Re: [PSES] Using a TDR for Shielding Effectiveness measurements

[Macy]

I use a spectrum analyzer with tracking generator option.

You have to play with the impedances but any 'sensitive' frequency regions pop 
out. Then relate to what's likely to emanate.

--- charles.gra...@dish.com wrote:

From: "Grasso, Charles" 
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Using a TDR for Shielding Effectiveness measurements
Date: Thu, 19 Apr 2018 15:23:27 +

Hello all,

In lieu of using shielded chambers/spectrum analyzers and such, has anyone used 
a TDR for
performing shielding effectiveness measurements?  The simplicity is tempting - 
but I am
dubious about the dynamic range?

I have poked about in the usual place - but didn't find any definitive studies. 
(I suppose
that is a clue in and of itself!)

Thanks

Charles Grasso
(w) 303-706-5467


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Re: [PSES] Looking for writer for EMC Filters

[Macy]

Ken,

Circa 2010 while EMC consulting on VERY low noise circuitry, I did DETAILED 
analyses and redesign of various RFI/EMI filtering interconnections including 
chip bypasses. Perhaps, a rehash of those efforts would be of interest.

BACKGROUND:
Upon examining examples of recommended RFI/EMI cabling isolation and chip 
bypasses [Bypasses should be a high quality 3 terminal filter creating low 
impedance to GND from two terminals and high impedances to isolate between 
throughput terminals] I discovered that most of the recommended bypass 
circuitry and the recommended specific components actually were far less than 
ideal filters. There were resonances that in NO way satisfied that design 
requirement. Over certain spectral ranges, the filtering did NOT even look like 
it was present, often high impedance to GND and excessive throughput. All 
caused by the resonances. The increases in impedance often went from a desired 
0.3, or 0.03 ohms to GND to more than 20-100 ohms to GND. To me, that is NOT a 
bypass anymore. Even small current demands can develop some large signals. Of 
course, having such a loss of low impedances is not important *IF* there are no 
signals in those spectral regions. However, with component tolerances, it's not 
really possible to 'fix' the spectral region accurately. Impact? In Production 
the full range of component tolerances will guarantee that a large number of 
the products would NOT be able to perform as well as the desired spec (and the 
Engineering Prototype). ...Low noise was very important.

ANALYSES and DESIGN
After discovering the potential calamity, impact to the Product, we embarked on 
a TRUE Engineering Design effort to create almost ideal 3 terminal filters. 
That is, two terminals are shorts to GND and throughput is highly isolated. 
Noise from chips could not get into the power distribution. Noise on the power 
distribution could not get into the chips. Of course the power supply from each 
chip's point of view was an ideal battery [well almost]. We set Bandwidth from 
DC to 1GHz, and hopefully up through 2GHz. Using manufacturers' data sheets to 
REALLY determine each chip's demands and requirements, we were able to create a 
'spec' for each 3 terminal bypass filter. 

RESULTS
Using a wide range of free tools, LTspice, octave, and femm 4.2; we created 
models for readily available components and then could predict their 
performances in the circuit. This also required analyzing near 'worst case' 
component tolerances and chip requirements. More importantly, these efforts 
included the effects of the PCB stackup, and every 'non-ideal' PCB layout. All 
to ensure, the filter specs were met. Noise was minimized and the efforts 
enabled true Engineering to quantify, "when is enough, enough?" 

In addition, the effects of plane cuts were determined, Noise on the Analog GND 
planes was reduced to microvolt levels. Yes, cutting a GND plane is generally 
considered a no-no. However, correctly cutting a GND plane is very much like 
creating a 'proper' box for a system. When you get up into the 10GHz ranges, 
sometimes cut planes are better. One just has to learn how to do it properly.

CONCLUSION
It is fairly easy to make low noise design and RFI/EMI design an Engineering 
function. Not some rote set of rules somebody else describes and you follow 
HOPING all works out well. Full control, first pass compliance and meeting of 
specs, AND confidence that high percentage of Production Units perform as one 
would wish.

- Robert Macy, PE -

--- k...@emc-seminars.com wrote:

From: Ken Wyatt <k...@emc-seminars.com>
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Looking for writer for EMC Filters
Date: Mon, 26 Mar 2018 08:45:17 -0600

Hi All,

I’m still looking for a writer that is well-versed in EMC filter design that 
can produce a white paper for ITEM Media (paid gig). The topics are not yet 
defined, but I can send additional information later.

Please reply directly.

Thanks, 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


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Instruct

Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]

[Macy]

Accuracy within 1%, if measured outside the source loop by 3X, which is like 
'far field'

--- ken.ja...@emccompliance.com wrote:

From: Ken Javor 
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]
Date: Mon, 27 Feb 2017 13:36:12 -0600

It's valid in the absence of a magnetic material (relative permeability =
1).  The 51.5 dB factor is based on the far field.

