 
required approvals. I have about an hour of work on each registration invested 
at this point for a total of two hours plus that much time to register and 
arrange for two different people if the register. Part of my time is making 
hotel reservations as the hotel and most meals are covered in the registration 
fee. Issuing a refund is a fair amount paperwork and record keeping, probably 
about an hour total for both.Basically, to save a few hundred dollars 
this company wants to cost me almost 10X that if I cannot fill the two seats 
(of six).

The problem is the no travel policy. I use Las Vegas McCarrann airport which 
must be the cheapest airport in the world because of being a vacation 
destination. I can fly to California for less than the cost of gas to drive 
there in a car ($49 ticket on SouthWest). The cost of their tickets should be 
about $300 or less per person round trip from their location compared to about 
$2000 per person already paid.

What do others do for a cancellation policy? In the past, I let someone come to 
a future delivery for no extra charge. In that case, the person had a personal 
reason for not being able to come. I try to be good to people as with the 
person just described plus I let unemployed engineers come at about to my cost 
if I have empty seats.

What would you do? I could use some advice.

Doug









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Re: [PSES] hot laptop

[Doug Smith]

Hi Everyone,

This "hot laptop" problem has been going on for many years now. I remember a 
story in the tech mags out of Silicon Valley about Apple laptops burning, 
really leaving an injury, on the order of ten years ago. Apple said the 
machines were not intended to be used on one's lap.

Doug








On Thu, 16 Aug 2018 20:58:12 +, "Nyffenegger, Dave"  wrote:

 




We agree I need a new laptop due to this issue alone. It’s not hot enough 
that it can’t be moved away quickly enough to prevent a permanent burn. 
But it is hot enough to leave sun-burn like splotches on skin if left to long 
over a thin layer of clothing. Hot enough to discolor some other 
materials it may rest on as well.



-Dave





From: Richard Nute [mailto:ri...@ieee.org]
Sent: Thursday, August 16, 2018 3:44 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] hot laptop







Its not the temperature, but the thermal energy that is transferred to a body 
part. Consider aluminum foil versus cast aluminum at the same 
temperature, say 140 F. The foil won’t burn you, but the cast aluminum 
sure will!



The thermal resistance of plastic will give you the time to disconnect from the 
140 F surface of your laptop before you suffer a burn.



You need a new laptop, too! 



Best regards,

Rich







From: IBM Ken ibm...@gmail.com
Sent: Thursday, August 16, 2018 12:31 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] hot laptop





Aren't we supposed to call them "notebook" computers now, so it can be claimed 
they're not intended for use on a lap? 







For what it's worth, I've measured up to 140F on the surface of my computer...







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Re: [PSES] hipot test

[Doug Smith]

Hi Doug and the Group,

In the case of my 48 Volt fire years ago, it was local heating from a power 
resistor that turned the FR-4 conductive and then the 48VDC flowing through 
that area created more heat and then positive feedback took over with negative 
results.

DougUniversity 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 Wed, 15 Aug 2018 14:39:36 -0600, Doug Powell  wrote:
 Pete,
 
Your statements may be true for many product types certified to 60950-1, 
61010-1, etc.  However when dealing with power conversion products that have 
secondary voltages well above mains voltages, this is no longer true.  In the 
region of 5,000 V and above, corona is a common occurrence in inhomogeneous 
fields and this has the effect of causing surface damage (carbonization) on 
insulation with any organic content.  Inorganic insulators such as ceramics and 
glass seem to be much less affected.  
 
Such phenomena is mentioned in Klaus Stimper's book, The Physical Fundamentals 
of Low-Voltage Insulation Co-ordination.
 
All the best,  Doug
 
 
 On Wed, Aug 15, 2018 at 10:04 AM Pete Perkins 
<0061f3f32d0c-dmarc-requ...@ieee.org> wrote:
All, This discussion goes around  year after year. 
 
   The test results reported – especially Nute – show 
that it takes dozens, maybe  hundreds of hipot tests to damage adequate 
insulation. 
 
   In the UK, so I hear, the gov’t safety folks expect 
each piece of equipment to be hipot retested annually to demonstrate adequate 
insulation.  We don’t hear a large hue and cry about failing equipment in that 
arena. 
 
   So from the experience and the data it is clear that 
both the engineering type hipot testing and the factory routine testing should 
not pose any problem to properly designed and manufactured products. 
 
   For line connected products it is foolishness to 
remove components for hipot testing.  If that is being done the product is not 
robust enough in the first place.  This includes DC line powered equipment 
since so much DC power is being installed and used in places where it is 
subject to the same lighting and starting impulses traditionally seen on AC 
line operated equipment.   
 
:>)  br,  Pete
 
Peter E Perkins, PE
Principal Product Safety & Regulatory Affairs Consultant
PO Box 23427
Tigard, ORe  97281-3427
 
503/452-1201
 
IEEE Life Fellow
p.perk...@ieee.org

 
From:
 Jim Hulbert 
Sent:
 Wednesday, August 15, 2018 5:25 AM
To:
 EMC-PSTC@LISTSERV.IEEE.ORG

Subject: Re: [PSES] hipot test

 
I disagree with your NRTL.  If the hipot test can degrade the insulation (we’re 
talking about a single test on the production line), then the insulation system 
is not up to par.  
 
Jim
 


 
From:
 Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com
]
Sent:
 Wednesday, August 15, 2018 12:18 AM
To:
 EMC-PSTC@LISTSERV.IEEE.ORG

Subject: Re: [PSES] hipot test

 
The NRTL I typically use always runs the hipot test for 60 seconds for type 
testing during product certification.  The listing reports always specify a 1 
second hipot for production line testing 100% of all units.  Their claim is 
that the hipot can degrade some insulation and should be kept to a minimum.
 
-Dave
 
From:
 Richard Nute [mailto:ri...@ieee.org
]
Sent:
 Tuesday, August 14, 2018 5:34 PM
To:
 EMC-PSTC@LISTSERV.IEEE.ORG

Subject: [PSES] hipot test

 
 
Hi Doug:
 
I've always viewed the purpose of hipot testing as verification only.  During 
engineering type testing, it is design verification. 
 
I disagree.  The hi-pot test determines the minimum electric strength of the 
insulation system.  Design is an indirect measure of electric strength by 
selecting the distances through solid and air (clearance) insulations.  
However, design rarely includes the shape of the electric field, which is a 
parameter that determines electric strength.  
 
Since hipot is so stressful to insulation…
 
Again, I disagree.  If the design is “good” (adequate electric strength), then 
the hi-pot test does not stress the insulation system.  See Agilent 
Technologies Optocoupler Input-Output Endurance Voltage Application Note 1074.
 
Best regards,
Rich
 
 
 
From:
 Doug Powell 
Sent:
 Tuesday, August 14, 2018 1:50 PM
To:
 EMC-PSTC@LISTSERV.IEEE.ORG

Subject: Re: [PSES] X & Y Cap rating due to hipot test
 
I've always viewed the purpose of hipot testing as verification only.  During 
engineering type testing, it is design verification.  During routine testing 
for manufacturing, it is workmanship and build verification.  

 

During type testing many safety standards w

Re: [PSES] circuit boards

[Doug Smith]

Hi Rich and the group,

I have seen FR-4 become conductive, start the board on fire, and burn up a rack 
of equipment! In that case the driving voltage was 48 VDC. Never let both sides 
of power come close on a board if heating can happen in the vicinity.

Of course, here in Boulder City, NV heating happens all the time. No need to 
warm up the car engine, it already is. Also, we have unlimited solar hot water 
from the cold water faucetI have become used to it, and at 71 years old, I 
still run miles and miles at 110 degrees at a brisk pace in the strong sun 
(along with a lot of younger people out here).



Doug Smith
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 Wed, 15 Aug 2018 13:09:54 -0700, Richard Nute  wrote:








My experience with circuit boards and plastics is that some formulations 
degrade with heat (pyrolysis) to a resistive state. I have a C14 
appliance inlet that has been overheated and I can measure the (cold) 
resistance with an ohmmeter (even today, some years after the incident). 
Same for printed wiring boards. 



When solid insulation becomes a resistor, all kinds of heating (and fire) can 
occur. 



Best regards,

Rich

IEEE Life Fellow







From: Pete Perkins 0061f3f32d0c-dmarc-requ...@ieee.org
Sent: Wednesday, August 15, 2018 12:29 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] hipot test





John,  your description sounds much like the failure 
mechanism seen is circuit boards which start in a small void and develop 
micro-arcing which feeds upon itself and eventually drives a large void that 
allows conductors to directly contribute current and destroy the board. 
I’ve investigated some destructive fires in equipment from such a source. And 
the circuit boards don’t need full hipot voltages to do this, line operated 
units eat themselves up quite handily. 


 No, I don’t mean to start anew thread here. 




:) br, Pete



Peter E Perkins, PE

Principal Product Safety  Regulatory Affairs Consultant

PO Box 23427

Tigard, ORe 97281-3427



503/452-1201



IEEE Life Fellow

p.perk...@ieee.org




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Re: [PSES] EN62311 - Human Exposure to Electromagnetic Fields

[Doug Smith]

Hi Ken and the group,

Ken you make very good points!

One interesting point. Heart disease and arthritis are, for the most part, 
nutritional deficiency diseases, easily avoided if one knows what one is doing, 
which most do not. It is not possible to get adequate amounts of required 
nutrients, like magnesium for instance, from our modern food. I have used 
engineering analysis of the published scientific literature to figure out what 
is lacking and manually add it back in. The result is me at 71 having no 
problems of aging or medicines, etc. Just the occasional athletic injury which 
I have encountered most of my life. I run miles and miles at 110 degrees in the 
desert with no ill effects! If any of you are interested in this, I uploaded 
years of accumulated information to a hidden directory of my website. It is not 
organized, just a lot of files. The URL is: http://emcesd.com/Health. Great if 
you are having insomnia some night.

Maybe we will know RF effects in detail like the above at some point.

Doug








On Thu, 5 Jul 2018 15:20:56 -0500, Ken Javor  wrote:






The precautionary principle, as harmless and common sense as it sounds, is at 
the root of much mischief. Said mischief is not inherent in the principle 
itself, but how it is used. Since anyone can come up with a “what if 
“scenario, the principle ends up applied indiscriminately. Just as John 
Woodgate describes, we have in place in the USA laws that prohibit any 
concentration of certain chemicals. These laws were passed when the ability to 
see a concentration might have been in the parts per million, but we have 
progressed to measuring parts per trillion, and the laws haven’t changed. If 
someone raises the issue of changing the law to allow some concentration above 
what is measurable, they are labeled as advocating pollution of the water 
supply, or air or whatever.

As is often noted, “the dose is the poison.” Many things which are poison in 
large quantities are beneficial at lower levels.

Aspirin comes to mind.

Some time in the early ‘90s the keynote speaker at a US-based IEEE EMC 
symposium was someone active in EMF effects on health. He went so far as to say 
that in addition to eliminating EMF due to overhead power lines, and the like, 
we could not simply hide in a shield room, because our bodies evolved to live 
in an environment not totally free of EMF, so that totally eliminating them 
would be as problematical as too much.

Consider the “thought” process here. Human beings evolved to survive with 
a life span of about 35 years. In the Stone Age, by 35 you were a 
grandparent and arthritis, rheumatism, and the other ills of old age had 
combined to make you a drag on the tribe. Discovery of Neanderthal man at 
first had them bent over and “Igor” like. It wasn’t until much later they 
realized that the skeletons had been ravaged by rheumatism/arthritis. The 
mistake was made because they could tell these people had died in their 
thirties, and that was deemed too early for these ills, so that they assumed 
these people were naturally misshapen.

In the USA at the beginning of the 20th century average life expectancy was in 
the forties. All those cowboys smoking in the old westerns made perfect sense – 
the last thing those guys expected to die of was emphysema or heart disease or 
cancer. The original USA social security retirement age of 65 was set to 
coincide with the mean date of expiration of the human body determined at that 
time.

A policy aimed at improving physical health and longevity but predicated on how 
we evolved is inherently flawed. Those of us past 35 or so are in 
uncharted waters as to what does or does not promote or constrain longevity.

Ken Javor
Phone: (256) 650-5261



From: John Woodgate j...@woodjohn.uk
Reply-To: John Woodgate j...@woodjohn.uk
Date: Thu, 5 Jul 2018 20:34:07 +0100
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EN62311 - Human Exposure to Electromagnetic Fields



There is another aspect to this, the 'precautionary principle'. This says that 
if you don't know the harmful level of something, you reduce its level to 
ALARP, 'as low as is reasonably practicable'. Unfortunately, of course, 
opinions differ very widely on what that level is, in many cases. This is why 
we see concentration limits of parts per trillion, because they are achievable 
(at a price), not because they are related to known effects.



I didn't grow up in strong EM fields, but in a concentration of lead (pipes, 
paint, cable sheaths) that would be regarded as horrifying now. If that 
reduced my intellectual capacity, much is explained.:-P


John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk http://www.woodjohn.uk;
Rayleigh, Essex UK

On 2018-07-05 20:12, John Woodgate wrote:





Yes, there are very big 'safety factors' built into the requirements, more in 
Europe than in USA. Much of the interest in Europe was generated by 
Scandinavian trades unions 

Re: [PSES] EN62311 - Human Exposure to Electromagnetic Fields

[Doug Smith]

Hi Michael and the group,

With the exception tissue heating generated by some sources at very high 
frequencies, I wonder if the EM field exposure worries today are a bit 
overblown. I started my experiments in high voltage (100,000+ Volts, and 
NOT static electricity) around age 13 and by age 14 was regularly immersing 
myself in 10,000+V/m, 300 kHz fields. It was fun, heating up screw driver 
blades from induction heating, lighting incandescent light bulbs (as well as 
fluorescent tubes) without wires, and more. About 600 Watts of RF energy was 
concentrated in the relatively small space I was in and I was uninjured! My 
kids all have two arms, two legs, and one head and I am still here almost 60 
years later and healthier than 90% of adults of any age from 18 on. Some of my 
friends say this explains a lot about me (frying brain cells) though.

I realize this is only one case, but have had a lot of high energy RF exposure 
throughout my life. Such as the field in my dorm room from my amateur radio 
transmitter being so strong that the fluorescent tubes in the room lit up with 
no power and blinked with Morse code. I had to remove the tubes from their 
fixtures and cover with towels so my roommate could sleep.

Still here,
Doug








On Thu, 5 Jul 2018 16:27:12 +0100, Michael Derby  wrote:






It’s not quite an “unintentional radiator” but if you had a wireless charger 
which did not contain any communication (e.g., a dumb charging signal without 
handshaking), then it would come within the scope of the EMCD and the LVD 
(not the RED), and RF Exposure would therefore be an issue under the LVD.



Michael.







From: McCallum, Andy [mailto:andy.mccal...@mottmac.com]
Sent: 05 July 2018 15:33
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EN62311 - Human Exposure to Electromagnetic Fields





Be surprised if any LVD could cause EMF large enough to pose a danger to Human 
Health. Intentional transmitters maybe, a rare beast to create those levels 
unintentionally at less than 1000V.



Andy 





From: John Woodgate [mailto:j...@woodjohn.uk]
Sent: 05 July 2018 10:28
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EN62311 - Human Exposure to Electromagnetic Fields





It applies to any LVD product, but there is a flow chart that shows that a 
simple assessment is possible if the product has no reasonable likelihood of 
producing sufficiently strong EMF.

John Woodgate OOO-Own Opinions Only

J M Woodgate and Associates www.woodjohn.uk

Rayleigh, Essex UK


On 2018-07-05 10:09, Amund Westin wrote:



EN62311 is listed in OJ and a harmonized LVD standard. 

Does EN62311apply to any LVD product or only products containing radio 
transmitters?





Best regards

Amund

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Re: [PSES] ESD question

[Doug Smith]

Hi John and the group,

Actually I was just kidding everyone. But I am going to start telling everyone 
my body is about 24 pF/ns and see what happens. I will keep an eye open for the 
men in the white coats with nets. Actually I have been watching for them for 
some time now. Just completed a run at 100 F. Will be running in 111+ F on 
Thursday at the peak of the afternoon. Some day I will act my age.

Doug








On Tue, 19 Jun 2018 22:29:44 +0100, John Woodgate  wrote:


I think the model should assume a spherical body of the relevant mass, which 
capacitance in the archaic unit 'centimetres' is equal to its radius in 
cm, and 1 cm = 1.13 pF. With all respect to Doug, I think the BCI is 
about as scientific as BMI, which is at least a pressure (kg/metre-squared) of 
some sort. I'm not sure what pF/ns would represent. 

Of course the capacitance of a spherical grandmother of any radius is 1 
nanafarad.

John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK

On 2018-06-19 22:06, Doug Smith wrote:







Hi Ken and the group,

The model started out in IEC 801-2 which had a 150 Ohm, 150 pF model. This 
eventually became IEC 6000-4-2 at 330 Ohms and 150 pF. Both were meant to model 
a piece of metal in a human hand. Such a discharge is an order of magnitude 
more severe, even for a tiny piece of metal in one's hand, than a discharge 
directly from a human hand if one measures the radiated EMI from these events.

The R and C above were the result of many measurements on people. The first 
engineers to describe the IEC 61000-4-2 pulse as it is today, with the sharp 
peak at the start, was Michael King and David Reynolds back when dinosaurs 
roamed the earth in the last century.

There is a semiconductor device handling spec called "Human Body Model" using 
100 pF and 1500 Ohms. But, for me, there are no good HBM simulators on the 
market as they all have metallic tips. They need a tip composed of material 
that has the same volume and surface resistivity as a human finger. There it 
goes, now no one can patent the idea...it is now in the public domain.

Since capacitance goes by surface area, we may need a new capacitance value as 
the population has gained weight. I propose we replace BMI (Body Mass Index) 
with the BCI (Body Capacitance Index) a combination of body free space 
capacitance in pF of a person and the number of nanoseconds (at one foot per 
nanosecond) it takes for light to go from head to foot. Like BCI = [body 
capacitance]/[body length in nanoseconds at the speed of light]. For me that 
might be about 25 pF/ns. Some of my friends might be about 45 pF/ns.

Wow, two ideas in the same email!

Doug



On Tue, 19 Jun 2018 15:34:57 -0500, Ken Javor  wrote:



What with Doug Smith being active in this sort of standard writing activity, I 
doubt it’s simply inertia.

Ken Javor
Phone: (256) 650-5261



From: John Woodgate j...@woodjohn.uk
Date: Tue, 19 Jun 2018 21:26:38 +0100
To: Ken Javor ken.ja...@emccompliance.com, 
EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question



Probably handed down on a stone tablet in 1910 and no-one had the courage to 
challenge it yet. (;-)


John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk http://www.woodjohn.uk;
Rayleigh, Essex UK

On 2018-06-19 21:18, Ken Javor wrote:



ESD question Anyone out there know the origins of the 150 pF/330 ohm gun model 
used in EN61000-4-2 and derivative standards? It seems it ought to be a human 
body model, but it isn't.

Ken Javor
Phone: (256) 650-5261 -



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Re: [PSES] ESD question

[Doug Smith]

Hi Chas,

I think at the time Michael King was developing the data for modern standards 
on ESD, David Pommerenke was likely just starting kindergarten. David came 
around much later, even later than the extensive work at Bell Labs I 
participated in characterizing simulators of the time. The model of the 
simulator predates David's work by many years as far as I know.

Doug








On Tue, 19 Jun 2018 21:08:16 +, "Grasso, Charles"  wrote:

  








Ken,



The gun model is derived from extensive research by Mike King and others (David 
Pommerenke) to derive
a pulse that reflects an ESD event from a human with an intervening metal 
object. 



I have copied Mike for his input. Dr Pommerenke is on the EMC blog.





Thanks



Charles Grasso

(w) 303-706-5467











From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Tuesday, June 19, 2018 2:35 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question





This message originated outside of DISH and was sent by: 
owner-emc-p...@listserv.ieee.org 

What with Doug Smith being active in this sort of standard writing activity, I 
doubt it’s simply inertia.

Ken Javor
Phone: (256) 650-5261







From: John Woodgate j...@woodjohn.uk
Date: Tue, 19 Jun 2018 21:26:38 +0100
To: Ken Javor ken.ja...@emccompliance.com, 
EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question



Probably handed down on a stone tablet in 1910 and no-one had the courage to 
challenge it yet. (;-)


John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk  http://www.woodjohn.uk;
Rayleigh, Essex UK

On 2018-06-19 21:18, Ken Javor wrote:




ESD question Anyone out there know the origins of the 150 pF/330 ohm gun model 
used in EN61000-4-2 and derivative standards? It seems it ought to be a human 
body model, but it isn't.

Ken Javor
Phone: (256) 650-5261 -



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Re: [PSES] Customer Requests for Risk Assessments

[Doug Smith]

HI Brian and the group,

With respect to providing information to your competitors, which I have seen 
happen to many of my clients when they furnish documentation to prospective 
customers, I would have them sign an NDA so they would be liable if the 
information was divulged to a third party without your permission. This would 
apply to quotes and other documentation like your risk assessment. I have seen 
companies take a quote from one of my clients and send it to a competitor to 
see if the competitor can beat the quote. The competitor underbids on the 
project even though are not even competent to do the work! Also your document 
should be marked company confidential, not for distribution. This is not 
unusual and you need to protect yourself and your company.

Doug








On Thu, 17 May 2018 13:56:55 -0500, Ken Javor  wrote:






Just commentary – no authoritative information. This sounds like the customer 
company’s lawyers looking to divert blame in the event of a lawsuit by showing 
due diligence on their part, and maybe, just maybe, redirecting the blame 
vector towards your company if someone can make the case your company didn’t 
adequately assess your product's risk.

Ken Javor
Phone: (256) 650-5261



From: "Kunde, Brian" brian_ku...@lecotc.com
Reply-To: "Kunde, Brian" brian_ku...@lecotc.com
Date: Thu, 17 May 2018 18:43:38 +
To: EMC-PSTC@LISTSERV.IEEE.ORG
Conversation: Customer Requests for Risk Assessments
Subject: [PSES] Customer Requests for Risk Assessments

Our company makes Laboratory Equipment (test and measurement analyzers).

Our company performs a Risk Assessment early in the development stage of all 
new products as so suggested by such documents. We generally use the EN ISO 
12100. Creating this document highlights the possible sources of risks and 
allows our engineers to design products with an inherent design which minimizes 
the risks as much as possible. Our Risk Assessment becomes a 
document with a lot of detailed information including calculations, test 
results, detailed data, and other design specifications. Such information 
is considered highly confidential by our company.

On occasion, and in increasing frequency, our company is asked by potential 
customers to provide them with a Risk Assessment Report for our products. 
Sometimes they threaten us such as they will not or cannot consider our 
products unless we provide such documentation. 

1. Why are customers asking for a Risk 
Assessment? Where did that requirement become from? 


2. Other than the potential loss of a sale, are 
we obligated to provide our customer with a Risk Assessment? I do not see 
such a requirement in the Directives or Standards we use. 


3. Any of you been receiving similar requests? If 
so, do you provide a Risk Assessment? If so, are you not worried about 
providing such information? Couldn’t this information be used against you 
in court? Is there a fear of providing useful information to your competitors? 


Part 2:
I have requested a sample of the Risk Assessment our customers are expecting 
our company to provide. The examples documents are for the most part 
meaningless with little real detail about anything. But, if that is all 
they want to make them happy, we are considering generating such a document 
just to satisfy these requests. Any comments?

When I ask our customers what information they are looking to gain from the 
Risk Assessment, they tell me they want to know the level of residual risks our 
products might have. I reply that all residual risks are well documented 
and warned about in the provided User Manual. However, this doesn’t seem 
to satisfy them. They still want a Risk Assessment Report. 

So are other companies having to generate a stripped down Risk Assessment with 
no real detail to satisfy these customer requests? Or is it just us?

Thanks for your input, comments, and suggestions.

The Other Brian

LECO Corporation Notice: This communication may contain confidential 
information intended for the named recipient(s) only. If you received this by 
mistake, please destroy it and notify us of the error. Thank you. 
-


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[PSES] Looking for good EMC PCB course for 10 GHz

[Doug Smith]

Hi Everyone,

There are a lot of good EMC courses for PCB layout and connector design at 10 
GHz frequencies. In my own courses, I do not duplicate topics that are treated 
well by others (mine are original content quite different that other offered 
courses) so I do not offer a course like this.

Can anyone suggest such a course.? I have included Lori on the address list. 
You can reply to the group, Lori, myself or a combination.

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
--

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[PSES] Doug Smith's second teaser : THE ANSWER

[Doug Smith]

Hi Paolo and the group,

It turns out I did reply to the SI-List but either not to this list or in html 
mode and it got rejected. It takes me more effort to reply to this group as I 
have to reconfigure my email program to use this list in 1970s style text mode 
and then back again for the rest of the world and some times I forget and some 
of my posts here bounce.

Can't post a picture so a few words will have to suffice.

First I will talk about a coax cable, but a practical case might be where you 
have a pair of wires in a shield to measure the resistance of a temperature 
sensor and we are worried about 80 MHz common mode noise on the pair so we add 
a shield.

A coax cable is composed of three conductors: the center conductor, the inside 
surface of the shield, and the outside surface of the shield. The two surfaces 
of the shield are independent conductors of current at practical frequencies 
because of skin effect.

If I extend the center conductor outside of the shield, the wire will conduct 
current and form an antenna. I can replace everything inside of the coax 
(center conductor,  inside surface of shield, and 50 Ohm source driving the 
cable) with a single 50 Ohm source (that is the definition of a 50 Ohm 
transmission line). If I do that, I have a 50 Ohm source driving an 
asymmetrical dipole: the outside of the shield on one side and the extended 
center conductor on the other. If the extended center conductor is very short 
(say 1/100th wavelength) current will not much flow out of the coax onto the 
center conductor and neither will there be much image current on the outside of 
the shield. In fact, this structure is an E-field probe! The source does not 
have to be 50 Ohms, if it is not that just means the dipole will have some 
other impedance source driving it.

The shield in this case, open and  not connected to anything at the end, works 
to  suppress radiation from the current flowing on the center conductor (which 
would be a great antenna if the shield were not present). But as the extended 
center conductor becomes longer it will accept current and its image will be on 
the outside of the shield as well, the other half of the dipole. In fact, at 
this point, you have equal currents flowing in opposite directions on the 
inside and outside surfaces of the shield!

I have some great pictures of this and some great scope plots from my monthly 
classes in Boulder City and at Oxford University,  but cannot post them to this 
1970s email system. :-(

Of course we are assuming the frequency  is low enough that the shielded cable  
does not have strange modes where it can radiate right out of the end of the 
coax like a waveguide. A reasonable assumption.

By application of Kirchoff's current law over very small distances 
(<<wavelength) and skin effect,  the current patterns become quickly obvious if 
drawn out on paper.

Skin effect is a very powerful effect!

The practical version of this is a small temperature or pressure sensor poking 
out the end of the cable but is very small and not capacitively coupled to 
nearby metal in a substantial way. In this case, we can just end the shield and 
it works.

I have pretty much tested out in the lab most every technical concept I have 
learned starting with some of Marconi's wireless work when I was age 11 (it 
worked). What I find is that everything I have been taught is mostly correct, 
but, there are some interesting and sometimes important exceptions.

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, 19 Feb 2018 12:00:02 +0100, Paolo Roncone  wrote:
  ---
--- Forwarded message --
From: Mark Hone
 <mark.h...@tpgroup.uk.com>
Date: Mon, Feb 19, 2018 at 9:48 AM
Subject: Re: [PSES] Doug Smith's second teaser
To: EMC-PSTC@listserv.ieee.org


 I’d like to second John’s query, as I haven’t seen the explanation either.
 
If it has been posted, are EMC-PSTC postings being lost somewhere? I have 
checked our company spam filters!
 
Regards,
 
Mark
 
From:
 John Woodgate [mailto:j...@woodjohn.uk
]
Sent:
 08 February 2018 14:15
To:
 EMC-PSTC@LISTSERV.IEEE.ORG

Subject: [PSES] Doug Smith's second teaser

 
I didn't see an explanation from Doug about the open-ended shield of a balanced 
twisted pair being OK. Did I miss it or is the solution still awaited?
-- 
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
 Disclaimer
TP Group plc, A2/1064 Cody Technology Park, Farnborough, Hampshire, GU14 0LX, 
United Kingdom. Registered No. 3152034

This email and any attached files are private and confidential and for the use 
of the addressee(s) 

[PSES] technical videos

[Doug Smith]

Hi Everyone,

You may not know I have a YouTube channel with tecnhnical videos. The URL is:

https://www.youtube.com/user/dougcsmith

Happy viewing!

Doug









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Re: [PSES] [SI-LIST] Re: shielded cable connections

[Doug Smith]

Goes to a temperature sensor in a metal box, for example.

Don't make this too hard everyone. It is very simple.

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, 5 Feb 2018 08:57:30 -0800, "Lee Ritchey"  wrote:

Connect the shields to what?  If the cable goes to an antenna, no connection
is needed.

-Original Message-
From: si-list-bou...@freelists.org [mailto:si-list-bou...@freelists.org] On
Behalf Of Chuck Corley
Sent: Saturday, February 3, 2018 8:28 PM
To: d...@emcesd.com
Cc: emc-p...@ieee.org; si-l...@freelists.org; si-list-bou...@freelists.org
Subject: [SI-LIST] Re: shielded cable connections

>A few years later another experiment brought the FCC to my house, but that
is another story. 
OK I'm hooked.  Someday (after you reveal your current mystery) you'll have
to tell that FCC story.

Chuck Corley
National Instruments 

On 2018-02-03 20:06, Doug Smith wrote:

> Hi All,
> 
> I have another riddle for you, this time a video is not needed.
> 
> We all know that cable shields need to be connected on both ends to work
at high frequencies, but do they?
> 
> Imagine the case of a source in a metal box driving a shielded cable,
let's assume it is shielded twisted pair and we are worried about the common
mode noise on the pair radiating or ESD noise getting in and saturating the
receiver in the box, exceeding its common mode range. We can also assume
that the shielded connector on the first metal box is ra eally good one with
a 360 degree connection to the box. The other end of the shielded cable goes
to another metal box with a passive circuit inside, say a temperature sensor
connected to the twisted pair wires. There is one special, but not uncommon,
case where it does not matter if the shield is connected to the second box
or not (or even if there is a second box at all), it will work in either
case! Do you know what that case is?
> 
> This is another experiment I do during my classes. I prove the conditions
needed for the situation above and what the limits are.
> 
> I am pretty much a lab rat and I have devised experiments to test the
limits of most all EE concepts I have learned. I find there is more than
meets the eye on most every principle. I started doing experiments like this
around age 11 when I duplicated one of Marconi's experiments to see if it
really worked, it did, although I suspect the neighbors may have had a rough
time watching TV that day in 1958. A few years later another experiment
brought the FCC to my house, but that is another story.
> 
> Doug
> 
> --
> To unsubscribe from si-list:
> si-list-requ...@freelists.org with 'unsubscribe' in the Subject field
> 
> or to administer your membership from a web page, go to:
> http://www.freelists.org/webpage/si-list
> 
> For help:
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> 
> List forum  is accessible at:
> http://tech.groups.yahoo.com/group/si-list
> 
> List archives are viewable at: 
> http://www.freelists.org/archives/si-list
> 
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu

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-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list

Re: [PSES] [SI-LIST] Re: shielded cable connections

[Doug Smith]

Because one of the assumptions is lots of CM noise on the pair. The pair could 
be DC to a temperature sensor and have so much common mode noise as to be a 
problem.

There is lots of CM noise to deal with in this example.

Although this does not necessarily have anything to do with a DC driven 
temperature sensor, that example is a significant hint.,

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, 5 Feb 2018 09:48:13 -0800, "Orin Laney"  wrote:

If it's a balanced feed, why bother with a shield at all? 

-Original Message-
From: si-list-bou...@freelists.org [mailto:si-list-bou...@freelists.org] On
Behalf Of Lee Ritchey
Sent: Monday, February 05, 2018 8:58 AM
To: cor...@sonic.net; d...@emcesd.com
Cc: emc-p...@ieee.org; si-l...@freelists.org; si-list-bou...@freelists.org
Subject: [SI-LIST] Re: shielded cable connections

Connect the shields to what?  If the cable goes to an antenna, no connection
is needed.

-Original Message-
From: si-list-bou...@freelists.org [mailto:si-list-bou...@freelists.org] On
Behalf Of Chuck Corley
Sent: Saturday, February 3, 2018 8:28 PM
To: d...@emcesd.com
Cc: emc-p...@ieee.org; si-l...@freelists.org; si-list-bou...@freelists.org
Subject: [SI-LIST] Re: shielded cable connections

>A few years later another experiment brought the FCC to my house, but 
>that
is another story. 
OK I'm hooked.  Someday (after you reveal your current mystery) you'll have
to tell that FCC story.

Chuck Corley
National Instruments 

On 2018-02-03 20:06, Doug Smith wrote:

> Hi All,
> 
> I have another riddle for you, this time a video is not needed.
> 
> We all know that cable shields need to be connected on both ends to 
> work
at high frequencies, but do they?
> 
> Imagine the case of a source in a metal box driving a shielded cable,
let's assume it is shielded twisted pair and we are worried about the common
mode noise on the pair radiating or ESD noise getting in and saturating the
receiver in the box, exceeding its common mode range. We can also assume
that the shielded connector on the first metal box is ra eally good one with
a 360 degree connection to the box. The other end of the shielded cable goes
to another metal box with a passive circuit inside, say a temperature sensor
connected to the twisted pair wires. There is one special, but not uncommon,
case where it does not matter if the shield is connected to the second box
or not (or even if there is a second box at all), it will work in either
case! Do you know what that case is?
> 
> This is another experiment I do during my classes. I prove the 
> conditions
needed for the situation above and what the limits are.
> 
> I am pretty much a lab rat and I have devised experiments to test the
limits of most all EE concepts I have learned. I find there is more than
meets the eye on most every principle. I started doing experiments like this
around age 11 when I duplicated one of Marconi's experiments to see if it
really worked, it did, although I suspect the neighbors may have had a rough
time watching TV that day in 1958. A few years later another experiment
brought the FCC to my house, but that is another story.
> 
> Doug
> 
> --
> To unsubscribe from si-list:
> si-list-requ...@freelists.org with 'unsubscribe' in the Subject field
> 
> or to administer your membership from a web page, go to:
> http://www.freelists.org/webpage/si-list
> 
> For help:
> si-list-requ...@freelists.org with 'help' in the Subject field
> 
> List forum  is accessible at:
> http://tech.groups.yahoo.com/group/si-list
> 
> List archives are viewable at: 
> http://www.freelists.org/archives/si-list
> 
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu

--
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Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
  

--
To unsubscribe from si-list:
si-list-requ...@freelists.org with 'unsubscri

[PSES] shielded cable connections

[Doug Smith]

Hi All,

I have another riddle for you, this time a video is not needed.

We all know that cable shields need to be connected on both ends to work at 
high frequencies, but do they?

Imagine the case of a source in a metal box driving a shielded cable, let's 
assume it is shielded twisted pair and we are worried about the common mode 
noise on the pair radiating or ESD noise getting in and saturating the receiver 
in the box, exceeding its common mode range. We can also assume that the 
shielded connector on the first metal box is ra eally good one with a 360 
degree connection to the box. The other end of the shielded cable goes to 
another metal box with a passive circuit inside, say a temperature sensor 
connected to the twisted pair wires. There is one special, but not uncommon, 
case where it does not matter if the shield is connected to the second box or 
not (or even if there is a second box at all), it will work in either case! Do 
you know what that case is?

This is another experiment I do during my classes. I prove the conditions 
needed for the situation above and what the limits are.

I am pretty much a lab rat and I have devised experiments to test the limits of 
most all EE concepts I have learned. I find there is more than meets the eye on 
most every principle. I started doing experiments like this around age 11 when 
I duplicated one of Marconi's experiments to see if it really worked, it did, 
although I suspect the neighbors may have had a rough time watching TV that day 
in 1958. A few years later another experiment brought the FCC to my house, but 
that is another story.

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/
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For policy questions, send mail to:
Jim Bacher:  
David Heald: 

[PSES] Answer to Measurement Dilemma

[Doug Smith]

Hi Everyone,

I gave the answer in a reply to a few people but realized others may not have 
seen the answer to the Measurement Dilemma.

First, for those who did not see the 3 1/2 minute video yet, here is the link:
https://youtu.be/qj-HBFMEJiY


The answer is:

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.

Every time one connects an unbalanced probe to a PCB, you get this effect which 
is an error in your measurement. The best way to see what the error is, is to 
short the probe to its ground lead and touch the tip to PCB ground, and you 
will see the error displayed. I have seen a lot of probes register 50 mV which 
can be a problem for small signal measuerments but I have seen errors of 4 
Volts due to switching power supply currents flowing in the system (not 
magnetic field emissions, that is a separate issue) and tens of Volts or more 
due to ESD in the room. If there is so much system noise that you can't make 
your measurement, your probe is telling you something, like maybe an EMC 
problem is lurking in the system.

Doug Smith
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
--

-

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 
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Website:  http://www.ieee-pses.org/
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David Heald: <dhe...@gmail.com>

Re: [PSES] Measurement Dilema - THE EXPLANATION!

[Doug Smith]

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 o

[PSES] Youtube channel

[Doug Smith]

Hi All,

If you go to:

https://www.youtube.com/results?search_query=doug+smith+esd

You will find my Youtube page with several tech experiments in addition to the 
one we are currently discussing.

Doug
University of Oxford, Course Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
--
Doug Smith
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Re: [PSES] Measurement dilemma

[Doug Smith]

Hi Ralph,

The result is not caused by sampling rate, 5 GSa/sec in this case. The result 
will be the same on any scope!

All instrumentation is working as designed and intended for measurements of 
signals like this. An analog scope would display exactly the same waveform 
(used to do the experiment with an analog scope a while back).

Doug








On Fri, 26 Jan 2018 23:13:21 +, Ralph McDiarmid  wrote:

  




Sample rate aliasing



When displaying a 40MHz signal on a DSO, I would want to select a time base 
that provided at least 400MS/s sampling rate.



If you were to use a 100MHz analogue scope, I would expect the effect to 
disappear.



That’s my 60s guess






Ralph McDiarmid
Product Compliance Specialist
Solar Business
Schneider Electric


D604-422-2622


3700 Gilmore Way
Burnaby, BC, V5G 4M1
Canada












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 







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[PSES] Measurement dilema

[Doug Smith]

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









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Re: [PSES] ESD question

[Doug Smith]

True, but for breaking down system barriers 50 nH is very small compared to 
things like a wire grounding a metal piece in the system or the power cord 
itself.

I have seen EMI filters on power supplies cause the supply to breakdown in 
response to 800 V ESD (power supply either unpowered or powered) and do it a 
half dozen times for one ESD hit. Not quite the same thing but it shows how 
insidious ESD can be.

Doug








On Sun, 7 Jan 2018 18:02:39 -0600, Ken Javor  wrote:






Agreed using numbers below, but 50 nH is huge compared to the loop area on a 
typical PCB that will see the coupling.

Ken Javor
Phone: (256) 650-5261



From: Douglas Smith d...@emcesd.com
Reply-To: Douglas Smith d...@emcesd.com
Date: Sun, 7 Jan 2018 10:19:40 -0800
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question


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 = 2,000 Volts

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 7, 2018 at 8:09, Cortland Richmond k...@earthlink.net wrote:

We are sometimes less than precise -- but it leads to interesting discussions.

Cheers,


Cortland Richmond

-Original Message-
From: Ken Javor
Sent: Jan 7, 2018 9:28 AM
To: Cortland Richmond , EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question

Re: [PSES] ESD question Cortland: Faraday Law purely inductive coupling from an 
ESD event doesn't cause potentials that breakdown dielectric barriers; it 
induces potentials that cause bit shifts. But to answer John Woodgate’s 
question literally, enough charge buildup with some capacitance eventually 
yields a potential high enough to cause dielectric breakdown. Since that is 
basic, I assume I misinterpreted his post.

Ken Javor
Phone: (256) 650-5261


From: Cortland Richmond k...@earthlink.net
Reply-To: Cortland Richmond k...@earthlink.net
Date: Sun, 7 Jan 2018 06:23:07 -0500
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question

Induction; I once saw motherboard testers shut down systems under test by just 
walking away from the work table at lunchtime. Sliding across the cloth chair 
seats generated a charge, and walking away biased the motherboards and shut 
everything down.

(They didn't have the funds for antistatic protection – so for a few months, we 
had them spraying the chairs with a solution of water and detergent. You could 
tell who worked there because the seats of their pants were wet...)


Cortland Richmond

-Original Message-
From: John Woodgate
Sent: Jan 7, 2018 4:10 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD question



Philosophical issue there. If the field is really static, what changed to cause 
the spark to happen when it did, rather than at some other time? (A cosmic ray 
would breach the stasis.)


John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk http://www.woodjohn.uk;
Rayleigh, Essex UK

On 2018-01-07 03:37, Doug Smith wrote:



Hi Ed and Ken,

An ESD event can be produced without any direct addition of charge. It only 
takes an E field and two conductors near each other as in:

http://emcesd.com/tt2001/tt060101.htm

http://emcesd.com/tt2001/tt050101.htm 
http://emcesd.com/tt2001/tt060101.htm;

Unobserved discharge not needed and generally is not involved with these type 
of events. Just a static E field will induce a spark.




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Re: [PSES] ESD question

[Doug Smith]

Hi Ed and Ken,

An ESD event can be produced without any direct addition of charge. It only 
takes an E field and two conductors near each other as in:

http://emcesd.com/tt2001/tt060101.htm

http://emcesd.com/tt2001/tt050101.htm

Unobserved discharge not needed and generally is not involved with these type 
of events. Just a static E field will induce a spark.

Doug








On Sun, 7 Jan 2018 00:17:35 +, Edward Price  wrote:

 








Ken:



My guess would be that there was an unobserved discharge from the fabric to the 
dangling earphone cord, which then discharged into your body capacitance in 
your ear canals (which were extra conductive due to trapped moisture filling 
the ear canals and the earbud orifices). I wonder if a vapor of perspiration 
and earwax will fluoresce?




Ed Price
WB6WSN
Chula Vista, CA USA






From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Friday, January 05, 2018 6:21 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] ESD question





Just curiosity.