Ken Javor
Phone: (256) 650-5261



> From: John Woodgate 
> Reply-To: John Woodgate 
> Date: Mon, 27 Feb 2017 18:07:27 -
> To: 
> Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General
> Use]
> 
> I doubt that, because it's valid at audio frequencies, which undoubtedly means
> 'near field'.
> 
> With best wishes DESIGN IT IN! OOO ­ Own Opinions Only
> www.jmwa.demon.co.uk J M Woodgate and Associates Rayleigh England
> 
> Sylvae in aeternum manent.
> 
> 
> -Original Message-
> From: Cortland Richmond [mailto:k...@earthlink.net]
> Sent: Monday, February 27, 2017 6:02 PM
> To: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General
> Use]
> 
> On 2/27/2017 12:23 PM, John Macaulay wrote:
>> The difference between dB(pT) and dB(µA/m) is 2 dB.
>> 
>> dB(pT) -2 = dB(µA/m)
> 
> This is
> 
> 
> true only in the Far Field.
> 

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[PSES] Is anyone working in "Ball Lightning"?

[Macy]

Anyone out there working in creating ball lightning? Interested in success and 
safety considerations.

  - Robert -

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Re: [PSES] Energy in certain items

[Macy]

Thanks to ALL who replied. Starting to meander off PSES topic. Just needed to 
compare to potential energy in 'ball lightning'

Is anybody in the group working in the area of generating ball lightning, as 
related to safety and success?

- Robert -

--- oconne...@tamuracorp.com wrote:

From: "Brian O'Connell" <oconne...@tamuracorp.com>
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Energy in certain items
Date: Mon, 22 Feb 2016 17:29:35 +

Actually ΔE ≈  Δmc2, but not relevant because energy (for ICE) is based on 
available molecular bond energy, so Sir Isaac’s kinetic models will prevail. 
Although probably relevant for a small percentage of photonic energy released 
during explosion or rapid combustion.



Brian



-Original Message-
From: Pawson, James [mailto:james.paw...@echostar.com]
Sent: Monday, February 22, 2016 1:17 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Energy in certain items



About 2.8x10^17 Joules for a gallon of petrol using E = mc^2

This is why I'm always disappointed by the mpg of my car

James





-Original Message-

From: Macy [mailto:m...@basicisp.net]

Sent: 19 February 2016 17:59

To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>

Subject: [PSES] Energy in certain items



Does anyone know the energy [joules] in a standard stick of dynamite, or a 
gallon of gasoline?

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[PSES] Energy in certain items

[Macy]

Does anyone know the energy [joules] in a standard stick of dynamite, or a 
gallon of gasoline?
 

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[PSES] Opening: Engineer/Technician Position in Arizona

[Macy]

PT/FT Electronic Engineer/Technician
REQUIRES: US Citizenship
LOCATION: New River, AZ, [adjacent to Anthem]
TIME: Nine month Project with potential of extension
PROJECT: Develop Advanced Eddy Current NonDestructive Instrumentation [NDI]

BACKGROUND: AJM Electronics was founded in Silicon Valley in 1974 to supply 
Engineering Exertise to clients developing Electronic Products for the 
Consumer, Industrial, Aerospace/Military, Medical, and Automotive Markets. 
During this Project, you will be working with/learning from a Stanford 
MSEE/Business Alumnus, registered Professional Engineer, developing NDI with 
capabilities not thought possible.

CIRCUITRY: OpAmps, Audio Frequency, Low Noise/Low Distortion/Magnetic 
Circuitry, Coils, Soundcard

SKILLS: First, setup/run a Lab, select/buy parts, and reconstruct BBD/debug. 
Familiar with electronic tools - scope, spectrum analyzer, use Soundcard, etc. 
Second, designing circuitry/system  Third, building/testing/verification

HUGE PLUSES: familiar with PC CAD Tools: LTspice, femm 4.2, octave [Matlab 
clone], OrCAD. familiar with technologies: DSP, FFT, Image Processing, C/C++ 
Real-Time/Data Acquisition/GUI

OPPORTUNITY: This Project requires well-rounded expertise and the ability to 
LEARN! You will explore basics of electronics that will expand and challenge 
your knowledge. To the right person, this can become a 'spin-off' company.

Contact: robert.a.m...@gmail.com

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Re: [PSES] Failure of Radiated emission

[Macy]

Wow! My experience a bit different. I've taken equipment to several test labs 
whose FCC data matches to better than 0.5 dB with the equipment generating data 
more than +/- 6dB!  and this was simple equipment that I set up using/following 
photographs. I attribute that wild range to 'impedances' of the radiating 
sources somehow interacting with the test lab's structures making the radiating 
sources more, or less, energetic and therefore different emanation values.

From memory, others have had similar experiences as discussed here.


--- kristiaan.carpent...@technicolor.com wrote:

From: Carpentier Kristiaan kristiaan.carpent...@technicolor.com
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Failure of Radiated emission
Date: Fri, 5 Sep 2014 15:35:16 +

Hi Doug,

Assuming both labs are qualified as you say, you also make the assumption that 
the 2nd lab has full knowledge about the setup of the EUT. And that's exactly 
the problem. That 2nd lab doesn't know and thus results may be different, even 
fail, due to the relative positions of the EUT and all its cabling, sending 
other kind of traffic, etc
If the 2nd lab has the report of the first, then results would be more or less 
the same.