Spent a week in the cold frozen north. Single Fahrenheit digits (above and 
below zero) outside, snow on the ground, 70 degrees inside – dry air. Was able 
to generate some pretty decent lightning simulations walking around and 
especially stripping a bed that had some sort of fuzzy (no doubt synthetic 
material) blanket. While stripping the bed, I was listening to a podcast on an 
iPhone, through wired earbuds. I could hear the discharges through the earbuds. 
That was some sort of interference, but not the question of interest here. What 
was interesting is that the bigger sparks not only zapped where I made contact 
(typically hands) but also from the earbuds to my inner ear (ouch)! That’s not 
what I said, but close enough.

The iPhone was in a leather pouch suspended from by belt. The hook around the 
belt was metal, the belt was leather, and there were (denim cotton) pants 
between the hook on the inside of the belt and my skin. To my understanding, 
the iPhone and earbuds should have been at near or the same potential I was, 
and even if not, it was certainly no sort of ground – completely isolated from 
anything except me.

So the question is why was there such a potential difference between iPhone and 
earbuds and me that my ears were zapped?

Ken Javor
Phone: (256) 650-5261

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Re: [PSES] EU Blue Guide

[Doug Smith]

Works in Google Chrome so that makes it platform independent! 
Win/Mac/ChromeBook/etc.

I think Chrome is the best way to view pdf files. Great for 
presentations/classes as well. Less of a security risk than Adobe and it does 
not take over your computer like Adobe sometimes does.

Doug






On Wed, 16 Aug 2017 16:41:47 -0600, Ken Wyatt  wrote:

Works for me using a Mac, Safari, and Preview to open it.


Ken



___



I'm here to help you succeed!Feel freeto call or email with any 
questionsrelated to EMC or EMI troubleshooting -at no obligation. I'm always 
happy tohelp!


Kenneth Wyatt
Wyatt Technical Services LLC

56 Aspen Dr.
Woodland Park, CO 80863


Phone: (719) 310-5418


Email Me!|Web Site|Blog

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Subscribe to Newsletter
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On Aug 16, 2017, at 4:33 PM, John Woodgate jmw1...@btinternet.com wrote:




Works for me, opening with NitroPro, so it’s not one of those that only opens 
with Acrobat.



With best wishes DESIGN IT IN! OOO – Own Opinions Only

www.jmwa.demon.co.ukJ M Woodgate and Associates Rayleigh England



Beware averages! They hide or discard data, and may distort it (them?).



From:Doug Powell [mailto:doug...@gmail.com]
Sent:16 August 2017 23:26
To:EMC-PSTC@LISTSERV.IEEE.ORG
Subject:[PSES] EU Blue Guide





Is anyone else having difficulty downloading a working copy of the Blue Guide 
athttp://ec.europa.eu/DocsRoom/documents/18027/







I've tried both formats to no avail.







thanks, Doug






--









Douglas E Powell

doug...@gmail.com
http://www.linkedin.com/in/dougp01






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For 

Re: [PSES] Another benefit of Time Domain EMI receivers

[Doug Smith]

That's a great story, Ken!

Doug






On Mon, 14 Aug 2017 09:29:04 -0500, Ken Javor  wrote:






Not a question to the group, a fable – a story with a lesson learned.

Was at the IEEE EMC Show south of DC this past week, and stuck around to attend 
a Friday afternoon session (!) One of the presentations concerned a test in 
which I had played a part, and it reminded me of something interesting that 
happened there. A lot of you will not have attended, and of those of you who 
did, perhaps not all had the fortitude to stick it out until the final hours. 
And, I had made a mental note to disseminate this information post-test, and 
then promptly forgot, as is my wont these days.

There was a spacecraft integration test where they decided for 
budget/schedule/risk reduction reasons not to move it into a SAC for the EMC 
portion, but leave it in a high bay, clean room facility where the balance of 
the testing occurred. The entire facility is just a few miles from a major 
airport, and it being an industrial plant, there are many mobile radios in use, 
and those sorts of intermittent transmissions being the most difficult to pin 
down as ambients, we decided to do an rf survey of the clean room facility and 
determined that we needed an rf tent to meet our ambient requirements.

We were using one of these newer EMI receivers which had the capability to look 
at large portions of the spectrum at once, as opposed to tuning and dwelling 
frequency-by-frequency. Using that capability, we could look at the entire 
launch vehicle command-destruct band (uhf, a 60 MHz wide band just above 400 
MHz) and also, separately, over the entire required spectrum at S-band. S-band 
had to be monitored to ensure payload transmitter compatibility with some 
launch site communication links operating at close to the same frequency. The 
command-destruct band was monitored to ensure that unintentional emissions from 
the spacecraft as a payload did not interfere with reception of that emergency 
command, in the event the launch had to be terminated after lift-off.

The first rf test was ensuring that the spacecraft didn’t emit excessively in 
the command-destruct band. When the tent was up, we noticed that from time to 
time the entire noise floor jumped up above our limit, and then settled down. 
Some of the less experienced engineers took this to be an intentional radio 
transmission, but as we were looking at a 60 MHz + wide spectrum, this clearly 
wasn't the answer. It had to be a broadband event, and it turned out to be 
either people brushing against the tent and depositing charge which then flowed 
all over, and/or the ventilation in the facility blowing over the tent and 
causing the material to bow and ripple like a sail, with the same undesirable 
ESD end result. We dealt with these problems by tying down that which could be 
tied down to avoid flapping in the breeze, and cordoning off the tent and 
placing “rf test in progress” signs around the periphery. People being people, 
even trained engineers and technicians, they completely ignored the roped off 
area and signs, so that in addition to the restricted zoning, after several 
violations and required retests, I assumed the responsibility for guarding the 
perimeter, doing so with much the same fervor as a junkyard dog, and just about 
as mean by the time it became obvious that all other enforcement had failed.

But all that aside, the point of the story is that with a traditional frequency 
sweep, these accidental discharges would have occurred at random frequencies to 
which the EMI receiver just happened to be tuned when the ESD event occurred, 
and it would have been very difficult to discern that these were in fact 
broadband events as opposed to random keying of transmitters around the plant 
or at the airport, i.e., attempting to discriminate between pulsed cw and 
impulsive signals. This is illustrated graphically in the MIL-STD-461G Table II 
supporting appendix material dealing with the proper use of such EMI receivers. 
The ability to observe a very wide portion of spectrum jumping up and then 
receding was a clear signal to the experienced observer of what was happening, 
and time domain capability, in addition to greatly speeding the test along, 
also allowed immediate interpretation of the clue, and then eventually, after 
solving the people problem by making use of the old (junkyard) dog EMC 
engineer, the entire problem was put to rest.

Ken Javor
Phone: (256) 650-5261



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Re: [PSES] Another benefit of Time Domain EMI receivers

[Doug Smith]

Hi Cortland and the group,

Back in Los Gatos, CA when our children were young, we had a Radio Shack 
wireless intercom that talked through the AC mains to the other wireless 
intercoms in the house. I really liked it. I quickly learned than when I pushed 
the "talk" button, it took down our DSL connection for the duration of the 
button push. It was a great way to kill the Internet when it was time for the 
kids to go to bed. A couple of "blips" and they got the message.

Doug






On Mon, 14 Aug 2017 19:43:23 -0400, Cortland Richmond  wrote:


Actually, my work when I retired from the Army army in 1983 was in that 
particular field, though the connections were somewhat more complex.

15 years later, I had occasion to take a .01 - 5 MHz loop antenna along to a 
telecoms provider who bought some of my employer's new DSL equipment. They said 
it was failing to operate from time to time but – again on a hunch – I 
connected the loop to the input of a 'scope and saw a great spike in the local 
H field where the receivers for our system were set up, the same room as the 
customers "test" Central Office. The transient was generated by randomly 
switching 95V 20 Hz ringing current, and getting into receivers _normally_ 
installed in subscriber dwellings.

Cortland Richmond


On 8/14/2017 6:02 PM, Ken Javor wrote:







Connecting the IF port to an o’scope used to be standard practice a long time 
ago to view a waveform to determine whether NB or BB in terms of rep rate 
compared to IFBW (nowadays that’s more easily done in zero span mode). I 
believe it is still done in TEMPEST testing for other reasons.

Ken Javor
Phone: (256) 650-5261

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Re: [PSES] Another benefit of Time Domain EMI receivers

[Doug Smith]

Hi Brian and the group,

I have always thought that test equipment, even expensive test equipment, is 
really cheap in reality. It costs US$250,00+ to fund an engineer at a company 
in the US, likely more in the Bay Area, Santa Barbara, LA, Orange County, and 
San Diego. So if you can invest in equipment and not waste the time of 
engineers, it is a great buy.A $100,000 instrument can pay for itself 
quickly, possibly in less than a year depending on what it does.

The exception to the above is cheap knock-off equipment, of which I just saw a 
some of at the EMC Symposium in Washington, D.C. There are cheap current probes 
and other test equipment (especially in the ESD field) on the market that do 
not work very well and customers are unaware of the problem. I would advise 
staying with high quality equipment from established manufacturers if you want 
to avoid costly mistakes. It is a little like trying to buy Li-ion batteries on 
Amazon, some good ones and many really junk/dangerous ones that do not even 
come close to their advertised ratings. I have bought both to check out the 
difference. The ones that meet their specs cost more but will not set your 
office on fire.

BTW, look up "explosion Boulder City" (without the quotes) to see the result of 
a cheap Li-ion battery at our local town council meeting a week or so ago.

Doug






On Mon, 14 Aug 2017 17:49:28 +, "Kunde, Brian"  wrote:

  








Have you ever priced out one of these? Ouch!!



The Other Brian





From: Rob Oglesbee [mailto:rogles...@radianresearch.com]
Sent: Monday, August 14, 2017 12:25 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Another benefit of Time Domain EMI receivers





I’ve had experience with them at a private test lab, and it makes going to 
those test labs that are still stuck in the 1990’s an excruciating experience.



Rob





From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Monday, August 14, 2017 12:08 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Another benefit of Time Domain EMI receivers





They are not required by any standard of which I am aware. They are 
specifically allowed for in CISPR 16-1-1, and also MIL-STD-461G, as noted. They 
are, in my opinion, the wave of the future, due to increased speed and better 
representation of broadband signals.

Ken Javor
Phone: (256) 650-5261




From: John Woodgate jmw1...@btinternet.com
Date: Mon, 14 Aug 2017 16:38:34 +0100
To: 'Ken Javor' ken.ja...@emccompliance.com, 
EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] Another benefit of Time Domain EMI receivers

Do many test houses have these broadband receivers? Are they required for any 
tests specified in standards (military or civilian)?


With best wishes DESIGN IT IN! OOO – Own Opinions Only
www.jmwa.demon.co.uk http://www.jmwa.demon.co.uk/; J M Woodgate and 
Associates Rayleigh England

Beware averages! They hide or discard data, and may distort it (them?).


From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: 14 August 2017 15:29
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Another benefit of Time Domain EMI receivers

Not a question to the group, a fable – a story with a lesson learned.

Was at the IEEE EMC Show south of DC this past week, and stuck around to attend 
a Friday afternoon session (!) One of the presentations concerned a test in 
which I had played a part, and it reminded me of something interesting that 
happened there. A lot of you will not have attended, and of those of you who 
did, perhaps not all had the fortitude to stick it out until the final hours. 
And, I had made a mental note to disseminate this information post-test, and 
then promptly forgot, as is my wont these days.

There was a spacecraft integration test where they decided for 
budget/schedule/risk reduction reasons not to move it into a SAC for the EMC 
portion, but leave it in a high bay, clean room facility where the balance of 
the testing occurred. The entire facility is just a few miles from a major 
airport, and it being an industrial plant, there are many mobile radios in use, 
and those sorts of intermittent transmissions being the most difficult to pin 
down as ambients, we decided to do an rf survey of the clean room facility and 
determined that we needed an rf tent to meet our ambient requirements.

We were using one of these newer EMI receivers which had the capability to look 
at large portions of the spectrum at once, as opposed to tuning and dwelling 
frequency-by-frequency. Using that capability, we could look at the entire 
launch vehicle command-destruct band (uhf, a 60 MHz wide band just above 400 
MHz) and also, separately, over the entire required spectrum at S-band. S-band 
had to be monitored to ensure payload transmitter compatibility with some 
launch site communication links operating at close to the same frequency. The 
command-destruct band was monitored to ensure that unintentional emissions from 
the spacecraft as a payload did not 

[PSES] no cost presentation at IEEE EMC venue next week

[Doug Smith]

Hi Everyone,

I am delivering a no cost 1/2 day seminar on the Monday afternoon next week at 
the EMC/SI Symposium venue. This event is by invitation only to keep the crowd 
manageable. There are a few seats left for those interested. Contact me 
privately via email or phone if you want to come. If I get overwhelmed, I may 
not be able to reply to everyone. Design engineers and engineering managers are 
the target audience as opposed to sales people (as for most of my 
presentations).

Brief description: I will be presenting on troubleshooting pulsed immunity 
problems in designs (like ESD and EFT) including material from my presentations 
at the Institute of Physics in 2015. Part of the presentation will be on a new 
technique I developed that can predict field failures in the design lab that 
all current testing methods miss. I will be demonstrating the new method as 
well as several other troubleshooting methods. Tek is furnishing test equipment 
for the presentation and the talk itself is sponsored by Fischer Custom 
Communications, a company well known in the EMC field.

Doug







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Re: [PSES] SD Card ESD Testing

[Doug Smith]

The discharge will be much more energetic than a CDM event as there is MUCH 
more energy stored off the card than the card itself in this case, but passes 
through the card. The capacitance is much higher than Tom realizes below. 
Somewhere below a CDM event and an IEC event.

eration is how will the card stand up to hundreds or thousands of small, 
ubiquitous  ESD events that cannot be felt by humans but cause slow degradation 
from not only insertion but handling over several months. No one tests for that 
yet. I have designed an apparatus that does that job and it has proven very 
useful.

Doug Smith

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 Wed, 22 Mar 2017 07:27:33 +0900, "T.Sato"  wrote:

On Mon, 20 Mar 2017 19:24:23 +,
  "Grasso, Charles"  wrote:

> Aside from the obvious air discharge tests around the SD card slot (with and 
> without the SD card installed) are there
> any concerns regarding the ESD performance of the SD card during INSERTION?

Only a guess...

SD card may be charged before insertion, and may cause discharge from those
contacts when inserted.
This situation may slightly similar to that simulated with charged device
model (CDM), and the discharge may be much faster than that of IEC 61000-4-2
and ISO 10605.
However, it's capacitance is low, and I think it will not become a serious
problem in general.

In case of Compact Flush card, I ever heard of a case where metalized label
on the card created an unexpected path for electrostatic discharges and
caused a problem when hold by hand and inserted to a device.

Regards,
Tom

-- 
Tomonori Sato  
URL: http://t-sato.in.coocan.jp

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Doug Smith
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
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[PSES] New additions to my website including archive of HF News and latest edition of HF News

[Doug Smith]

Hi Everyone,

I have added some new articles and reorganized parts of my website to make 
information a little easier to find. There are hundreds of articles, podcasts, 
and published papers on my site that I have written. Here are some links:

http://emcesd.com/#HFNews
        These are my HF News letter archives. The latest issue covers  Ferrite 
for ESD/EFT/EMC, a new entry.

http://emcesd.com/#Podcasts
Audio podcasts on technical and EE career topics 

http://emcesd.com/#Papers
My published papers and articles

http://emcesd.com/#TechnicalTidbits
My short technical articles (hundreds of them) on  circuit design, 
troubleshooting, EE, EMC, ESD, etc.

These sections only account for a portion of the whole page of engineering 
candy. Feel free to browse.


Happy reading/listening!
Doug Smith
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
--

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[PSES] latest HFNews

[Doug Smith]

Hi Everyone,

I am working on several new projects, some of them related to new ESD tests 
that overcome the significant limitations of standard ESD testing, such as low 
duty cycle of ESD tests and not finding damage accumulating over time from low 
level ESD events which are very common in the field. No current ESD test 
equipment addresses these problems and working on related problems for my 
clients has spurred me on to solving these test issues. News on these will 
first appear in my HFNews newsletter and later on my website http://emcesd.com .

Here is the link to my latest HFNews. It is longer in the third issue with lots 
of links to engineering information, some instructive and some entertaining. 
Topics include analog design robustness and, of course, ESD as well  in this 
issue.

http://conta.cc/2kTXRJl

If you send me an email with "HFNews" I will put you on the email list. I will 
not be posting every issue here, so that is the best way to receive each issue 
if you want.
 
Doug Smith
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
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[PSES] HFNews letter is out!

[Doug Smith]

Hi All,
 
I have just published my first real (not test) issue of HFNews. You can view it 
at: http://conta.cc/2k7Vykk 
 
I plan to expand it as time goes on adding more links and even multi-media 
files. The plan is to publish each Friday, travel schedule permitting. In 
addition, this first issue in on ESD, a subject dear to my heart, but future 
issues will include EMC and other topics of interest to the engineering 
community like SI, design hints and troubleshooting, and general engineering 
knowledge. They will also more links and be somewhat longer. One of the links 
is to a really funny ESD video which some of you have no doubt seen. Can you 
find it?
 
If you want to subscribe, just send an email to me at d...@dsmith.org with 
HFNews (no spaces) in the subject line. Each email comes with a link to 
unsubscribe if you want. 
 
Also, if you have an event you would like me to add, just send me a description 
and link to the information. I also welcome short (several paragraphs possibly 
with a picture or two, even a short video) articles as well. Just contact me, 
and I will be happy to publish it. 
 
I used to publish HFNews manually but it became too time consuming to continue. 
Modern technology lifts a lot of the burden of publishing newsletters so I am 
starting up again. Should be a good ride. 
 
Doug

University of Oxford
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
--

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[PSES] Starting HFNews newsletter

[Doug Smith]

Hi All,
 
I used to publish a weekly short tech newsletter HFNews. I tried to do it 
manally which became too much work managing a list of 600 addresses. But now, 
my webhosting company has made it much easier with some automated tools, so I 
am going to start it up again.
 
I will publish normally on Friday afternoons some EE/tech blog posts as well as 
a list of useful engineering related links and other information. I have the 
first test issue ready to go for Tuesday.
 
If you want to sign up, send me an email with "HFNews" as the subject, no text 
necessary unless you want to include some. You will be sent an opt-in email and 
have the opportunity to opt-out at anytime. I will not sell or provide the 
email list to anyone for any reason (except if legally required to, in which 
case I will blast out an email in advance).
 
There will be no paid advertising in the newsletter.
I think you will enjoy the newsletter.
 
Doug


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[PSES] shielded magnetic field probes do not work the way most say they do!

[Doug Smith]

Hi Everyone,
 
We often hear that shielded magnetic field probes reject electric fields and 
therefore are better. This, however, is not generally true. The E-field 
rejection only happens for fields symmetric around the centerline of the loop. 
This is satisfied in the far field but not in the near field, say when held up 
to a PCB to "sniff" sources of emissions. A coax structure is just a 
transformer where the shield inductance equals the mutual inductance between 
the shield and the center conductor, for example as shown in Henry Ott's book.
 
In fact, the presence of the shield causes resonance problems at frequencies 
well below the self resonance of the loop itself than cause the performance of 
an unshielded loop to be better for some applications. During my seminars I do 
an experiment to show this effect and how to easily measure the E-field 
component of the output of a magnetic probe, shielded or not. In fact, there is 
a lot of "common knowledge" that is not quite right that I cover in my classes.
 
Here are some articles I have written on the subject.
 

  * June 2008, The Square Shielded Loop - Part 2, Parasitic Coupling
(Electric Field Shielding of Magnetic Loops is Not Always Effective!)
  * July 2008, The Square Shielded Loop - Part 3, Parasitic Coupling Between 
Unshielded Wire Loops
  * August 2008, The Square Shielded Loop - Part 4, Coupling to a PCB
(From Shielded and Unshielded Magnetic Loops)

Also see my IEEE EMC paper relating to this effect:
 
http://emcesd.com/pdf/emc99-w.pdf
 
See pages 560 and 561 of the paper.
 
Doug


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[PSES] scope probe free webinar joining information

[Doug Smith]

Hi All,
 
Here is the information for the Friday morning webinar. First 24 computers are 
in, after that the conference will be full. If it fills up, I may schedule 
another one. 
 
Doug Smith
University of Oxford
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
--
 
 
1.  Please join my meeting, Jul 15, 2016 at 9:00 AM PDT. 
https://global.gotomeeting.com/join/550707813
 
2.  Use your microphone and speakers (VoIP) - a headset is recommended. Or, 
call in using your telephone. 
 
Dial 1 (872) 240-3212
Access Code: 550-707-813
Audio PIN: Shown after joining the meeting
 
Meeting ID: 550-707-813
 
GoToMeeting®
Online Meetings Made Easy®
 
Not at your computer? Click the link to join this meeting from your iPhone®, 
iPad®, Android® or Windows Phone® device via the GoToMeeting app. 

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Re: [PSES] Oscilloscope probe calibration

[Doug Smith]

Hi Ed and the group,
 
If you are refering to the compensation output, it never needs to be
calibrated. Amplitude is unimportant, as is frequency as long as it is
low, 500 to 1000 Hz. The beauty of the probe cal is the generator
parameters are unimportant as long as the freq is low and the wave
looks squarish on the rise and fall times on a 1 ms/div time scale. If
you cal the probe with a 5 MHz square wave you need to know its
amplitude accurately, but not at 1000 Hz. I will cover this on the
webinar on Friday. If we overflow, I can repeat it later.
 