Best regards,
Kris Carpentier

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Re: [PSES] Failure of Radiated emission

[Macy]

It is my understanding that what you say is correct. From memory, PROVING 
something complies is different than VERIFYING something complies. For example, 
as a customer, or a monitoring entity, when 'verifying'; you are allowed a 
single tone over the limit, because statistically that can just happen. BUT if 
you are PROVING compliance and using a single unit, you should have at least 
2.6dB margin to the limit. And testing 3 units, be less than the limit. Isn't 
that from the VDE standards years ago?



--- kristiaan.carpent...@technicolor.com wrote:

From: Carpentier Kristiaan kristiaan.carpent...@technicolor.com
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Failure of Radiated emission
Date: Fri, 5 Sep 2014 14:35:44 +

Hi group,

A ITE product is tested to EN55022 Radiated emission with a well defined setup 
(cables, traffic, etc...) trying to find the worst case emissions and it passes.
I think finding the real worst case emission for all frequencies with one and 
the same set-up is in practice not possible in practice.

That same product is retested by a customer or in case of market surveillance 
campaigns, then it is most likely not tested with the same set-up and results 
may fail.
Would this be an issue or is it acceptable that it is retested with the same 
set-up as the initial testing? I refer to CISPR22, clause 8.4 that states that 
the operational conditions of the EUT shall be determined acc. to typical 
use.The operat mode and rationale shall be stated in the report.

So to me it looks sufficient to test a typical set-up, do your best to not make 
it best case and describe everything in the report.

Any other thoughts?

Best regards,
Kris Carpentier

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Re: [PSES] DC Magnetic emissions.

[Macy]

try these people. They make a 12 digit magnetic field meter, YES 12 digits!

earth's field approx 50uT, 


Geometrics has been a world leader in the design and manufacture of geophysical 
instrumentation since 1968. 
  http://www.geometrics.com 

Geometrics  408 954 0522
2190 Fortune Drive  fax 408 954 0902
San Jose, CA  95131


--- sdd...@gmail.com wrote:

From: S Drysdale sdd...@gmail.com
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] DC Magnetic emissions.
Date: Sat, 24 May 2014 21:28:18 -0400

Good day all,

Is anyone here familiar with very sensitive DC magnetic emissions?  I am
particularly interested in performing measurements in the low mG range,
well below the value of the earths magnetic field.   I believe a 3 axis
helmholtz coil for earth field compensation and a sensitive DC milligauss
meter will be required.  Any specifications, methods, guidance documents,
equipment recommendations, or general advice would be greatly appreciated.

Best Regards,
Scott Drysdale
OOO - Own Opinions Only

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Re: [PSES] DC Magnetic emissions.

[Macy]

Helmholtz coils produce a field of approx 'uniform' to 1% over a volume of one 
third your coil's volume. In other words, a coil 2 meters by 1 meter height 
produces a uniform field about 30 cm cube. Or, is that 60 by 30 ?? can't 
remember now, but easy to check. Do you have femm 4.2? do an axisymmetric model 
and can find out.

It's pretty easy to measure 20nT variation within 50uT background, you may not 
need a bias. Use two sensors and subtract the two signals like differential 
probes on a scope where you're removing the common mode.


--- sdd...@gmail.com wrote:

From: S Drysdale sdd...@gmail.com
To: Macy m...@basicisp.net
Subject: Re: [PSES] DC Magnetic emissions.
Date: Sun, 25 May 2014 20:03:00 -0400

Hi Macy,

Much appreciated. It does help, and we'll look at pricing and leadtime.  I
think my main problem is going to be how to deal with the ambient
environment and how to properly use helmholtz to cancel the field.

Best Regards,
Scott Drysdale
OOO - Own Opinions Only




On Sun, May 25, 2014 at 9:08 AM, Macy m...@basicisp.net wrote:

 try these people. They make a 12 digit magnetic field meter, YES 12 digits!

 earth's field approx 50uT,


 Geometrics has been a world leader in the design and manufacture of
 geophysical instrumentation since 1968.
   http://www.geometrics.com

 Geometrics  408 954 0522
 2190 Fortune Drive  fax 408 954 0902
 San Jose, CA  95131


 --- sdd...@gmail.com wrote:

 From: S Drysdale sdd...@gmail.com
 To:   EMC-PSTC@LISTSERV.IEEE.ORG
 Subject: [PSES] DC Magnetic emissions.
 Date: Sat, 24 May 2014 21:28:18 -0400

 Good day all,

 Is anyone here familiar with very sensitive DC magnetic emissions?  I am
 particularly interested in performing measurements in the low mG range,
 well below the value of the earths magnetic field.   I believe a 3 axis
 helmholtz coil for earth field compensation and a sensitive DC milligauss
 meter will be required.  Any specifications, methods, guidance documents,
 equipment recommendations, or general advice would be greatly appreciated.