Doug

On Tue, 12 Jul 2016 12:55:10 -0700, Ed Price  wrote:

  I have had many occasions where I got a scope back from
metrology and they had checked the calibration of each input channel
(usually using the 50 Ohm option), always separate of the probes. But
even worse, they never seemed to check the front-panel calibration port
(they treated that just like the many ports on the rear which were
never actually calibrated or validated).
 
 
Does your current calibration source test the parameters of the front
panel calibration port? (I found it interesting that there was a trend
to de-emphasize those calibration ports, moving them to the rear or
sometimes not even having one.)
 
 
Ed Price
WB6WSN
Chula Vista, CA USA
 
 
From: Ken Wyatt [mailto:k...@emc-seminars.com]
Sent: Tuesday, July 12, 2016 9:39 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Oscilloscope probe calibration
 
 
Doug, you’re such a tease! :-)
 

___
 
 
I'm here to help you succeed! Feel free to call or email with any
questions related to EMC or EMI troubleshooting - at no obligation.
I'm always happy to help!
 

Kenneth Wyatt
Wyatt Technical Services LLC
 
56 Aspen Dr.
Woodland Park, CO 80863
 

Phone: (719) 310-5418
 
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Re: [PSES] Oscilloscope probe calibration

[Doug Smith]

David,
 
I can save you a lot of time in a few minutes. Give me a call tomorrow.
Too much to type here, but what you are seeing is not unusual. The
interface between the 10X Hi-Z probe and the scope is not defined
electrically for the public, much more complicated than one would
expect, so you cannot mix these probes with a different brand of scope.
Adjustment errors can far exceed 40% as well.
 
Any cal lab that understands these probes would not cover the
compensation port. If they do, you might consider taking your business
to another lab. In the meantime, have them call me and I will set them
straight.
 
Doug

On Mon, 11 Jul 2016 21:49:51 +, "Schaefer, David"  wrote:

  All,
 
 
We’re seeing an issue with scope probes, and I’d appreciate
suggestions, or just information on how others handle calibration.
I’ve got two problems with passive scope probes.
 
 
First, probe compensation. Compensation depends on the capacitance of
the scope being used, so the probe would be adjusted to match that
capacitance. Well if the cal house is using a different scope,
they’ll adjust it to match their capacitance, which may not be what
we need. Also, many times the cal sticker then covers the adjustment
port, implying the user should not be adjusting that value. I disregard
the stickers, but it isn’t a good habit to get into.
 
 
Second, we’re seeing variance between  in cal probes based on what
they’re measuring. I had four probes measuring a 1 microsecond rise
time transient signal. All were within 5% of the expected peak voltage.
Next, all four probes measured a 5 ns rise time transient. Three peak
voltages were within 10-15% of the measured 100V(not great, but
acceptable). The fourth consistently read around 138 V. Nearly 40% off,
just by changing the rise time. 5 ns might be at the edge of the
probe’s bandwidth, but I’d expect a decrease in level, not an increase.
 
 
These were all calibrated probes, and three were identical models. The
one that was way off wasn’t the odd model. Our cal house measures a
DC voltage for accuracy, and bandwidth.
 
 
What’s causing the inaccuracy? How can I prevent this problem in the
future? Moving to all active probes isn’t an option right now.
 
 
Thanks,
 
 
David Schaefer
 
 
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Re: [PSES] Oscilloscope probe calibration

[Doug Smith]

Hi Rich,
 
Although useful, the literature from measurement companies and be
misleading and rarely descirbe the situation completely. Maybe I should
hold a short free webinar for anyone interested. I probably have more
information on this than any other source. If I do the webinar, the
limit is 24 computers on the connection, first come, first served.
Contact me privately if interested, would do it later this week in the
morning Pacific Time, domestic US or UK only.
 
Doug

On Mon, 11 Jul 2016 19:03:47 -0700, Richard Nute  wrote:

   
We’re seeing an issue with scope probes, and I’d appreciate
suggestions, or just information on how others handle calibration.
 
 
Start by studying this pamphlet:
 
 
http://circuitslab.case.edu/manuals/Probe_Fundamentals-_Tektronix.pdf
 
http://www.ni.com/white-paper/14825/en/#toc1
 
 
If you still have issues, ask again.
 
 
 
Rich
 
 
 
 
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[PSES] Pi facts

[Doug Smith]

Hi All,
 
Pi is a very important constant to EEs. But we rarely have fun with it. So here 
is a way to enjoy Pi!
 
My oldest son, a new CS graduate, just posted a free app for iOS called 
"Birthday Pi." It has lots of interesting facts about Pi (like the sum of the 
first 144 digits is 666) and also will tell you what digit of pi your birthday 
(or any date) starts on. For instance, for a person born today, the birthdate 
starts at the 11679th digit of Pi and my birthday starts at the about the 
25,000th digit of Pi. It is a fun app to play with.
 
Search for "Birthday Pi" by David Smith on the iOS store. His resume is also 
ready for those who need a CS major. Contact me privately and I will put you in 
contact with him if you would like his resume, which for his young age is 
pretty impressive!
 
Doug


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Re: [PSES] High Voltage target for measuring currents of HV events

[Doug Smith]

Hi Doug and the group,

The picture with three arcs was from one frame of a 60 frame/sec short 
video I took while another person held the generator. So it was not a 
time exposure. I think there was only one active spark and the other 
paths were in the process of extinguishing as they did not have 
much current. I have another frame with 1/2 of the path showing the 
spark which was climbing u[p from the target to the HV tip, sort of 
like pictures you see of lightning. 

Once a spark is active, I don't think any new ones can form because the 
voltage across the gap is pulled too low during the active spark. Maybe 
someone on the list can shed some light on this. 

Risetimes of the current waveform had components from subnanosecond to 
tens of nanoseconds. Voltage was generated at about 500 kHz with about 
50kV peak voltage. The power supply was not filtered so there is a 120 
Hz modulation as well. The 120 Hz modulation gave the sparks a nice 
buzz as in science fiction movies. 

I started conducting high voltage experiements at 100 kV and higher 
(and NOT static electricity) when I was about 14 years old. My 
experiments brought the FCC to my house to investigate why no one in 
the neighborhood could watch TV. Between ages 11 and 14, I recreated 
for myself experiments of Marconi and Tesla to make sure those guy were 
actually right. If my Mom had realized how dangerous some of my 
experiments were, she would have fainted. Had a lot of fun vaporizing 2 
Watt, 1000 Ohm carbon comp resistors to dust. Been doing this kind of 
stuff for amusement ever since. 


Doug
University of Oxford
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 Thu, 26 May 2016 11:57:53 -0600, Doug Powell <doug...@gmail.com> wrote:
The first picture of Doug is not so surprising... 


The next one with the blue corona cloud and ‎at least three 
discharges is interesting. Was the HV increasing on a ramp of some 
kind? It is apparent this was a long exposure photo and the corona 
cloud was visible long enough to be captured in the photo. 

In any case, it is a nice photo as this demonstrates the arcing moves 
around to slightly different positions as ionization process consumes 
‎immediately available gases. Also several locations on the screw 
head were receiving arcs. 


Thanks! Doug


Douglas E Powell‎
doug...@gmail.com (business)
‎https://www.linkedin.com/in/dougp01

 
‎



Sent from my BlackBerry 10 smartphone on the Verizon Wireless 4G LTE network. 
  Original Message  

From: Brian O'Connell
Sent: Thursday, May 26, 2016 10:58 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Reply To: Brian O'Connell
Subject: Re: [PSES] High Voltage target for measuring currents of HV events

Interesting. Two questions:
1. Is the discharge actually multi-path(parallel), or is the image 
exposed for period of time where multiple, sequential streamers were 
recorded?
2. Would there not also be significant current flowing that is less 
than the 1MHz rating of the probe?


Brian

-Original Message-
From: Doug Smith [mailto:d...@emcesd.com] Sent: Wednesday, May 25, 
2016 10:01 PM

To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] High Voltage target for measuring currents of HV events

Hi All,

I have been doing some high voltage measurements of currents lately 
to support development of a new troubleshooting and failure mode 
analysis method which will be complete shortly. That information 
will be in my seminars this summer and eventually next year in a 
published paper. But at this point I have posted on my website a 
target for measuring currents due to discharges of 50 kV+ that 
insulates the current probe and with that constraint, minimizes the 
inductance of the measuremed current path. The new method relates to 
finding possible low probability failure modes that may occur in the 
field that are likely missed in normal SI and EMC testing but may 
still be important especially to those in the medical, aerospace, and 
automotive fields. The article is at: 
http://emcesd.com/tt2016/tt052416.htm and contains a surprising 
picture. Let me know if you notice the surprising feature in one of 
the pictures. 

Be sure to look over the main page at http://emcesd.com as I have 
been adding to it lately, including this latest article which is at 
the bottom of the index page.  

Doug

University of Oxford
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom

-

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All emc-pstc postings are archived and searchable on the 

[PSES] High Voltage target for measuring currents of HV events

[Doug Smith]

Hi All,

I have been doing some high voltage measurements of currents lately to support 
development of a new troubleshooting and failure mode analysis method which 
will be complete shortly. That information will be in my seminars this summer 
and eventually next year in a published paper. But at this point I have posted 
on my website a target for measuring currents due to discharges of 50 kV+ that 
insulates the current probe and with that constraint, minimizes the inductance 
of the measuremed current path. 

The new method relates to finding possible low probability failure modes that 
may occur in the field that are likely missed in normal SI and EMC testing but 
may still be important especially to those in the medical, aerospace, and 
automotive fields. 

The article is at: http://emcesd.com/tt2016/tt052416.htm and contains a 
surprising picture. Let me know if you notice the surprising feature in one of 
the pictures. 

Be sure to look over the main page at http://emcesd.com as I have been adding 
to it lately, including this latest article which is at the bottom of the index 
page. 
 
Doug

University of Oxford
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
--
 

-

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<emc-p...@ieee.org>

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Re: [PSES] measurement of transient radiation emission

[Doug Smith]

Hi Li,
 
To give credit where credit is due, the antenna was designed and build
by Jon Barth, http://barthelectronics.com . It is a tapered 50 Ohm
transmission line with a ferrite balun.
 
Doug

On Fri, 13 May 2016 00:14:31 +0800, Li Di  wrote:

  Hi Mr. Doug and the group,
 
First, thanks a lot for all kind replies. I tried Aaronia HF60105 with
BicoLOG 20100 antenna. Its minimal sweep time is 1ms. I couldn't get
any transient signal on the spectrum analyzer. I tried to change the
distance and position but failed to record. So I think HF60105 is too
slow and it is not a real time tool. My next plan is to get a real
spectrum analyzer. To keep down the cost, I need to choose the
configuration of spectrum analyzer and antenna carefully. For this
case, it is not necessary to get a very accurate result. For the use of
o'scope, I did not try this with antenna. I just tried spectrum
analyzer with a current probe to catch the conducted transient. In the
facility, I think there are radiated transient and conducted transient.
But I got nothing becaseu of the spectrum. Anyway, I will think about
all advice later to try again.
 
 
Best regards,
 
 

-

  Li Di
Conorth Technologies Co., Ltd.
---
Address: Room 212, Building C, No.15 Baiziwan Road, Chaoyang District, Beijing
Tel (Fax): 0086-10-60530811 (Office)
Mobile: 0086-13701332910
li...@conorthtech.com
.com
--

   
From: Doug Smith
Date: 2016-05-12 23:33
To: EMC-PSTC
Subject: Re: [PSES] measurement of transient radiation emission
Hi Ken and the group,
 
When building up the spectrum over many fast impulse events, like ESD,
I suspect the analyzer display is not calibrated as an event that is
over in 5 nanoseconds or less (fast part of ESD) is not around long
enough for the analyzer to "lock on" accurately to the signal. The
envelope/shape of the plot can give an idea of the bandwidth, but the
amplitude displayed is not likely accurate in most cases.
 
Doug

On Thu, 12 May 2016 07:54:51 -0600, Ken Wyatt  wrote:

  Hi Li Di, 
Both Ed and Cortland gave you some good advice. Capturing the frequency
content of a transient signal is main “claim to fame” of the
real-time (RT) spectrum analyzer and you might want to refer to the new
guide we published recently, “Real-Time” Spectrum Analyzer Mini
Guide”, which may be downloaded here:
 
http://www.interferencetechnology.com (click on the guide in the upper
left corner of our home page)
 
RT analyzers are the ideal solution to capturing transient events
within their RT bandwidth, which can range from 27 to 500 MHz,
typically. However, for a spark event, as you’re describing, the
energy will greatly exceed the real-time bandwidth of any RT analyzer
I’m aware of. As Ed suggests, I’ve managed to capture repeated
events using the “max hold” feature of a swept analyzer, but you
must let the spectral envelope build up gradually. This may be good
enough for your purposes and I would expect the bulk of the energy to
extend out to 2-3 GHz. 
 
The other alternative, as Cortland suggests is to use a fast
oscilloscope of at least 6 GHz bandwidth to capture the transient and
convert to frequency via the FFT feature. I’ve captured spark events
successfully with this method, but you’ll have to manually figure out
the gains and losses in the system to calculate the actual E-field
generated from the spark.
 
One other possible alternative would be to use one of the newer
FFT-based spectrum analyzers that can perform the capture with very
little “dead time”.
 
Cheers, Ken___
 
I'm here to help you succeed! Feel free to call or email with any
questions related to EMC or EMI troubleshooting - at no obligation.
I'm always happy to help!

Kenneth Wyatt
Wyatt Technical Services LLC
56 Aspen Dr.
Woodland Park, CO 80863

Phone: (719) 310-5418

Email Me! | Web Site | Blog
The EMC Blog (EDN)
Subscribe to Newsletter
Connect with me on LinkedIn

  On May 11, 2016, at 11:52 PM, Li Di  wrote:
Hello All,
 
I need to measure the transient radiation emission from a big
industrial system. There is a discharg between its two electrodes with
high voltage difference. My client wants to measure the transient
interference at their facility. I plan to use spectrum analyzer and
antenna (or near field probe). But the scan time of some spectrum
analyzers is long. It is not easy to catch the inteference. Could
anyone give me some advice? Thank you very much.
 
 
Best regards,
 
 

-

  Li Di
Conorth Technologies Co., Ltd.
---
Address: Room 212, Building C, No.15 Baiziwan Road, Chaoyang District, Beijing
Tel (Fax): 0086-10-60530811 (Office)
Mobile: 0086-13701332910
Email: li...@conorthtech.com
Website: www.conorthtech.com
--

-

This message is from the IEEE Prod

Re: [PSES] measurement of transient radiation emission

[Doug Smith]

Hi Li and the group. 

Do you know for sure you need a frequency plot? A time domain plot is 
often more useful. 

Not sure if my last post came through, so here are two links from my 
website that describe probably the best time domain antenna with flat 
frequency response:


http://emcesd.com/tt2001/tt120101.htm

http://emcesd.com/pdf/eos01-w.pdf

Doug

University of Oxford
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 Fri, 13 May 2016 00:14:31 0800, Li Di <li...@conorthtech.com> wrote:

Hi Mr. Doug and the group,
 
First, thanks a lot for all kind replies. I tried Aaronia HF60105 with 
BicoLOG 20100 antenna. Its minimal sweep time is 1ms. I couldn't get 
any transient signal on the spectrum analyzer. I tried to change the 
distance and position but failed to record. So I think HF60105 is too 
slow and it is not a real time tool. My next plan is to get a real 
spectrum analyzer. To keep down the cost, I need to choose the 
configuration of spectrum analyzer and antenna carefully. For this 
case, it is not necessary to get a very accurate result. For the use of 
o'scope, I did not try this with antenna. I just tried spectrum 
analyzer with a current probe to catch the conducted transient. In the 
facility, I think there are radiated transient and conducted transient. 
But I got nothing becaseu of the spectrum. Anyway, I will think about 
all advice later to try again. 
 

 
Best regards,
 
 

-

Li Di
Conorth Technologies Co., Ltd. 
---

Address: Room 212, Building C, No.15 Baiziwan Road, Chaoyang District, Beijing
Tel (Fax): 0086-10-60530811 (Office)
Mobile: 0086-13701332910
li...@conorthtech.com
.com
--

 
From: Doug Smith
Date: 2016-05-12 23:33
To: EMC-PSTC
Subject: Re: [PSES] measurement of transient radiation emission
Hi Ken and the group,
 
When building up the spectrum over many fast impulse events, like ESD, 
I suspect the analyzer display is not calibrated as an event that is 
over in 5 nanoseconds or less (fast part of ESD) is not around long 
enough for the analyzer to "lock on" accurately to the signal. The 
envelope/shape of the plot can give an idea of the bandwidth, but the 
amplitude displayed is not likely accurate in most cases. 
 

Doug

On Thu, 12 May 2016 07:54:51 -0600, Ken Wyatt <k...@emc-seminars.com> wrote:

Hi Li Di, 
Both Ed and Cortland gave you some good advice. Capturing the frequency 
content of a transient signal is main “claim to fame” of the 
real-time (RT) spectrum analyzer and you might want to refer to the new 
guide we published recently, “Real-Time” Spectrum Analyzer Mini 
Guide”, which may be downloaded here:

 
http://www.interferencetechnology.com (click on the guide in the upper 
left corner of our home page)

 
RT analyzers are the ideal solution to capturing transient events 
within their RT bandwidth, which can range from 27 to 500 MHz, 
typically. However, for a spark event, as you’re describing, the 
energy will greatly exceed the real-time bandwidth of any RT analyzer 
I’m aware of. As Ed suggests, I’ve managed to capture repeated 
events using the “max hold” feature of a swept analyzer, but you 
must let the spectral envelope build up gradually. This may be good 
enough for your purposes and I would expect the bulk of the energy to 
extend out to 2-3 GHz. 

 
The other alternative, as Cortland suggests is to use a fast 
oscilloscope of at least 6 GHz bandwidth to capture the transient and 
convert to frequency via the FFT feature. I’ve captured spark events 
successfully with this method, but you’ll have to manually figure out 
the gains and losses in the system to calculate the actual E-field 
generated from the spark. 
 
One other possible alternative would be to use one of the newer 
FFT-based spectrum analyzers that can perform the capture with very 
little “dead time”. 
 

Cheers, Ken___
 
I'm here to help you succeed! Feel free to call or email with any 
questions related to EMC or EMI troubleshooting - at no obligation. 
I'm always happy to help!


Kenneth Wyatt
Wyatt Technical Services LLC
56 Aspen Dr. 
Woodland Park, CO 80863


Phone: (719) 310-5418

Email Me! | Web Site | Blog
The EMC Blog (EDN)
Subscribe to Newsletter
Connect with me on LinkedIn

On May 11, 2016, at 11:52 PM, Li Di <li...@conorthtech.com> wrote:
Hello All,
 
I need to measure the transient radiation emission from a big 
industrial system. There is a discharg between its two electrodes with 
high voltage difference. My client wants to measure the transient 
interference at their facility. I plan to use spectrum analyzer and 
antenna (or near fie

Re: [PSES] measurement of transient radiation emission

[Doug Smith]

Hi All,
 
Such a broadband antenna, a TEM antenna, is described in one of my
papers posted on my website:
 
http://emcesd.com/pdf/eos01-w.pdf
 
And one of my articles describing this antenna in detail:
 
http://emcesd.com/tt2001/tt120101.htm
 
Connected to a scope of adequate sampling rate and bandwidth, the scope
display can easily be converted to Volts/meter of field strength (see
article above). The amplitude of the transient field is often more
important than the frequency domain view as the time domain view
directly relates to the abiltity to upset nearby equipment and damage
sensitive components like disk drive heads.
 
Doug

On Thu, 12 May 2016 09:37:13 -0500, Ken Javor  wrote:

  Re: [PSES] measurement of transient radiation emission The
newest generation of EMI receivers incorporate 80 MHz front ends which
then use FFT techniques to portray the frequency domain spectrum using
the actual required measurement bandwidth (120 kHz below 1 GHz, 1 MHz
above it).  But that likely isn’t the issue concerning whoever want
this measurement.  The issue is likely the actual time domain field
intensity over as broad a range as can be encompassed. That means an
o’scope and a broadband antenna.  Since this is a high intensity
discharge, preamps shouldn’t be necessary. What will be necessary is
a an antenna whose factor is constant over the frequency range of
interest, else it colors the measured results. Flat and wide transducer
factors are usually associated with active antennas, which are also
associated with low-level measurements that don’t saturate the
electronics.  Some assessment of the expected peak field intensity is
thus in order. Also, the distance from the arc must be specified, and
this based is on whatever problem interaction is of concern here.

Ken Javor
Phone: (256) 650-5261

-
From: Li Di
Reply-To: Li Di
Date: Thu, 12 May 2016 13:52:07 +0800
To:
Subject: [PSES] measurement of transient radiation emission

 
Hello All,

I need to measure the transient radiation emission from a big
industrial system. There is a discharg between its two electrodes with
high voltage difference. My client wants to measure the transient
interference at their facility. I plan to use spectrum analyzer and
antenna (or near field probe). But the scan time of some spectrum
analyzers is long. It is not easy to catch the inteference. Could
anyone give me some advice? Thank you very much.