 Best Regards,
 Scott Drysdale
 OOO - Own Opinions Only


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Re: [PSES] Audio Frequency Induction Loop

[Macy]

Years ago, in Bay Area, CA [San Francisco's doctor's office located on 2nd 
floor, that's 1st floor to Brits] the high power AC lines that drooped by 
outside the second floor of a doctor's office were making 'wavy' patterns on 
all the monitors. It was a pronounced walking pattern moving up the screen, 
made you 'sea sick' after a while. You can imagine his complaining and trying 
to obtain mitigation from the utilities companies. 



--- j...@jmwa.demon.co.uk wrote:

From: John Woodgate j...@jmwa.demon.co.uk
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Audio Frequency Induction Loop
Date: Sat, 25 Jan 2014 14:35:55 +

In message 003f01cf19cf$d908f000$8b1ad000$@cox.net, dated Sat, 25 Jan 
2014, Ed Price edpr...@cox.net writes:

 On almost every field investigation I have done, the conventional 
wisdom has been wrong. That is, whatever everybody at the site claims 
the problem is, that?s almost never what it really turns out to be

Indeed; I had a case where an induction-loop system exhibited 
interference that sounded just like fluorescent lamp interference, but 
it wasn't. The amplifier design had a problem; the circuit board was 
getting induced currents from the magnetic field of the mains 
transformer.
-- 
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] Audio Frequency Induction Loop

[Macy]

Is there any mitigation of the magnetic fields due to the supply of current 
being split? For example, some current coming from one direction along the 
cable and some coming from the other? The reverse directions of the currents 
act a lot like twisted pair and cancel the fields a bit, at least near the 
train.

I don't know what values are in the spec you referenced, but standing within 10 
feet of the light rail in San Jose, CA as it passed, I rarely measured more 
field that 1-2uT down into the 5Hz bandwidth. Actually, I couldn't tell how 
much came from motor drive and how much came from deflection of earth's field, 
because gasoline powered large semi's going by produced a lot of change too.




--- andy.mccal...@mottmac.com wrote:

From: McCallum, Andy andy.mccal...@mottmac.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Audio Frequency Induction Loop
Date: Fri, 24 Jan 2014 14:25:55 +

Hi

Anyone aware of any interference from Trams (750V DC Overhead Catenary Systems, 
max current 1000A) on AFIL systems (EN  60118-4:2006). From my very basic 
calculation you need a significant separation distance (in excess of 25m). Any 
previous studies or examples would be most helpful.

Regards

Andy

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Re: [PSES] Puzzle

[Macy]

That's sounds like the battle I had to keep 'forbidden bands' in the 1GHz to 
10GHz range inside a METAL case!  NOTHING worked after the fact, short of 
copper tape around the whole thing, solidly. 

How 'stable' is that tone? You mentioned parasitic oscillation? Anyway to 
dither a clock and see which affects the tone.



--- lfresea...@aol.com wrote:

From: Derek Walton lfresea...@aol.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Puzzle
Date: Sat, 7 Dec 2013 10:27:35 -0500

Good day folks,


I'm faced with a challenge that's confusing me a bit, and I'm concerned I'm 
overlooking something.


I have a small box, about 4 by 6 by 2 that contains some Ethernet circuitry. 
Normally there are cables that come and go from this box.


During RE testing, there are several very strong emissions ( above 200 MHz ) 
that exceed all other noise made by the box. As yet, we have not been able to 
link them with any of the anticipated frequencies one would expect. In chasing 
the source down I have taken a number of steps which are:


1) Disconnect all cables except the power.  There was no change on the large 
spikes, other noise came down as anticipated.


2) Added several ferrites on the power cable. No change.


3) Added two feed through type caps at the power entry point. No change.


4) Wrapped the box completely in Aluminium foil. No change.


5) Checked Ambients... Nothing, quiet.


6) Replaced power source. No change.


7) Rotated box, very minor change in amplitude.


This box is a new version of an existing design that does not have the same 
issue and close field probing is very difficult inside the box. My suspicion is 
that a small daughter board is the source, but this cannot be removed from the 
box without destruction. A new box has been ordered build without that board. 
That may not arrive for a few weeks.


In the meantime, can anyone make suggestions about what may cause this noise, 
besides parasitic oscillations/faulty parts, and what radiating mechanisms can 
be uninfluenced with the protection measures I took.


Many thanks,


Derek Walton.
L F Research.





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Re: [PSES] Job Opening for EMC Engineer

[Macy]

Not sure what exactly you want to specialize in, inside EMC.

However here is my advice:
1. KNOW EVERY RULE
2. CHANGE MINDSET
3. MAKE CONTACTS
and these two are REALLY important:
4. BECOME A TEACHER
5. LEARN, LEARN, LEARN; EXPERIMENT = become a Hands On Expert

KNOW EVERY RULE! To me, an EMC Engineer is a walking encyclopedia resource. 
Knows applicable rules and testing requirements. Knows every applicable NRTL 
[multiple ones] along with prices/estimation of ANY compliance testing [and 
TIME to test] For example an EMC Engineer will know the answer to the question, 
What do we need in order to get such and such product sold in ?? Knows the 
labs to go to, how much to budget for testing cost, how much time, and how many 
number of units for testing. Will partner with Safety, because UL type labs 
destroy stuff. 

CHANGE MINDSET! Think in terms of 'executive' and NOT 'engineer' Do NOT be a 
'fireman'. Be pre-emptive! KNOW every product your firm IS developing and 
probably WILL be developing. Always 'nose around' because EMC is usually, and 
catastrophically, left to the end of the Product Development cycle. You NEVER 
want to face the demand, We're ready to go to Production, so fix it, but don't 
change anything! Plan, plan, plan! Make certain there are enough 
representative samples. Product managers usually assume the units made for 
'checking' Production will suffice NOT TRUE! Allocate units for TEST and SAVE 
them, store them [if volume of production allows] To be effective here one must 
be equally comfortable with Marketing, Manufacturing, Engineering, AND 
Financial Depts. Same level of respect as Legal, because compliance is a 
'legal' issue. Set parameters. For example Sony REQUIRES 8dB margin at the Test 
Lab! Not as easy as it sounds. HP used to set 6 dB [sigh, those were the days]

MAKE CONTACTS! You will need access to resources, services, and [sometimes] 
agency approval people. For expertise and advice go to the local IEEE EMC 
meetings [do not have to be an IEEE member to go]. Develop a list of Test Labs 
[especially people inside the labs] and use them to inform/confirm 
requirements. It is important to KNOW the people, and have them know you, in 
various countries, organizations, and agencies. Try to become a 
'representative' of your firm as rules are being made.

BECOME A TEACHER! Make EMC part of the Design cycle, not an obstacle to 
overcome AFTER the fact. It's always easier and cheaper to implement design 
impacts early in the process. That means giving some short tutorials, lessons, 
'rules-of-thumb', and most importantly, BASIC CONCEPTS of 'Designing for EMC' 
to Engineering, so when they are faced with a design trade-off they decide the 
'right' way. And, wedge into the schedule some DESIGN REVIEWS! If Engineering 
hides their designs something is wrong anyway. Be prepared to do design reviews 
informally, lunch conversations, small bit of 'show-and-tell' during a coffee 
break, or please brag about your design questions. You can do Design Review 
without slowing down the development process, but YOU MUST KEEP ON TOP OF IT! 

LEARN, LEARN, LEARN; EXPERIMENT  Experiment means to try things just to see the 
effect [develop EXPERIENCE]. An EMC Engineer is expected to know how to head 
off EMC problems and know how to solve EMC problems - especially within the 
real life constraint of necessary design trade-offs. Nothing helps more than a 
thorough knowledge of RF/Microwave, ESD/LIGHTNING, and Mechanical structures. 
Use any 'visualization' technique you can to be able to understand what's 
happening and how to convey that to others. Sources for learning: 
Instrumentation firms selling their wares - have them demo for you. Test Labs 
trying to sell test time explain in great detail how tests are performed. The 
aformentioned EMC meetings usually provide lectures. And, with the internet, 
this excellent group will answer anything.

I cannot stress enough the importance of learning why/how EMC works on a 'real' 
level. Every Engineer has design constraints and real-life physical constraints 
and it does not help to tell them simply do it this way when it is simply NOT 
possible. [I actually got some clients away from Mike King, in LA, because when 
his client failed EMC, he simply pragmatically responded with something along 
the line of You didn't do what I told you to. Actually, what Engineering 
really needs is an UNDERSTANDING of EMC, then when faced with a trade-off; THEY 
can decide the way that has the least negative impact. Everybody wins. So, 
learn AND teach.

Also, set up pre-testing site near your firm's Engineering location for you and 
the Engineers to see the effects of some of their decisions - real time. And 
prepare some short demos and seminars. All hands on with practical examples 
they can walk away with.

Regards,
Robert Macy, PE

AJM International Electronics
P O Box 74241
46007 N 38th Ave, Suite 100
New River, AZ  85087
tel: 480 466 0895
fax: 623 465 2974
  m

Re: [PSES] Spring Lab Cleaning

[Macy]

Don,

In your area is Priority Test Equipment:
Priority Test Equipment, Inc.   888 278 2230
700 Harvest Park Drive, Suite D
Brentwood, CA  94513
tel: 925-513-7300
fax: 925-513-7338
   http://www.prioritytest.com/

contact the owner
 Nanette Throne nthr...@prioritytest.com

They buy and sell, easy people to work with.

Regards,
Robert Macy, PE

AJM International Electronics
  [formerly in Silicon Valley]
P O Box 74241
46007 N 38th Ave, Suite 100
New River, AZ  85087
tel: 480 466 0895
fax: 623 465 2974
  m...@basicisp.net


--- dclay...@colfaxnet.com wrote:

From: DG Clayton dclay...@colfaxnet.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Spring Lab Cleaning
Date: Fri, 22 Mar 2013 10:59:47 -0700

Test Equipment For Sale:
ETS model 6502 active loop 10Hz-30mHz   $1500
ETS model 3301B active monopole 30Hz-50mHz  $1050   
ETS model 3825/2 LISN 25A 120/240   $1200
2KVA isolation transformer 240/480 to 120/250$600
The above test equipment offered at 1/3 current market price.