Best regards,

 

-

  Li Di
Conorth Technologies Co., Ltd.
---
Address: Room 212, Building C, No.15 Baiziwan Road, Chaoyang District, Beijing
Tel (Fax): 0086-10-60530811 (Office)
Mobile: 0086-13701332910
Email: li...@conorthtech.com
Website: www.conorthtech.com
--

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Re: [PSES] measurement of transient radiation emission

[Doug Smith]

Hi Ken and the group,
 
When building up the spectrum over many fast impulse events, like ESD,
I suspect the analyzer display is not calibrated as an event that is
over in 5 nanoseconds or less (fast part of ESD) is not around long
enough for the analyzer to "lock on" accurately to the signal. The
envelope/shape of the plot can give an idea of the bandwidth, but the
amplitude displayed is not likely accurate in most cases.
 
Doug

On Thu, 12 May 2016 07:54:51 -0600, Ken Wyatt  wrote:

  Hi Li Di, 
Both Ed and Cortland gave you some good advice. Capturing the frequency
content of a transient signal is main “claim to fame” of the
real-time (RT) spectrum analyzer and you might want to refer to the new
guide we published recently, “Real-Time” Spectrum Analyzer Mini
Guide”, which may be downloaded here:
 
http://www.interferencetechnology.com (click on the guide in the upper
left corner of our home page)
 
RT analyzers are the ideal solution to capturing transient events
within their RT bandwidth, which can range from 27 to 500 MHz,
typically. However, for a spark event, as you’re describing, the
energy will greatly exceed the real-time bandwidth of any RT analyzer
I’m aware of. As Ed suggests, I’ve managed to capture repeated
events using the “max hold” feature of a swept analyzer, but you
must let the spectral envelope build up gradually. This may be good
enough for your purposes and I would expect the bulk of the energy to
extend out to 2-3 GHz. 
 
The other alternative, as Cortland suggests is to use a fast
oscilloscope of at least 6 GHz bandwidth to capture the transient and
convert to frequency via the FFT feature. I’ve captured spark events
successfully with this method, but you’ll have to manually figure out
the gains and losses in the system to calculate the actual E-field
generated from the spark.
 
One other possible alternative would be to use one of the newer
FFT-based spectrum analyzers that can perform the capture with very
little “dead time”.
 
Cheers, Ken___
 
I'm here to help you succeed! Feel free to call or email with any
questions related to EMC or EMI troubleshooting - at no obligation.
I'm always happy to help!

Kenneth Wyatt
Wyatt Technical Services LLC
56 Aspen Dr.
Woodland Park, CO 80863

Phone: (719) 310-5418

Email Me! | Web Site | Blog
The EMC Blog (EDN)
Subscribe to Newsletter
Connect with me on LinkedIn

  On May 11, 2016, at 11:52 PM, Li Di  wrote:
Hello All,
 
I need to measure the transient radiation emission from a big
industrial system. There is a discharg between its two electrodes with
high voltage difference. My client wants to measure the transient
interference at their facility. I plan to use spectrum analyzer and
antenna (or near field probe). But the scan time of some spectrum
analyzers is long. It is not easy to catch the inteference. Could
anyone give me some advice? Thank you very much.
 
 
Best regards,
 
 

-

  Li Di
Conorth Technologies Co., Ltd.
---
Address: Room 212, Building C, No.15 Baiziwan Road, Chaoyang District, Beijing
Tel (Fax): 0086-10-60530811 (Office)
Mobile: 0086-13701332910
Email: li...@conorthtech.com
Website: www.conorthtech.com
--

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-

Re: [PSES] Commom mode current vs. differential mode current and LISN

[Doug Smith]

Hi Ken and the group,
 
I always thought that the FCC measures the wrong quantity for conducted
emmissions. What shoud be measured is all conductors (two or three
including phase/neutral/protective earth) together as common mode
current as that is what radiates from the long power lines causing
problems for shortwave receivers and Amateur Radio Operators. The old
demonstration of conducted EMI into AM radios is not so useful,
especially today.
 
Below 30 MHz, most devices are not large enough to radiate efficiently,
but the power wiring is long enough to radiate. I have a case of EMI in
my house from two Feit Electric LED floodlights that meet conducted
emissions, but I can't use a hand held, battery powered, shortwave
receiver when the two are on except to walk quite a distance from that
part of the house. The FCC test may catch this case, but apparently not
for me, as there are only two wires but that is not the case for other
devices.
 
So phase+neutral could be noisy with respect to protective earth but as
long as it is balanced by an opposite current on protective earth,
radiation should be low.
 
Any other Amateur Radio operators want to weigh in on this?
 
Doug (K4OAP, since 1959)
 

On Tue, 29 Mar 2016 16:13:58 -0500, Ken Javor  wrote:

  Re: [PSES] Commom mode current vs. differential mode current and
LISN Disagree. Westin had it right. A current probe can be used to
isolate either cm or dm current. If at any frequency the signal
amplitude on individual line and neutral conductors are very close,
then all you can say is that at that frequency either cm or dm
predominates, but you can’t say which.  With a LISN, a separate
device must be used. Mark Nave of EMC Services designed a three port
device (connects to each LISN port and to the EMI receiver) trademarked
LISNMATE in the 1980s to isolate common mode, and sometime later he
produced LISNMARK, which isolated DM.  Within the past decade, Ray
Adams while at Fischer Custom Communications packed both functions in
one piece of equipment, which if memory serves was named LISNUP.

EMC Services, Mark Nave’s company, is no longer producing his
products, but I believe the FCC product is still available.

Ken Javor
Ph. (256) 650-5261

-
From: Elliott Martinson
Reply-To: Elliott Martinson
Date: Tue, 29 Mar 2016 20:36:18 +
To:
Conversation: [PSES] Commom mode current vs. differential mode current
and LISN
Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN

http://www.hottconsultants.com/techtips/CM_vs_DM%20Conducted_Emission.html
This is a great resource for your question.
 
Your second point kind of contradicts your first, if it’s trying to
say what I think it is. DM and CM each show up on L, but the same is
true for N. It’s a linear combination of both, so even if L and N are
almost equal, you can’t say anything about the proportion of DM to CM
currents.
 
If they are not equal, then this implies current is travelling back via
the ground conductor and/or energy’s being lost to radiated emissions.
 
What you need is a physical circuit to do the adding/subtracting of the
LISN outputs. (otherwise your 3rd bullet point is correct)
 
Your 4th bullet, well I refer you to the link above.
 

Elliott Martinson
Product Assurance Specialist I
Electronic Theatre Controls
3031 N PLEASANT VIEW RD
MIDDLETON WI 53562-4809
Work: 608.824.5696 / Cell: 608.209.9897
elliott.martin...@etcconnect.com
 

From: Amund Westin [mailto:am...@westin-emission.no]
Sent: Tuesday, March 29, 2016 1:23 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Commom mode current vs. differential mode current and LISN

Please correct me, if I am wrong (that happens quite often …):

·    Let one wire (L) pass through a current clamp, and you
measure the combination of current mode and differential mode currents

·    Do the same with wire N. If L and N are (almost)
equal, you either have major part of DM currents or major part of CM
current

·    Let both wire (L and N) pass through a current clamp,
and you measure the only CM current (DM is canceled)

·     When doing conducted emission test by LISN, you
actually get what you get. LISN do not see the difference between CM or
DM. From LISN measurements, you can’t say if noise is CM or DM.

B.regards

Amund

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Re: [PSES] SV: [PSES] Fwd: [PSES] Current probe for CM currents

[Doug Smith]

That is why it is very difficult to make current probes well shielded 
enough and certainly with a flat transfer impedance that covers a few 
decades of frequency. The cost of a good current probe, for instance an 
F-33-1 or F-61 is less than what it has already cost your company in 
time lost. 


Doug

Douglas C. Smith
University of Oxford Course Tutor
D C Smith Consultants
PO Box 60941
Boulder City, NV 89006
Email: d...@dsmith.org
Web: http://www.dsmith.org
Web: http://emcesd.com
Tel: 702-570-6108
Mobile: 408-858-4528

On Sun, 31 Jan 2016 17:49:08 -0600, Ken Javor 
 wrote:
You needed a metal shield to prevent capacitive coupling. 


Ken Javor
Phone: (256) 650-5261


> From: Amund Westin 
> Reply-To: Amund Westin 
> Date: Sun, 31 Jan 2016 20:21:48 +0100
> To: 
> Subject: [PSES] SV: [PSES] Fwd: [PSES] Current probe for CM currents
> > A clamp-on ferrite with a few turns of wire and connected to a spectrum
> analyzer, worked out to be a good tool for measuring CM currents on single
> cables. It gave me some measured numbers [dBuV], and then I worked 
on trying

> to get the numbers down :)
> > But when I placed the home-made probe on wires / cables inside a 
noisy rack,

> problems started. The probe picked up almost all kinds of frequencies, even
> when no cables or wires where going through the probe (ferrite). 
> > > > This lesson told me that a simple home-made current probe 
works good on a

> stand-alone cable, but it does not work that good then measurements are
> carried out closed to other noisy sources. Then you might need a more
> professional current clamp. 
> > > > #Amund

> > > > > > > > > > > > Fra: Ken Javor [mailto:ken.ja...@emccompliance.com]
> Sendt: 15. januar 2016 17:53
> Til: EMC-PSTC@LISTSERV.IEEE.ORG
> Emne: Re: [PSES] Fwd: [PSES] Current probe for CM currents
> > > > I think it is important to not lose sight of the original 
query that started

> this thread. The query was about whether placing a current probe around a
> cable perturbed the current to be measured. 
> > There is no doubt that radiated emissions can originate within an 
equipment

> enclosure separately from driving common mode currents on a cable, but that
> wasn't the query. In fact, the poster was probing cables within a 
large rack
> (enclosure) looking for a source within an enclosure. 
> > Ken Javor

> Phone: (256) 650-5261
> > > > _ > > From: Bill Owsley <00f5a03f18eb-dmarc-requ...@ieee.org
>  >
> Reply-To: Bill Owsley  >
> Date: Fri, 15 Jan 2016 07:26:08 +
> To:  >
> Subject: Re: [PSES] Fwd: [PSES] Current probe for CM currents
> > If you can measure common mode noise on a cable, you have a 
problem from the

> port !!
> Note the world famous Ott's math on this effect in his 1st edition. Might
> be in his 2nd too. 
> > I have used both e-field and h-field (current clamp) at the same time. 
> We are engineers so figure out how I did that!
> And since some of the work is below 30 MHz, I have also added a 
loop antenna
> for a 3rd measurement. 
> My approach is if I find any emission, locally, near field, bench stuff,
> that varies by position over the area of the product, then I have a 
problem. 
> E-field scan,using a o'scope probe. H-field scan usually using a personally

> built small loop, and any other sort of scan, conducted or radiated, that I
> can make up at the moment. 
> I work for a homogeneous field in the scans over the area of the product. 
> My assumption is that if I find a homogeneous field, then there are no or

> low emission gradients which can equate to a field at a distance. So get
> creative, and redundant, by different methods for measuring the emissions. 
> Ironic, I am good at mashing all emissions, and then they hand me an

> intentional radiator and ask that I don't kill the fundamental. What ? You
> mean I have to pick what to mash, and what not to mash?
> Ok, so I caught on quick enough to keep the job. 
> > > ps. I suffer from not being able to use a leaky enclosure. I 
don't get any
> shielding for the products. 
> Cable shielding that is bogus terminated, but at the low frequencies of
> interests, it works. 
> Then I have to deal with the higher frequencies, the harmonics !!!

> Plastic covers and pcb and cables up to 15 KW or more of digital BS to make
> an analog signal. 
> And then 'normal' digital signals for the ADC circuits all in the middle of
> this. 
> Management is like, we have done it this way for over 25 years and 
so we are
> not changing it now. 
> It works (I have to make it work) so don't change anything. Sucks to be me
> - but I do like a challenge. 
> > > > > > > > > > > > > > > > _ > > > From: Ken Wyatt 
 >

> > -
> 

Re: [PSES] Fwd: [PSES] Current probe for CM currents

[Doug Smith]

Hi Everone,

Here is an interesting case where a ferrite core can actually perform 
an impedance matching function and increase emissions on a cable:


http://emcesd.com/tt120199.htm

Doug

On Fri, 15 Jan 2016 09:40:22 -0800, Ed Price  wrote:
I would add a caution to Ken's comment about common mode cable currents

creating RE. Yes, the CM currents certainly do create RE, but you need to
probe the cables at several intervals to understand those current paths. It
is not immediately obvious that all CM current flowing on a cable at one end
of a cable does not necessarily flow at the other end of that cable. 
Especially where cables are bundled, or where they pass closely along a

chassis or structural member, there are possibilities for that current to
couple off of the cable. The current flow will follow the impedances, both
at the ends and at other fortuitous nodes. This is one of the reasons that a
ferrite absorber might work much better at one position along a cable than
at another position and also why RE might be dependent on something as
obscure as cable bundle tightness. 


Ed Price
WB6WSN
Chula Vista, CA USA



From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Friday, 
January 15, 2016 8:53 AM

To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Fwd: [PSES] Current probe for CM currents



I think it is important to not lose sight of the original query that started
this thread. The query was about whether placing a current probe around a
cable perturbed the current to be measured. There is no doubt that 
radiated emissions can originate within an equipment

enclosure separately from driving common mode currents on a cable, but that
wasn't the query. In fact, the poster was probing cables within a large rack
(enclosure) looking for a source within an enclosure. 


Ken Javor
Phone: (256) 650-5261



_ From: Bill Owsley <00f5a03f18eb-dmarc-requ...@ieee.org>
Reply-To: Bill Owsley 
Date: Fri, 15 Jan 2016 07:26:08 +
To: 
Subject: Re: [PSES] Fwd: [PSES] Current probe for CM currents

If you can measure common mode noise on a cable, you have a problem from the
port !!
Note the world famous Ott's math on this effect in his 1st edition. Might
be in his 2nd too. 

I have used both e-field and h-field (current clamp) at the same time. 
We are engineers so figure out how I did that!

And since some of the work is below 30 MHz, I have also added a loop antenna
for a 3rd measurement. 
My approach is if I find any emission, locally, near field, bench stuff,
that varies by position over the area of the product, then I have a problem. 
E-field scan,using a o'scope probe. H-field scan usually using a personally

built small loop, and any other sort of scan, conducted or radiated, that I
can make up at the moment. 
I work for a homogeneous field in the scans over the area of the product. 
My assumption is that if I find a homogeneous field, then there are no or

low emission gradients which can equate to a field at a distance. So get
creative, and redundant, by different methods for measuring the emissions. 
Ironic, I am good at mashing all emissions, and then they hand me an

intentional radiator and ask that I don't kill the fundamental. What ? You
mean I have to pick what to mash, and what not to mash? Ok, so I 
caught on quick enough to keep the job. ps. I suffer from not being 
able to use a leaky enclosure. I don't get any
shielding for the products. 
Cable shielding that is bogus terminated, but at the low frequencies of
interests, it works. Then I have to deal with the higher frequencies, 
the harmonics !!!

Plastic covers and pcb and cables up to 15 KW or more of digital BS to make
an analog signal. 
And then 'normal' digital signals for the ADC circuits all in the middle of
this. 
Management is like, we have done it this way for over 25 years and so we are
not changing it now. It works (I have to make it work) so don't 
change anything. Sucks to be me
- but I do like a challenge. 















_ From: Ken Wyatt 

-

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David Heald: 

Re: [PSES] pre-compliance spectrum analyzer

[Doug Smith]

Since a spectrum analyzer front end is usually wide open for the entire 
bandwidth, a signal out of the range you are looking at could be 
overloading the analyzer causing incorrect readings for the signals yor 
are looking at. Having a tuned front end is one of the advantages of an 
EMC receiver. 


Doug
University of Oxford
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 Fri, 8 Jan 2016 16:08:23 +, Elliott Martinson 
<elliott.martin...@etcconnect.com> wrote:

http://www.ieee.li/pdf/essay/receiver_v_sa.pdf
I just noticed you linked to a spectrum analyzer, yet I was talking 
as if we were discussing EMI receivers. There are several key 
differences even though I would have thought they were practically 
the same thing had I not done some research. I noticed the maximum 
sweep time on that spectrum analyzer is 1000s, or 16m40s. So that 
point about it taking hours may seem wrong (at first). But, for good 
measurements on a spectrum analyzer, you have to do only a small 
portion of the total bandwidth at once, because with, say, 30MHz to 
1GHz frequency range, the measurements would be a whopping 2MHz 
apart! This is bad, because often, problem peaks may be very narrow 
digital ones, which could easily be missed without testing only a 
small portion of the spectrum at once. When that's taken into 
consideration, it may well take hours, but also require more human 
intervention during measurement. Before getting a spectrum analyzer, 
it might be useful to check out the link at the top (unless y!
ou're already fully aware of the differences). I guess it really 
depends on what you're trying to do. 


Elliott Martinson
EMC Test Technician
Electronic Theatre Controls
3031 N PLEASANT VIEW RD
MIDDLETON WI 53562-4809
elliott.martin...@etcconnect.com


-Original Message-
From: Elliott Martinson [mailto:elliott.martin...@etcconnect.com] 
Sent: Friday, January 08, 2016 9:52 AM

To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] pre-compliance spectrum analyzer

At my workplace, we've got one of these: 
https://www.rohde-schwarz.com/product/esrp-productstartpage_63493-35077.html 
and it's pretty nice. Especially its huge dictionary of GPIB 
remote-control commands, which makes interfacing with LabVIEW 
convenient. 
R makes good products. However, I have never used nor seen the one 
you linked to. 
I noticed no mention anywhere of FFT/time-domain scanning on the page 
or the brochure (it'd be mentioned if it was a feature). That is a 
HUGE weak point IMO, if measurement time is at all important. There 
is no CISPR-Average scanning either, though RMS is probably similar 
enough. Are you trying to find something that's relatively 
inexpensive? Because it may be worth considering the expenses from 
the time costs as well. Time-domain scanning can make something 
that'd take several hours take only a few minutes, or possibly 
seconds (depending on context). If you stick to peak scans, it may 
not be so bad. It'll look noisier than quasi-peak, but that's okay 
since it's better to err on the side of less noise. 


-Elliott

-Original Message-
From: Amund Westin [mailto:am...@westin-emission.no]
Sent: Friday, January 08, 2016 2:05 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] pre-compliance spectrum analyzer

Sorry for incorrect subject ... I'll try again:

---

Looking for a pre-compliance spectrum analyzer for in-house checking. 
Found this one from R 
http://value.rohde-schwarz.com/vi/value/spectrum-analyzers/hms-spectrum-analyzer.html


Anyone who have used this one?

Regards

Amund

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Re: [PSES] Best antenna for IEC 61000-4-3

[Doug Smith]

How about having an Amateur Radio Operator design an antenna optimized 
for the lower frequencies? Or design one, one's self. Then calibrate it 
against a known antenna. Should not be difficult. 


Doug
University of Oxford
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
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Web: http://www.dsmith.org
--

On Fri, 8 Jan 2016 14:44:07 -0800, "Ghery S. Pettit" 
<n6...@comcast.net> wrote:
Talk to the antenna vendors. 20 V/m with 100 Watts is going to be tough. 


Ghery Pettit

-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Friday, 
January 08, 2016 12:33 PM

To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Best antenna for IEC 61000-4-3

I'm looking for suggestions on the best antenna to use for Radiated Immunity
test according to IEC 61000-4-3 between 80Mhz and 1Ghz. (we use a dual ridge
horn above 1Ghz). 


Our goal is to find an antenna which is not too large, yet, will give us
good gain at the low end so we can generate 18-20V/m with a 100 watt
amplifier. 


I've looked at the hybrid antennas and they just don't seem to have enough
gain at the low end. It appears that most labs that use this type of antenna
requires a 200 watt amp. 


Looks like a Log Periodic has much better gain and should work but we don't
want the radials to get too close to the floor. Plus, some of these are
nearly 2 meters long. 


Any suggestions or recommendations? What antenna do you use and how much
power do you required to achieve 10V/m with 80% AM modulation without
clipping??

Thanks,

The Other Brian




LECO Corporation Notice: This communication may contain confidential
information intended for the named recipient(s) only. If you received this
by mistake, please destroy it and notify us of the error. Thank you. 


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Re: [PSES] PoE Injectors

[Doug Smith]

Hi Chas and the group,
 
It was the design layout of the PCB of the POE, and it was easy to see
(no PHY used). The magnetics may have played a part but the layout is
terrible in some of these devices. They are not designed by engineers
of any competence. In my article, I was very careful to make sure the
end points of the Ethernet connection and cable were not a factor,
described in the article.
 
There is no PHY in this case, just inductors to inject the DC onto the
Ethernet connection. No active circuitry was involved as I remember.
 
Doug
 
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, 19 Oct 2015 21:29:14 +, "Grasso, Charles"  wrote:

  Hello Doug – in your tidbit you indicated that the pwb layout
was (likely) responsible for the
increased emissions at the below 100MHz range.  It has been my
experience that when
the magnetics are placed inside a connector, that the emissions are
more influenced from
the imbalance in the cores and assembly that the layout.  Nowadays
there is literally
no ambiguity in the layout – the traces go from the phy in the SoC to
the connector -
that’s it!  [I am assuming that the design guidelines from the
connector/phy manufacturer
are being followed] Also how do you isolate the influence of the cable
in your measurements?
 