12'X16' copper screen room w/3 phase AC filters,
partial anechoic absorbers. Inquire

Don Clayton
ESR Engineering Inc.
1-530-273-8836
Located in Northern California

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[PSES] ELF

[Macy]

[Fourth attempt to get MY mail server to post to the group, so a lot of 
information has been removed.]

Need table that shows recommended limits up to 1MHz. 

No interest in electric fields. 

Anybody have such a table? or URL that shows such a table? 

Regards,
Robert

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Re: [PSES] ELF

[Macy]

Cortland,

Thank you for the URL AND the excerpt.

Not good news, wanted to have 100uT, not 2uT  

I sure remember years ago seeing something like 2mT, especially at AC mains 
frequency was allowed. Utilities companies pushed for that because the parks 
and playgrounds under the power lines were a bit 'hot'


--- k...@earthlink.net wrote:

From: Cortland Richmond k...@earthlink.net
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ELF
Date: Sat, 7 Jul 2012 13:33:06 -0400

Try FCC OET 65: 
http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet65/oet65.pdf

However, (excerpted)

Radio frequency (RF) spectrum
Although the RF spectrum is formally defined in terms of frequency as 
extending from 0 to 3000 GHz, for purposes of the FCC's exposure 
guidelines, the
frequency range of interest in 300 kHz to 100 GHz._
_

also

/
/

(B)Limits for General Population/Uncontrolled Exposure

__

Frequency Electric Field Magnetic Field Power Density Averaging Time

Range Strength(E) Strength(H) [E^2 ], [H^2 ] or S

(MHz)(V/m)(A/m) (mW/cm^2 ) (minutes)

__

0.3-1.34614 1.63 (100)* 30

1.34-30 824/f 2.19/f(180/f2)*30

30-300 27.5 0.073 0.2 30

300-1500-- -- f/1500 30

1500-100,000 -- -- 1.0 30

__

f = frequency in MHz *Plane-wave equivalent power density



Cortland Richmond /
/
On 7/7/2012 1215, Macy wrote:
 [Fourth attempt to get MY mail server to post to the group, so a lot of 
 information has been removed.]

 Need table that shows recommended limits up to 1MHz.

 No interest in electric fields.

 Anybody have such a table? or URL that shows such a table?

 Regards,
 Robert




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Re: [PSES] Magnetic noise level around 10 kHz

[Macy]

John,

Somewhere around here I have a plot of background noise in a 'new' electronic 
lab, the type with metal conduits.

The fields were 'specular' flat out to around 2kHz then rolled off and down 
until you could see the specular tones of the horizontal flyback from the old 
PC Monitors sitting around the lab and in the other rooms.

The AC mains started in the range of 10nT although I've seen as high as 300nT, 
but whatever it starts at the harmonics roll down starting around 2kHz as 
though there's a single RC filter on the line. The tones at 15kHz coming from 
the old PC monitors are pretty energetic and there harmoniccs are constant out 
to around 3rd and 5th harmonics.

The reason I mention specular, is because bandwidth won't change peak reading 
much.  only broadband noise, like white noise is changed by the BW setting.

I'll see if I can find the plot, it is VERY representative.

uh, the A/m is of course, 
at 50/60Hz, B/uo = 10nT/(4 pi 1e-7) or about 78 dBuA/m

assume the roll off at 2kHz, by 20kHz that should be 40 dB down, until the 
flyback F

we're talking around 38 dBuA/m up to some maximum of 68 dBuA/m for our lab, 
which used knob and tubes in a wood building. 

I'll look for the plot

Regards,
Robert

--- j...@jmwa.demon.co.uk wrote:

From: John Woodgate j...@jmwa.demon.co.uk
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Magnetic noise level around 10 kHz
Date: Fri, 6 Jul 2012 21:47:15 +0100

If you measured the background magnetic noise level in dBμA in a 
typical office at around 15 kHz, using an RBW of 300 Hz and a VBW of 1 
kHz, what would be a typical result? Measurements at 3 kHz and every 3 
kHz up to 24 kHz would be helpful but not essential.

A result using a Schwartz beck FMB 1538 magnetic antenna would be 
particularly pertinent. I have an ill-informed agitator to combat.
-- 
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
Instead of saying that the government is doing too little, too late or too
much, too early, say they've got is exactly right, thus throwing them into
total confusion.
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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[PSES] test message MYBasicISP.net mailserver

[Macy]

test to determine if the mail server sends to IEEE group

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Re: [PSES] Acoustic Noise Glossary

[Macy]

Thank, Ed. Provided quite a chuckle here.

Not EVEN going to comment on some entries.


--- edpr...@cox.net wrote:

From: Ed Price edpr...@cox.net
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Acoustic Noise Glossary
Date: Thu, 28 Jun 2012 14:58:31 -0700

...snip...

Wind Noise

Any noise caused by air movement in, out or around the vehicle.

 

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[PSES] FWD: Question about unlicensed bands in Korea

[Macy]

Found this question posted on the Usenet group, sci.electronics.design, and 
thought someone here could answer best.