After all the internal signal wires could be twisted differently as you
move the cable... Y/N??
 
 
Best Regards
 
Charles Grasso
 
Compliance Engineer
 
Echostar Communications
 
(w) 303-706-5467
 
(c) 303-204-2974
 
(t) 3032042...@vtext.com
 
(e) charles.gra...@echostar.com
 
(e2) chasgra...@gmail.com
 
 
From: Doug Smith [mailto:d...@emcesd.com]
Sent: Sunday, October 18, 2015 1:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] PoE Injectors
 
 
Hi Bill,
 
 
 
Keep in mind that many POE adapters on the market will cause an
emissions problem because they are poorly designed and unbalance the
Ethernet pairs creating common mode currents.
 
 
 
See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm
 
 
 
When you open some of them and look at the design, it is obvious they
were not designed by engineers.
 
 
 
Doug
 
 
 
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 Sun, 18 Oct 2015 18:50:30 +, Bill Owsley  wrote:
 

  Somewhere in the references at the end, you might find which
devices that these standards apply to.
 
There are number of exceptions.  And there may have been changes since
doc was published.
 
In the past I have emailed Victor with questions.
 
- Bill
 
 
 

 

-

From: Scott Douglas
To:  EMC-PSTC@LISTSERV.IEEE.ORG
Sent: Sunday, October 18, 2015 2:04 AM
Subject: [PSES] PoE Injectors

 

Hello All,

I am wondering if PoE injectors need to be ErP compliant? If so, what
efficiency level? Does anyone know of any such injectors that are compliant?

The injector would be used to power a product and not a switch, router,
or access point.

Any and all comments appreciated.

Regards,
Scott

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Re: [PSES] PoE Injectors

[Doug Smith]

Hi Bill,
 
Keep in mind that many POE adapters on the market will cause an
emissions problem because they are poorly designed and unbalance the
Ethernet pairs creating common mode currents.
 
See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm
 
When you open some of them and look at the design, it is obvious they
were not designed by engineers.
 
Doug
 
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 Sun, 18 Oct 2015 18:50:30 +, Bill Owsley  wrote:

  Somewhere in the references at the end, you might find which
devices that these standards apply to.
There are number of exceptions.  And there may have been changes since
doc was published.
In the past I have emailed Victor with questions.
- Bill
 

-
 From: Scott Douglas
Subject: [PSES] PoE Injectors

Hello All,

I am wondering if PoE injectors need to be ErP compliant? If so, what
efficiency level? Does anyone know of any such injectors that are compliant?

The injector would be used to power a product and not a switch, router,
or access point.

Any and all comments appreciated.

Regards,
Scott

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Re: [PSES] PCB via holes - radiated emission

[Doug Smith]

Hi Chas and the group,

I have noticed in my measurements that sometimes a signal via will 
casuse significant radiated emissions not from the via itself but from 
voltage generated between the planes. I have seen this effect at much 
lower frequencies than via effects normally, at the resonant frequency 
of the board as a whole, often a few hundred MHz.  And having a 
gnd-gnd via 1/40 of a wavelength away is much too distant to cut down 
significantly on the emissions. I present the data in some of my 
courses and presentations (IEEE and such) which some people on the list 
have seen. 


Doug

University of Oxford 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 Wed, 19 Aug 2015 19:52:04 , Grasso, Charles 
charles.gra...@echostar.com wrote:


0.1mm = 4mils (right?)
 
IMO – the change will NOT change your emissions profile. 
However – only another emissions test will be definitive. 
 

Your trace impedance* will *change so I suggest you
use a solver to ensure that final impedance  will still be acceptable. 
 

 
Best Regards
 
Charles Grasso
 
Compliance Engineer
 
Echostar Communications
 
(w) 303-706-5467
 
(c) 303-204-2974
 
(t) 3032042...@vtext.com
 
(e) charles.gra...@echostar.com
 
(e2) chasgra...@gmail.com
 
 
From: Amund Westin [mailto:am...@westin-emission.no]
Sent: Wednesday, August 19, 2015 3:55 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] PCB via holes - radiated emission
 
 
Have previously done some radiated emission tests on a multi-layer PCB 
with good results. 
 

 
Now, all the via holes will change in the next layout revision. 
That’s because the original PCB had a lot of short-circuits between 
via holes and inner layers, due to inaccurate process by the PCB 
manufacturer. The spacing between the via holes and inner layers will 
now be increased by approximate 0.1mm. 
 

 
I can hardly see that this change will cause any major impact on the 
radiated emission tests. It will still be the same (clock) components 
on the PCB and all the traces are unchanged. There will be different 
coupling between the via hole and inner layer planes. Can less coupling 
result in higher radiated emission? Maybe because of resonances due to 
less area for inner layers, but we talk about very small changes … 
0.1mm. 
 

 
Right now, we have 10dB margin @ 1600MHz. 
 
Increased distance between via holes and inner layer by 0.1mm will not 
make any significate change, I guess. 
 

 
Comments?
 
 
Best regards
 
Amund
 
 
 
 
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Re: [PSES] Dual polarity DC electric strength test

[Doug Smith]

Actually, discharges involving insulators appear to be polarity
senstive from recently published data. I have confirmed this with lab
measurements. Not sure how this effects safety.
 
Doug

On Wed, 5 Aug 2015 11:52:06 -0700, Richard Nute  wrote:

   
 
Hi Charlie:
 
 
 

The standard is incorrect in requiring tests of both polarity d.c. 
There is no physical rationale for both polarities. 

 
 
Go on, I’ll bite J
 
What’s this requirement doing in the standard then?
 
 
Because it appears in IEC 60664-1, sub-clause 6.1.2.2.2.3.
 
 
 
Best regards,
 
Rich
 
 
   
 
 
 
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Re: [PSES] Dual polarity DC electric strength test

[Doug Smith]

Hi John and the group,

Thanks! The data I saw is in a paper that was submitted to the EMC 
Symposium in Dresden and left me with the impression it was new. Having 
read the paper, I set up an experiment in the lab and true enough, the 
discharge current onto an insulator (amps for ns or so) is quite 
different for - and + discharges, much greater for -. The application 
was for the exposed parts of systems but looks like it could affect 
nearby breakdown in air too. 

I do a lot of this kind of thing. When I come across new (to me) 
information, I set up an experiment to measure the effect. Sometimes I 
find that there are a lot of caveats in published material that were 
not mentioned. The first time I did this, I was around age 12 and I 
recreated one of Marconi's experiments in my bedroom to make sure it 
really worked. 


Doug
University of Oxford 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 Wed, 5 Aug 2015 21:57:19 +0100, John Woodgate j...@jmwa.demon.co.uk wrote:
In message 20150805123657.7o15cirvwgwkw...@hostingemail.xo.com, dated

Wed, 5 Aug 2015, Doug Smith d...@emcesd.com writes:

Actually, discharges involving insulators appear to be polarity 
senstive from recently published data. I have confirmed this with 
lab measurements. Not sure how this effects safety. 

I don't think this is particularly new, although no doubt it's much 
better quantified these days. The chemical composition affects if, 
and how much, ionization and consequent electron emission occurs at 
the surface. So if the discharge path has different insulating 
materials at each end, polarity sensitivity is to be expected. 
-- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk

When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] Off Topic - Warranty Question

[Doug Smith]

Hi Scott,

I had not heard of anything like this.It would seem a very difficult 
thing to do since variations between products would result in a real 
mess of regulations. Some products should not, in fact, could not, be 
warranteed for a specific lenght of time like two years because of the 
nature of the product. 

However, I would like to see a 5 year warrantee on all medical treatements. 


Doug Smith
http://emcesd.com
http://DesertLabRat.com

On Wed, 1 Jul 2015 19:17:16 -0700, Scott Douglas 
sdouglas...@gmail.com wrote:

Hello People,


This is not a compliance type question (at least I don't think so). 

Question comes up, is there anywhere written into law or regulation 
that a manufacturer of electronic product must provide a warranty on 
a product? More specifically, is there any term associated with such 
a requirement?


One of our international sales guys thought the EU had a minimum two 
year warranty requirement. But we can't find that in writing anywhere 
we have looked. Any input from the group will be much appreciated. 

Thank you in advance for your comments. 


Regards,
Scott

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[PSES] Latest Technical Tidbit and my Institute of Physics paper

[Doug Smith]

Hi Everyone,

I have just posted my latest Technical Tidbit on internal generation of 
EFT and ESD withing power supplies, a real nasty effect, and also my 
recent paper I wrote for the Institute of Physics on the subject. The 
link on my website to the Technical Tidbit that introduces my Institute 
of Physics paper is at:


http://emcesd.com/tt2015/tt061616.htm

This material will be discussed in detail in Boulder City, NV in July 
(along with many other topics).


Doug

--
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[PSES] repeat of EMC lab test error presentation for those who missed the first time

[Doug Smith]

  
  
Hi All,

There was a mix up on which month the presentation was, should have
been May and I said June. So here is the updated data:



  EMC test errors

Wed, May 27, 2015 9:30 AM - 10:00
  AM PDT


   
  Please join my meeting from your computer,
tablet or smartphone.
 https://global.gotomeeting.com/join/466318909
  
  
   You can also dial in using your
phone.

United States +1
(224) 501-3412  


Access
  Code: 466-318-909

  

EMC lab test errors are more common than you would think and can
cost your company BIG! This presentation covers some of my
experiences and ways to spot errors that can label a "passing"
system as "failing" or viceversa. A copy of the slides will be sent
to the people attending. No need to register Just click on the link
above. The first 25 people are "in." Of course, more than one person
can be at each computer. Having a group in a meeting room
facilitates discussion of the topic.

Please mute your microphone after joining to avoid noise on the
connection during the presentation. Questions are welcome at any
point during the presentation (unmute your mic).

I will open the conference 20 minutes early. If this is your first
time on GoToMeeting, it may take a few minutes to join the
connection.

Doug
-- 
University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
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[PSES] Design by committee disasters!

[Doug Smith]

  
  
Hi All,

Here are some thoughts of mine on two examples of
design-by-committee in the EMC field which ended, in my opinion, a
poor outcome:

First, is the LISN (line impedance stabilization network),
used in conducted emissions testing. I cant believe that a design
would be included in standards that can easily source a 1000 Volt
transient out of an innocent looking BNC connector intended for
connecting to a spectrum analyzer. But that is what happens and many
people have burnt out the input of their spectrum analyzer by
connecting it to a LISN.

The LISN design should not rely on people realizing the BNC output
cannot be connected to a spectrum analyzer and putting in various
protecting circuits between the spectrum analyzer and LISN.

Just on the surface, it seems the original LISN circuit was a
concept proposal not a real design, or the designer was completely
unfamiliar with the nature of the AC mains the LISN is used with, or
both.

Second, is the capacitive clamp used with IEC 61000-4-4,
Electrical Fast Transients. By the way, EFT bursts as well as
inductive kick are what causes the problems above with the LISN.

The problem arises in that the capacitive clamp was poorly
understood at the time it was included in the standard. It is quite
directional and sends much more energy towards the auxiliary
equipment than the equipment under test! In turns of peak current,
the auxiliary equipment gets 30% to 100% more than the EUT,
depending on the nature of how the common mode impedance of the
auxiliary equipment interacts with the capacitive clamp.

Not a good design!

Does anyone else have examples like this?

Doug
-- 
University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
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[PSES] Brick power supplies and test errors (two topics)

[Doug Smith]

  
  
Hi All,

A number of you have attended my web presentation on ESD/EFT
internally generated in system power supplies. As little as 500 V of
applied ESD or EFT is able to break down the supply in both
polarities for only one applied polarity. I have posted on this
before. Now, in addition, to the small wall plug power supplies
tested, I have now confirmed that "brick" type supplies used in PCs
can also exhibit these characteristics. Next to try on larger
internal power supplies, likely to see the effect here too. We will
see.

When I was at Auspex Systems (1996-2001) we
had 8 EMC radiated emissions tests performed on our equipment
(three 1500 lb cabinets full of disk drives). Of these, 4 tests
had significant test errors, two major and two minor errors, but
all had a large impact to our company! The tests were done at
three different labs over time, all made at least one error.
"Trust but verify."

In 2010-2011, I evaluated 8 ESD guns, all had current
calibration stickers. 2 of the 8 did not produce the correct
output, off by a lot. "Trust but verify." (Any of
you know who said that quote? It is someone from a completely
different field from us.) All the bad data I have ever seen, came
from "calibrated" equipment.

Here are some links on the above topics (if your computer puts a
"[1]" in the link, remove it. Internet files do not end with "[1]":

http://www.emcesd.com/tt2014/tt120214.htm
(my latest Technical Tidbit)

December 2010,
  Comparing "IEC 61000-4-2 Compliant" ESD Simulators


March 2011,
  Using High Frequency Measurement of ESD Current to Find Problems
  with an ESD Simulator

Also check out my YouTube channel tech videos, 100,000 view now.
Look for "Doug Smith EMC" and that should bring up my channel. I am
not one of the Doug Smiths who are musicians.

Doug
-- 
University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
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[PSES] EMC test lab errors

[Doug Smith]

  
  
Hi All,

I just posted my latest Technical Tidbit on EMC lab test errors.
Unfortunately these are more common than one would hope, sometimes
"failing" a passing product and sometimes "passing" a failing
product (may not be as desirable as first appears).

Abstract: EMC testing is a
required part of bringing a product to market. Passing the test
itself
can be a real headache for developers and marketers, but what if the
test was performed in error and the test results are not valid!
This is a real problem in the more general field of lab testing as
well
as specifically EMC testing. Some thoughts are shared on the topic.

The link to the article is:

http://www.emcesd.com/tt2014/tt120214.htm

Other links on my site of interest:

http://emcesd.com

A new phenomena! Some system power supplies can convert a system ESD
hit into dozens of ESD hits and even convert EFT on the power line
into nasty ESD hits even when the applied pulse is a small fraction
of the power supply breakdown voltage! Some of the characteristics
are:
 Some of the nastiest ESD waveforms you
will ever see. Over a period of a few microseconds, many Human Metal
Waveforms, Cable Discharge Waveforms, corona discharges, and ESD
events
embedded in other ones, of both polarities can be generated from a single ESD event applied to the
  product.
It is like every possible ESD waveform that can be, is generated
from a
single applied ESD event. The results have been duplicated in three
different laboratories with different scopes, different ESD
simulators,
and different power supplies. And, this effect often happens at a
small
fraction of the rated barrier breakdown voltage of the power supply!
 To date, this newly discovered effect has been
observed in small power supplies operating off the AC mains with a
two
wire interface, but it is possible others may have the same
response.
These kind of power supplies can include small supplies directly
plugged into the mains, brick type supplies used with PCs, and
equipment with a two wire mains interface like: stereo amplifiers,
set
top cable and satellite boxes, a lot of consumer equipment, and some
industrial equipment.
 I have dozens of waveforms I have taken on this effect
resulting from both ESD and EFT.

http://emcesd.com
Almost 300 papers, articles, and videos are not posted on the site!
Great cure for insomnia.

Doug
-- 
University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

  

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Re: [PSES] Noisy DC / DC converter

[Doug Smith]

Hi Brian,

One needs to be a little careful with caps on the output. I have seen 
many cases where they form a resonant circuit with the inductance of 
wires connected to the supply and make the problem even worse.


How about a puzzle? How do you make a non-resonant capacitor using three 
components?


Doug

University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

On 12/1/14 12:30 PM, Brian Oconnell wrote:

Have seen somewhat useable app notes  by Vicor, Calex, Interpoint for dealing 
with DC/DC switching noise.

For DC stuff, typically recommend caps, as there can be secondary affects (be 
careful if you must meet LPS/Class 2). If no spacing or thermal issues, a tight 
can or some level of close-in shielding referenced to secondary can be best 
solution if input not referenced to output.

Brian

-Original Message-
From: Amund Westin [mailto:am...@westin-emission.no]
Sent: Monday, December 01, 2014 11:48 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Noisy DC / DC converter

Got a DC / DC converter in an ITE.
From a radiated emission plot, I can see lot of spikes with spacing 330kHz in 
the region 30-80MHz.
The DC / DC converter datasheet tells that the switching frequency is 330kHz.
No suppression components around the converter. I assume a common mode choke 
could block some on the noise, so it does not enter the power supply cable, 
which may act as an antenna in this case.

Any other tricks for EMI suppression of DC / DC converters?


#Amund

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Re: [PSES] SV: [PSES] EMC test lab errors

[Doug Smith]

  
  
Hi Amund,
  
  That will catch non-functional test equipment. There are
  unfortunately a lot of test setup, just not following the standard
  to the word, and other kinds of errors I have run into.
  
  Doug
  
  University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

  On 12/1/14 11:59 AM, Amund Westin wrote:


  
  
  
  
Thanks, Doug. Good article.
I always ask for an ambient emission scan
before I turn on the EUT. The ambient and EUT ON plots
shall not be equal J 

Best regards
Amund









  
Fra:
Doug Smith [mailto:d...@emcesd.com] 
Sendt: 1. desember 2014 20:31
Til: EMC-PSTC@LISTSERV.IEEE.ORG
Emne: [PSES] EMC test lab errors
  


Hi All,
  
  I just posted my latest Technical Tidbit on EMC lab test
  errors. Unfortunately these are more common than one would
  hope, sometimes "failing" a passing product and sometimes
  "passing" a failing product (may not be as desirable as first
  appears).
  
  Abstract: EMC testing is a required part of bringing a
  product to market. Passing the test itself can be a real
  headache for developers and marketers, but what if the test
  was performed in error and the test results are not valid!
  This is a real problem in the more general field of lab
  testing as well as specifically EMC testing. Some thoughts are
  shared on the topic.
  
  The link to the article is:
  
  http://www.emcesd.com/tt2014/tt120214.htm
  
  Other links on my site of interest:
  
  http://emcesd.com
   A new phenomena! Some system power supplies can convert
  a system ESD hit into dozens of ESD hits and even convert EFT
  on the power line into nasty ESD hits even when the applied
  pulse is a small fraction of the power supply breakdown
  voltage! Some of the characteristics are:
   Some of the nastiest ESD waveforms you will ever see.
  Over a period of a few microseconds, many Human Metal
  Waveforms, Cable Discharge Waveforms, corona discharges, and
  ESD events embedded in other ones, of both polarities can be
  generated from a single ESD event applied to the product.
  It is like every possible ESD waveform that can be, is
  generated from a single applied ESD event. The results have
  been duplicated in three different laboratories with different
  scopes, different ESD simulators, and different power
  supplies. And, this effect often happens at a small fraction
  of the rated barrier breakdown voltage of the power supply!
   To date, this newly discovered effect has been observed
  in small power supplies operating off the AC mains with a two
  wire interface, but it is possible others may have the same
  response. These kind of power supplies can include small
  supplies directly plugged into the mains, brick type supplies
  used with PCs, and equipment with a two wire mains interface
  like: stereo amplifiers, set top cable and satellite boxes, a
  lot of consumer equipment, and some industrial equipment.
   I have dozens of waveforms I have taken on this effect
  resulting from both ESD and EFT.
  
  http://emcesd.com
  Almost 300 papers, articles, and videos are not posted on the
  site! Great cure for insomnia.
  
  Doug 
-- 
University of Oxford 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
 | q-( ) | o | Email: d...@dsmith.org
 \ _ / ] \ _ / Web: h

Re: [PSES] Noisy DC / DC converter

[Doug Smith]

Hi All,

Depending on the system requirements, For mains supplied units, I like 
to use the chassis of the power supply to short circuit the noise 
currents so they keep inside of the supply. That usually means, 
connecting through very low inductance, the circuit ground to the power 
supply chassis at its output. A 4 cm wire is too long.


Doug

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Department for Continuing Education
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On 12/1/14 11:47 AM, Amund Westin wrote:

Got a DC / DC converter in an ITE.
From a radiated emission plot, I can see lot of spikes with spacing 330kHz
in the region 30-80MHz.
The DC / DC converter datasheet tells that the switching frequency is
330kHz.
No suppression components around the converter. I assume a common mode choke
could block some on the noise, so it does not enter the power supply cable,
which may act as an antenna in this case.

Any other tricks for EMI suppression of DC / DC converters?


#Amund

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Re: [PSES] New electrical phenomenon reproduced tonight!

[Doug Smith]

Or, since we are talking about leakage inductance, one should be able to pick 
up a ringing waveform with just a loop of wire loaded with 50 Ohms. But for 
both methods I would have to destroy some power supplies to get inside. Not 
willing to do that yet.

Doug
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 On Nov 9, 2014, at 13:00, John Woodgate j...@jmwa.demon.co.uk wrote:
 
 In message 984890CC1A6246F6861A91866248361E@delld28c3cd7db, dated Wed, 5 
 Nov 2014, Richard Marshall richard.marshal...@btinternet.com writes:
 
 That would provide a mechanism that doesn't involve any very unusual 
 mechanisms.
 
 Clever.
 
 An easy check would be to apply magnets to saturate the EMC filter c
 
 Clever squared. Typical Richard.
 -- 
 OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
 Quid faciamus nisi sit?
 John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
 
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Re: [PSES] New electrical phenomenon reproduced tonight!

[Doug Smith]

I would send a sample waveform to the group, but attachments cause a post to be 
deleted.

Doug
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 On Nov 4, 2014, at 23:56, John Woodgate j...@jmwa.demon.co.uk wrote:
 
 In message 54596079.8060...@emcesd.com, dated Tue, 4 Nov 2014, Doug Smith 
 d...@emcesd.com writes:
 
 Don't have a good explanation yet as I am hesitant to take apart one of the 
 supplies that is the worst offender as it is the supply for a D-Link router 
 I have. I am beginning to formulate possible mechanisms. But from the point 
 of view of equipment, supplies that do this should not be used. I have been 
 using a simple test setup (on a normal lab bench, not a standards based 
 setup) that would suffice for prescreening supplies.
 
 There is some sort of discharge happening and the delay could be the time it 
 takes for a discharge to form. I have been able to repeat the results with 
 ESD as the stimulus in three different labs using different equipment.
 
 Understood. I wonder if this effect may be involved in the power 
 supply/charger fires that seem to be increasing in number.
 -- 
 OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
 Quid faciamus nisi sit?
 John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
 
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[PSES] New electrical phenomenon reproduced tonight!

[Doug Smith]

Hi All,

I was able to measure in my lab late tonight, a very important extension 
of an effect I discovered earlier. That discovery describes how some 
power supplies can take in a single ESD pulse and generate from it many 
ESD pulses of both polarities with both human metal model and cable 
discharge current waveforms embedded in corona discharges from the 
single original ESD pulse.


Tonight, I was able to create the same effect using EFT (electrical fast 
transient) pulses. Some power supplies can take a single EFT pulse and a 
microsecond to several microseconds later generate one or more EFT 
pulses, some larger that the stimulus one, embedded in corona discharges!


This is very bad as EFT occurs much more than ESD and is not visible to 
equipment operators. The EFT can be amplified and made worse by some 
power supplies! This could easily the the cause of equipment failure 
either at compliance testing or in the field.


This appears to be a new phenomena that I have not seen published. I 
have been able to reproduce the ESD version at a NASA Ames laboratory, 
my own laboratory, and at an ESD test site on the US East Coast using 
different ESD simulators and equipment.


If you are interested in this, contact me privately at d...@dsmith.org 
or call me.


Doug

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Re: [PSES] New electrical phenomenon reproduced tonight!

[Doug Smith]

Hi John,

The timing of microseconds is orders of magnitude slower than the size 
of the test setup relative to the speed of light in conductors, 1 ft/ns 
in free space and maybe 1.5 to 2 ns/ft in most conductors. The test 
setup used about six feet of cable, 12 ns at most.


The applied voltage of the pulse was much lower than rated breakdown of 
power supply, less than 500 Volts.


I have added the results to my planned (every) Thursday presentation via 
web which this weeks describes ESD as a stress that causes this also.


Doug

University of Oxford Tutor
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On 11/4/14 11:54 AM, John Woodgate wrote:
In message 545898ce.1050...@emcesd.com, dated Tue, 4 Nov 2014, Doug 
Smith d...@emcesd.com writes:


Tonight, I was able to create the same effect using EFT (electrical 
fast transient) pulses. Some power supplies can take a single EFT 
pulse and a microsecond to several microseconds later generate one or 
more EFT pulses, some larger that the stimulus one, embedded in 
corona discharges!


Is this some sort of St Elmo's Fire effect, i.e. RF energy scoots 
around 'trying to find' a pointed conductor to discharge from? I 
suppose 'several microseconds' can be understood in terms of the 
propagation of the energy being much slower in conductors than the 
speed of light.


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Re: [PSES] New electrical phenomenon reproduced tonight!

[Doug Smith]

Hi John,

Don't have a good explanation yet as I am hesitant to take apart one of 
the supplies that is the worst offender as it is the supply for a D-Link 
router I have. I am beginning to formulate possible mechanisms. But from 
the point of view of equipment, supplies that do this should not be 
used. I have been using a simple test setup (on a normal lab bench, not 
a standards based setup) that would suffice for prescreening supplies.


There is some sort of discharge happening and the delay could be the 
time it takes for a discharge to form. I have been able to repeat the 
results with ESD as the stimulus in three different labs using different 
equipment.


Doug

University of Oxford 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
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

On 11/4/14 2:07 PM, John Woodgate wrote:
In message 545949e9.7010...@emcesd.com, dated Tue, 4 Nov 2014, Doug 
Smith d...@emcesd.com writes:


The timing of microseconds is orders of magnitude slower than the 
size of the test setup relative to the speed of light in conductors, 
1 ft/ns in free space and maybe 1.5 to 2 ns/ft in most conductors. 
The test setup used about six feet of cable, 12 ns at most.


So do you have any explanation of the delay? I was imagining some sort 
of serial build-up of energy, not a 'straight line' propagation effect.


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[PSES] Latest Technical Tidibit on circuit debugging - resend

[Doug Smith]

  
  
Hi All,

First send bounced because the message had a graphic signature area.
Here goes:

I just posted my October 2014 Technical Tidbit:

Technical Tidbit - October 2014
Direct RF Injection for Circuit Debugging
(A Video Presentation)

Here is the link:
http://www.emcesd.com/tt2014/tt100914.htm

Link to my home page:
http://emcesd.com
There is about 250 articles and journal papers I have written posted
on the site.

Doug
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Department for Continuing Education
Oxford, Oxfordshire, United Kingdom 
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[PSES] Caution to those who live outside of California and got there on business!!! (Don't)

[Doug Smith]

Hi All,

Just a note to those of you, especially consultants, but potentially 
anyone who visits California, even for a day, on business.


CA has new rules that require companies there (they don't all know about 
it yet but will be in trouble after the first of the year if they don't) 
to withhold CA income tax from payments made to people from out of state 
if any of the work was done in CA.


You need to fill out a tax form for every job/trip! It is California 
Form 587, Nonresident Withholding Allocation Worksheet. In my case the 
client ignored the form and sent the maximum 7% of the gross proceeds in 
to CA.


The company for whom you do work is required to deduct 7% from the gross 
payment to you, no allowance for expenses or, at least for the last job 
I did, the fact the job required 3 days in NV and two in CA. They took 
out 7% and sent it to the CA state government.


The accounting for this is going to be tricky as you have to keep track 
and justify how much of the work was in CA and how much elsewhere. In 
the end, CA may extract up to 10% of your payment, 13% if you are really 
well off. I suspect the accounting and submitting tax forms will cost as 
much as the tax, or more.


So starting now I am dividing my fee by 0.93 to cover the tax and 
probably need to at least double that to cover my time and the 
accountants time to keep track of all of this. I am thinking along the 
lines of $500/day additional to CA companies until I get a better idea 
of what this is going to cost.


Although we don't have an income tax in NV they get it in other ways, 
such as $2000/year from me for a special rental car tax meant to hit 
tourists, as well as other taxes. I you come in from Massachusetts, for 
instance, you will be required to pay MA and CA income taxes! That plus 
Federal will be over 50% for most engineers (CA is 10% at $44,000 per 
year).


I am interested to find out if I am the first person to run into this. 
If you go into CA for work purposes you will be hit for this. I plan to 
ask the CA tax people which precinct they are going to allow me to vote in.


Doug

--
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Oxford, Oxfordshire, United Kingdom
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 ___  _Doug Smith
  \  / )   P.O. Box 60941
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[PSES] Audio sources, class D digital amps, radiated emissions, and philosophy

[Doug Smith]

  
  
Hi All,

Just finished and posted my August 2014 Technical Tidbit titled:


Radiated Emissions
Can be Strongly Affected by Driving Signals, A Problem for
Emissions Testing
(An Example Using a Class D Stereo Audio Amplifier)
  


  

  


  


Abstract: Radiated emissions
from electronic equipment can be a strong function of how the
equipment
is operated. In the case of class D audio amplifiers, the audio
signal
driving the amplifier can have a large effect on emissions. Test
results and implications are discussed as they relate to the
philosophy
of radiated emissions testing.

The link to the article is:
http://www.emcesd.com/tt2014/tt081914.htm

The link to the main page: http://www.emcesd.com/
(lots of new stuff there)

Check to make sure your computer does not corrupt the links above.
They should look just as above with no other symbols or numbers
added as Windows sometimes does at the end of the link of the form
"[1]".

Doug
-- 
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom 
--
 ___  _    Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
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[PSES] latest article on troubleshooting designs for radiated and conducted immunity

[Doug Smith]

  
  
Hi Everyone,

I have been back to writing again. Here is my latest article:


Technical
Tidbit - March-April 2014
Troubleshooting Radiated and Conducted Immunity Problems in the
Development Lab

  
This
  month's Technical Tidbit describes a handy test method for
  finding and
  fixing radiated and conducted immunity problems, simply, right
  on the
  development lab test bench.
  
  



Abstract: Tackling radiated and conducted immunity
  problems can be difficult
  because of the high cost of the equipment and chamber normally
  used to
  perform these tests. An inexpensive test bench setup that can
  effectively find radiated and conducted immunity problems is
  presented.
  
  The link is: http://www.emcesd.com/tt2014/tt040114.htm
  
  In addition, the top of my main page at http://emcesd.com had
  become cluttered, first several screens, so I cleaned it up a lot.
  Take a look if you are interested. There are also some Technical
  Tidbits on analog op amp design as well I have added in the last
  few months for the December and January Technical Tidbits.


Doug
-- 
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[PSES] Analog Designer's Notebook - Part 2 Technical Tidbit plus more

[Doug Smith]

  
  
Hi Everyone,

I posted my latest Technical Tidbit a few days ago. Although about
analog op amps there is a definite slant towards SI and EMC. You
would not think a low frequency op amp needs to be bypassed on the
power as it if were a high speed digital IC, but the need is there.
--

Technical
Tidbit - January 2014
Analog Designer's Notebook Part 2 - The Importance of Good Power
Bypassing

  
This
  month's Technical Tidbit describes the importance of good
  power bypassing for op amps, even low frequency ones.
  
  



Abstract: Power bypassing is
  more important than one would think for analog ICs like op amps.
  Even low frequency op amps need
  high quality power bypassing to prevent the op amp from breaking
  into oscillation at a much higher frequency than the unity gain
  bandwidth of the device. The reason for this and recommendations
  are
  presented.
--

The link to the article is http://www.emcesd.com/tt2014/tt010114.htm

However, I have been adding new features to the site. Take a look
around the http://emcesd.com above the list of articles.

Doug
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   =   Boulder City, NV 89006-0941
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[PSES] Shielding degradation from a staple in a shielding bag

[Doug Smith]

Hi Everyone,

I thought you might be interested in this article published in 
InCompliance Magazine on shielding degradation in a shielding bag from 
pin holes and staples. There is application to the development lab as 
well in packaging operations in your companies.


Here is the link:

http://www.incompliancemag.com/index.php?option=com_contentview=articleid=2086:a-1kv-discharge-directly-onto-a-staple-leads-to-increased-energy-penetration-inside-metallized-static-shielding-bagscatid=43:basicsItemid=184

Doug

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[PSES] Analog Designers Notebook - Improving Opamp RF immunity

[Doug Smith]

  
  
Hi Everyone,

I thought I would post an analog design Technical Tidbit this month:


Technical
  Tidbit - November 2013
  Analog Designer's Notebook Part 1 - Improving Opamp RF Immunity


  

  


  
  Abstract: Radio frequency (RF)
  energy can cause DC offset and noise in opamp circuits,
  even voice
  frequency circuits. The RF energy may originate from
  external sources
  or even be high frequency noise from digital circuits on
  the same PCB.
  A simple way of improving the RF immunity of an opamp
  circuit that can
  help in many cases is described as well as a precaution
  that should be
  taken when this technique is used.
  
  The link to the article is:
  http://www.emcesd.com/tt2013/tt110113.htm




  


Doug
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[PSES] RFID antenna parasitic resonances affect operation

[Doug Smith]

  
  
Hi Everyone,

I just posted my Technical Tidbit for September 2013 on how
parasitic resonances in ane RFID antenna can affect RFID operation
and how to measure these parasitic resonances as well as an example.


Technical
Tidbit - September 2013
Parasitic Resonance in an RFID
  ~10 MHz Antenna - Measurement and Characterization


Abstract: Low frequency RFID transmitting
  antennas often have self-resonances at much higher frequencies
  than the
  frequency of operation that can cause problems, such as unintended
  radiated emissions. Such a case is described.

If you have trouble following the links below, please contact me. XO
Communications had a nearly one day outage yesterday and not all
browsers may get access yet. On my computer this afternoon Safari,
Opera, and Google Chrome worked but Firefox did not (yes, I cleared
the cache and tried reloading).

link to the article: http://emcesd.com/tt2013/tt090813.htm
(If your Windows computer adds a "[1}" to the link, you need to
manually remove it.)

Link to the home page of the site: http:emcesd.com

Doug
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   =   Boulder City, NV 89006-0941
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[PSES] Further investigation about hand-metal ESD

[Doug Smith]

  
  
Hi Everyone,

I just posted my Technical Tidbit for July. Here is the information:


Technical
  Tidbit - July 2013
  
  Human Metal ESD
Characteristics, Size of Metal Object
  (Intensity of ESD from a
  metal object in a human hand is not significantly affected by
  the size of the metal object)




  

This
month's Technical Tidbit presents data showing that the size
of a metal
object in a human hand does not strongly affect the
intensity of EMI
generated by the ESD event.
  
  



Abstract: The intensity of an
  ESD event from a human hand is affected strongly by the presence
  of
  metal held in the hand. Data is
  presented to show that the peak amplitude of the EMI generated by
  a
  discharge directly from a metal object in a human hand is not
  strongly
  affected by the size of the metal object held. Any size piece of
  metal
  intensifies the ESD event significantly.
  
  The link to the article is:
  http://www.emcesd.com/tt2013/tt072113.htm
  
  Your computer may corrupt the link above by appending "[1]" to the
  .htm. Just remove the "[1] and the link will work. So far only
  Windows computers seem to have this problem. Let me know if this
  occurs on a different operating system. I have not used Windows
  for over ten years now.
  
  Doug


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[PSES] A Collection of ESD measurements

[Doug Smith]

  
  
Hi Everyone,

I just posted my Technical Tidbit for June 2013, "A Collection of
ESD Measurements."

This is the fourth time since starting my website, http://emcesd.com
, in June of 1999 that I have posted an article written by a guest
contributor. This time the guest contributor is Geoff Weil.

Geoff is an excellent designer especially of analog circuits and
especially if they contain high voltage. He designed the well known
KeyTek Mini-Zap ESD simulator years ago as well as the KeyTek
ZapMaster and several Electrical Fast Transient generators. He is
currently working on voltage-boosted alpha source ionizers and high
voltage pulse generators.


Abstract: A collection of
measurements by guest contributor, Geoff Weil, is presented that
shows
characteristics of several different types of ESD including Human
Metal
Model, bare finger tip (Human Body Model), Charged Device Model, and
Furniture discharges. By collecting these measurements all in one
document, comparison between the different types of ESD are easy to
make.

The article is located at: http://www.emcesd.com/tt2013/tt060213.htm
and contains a link to Geoff's paper in pdf format.

The I have added information in the first few screens from the top
of the home page of http://emcesd.com including some recent
non-technical exploits. There are also pictures of Boulder City, NV
there.

Doug
-- 
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 ___  _    Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
_ / \ / \ _TEL/FAX: 702-570-6108/570-6013
  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
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[PSES] Intensity of ESD for skin and hand-metal discharges

[Doug Smith]

  
  
Hi All,

I have just posted my April 2013 Technical Tidbit:


Technical
Tidbit - March 2013
Human Metal vs. Human Body ESD
(Metal in a human hand significantly increases ESD intensity)


Abstract: The intensity of an
ESD event from a human hand is affected strongly by the presence of
metal held in the hand. System level standards like IEC 61000-4-2
usually model a human ESD event from metal held in the hand. Data is
presented to show that a discharge directly from human skin is much
less intense than a discharge through intervening metal held in the
hand.
  
There is a ratio of 40:1 or greater in the
voltage induced
in nearby circuitry by these two types of ESD events!

The link to the article is;
http://www.emcesd.com/tt2013/tt042013.htm

On a more personal note, check out one of my non-technical
adventures, the Devil Dash, a
footrace combined with an obstacle course (barbed wire, mud, rough
terrain, etc.). Click
  here
to see an interesting twist to the story. The event took place in
Bootleg Canyon, here in
Boulder City, NV March 23, 2013, on a much colder than normal day. I
finished faster than 90% those entered, who on average were less
than half my age!

Doug
-- 
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 ___  _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
_ / \ / \ _TEL/FAX: 702-570-6108/570-6013
  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
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Re: [PSES] test setup for table top ungrounded equipment 61000-4-2 IEC:2008 figure 6 page 20

[Doug Smith]

Hi Gary and the group,

When splitting hairs on the testing, keep in mind that the test is nowhere 
close to a bad case if ESD. So you have to convince yourself that you will have 
adequate field performance from your customer point of view. Many times this 
can be done, but not always.

Doug

Tel:   702-570-6108
Mobile: 408-858-4528
Email:   d...@dsmith.org
Sent: from my iPhone

On Mar 7, 2013, at 11:34, McInturff, Gary gary.mcintu...@esterline.com 
wrote:

 Interesting thought. It’s standard for my gun return to run between the HCP 
 and the ground plane to a connecting point at the rear corner of the ground 
 plate. Why, It’s just a people oriented convenience that keeps everything out 
 of the way during test. I’ve never really looked at it at the test facility 
 but my memory says it does not run between the plates of this capacitor – but 
 they agree with my results. I’m clueless how the client does it but I’m about 
 to find out.
 
  
 
 I’m also going to find some newer production samples of the EUT and see how 
 they respond, maybe there is a product change I’m unaware of.
 
 Thanks
 
  
 
 Gary
 
  
 
 From: ce-test, qualified testing bv - Gert Gremmen 
 [mailto:g.grem...@cetest.nl] 
 Sent: Thursday, March 07, 2013 10:23 AM
 To: McInturff, Gary; Ken Wyatt
 Cc: EMC-PSTC@LISTSERV.IEEE.ORG
 Subject: RE: [PSES] test setup for table top ungrounded equipment 61000-4-2 
 IEC:2008 figure 6 page 20
 
  
 
 How about the return path of the esd gun ?
 
 Part of the ESD effect is the H-field during discharge in the ground loop.
 
 The highest frequencies discharge to the internal “air”capacitor
 
 (single plate capacitor) in the gun, but eventually a (still high frequency) 
 current (10Amps or so)
 
  flows through the ESD gun’s ground cable  to the ground plane of the setup.
 
 A different lay-out of the return cable produces a different loop  and EUT 
 H-field.
 
 I agree with Douglas that the discharge resistors (if not to parasitic) do 
 not impact
 
 the impulses at all. (unless they are SMD   ;)) ).
 
  
 
 Gert Gremmen
 
  
 
 Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens McInturff, Gary
 Verzonden: donderdag 7 maart 2013 17:00
 Aan: 'Ken Wyatt'
 CC: 'EMC-PSTC@LISTSERV.IEEE.ORG'
 Onderwerp: RE: [PSES] test setup for table top ungrounded equipment 61000-4-2 
 IEC:2008 figure 6 page 20
 
  
 
 Agree, but nothing I can do about that, so I’m making sure what I can control 
 is in fact controlled. (It has been tested during earlier development at two 
 different sites, and different ESD guns with similar result acceptable 
 results, and in fact margin tested. But by the time it got to the customers 
 lab I first noticed that they were not actually following the specification. 
 I pointed that out and they made some corrections per the standard, but I 
 still think there is a difference. Whether or not the difference is part of 
 the problem or not is undetermined at this point, but as that part of the 
 equation can be handled if we just had a definitive definition of setup up so 
 that we can just not have to worry about that while finding and solving the 
 root problem.
 
 Thanks
 
 Gary
 
  
 
 From: Ken Wyatt [mailto:k...@emc-seminars.com] 
 Sent: Wednesday, March 06, 2013 5:36 PM
 To: McInturff, Gary
 Cc: EMC-PSTC@LISTSERV.IEEE.ORG
 Subject: Re: [PSES] test setup for table top ungrounded equipment 61000-4-2 
 IEC:2008 figure 6 page 20
 
  
 
 Are you both using the same ESD simulator? There's a huge difference between 
 different brands, with some producing large radiated E-fields.
 
 Kenneth Wyatt
 
 Wyatt Technical Services LLC
 
 Woodland Park, CO
 
 k...@emc-seminars.com
 
 www.emc-seminars.com
 
 (Sent from my iPad)
 
 
 On Mar 6, 2013, at 5:48 PM, McInturff, Gary gary.mcintu...@esterline.com 
 wrote:
 
 The problem is I don’t know if it makes a difference Dan. We certainly were 
 getting different results from a lab – and I trust the lab itself. But it 
 didn’t match what I had here nor the results from my normal certification 
 lab. We tested two units and got the same results, and now the customer uses 
 yet another lab with different results. Even given the vagrancies of ESD 
 testing I can’t put my finger on the problem. That’s what got me to verifying 
 the setup. Incidentally during the original successful tests I actually tried 
 it both ways, with the bleed cables in parallel, and with the HCP cable 
 removed – as I suspect should be the case (maybe) and that didn’t make a 
 difference at that time.
 
 But as I said I’m trying to eliminate the easy stuff first – test setup, both 
 mine and the lab that is failing the equipment.
 