Regards,
Robert


=-=-=
From: fasf
Date: Jun 4, 3:58 am 

Hi, 
i have a wireless product made for european market at 868MHz. I want 
to show this product in a korean exibition: i can use it or not? If 
not, what are the unlicensed bands that can be used? 
Thanks

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Re: [PSES] Statute of limitations

[Macy]

Common sense and confirmation from following this thread it is clear that as 
components 'improve' and change there is great likelihood of upper tones 
creeping up, possibly out of compliance on marginal products.

What is NOT clear is whether knowing that is likely MUST a retest be done.

Would RETEST be required as 'due diligence', or maintenance of CB, or instead, 
as the client desires, simply 'ostrich' it?  

As with most expenditures for EMC issues, need to point to the legaleze that 
requires it.

Regards,
Robert Macy, PE

AJM International Electronics
  [formerly in Silicon Valley]
P O Box 74241
46007 N 38th Ave, Suite 100
New River, AZ  85087
tel: 480 466 0895
fax: 623 465 2974
  m...@basicisp.net


--- g.grem...@cetest.nl wrote:

From: ce-test, qualified testing bv - Gert Gremmen  
g.grem...@cetest.nl
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Statute of limitations
Date: Tue, 29 May 2012 20:20:39 +0200

Where this happens even more  frequently is in switching FETin SMPS-es. 

Modular plug-in, OEM or self designed,  chances are good that the FETS
you buy today are MUCH faster than their equivalent (or even same type)
a few years ago. Expect harmonics to 200 MHz, where an upper limit of 30
MHz was common.

 

Gert Gremmen

 

Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Ted Eckert
Verzonden: dinsdag 29 mei 2012 19:39
Aan: EMC-PSTC@LISTSERV.IEEE.ORG
Onderwerp: RE: Statute of limitations

 

I've had a number of cases where an IC vendor did a die shrink on an IC
without rescaling the pin drivers. Even though the IC ran at the same
speeds, the edges were much sharper leading to problems at higher
harmonics. I would suspect that a number of ICs in your system have
undergone die shrinks. The IC vendors are always looking for ways to get
more chips out of a single wafer.

 

Ted Eckert

Compliance Engineer

Microsoft Corporation

ted.eck...@microsoft.com

 

The opinions expressed are my own and do not necessarily reflect those
of my employer.

 

From: McInturff, Gary [mailto:gary.mcintu...@esterline.com] 
Sent: Tuesday, May 29, 2012 10:16 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Statute of limitations

 

Is there any time limit on how long a test result is valid for an EMC
test - if the product hasn't changed. CB reports have a 3 year shelf
life, after which the various CB participants are obligated to take the
reports on face value and could require inspection or retest, but I
don't know if the same is true for EMC test when meeting the EU
directives. Actually I guess the requirement for a CB update every three
years isn't truly a requirement for meeting the directives either. The
CB report is a tool to help show conformity.

 

Bottom line the last EMC test was in 2004, and the clock speeds are
pretty low - 12 MHz, so I don't think even the new upper frequency test
range requirements of EN55022 affect the results. 

I'm inclined to test, the customer is not. 

 

Gary McInturff

Reliability/Compliance Engineer

 

 

 

 

Esterline Interface Technologies

Featuring

ADVANCED INPUT, MEMTRON, and LRE MEDICAL products

 

600 W. Wilbur Avenue

Coeur d'Alene, ID  83815-9496

Office:208-635-8306

Cell:  509 868 2279

Toll Free: 800-444-5923 X 1238

gary.mcintu...@esterline.com mailto:brian.s...@esterline.com 

 

 

www.esterline.com/interfacetechnologies
http://www.esterline.com/advancedinput 

 

Technology, Innovation, Performance...

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Re: [PSES] Current probe article published

[Macy]

Nice.

Anyway to get a pdf version?

--- k...@emc-seminars.com wrote:

From: Ken Wyatt k...@emc-seminars.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Current probe article published
Date: Mon, 14 May 2012 09:13:55 -0600

Hi All,

I recently published an article on current probes for Interference Technology 
(March 2012, 2012 EMC Directory  Design Guide) that describes how they work, 
how to use them to troubleshoot common-mode emissions from cables and how to 
make your own DIY probe. I also compare the performance of various DIY probes 
with a well-known commercial probe.

http://www.interferencetechnology.com/the-hf-current-probe-theory-and-application/

Cheers, Ken
___
Kenneth Wyatt
Wyatt Technical Services LLC
Woodland Park, CO
Email Me! | Web Site | Blog
Subscribe to Newsletter
Connect with me on LinkedIn


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Re: [PSES] Slip Rings and EMI

[Macy]

EMI considerations: emanations relate to amount of energy available, little 
energy = little emanations
1. voltage surges are usually 'shielded' by metal structures, including the 
slip ring.
2. current surges are related to the amount of current being carried and area 
of the loop. Small amount of current in combination with small loop area = 
little emanations.
3. spectral content - pretty low frequency, in my experience the rise and fall 
times of mechanical contacts making and breaking are extremely slow, in the 
audio range. which translates to...
* Radiated Emissions above 30MHz is unlikely 
* Conducted Emissions in the 10kHz to 30MHz range is possible being caused by 
capacitive coupling of voltage or inductive coupling of CURRENT [the most 
likely transfer path]. Easy to mitigate with twisted pairs and reduced loops 
[both source loop *and* receive loop], lowered power, and proximity [move away 
from each other].