  
 
 Thanks
 
  
 
 Gary
 
  
 
  
 
 Gary
 
  
 
 From: Dan Roman [mailto:danp...@verizon.net] 
 Sent: Wednesday, March 06, 2013 4:44 PM
 To: McInturff, Gary; EMC-PSTC@LISTSERV.IEEE.ORG
 Subject: RE: [PSES] test setup for table top ungrounded equipment 61000-4-2 
 IEC:2008 figure 6 page 20
 
  
 
 Interesting.  I have done the testing with 

[PSES] LVDS signal corruption and system problems

[Doug Smith]

  
  
Hi All,

Just back in Boulder City, NV from a week on the road and I just
posted my latest Technical Tidbit, this one on LVDS problems. Once
in a while I see a trend in system problems and this specific one
can be a bad one involving LVDS signal corruption.


Technical
Tidbit - February 2013
LVDS, Be Careful of EMI Induced
  Signal Corruption
(ESD and
EFT Induced Errors)


Abstract: LVDS, Low Voltage
  Differential Signaling, offers improvement in signal quality and
  EMC
  emissions, however it is not always effective against external
  pulsed
  stresses such as ESD and EFT. Limitations of LVDS are discussed
  and
  recommendations made.
  
  The link is:
http://www.emcesd.com/tt2013/tt020613.htm
(just one of hundreds of articles and papers at
http://emcesd.com ).

URLs to my website:
http://emcesd.com
http://DesertLabRat.com
http://www.dsmith.org

If the link does not work, you will see something like "[1]"
added to the end of the URL (I didn't put it there), delete it
and the link will work.
  
  

Doug
-- 
--
 ___  _    Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
_ / \ / \ _TEL/FAX: 702-570-6108/570-6013
  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
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[PSES] Summary of my 78 EMC papers and articles

[Doug Smith]

  
  
Hi Everyone,

My Technical Tidbit article for the month is a bibliography of my 78
published papers and articles on the topic with links to each
publication for easy reference. Between last month (ESD) and this
month (EMC) about 1/2 of my total number of publications are grouped
for easy reference. The rest are on general design and measurement
techniques.


Technical
Tidbit - December 2012
A Collection of Published Papers
  and Technical Tidbits on EMC
  Design and Troubleshooting


  

This
month's Technical Tidbit contains a bibliography of papers
and
Technical Tidbits on EMCESD.com covering topics related to
EMC, a
subset of 78 of the 200+ papers and articles on the site.
This
bibliography should make it easier to find articles about
EMC on this
site.
  
  



Abstract: There are well over 200 Technical
  Tidbit articles and papers now on
  this site, so from time to time, a summary of articles on various
  topics will be posted. This month, the summary lists all of the
  Technical Tidbit articles and papers that pertain to EMC issues,
  mostly in the frequency domain. This summary should make it easier
  to find articles about EMC on this site.
  
  The link to the article is:
  http://www.emcesd.com/tt2012/tt120212.htm
  Be sure you have a valid link as some Windows computers add a
  "[1]" to the link making it not work. The link should end in .htm.
  Correct in your browser as needed.


Doug
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[PSES] Bibliography of my published papers and articles on ESD

[Doug Smith]

  
  
Hi All,

I have well over 200 articles and papers on my high frequency
measurements site, http://emcesd.com now. So, from time to time I
will post a bibliography of papers on popular topics. This month's
Technical Tidbit is such a bibliography on ESD design and
troubleshooting.


Technical
Tidbit - October-November 2012
A Collection of Published Papers and Technical Tidbits on ESD Design
and Troubleshooting


Abstract: There are well over
200 Technical Tidbit articles and papers now on this site, so from
time
to time, a summary of articles on various topics will be posted.
This
month the summary lists all of the Technical Tidbit articles and
papers
that pertain to Electrostatic Discharge. This summary should make it
easier to find articles about ESD on this site.

The link to the bibliography is:
http://www.emcesd.com/tt2012/tt102612.htm or alternately:

http://DesertLabRat.com/tt2012/tt102612.htm

Doug
  
-- 
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 ___  _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
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  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
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[PSES] CAD programmer/draftsmam

[Doug Smith]

Hi All,

If any of you know of an open position for a person with good skills 
with programs like ProEngineer and AutoCAD (and others), let me know and 
I will pass along to a good candidate I know for the position. Bay 
Area/Silicon Valley preferred.


Doug

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[PSES] Extension of a method to measure voltage breakdown and charge objects

[Doug Smith]

  
  
Hi All,

Just posted my Technical Tidbit for the month at http://emcesd.com
or alternately http://DesertLabRat.com .

Technical
  Tidbit - September 2012
  Measuring Breakdown Voltage
and Charging Objects With an ESD Simulator - Part 2
  (A
  method that works with most ESD simulators)

Abstract: Measuring
  breakdown
  voltage and charging objects using an ESD simulator are useful lab
  techniques for finding problems in a system design related to
  charging
  or breakdown such as those related to ESD or lightning. The July Technical
Tidbit
  covered a simple method using a specific ESD simulator for this
  purpose. A general
  method is presented here that can be used with most ESD
  simulators.


The link to the article is:
http://www.emcesd.com/tt2012/tt091612.htm
The previous article on this subject is at:
http://www.emcesd.com/tt2012/tt072212.htm

Doug
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  \  / )   P.O. Box 60941
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  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
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[PSES] Lightning damage and ESD waveforms

[Doug Smith]

  
  
Hi All,

I thought you might enjoy my podcast below. It is in the Free Audio
section of CircuitAdvisor.com, the direct link is below.

 Good Morning From Boulder City for August 31, 2012 
 
Lightning, ESD air discharge, and CDM and other ESD models
http://www.circuitadvisor.com/main/audio/93

Doug

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 ___  _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
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  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
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[PSES] Measuring Breakdown Voltage in an interesting way

[Doug Smith]

  
  
Hi All,

Although a little late this month, I have posted my latest Technical
Tibit this month on an unusual use for at least one ESD simulator.

Technical Tidbit - July 2012
Measuring Breakdown Voltage With an ESD Simulator
(Special simulator characteristics
are needed)

  

This month's Technical Tidbit
describes how to use and ESD simulator to make high voltage
breakdown measurements. But beware! Special charactericts of
the simulator are needed that are not necessary for normal
ESD testing and most simulators cannot be used this way.
  


Abstract:Measuring high voltage
  breakdown has many uses including tracking down the cause of
  equipment failure and ascertaining compliance to safety standards.
  Some ESD simulators can be used to measure DC breakdown voltage
  and have the advantage that they can measure breakdown to voltages
  in excess of 10,000 volts. Not all ESD simulators can do this and
  the special characteristics required are discussed and an example
  is given of how this method was used to track down an equipment
  problem.

Starting this week I am starting a new podcast series "Good Morning
from Boulder City." Each podcast will be about 5 or 6 minutes long
and will discuss a couple of interesting technical topics. I will
publish these each morning I am in the office (now that I have a
good setup for doing this) as well as add additional technical
videos to the site. The Good Morning from Boulder City series will
be on the free side of the site and the first one has been posted at
http://circuitadvisor.com . The shortcut to the podcast is:

http://circuitadvisor.com/main/audioList/7/0

I will be posting another one to day or tomorrow. If you go to
circuitadvisor.com and click on "Free Audio" and "General Interest,"
that is where they will be.

Doug
-- 
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 ___      _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
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  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
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[PSES] Damaging electronic components from across the room!

[Doug Smith]

  
  
Hi All,

I have just posted my latest Technical Tidbit for May-June. The
postings for May and June are combined because of the time overhead
of moving from Los Gatos, CA to Boulder City, NV.


Technical Tidbit - May-June 2012
Destroying Electronic Components
  from Across the Room With ESD
(Today's
sensitive components are really sensitive!)

  

This month's Technical Tidbit
describes how modern sensitive components can be damaged by
an ESD event several meters away!
  


Abstract:Electronic components are
  getting smaller and more sensitive every day, and with this comes
  a greater possibility of damage from electrical stresses in the
  environment. Some devices are so sensitive, they can be destroyed
  by an ESD event across the room because the radiated fields from
  the ESD event generate enough current in wires to do this.
  Measurement of currents in a one meter cable from a remote, small
  ESD event are presented and related to device damage thresholds.

The link to the article is: 
http://emcesd.com/tt2012/tt052212.htm or
http://DesertLabRat.com/tt2012/tt052212.htm

Yes, I have added a new domain name: http://DesertLabRat.com which
currently points to my main website.

Doug

-- 
---
___  _   Doug Smith
 \  / )  P.O. Box 60941
  =  Boulder City, NV 89006-0941
   _ / \ / \ _   TEL/FAX: 702-570-6108/570-6013
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
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 \ _ /]\ _ / Website: http://www.dsmith.org
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[PSES] ad code injection?

[Doug Smith]

  
  
Hi All,

I just found a disturbing trend used by some Internet providers,
especially ones in places like hotels. That being injecting code in
to any web page visited. As you know, I do not accept advertising
for others on my website http://emcesd.com but you may see ads I
have not put there. Below is a clip from an article on
blogs.nytimes.com and a link to the full article. If you ever see an
ad on my website from someone else, can you please capture a screen
shot and send it to me? I do not use annoying techniques, like
blinking banners, on my web page, in fact it is just flat html with
out even _javascript_. I try to make my site as informative to
engineers as possible without flashy banners and such.

http://bits.blogs.nytimes.com/2012/04/06/courtyard-marriott-wifi/

"

On its Web site,
  a company called RG Nets, which makesRevenue eXtraction Gateway, explainsthat its system rewrites
  every Web page on the fly so that it can include a banner ad. As
  you can see, the pervasive nature of the advertising banner on all
  Web pages guarantees banner advertising impression, a narrator
  says in the video."

I am late this month on my Technical Tidbit because of my move from
Silicon Valley to Boulder City, NV, where I am at the moment.

Doug

-- 
---
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 \  / )  P.O. Box 60941
  =  Boulder City, NV 89006-0941
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 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
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 \ _ /]\ _ / Website: http://www.dsmith.org
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[PSES] Air discharge ESD revisited

[Doug Smith]

  
  
Hi Everyone,

I have just posted my latest Technical Tidbit:


Technical
  Tidbit - March 2012
  Air Discharge ESD Current
Waveforms Revisited
  (high frequency ESD current
measurements on system cables)
  

  
  This month's Technical
  Tidbit further investigates the implications of ESD events
  in air as opposed to contact discharge described in ESD
  standards.

  
  
  Abstract:Electrostatic Discharge,
ESD, in air can result in highly variable current waveforms in
both the discharge itself and in cables of equipment subjected
to ESD. Examples of some nasty current waveforms induced in
system cables are given and the implications discussed.




The link is: http://emcesd.com/#current_tidbit (this link will
always point to my latest Technical Tidibt

Sometimes email programs add a "[1]" at the end of the link above
which breaks it. If this happens just delete the [1] at the end to
make a valid web address.

Doug

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---
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 \  / )  P.O. Box 1457
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   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
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 \ _ /]\ _ / Website: http://www.dsmith.org
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Re: [PSES] Melting BNC connectors

[Doug Smith]

Hi John and the group,

There were no markings of any kind on the devices. I bought several from 
a surplus house here in Silicon Valley so the source is unknown. Easy 
problem to test for though, buy one first, heat it up, results obvious.


Doug

On 2/9/12 5:52 AM, John Woodgate wrote:
In message 
cafcezxnyxbsra+tug1lb0crgdn-vn7ew4oigzapx3a+woqk...@mail.gmail.com, 
dated Thu, 9 Feb 2012, N.Shani nshani...@gmail.com writes:


Doug, you could do all of us a great service if you mentioned what  
how the connector was marked, or where it was sourced.
We all take short cuts every so often, so a Buyer Beware with a bit 
more details will be appreciated.


I don't see any great problem in the use of pewter or similar as the 
body of a connector for indoor use. Pewter just goes dull on exposure 
to the air; it does not normally corrode, although alkalis should be 
avoided. In any case, I expect the connector would be nickel-plated.


I didn't find any resistivity data, but tin is about 7 times the 
resistance of copper. However, the current density in connector bodies 
is usually very low.


--
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
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[PSES] Melting BNC connectors

[Doug Smith]

  
  
Hi Everyone,

I have been traveling and am a few days late on my latest Technical
Tidbit. Here are the details:

Technical Tidbit - February 2012
The Melted BNC Adapter

  

This month's Technical Tidbit
describes an unusual side effect of trying to use
inexpensive BNC hardware.
  


Abstract:I often solder wires or
  components to BNC hardware to make voltage probes and magnetic
  loop probes. The process usually goes smoothly, except this time.
  Who would have guessed that the metal portion of BNC hardware
  could melt from the heat of soldering!
  
  The link to the article is:
http://emcesd.com/tt2012/tt020812.htm

If you see a "[1]" at the end of the above link placed there by
software not resident on my computer, you must remove it from
the link for the link to work. Alternately you can copy the link
without the [1] into a browser.
  
  This spring, I will be moving from Los
Gatos, CA to Boulder City, NV and setting my office up there as
well as my residence (phone and Internet lines are being
installed next week in the office). If you want to see what I am
up to there, go to http://emcesd.com (near the top of the page)
where I have posted pictures and information. Feel free to come
for a visit and see the Lake Mead National Recreation Area! I
will give you a personal tour.

Doug
-- 
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
|  q-( )  |  o  |Email:   d...@dsmith.org
 \ _ /]\ _ / Website: http://www.dsmith.org
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[PSES] fused plugs or short cords

[Doug Smith]

Hi Everyone,

I am looking for fused plugs (sort of like the ones used in the UK, but 
for the US) or a short (one foot) extension with a fuse in it. I would 
like for it to use standard fuses and will likely fuse at about 4 
Amperes. Does anyone know of a source? Many years ago I used to use 
Elmenco fused plugs on my ham radio gear, but now need a three prong 
version with the fuse only on the hot side for a commercial application 
(would like a few for myself also).


A version that would plug into an outlet and the provide a fused socket 
to provide power would be ideal.


I have looked on Google and have not been able to come up with anything 
good. The closest I have come is a fused two prong plug for Christmas 
tree lights. Close, but not three prong.


Doug

--
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
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 \ _ /]\ _ / Website: http://www.dsmith.org
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Re: [PSES] fused plugs or short cords

[Doug Smith]

Hi Brian,

Thanks for the information, but I need a UL certified device. If I build 
it, I will be responsible for it, also the time required to build would 
make the device fairly expensive.


Doug

On 1/26/12 10:52 AM, Brian Oconnell wrote:

Build with Bussman HEB series in-line fuse-holder.

Tumbler, Quail and others have NEMA 5-15 plug with fuse-holder -  not good.

Brian

-Original Message-
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Doug
Smith
Sent: Thursday, January 26, 2012 10:30 AM
To: emc-pstc
Subject: fused plugs or short cords

Hi Everyone,

I am looking for fused plugs (sort of like the ones used in the UK, but
for the US) or a short (one foot) extension with a fuse in it. I would
like for it to use standard fuses and will likely fuse at about 4
Amperes. Does anyone know of a source? Many years ago I used to use
Elmenco fused plugs on my ham radio gear, but now need a three prong
version with the fuse only on the hot side for a commercial application
(would like a few for myself also).

A version that would plug into an outlet and the provide a fused socket
to provide power would be ideal.

I have looked on Google and have not been able to come up with anything
good. The closest I have come is a fused two prong plug for Christmas
tree lights. Close, but not three prong.

Doug





--
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
|  q-( )  |  o  |Email:   d...@dsmith.org
 \ _ /]\ _ / Website: http://www.dsmith.org
---

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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:
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Attachments are not permitted but the IEEE PSES Online Communities site at 
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Re: [PSES] Goodbye

[Doug Smith]

  
  
Hi Ed,

Best wishes from this end for you and your family. We will miss your
posts.

I am one of those that will likely keep doing engineering stuff
until I drop. Been doing this since age 10 for 54 years now. I
figure another 30 or 40 years to go, if my wife can put up with
solder blobs on the rug and such.

Doug


On 1/3/12 8:46 AM, Price, Edward wrote:

  
  
  
  
This is
  just a short note to let all my friends on the EMC-PSTC
  list know that I am retiring, effective 3 January 2012.
  Yes, I finally made my decision, and soon Ill be no more
  than a puff of smoke on the horizon.

It may
  sound overly sentimental, but the people on the EMC-PSTC
  list have helped to make my efforts a bit easier on so
  many occasions, and I will remember so many of you.

By the time
  you read this, my Cubic mail account will likely be
  closed, so if you would like to reach me, use my edpr...@cox.net
  address (I also subscribed my home address to the list). I
  will probably be taking a little vacation from EMC for a
  while, but I doubt I can ever leave it completely, so Ill
  still be available for free advice and maybe a project or
  two.

Thanks for
  a great 15 years of intriguing questions, provocative
  assertions, good advice, and even a few laughs about our
  shared conditions!



  Ed Price
  ed.pr...@cubic.com
WB6WSN
  NARTE
Certified EMC Engineer
  Electromagnetic
Compatibility Lab
  Cubic Defense
Applications
  San Diego,
CA USA
  858-505-2780

Military  Avionics EMC Is
Our Specialty

  
  -
  
  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://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
  
  For help, send mail to the list administrators:
Scott Douglas emcp...@radiusnorth.net
Mike Cantwell mcantw...@ieee.org
  
  For policy questions, send mail to:
Jim Bacher j.bac...@ieee.org
David Heald dhe...@gmail.com
  


-- 
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
|  q-( )  |  o  |Email:   d...@dsmith.org
 \ _ /]\ _ / Website: http://www.dsmith.org
---

  

-

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://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
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Mike Cantwell mcantw...@ieee.org

For policy questions, send mail to:
Jim Bacher  j.bac...@ieee.org
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Re: [PSES] Goodbye

[Doug Smith]

Hi Brian,

I try to keep it hidden from her.

Doug

On 1/3/12 12:46 PM, Brian Oconnell wrote:

Ed
Beware of retirement 'creep' - typically originates from spouse. Stay well.


Doug
The wife allows a soldering iron in the house? I am impressed.


Brian

-Original Message-
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Doug Smith
Sent: Tuesday, January 03, 2012 12:14 PM
To: Price, Edward
Cc: emc-p...@ieee.org
Subject: Re: Goodbye

Hi Ed,

Best wishes from this end for you and your family. We will miss your posts.

I am one of those that will likely keep doing engineering stuff until I
drop. Been doing this since age 10 for 54 years now. I figure another 30 or
40 years to go, if my wife can put up with solder blobs on the rug and such.

Doug

On 1/3/12 8:46 AM, Price, Edward wrote:
This is just a short note to let all my friends on the EMC-PSTC list know
that I am retiring, effective 3 January 2012. Yes, I finally made my
decision, and soon I’ll be no more than a puff of smoke on the horizon.

It may sound overly sentimental, but the people on the EMC-PSTC list have
helped to make my efforts a bit easier on so many occasions, and I will
remember so many of you.

By the time you read this, my Cubic mail account will likely be closed, so
if you would like to reach me, use my edpr...@cox.net address (I also
subscribed my home address to the list). I will probably be taking a little
vacation from EMC for a while, but I doubt I can ever leave it completely,
so I’ll still be available for free advice and maybe a project or two.

Thanks for a great 15 years of intriguing questions, provocative assertions,
good advice, and even a few laughs about our shared conditions!


Ed Price
ed.pr...@cubic.com WB6WSN
NARTE Certified EMC Engineer
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA  USA
858-505-2780
Military  Avionics EMC Is Our Specialty

-

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 toemc-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://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglasemcp...@radiusnorth.net
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David Heald:dhe...@gmail.com



--
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
|  q-( )  |  o  |Email:   d...@dsmith.org
 \ _ /]\ _ / Website: http://www.dsmith.org
---

-

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://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas emcp...@radiusnorth.net
Mike Cantwell mcantw...@ieee.org

For policy questions, send mail to:
Jim Bacher:  j.bac...@ieee.org
David Heald: dhe...@gmail.com

[PSES] Common mode current measurements - a powerful troubleshooting technique

[Doug Smith]

  
  
Hi Everyone,

Just finished up my first Technical Tidbit article for the new year,
discussing common mode current measurements. Here are the details:


Technical
  Tidbit - January 2012
  Measuring Common Mode Currents
to Troubleshoot EMC Problems
  

  
  This month's Technical
  Tidbit describes why common mode current measurements are
  a powerful troubleshooting tool for the development lab.

  
  
  Abstract:EMC testing usually
comes at the end of project development. And when the equipment
fails one of the tests, everything usually grinds to a halt.
Often this results in engineers trying to diagnose the problem
at the EMC test lab. Unless one is lucky, this generally does
not produce the desired results. Use of common mode current
measurements on cables is described and shown to be a powerful
method to debug EMC problems as part of an EMC troubleshooting
toolkit.



The link to the article is: http://emcesd.com/tt2012/tt010212.htm

Separately, I am planning a move to Boulder City, NV in the coming
months. My office will be located in the historic Boulder City Dam
Hotel and Museum. If you would like to see some pictures of the
area, use these links:


For pictures of Boulder City, NV click here
For information on Boulder City, NV click
  here
For information on the Boulder City Dam Hotel and Museum, the
location of my new office, click
  here

Doug
-- 
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
|  q-( )  |  o  |Email:   d...@dsmith.org
 \ _ /]\ _ / Website: http://www.dsmith.org
---

  

-

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:
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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.


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