Forgot to add, assume this is in atmosphere, changes if in vacuum.

Regards,
Robert


--- david.car...@plexus.com wrote:

From: David Carney (Neenah) david.car...@plexus.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Slip Rings and EMI
Date: Thu, 3 May 2012 12:18:48 -0500

We're considering a slip ring in a design to pass some wires through a
rotating motor shaft, and we have never used one before.  Are there any
EMI concerns with this architecture?  If there are concerns, what types
of mitigations are used for EMI when slip rings are used?  If slip rings
are to be avoided for certain types of signals due to EMI concerns, what
other alternatives should we consider?

Thanks.

David T. Carney P.E. (WI)
Senior Design Engineer
Plexus Engineering Solutions
Neenah Design Center
920.751.5646

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Re: [PSES] SAR - MPE

[Macy]

I used femm 4.2 and Hershey MC models to predict results of SAR testing and got 
better than 5% accuracy when compared to measurements on beef fat slabs from a 
local butcher. Just remember PSpice, LTspice, and femm ALL use peak voltage so 
must use sqrt(2)* Vrms value, else be off by 2:1 in power calculations.  The 
wrong direction.

Interesting question, whether the SAR rms value is independent of frequency. 
The models suggest you can calculate each and simply add the power. I do not 
remember any non-linearity coefficients in them, simply ables of conductivity 
vs freq etc.  But considering the perversity of nature and the conductivity 
being frequency dependent, you may find you get more heat than expected.  


I believe this company sells SAR predicting software, or will do it for you: 
notes from telco with Chad:
10/7/08  888 773 6266 x285  Chad  10:20  use SAR Models from Hershey Medical 
Center they contain characteristics of tissue versus frequency  

Remcom  1-888-773-6266
315 South Allen Street, Suite 222
State College, PA 16801 
 Tel: 814-861-1299 
 1-888-773-6266 (1-888-7REMCOM) Toll-Free in U.S. and Canada 
 Fax: 814-861-1308 
 1-888-973-6266 (1-888-9REMCOM) Toll-Free in U.S. and Canada 
  http://www.remcom.com


Good luck
Regards,
Robert


--- rehel...@mmm.com wrote:

From: Robert Heller rehel...@mmm.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] SAR - MPE
Date: Mon, 9 Apr 2012 11:13:32 -0500

Anyone familiar with SAR and MPE testing? 

If equipment passes SAR can you assume that it passes MPE?

Can simultaneous transmissions at two different frequencies be tested or 
is it calculated? Is the heating effect additive?

Thanks,
Bob Heller
3M Company, 76-1-01
St. Paul, MN 55107-1208
Tel: 651-778-6336
Fax: 651-778-6252


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[PSES] Fwd List of Test Equipment for Sale

[Macy]

Ladies/Gentlemen:

I am not associated with this firm, nor benefit from any sales they may make.
I have worked with this firm before and appreciated their Quality of Products 
and Professionalism at supplying Test Equipment.

I thought someone in this group may benefit from new contact and from the Test 
Equipment they are offering.

Regards,
Robert


The following email is TEXT only:
=-=-=
From:   Jennifer DuMond jdum...@prioritytest.com 
To: 'undisclosed recipients' nthr...@prioritytest.com
Subject:Priority Test - March Check In!
Date:   Mon 03/12/12 06:22 PM

Hi - 

How are you?

Are you looking to buy (refurbished), rent, sale or repair any test equipment 
today?

Remember -  We specialize in refurbished Agilent, Tektronix, Fluke, RS, 
Instek, SRS, SmartBits, (plus an additional 400 manufacturers) for electronic 
test equipment such as oscilloscopes, power supplies, spectrum and network 
analyzers, probes, amplifiers, electronic loads, accessories plus much more.

We  have the following items FOR SALE (manual and power cord included only - 
calibration extra):

TEK TDS694C - 3GHz/4 channel - 10 GS/s digital oscilloscope - $5995
ANR MG3633A - 10kHz-2700MHz Synthesized Signal Generator - $3795
EIP 578 - 26.5 GHz Frequency Counter - $3995
AT/HP 3325B - Synthesizer/Function Generator - $795
AT/HP 3458A - Multimeter w/cal certificate - $5995 w/cal cert
AT/HP 437B - RF Power Meter - $200/ea
AT/HP 438A - 50 MHz power meter - $250/ea
AT 85033D - Calibration Kit 3.5MM - $2795
SmartBits 6000B - 20 module mainframe - $2495
TEK VM700A - Video Measurement Test Set - $1495
Chroma 6314 w/63103 - Load with 1 module - $1995

Happy upcoming St. Patrick’s Day!  

Remember to give us a call or email when you need to buy, rent or repair test 
equipment  – We’re happy to help!

Thanks again and have a great day!  

Nanette  Jennifer  Chelsea

Nanette Throne
Account Manager
Priority Test Equipment   
925-513-7300 ofc  
925-513-7338fax   
925-759-1093 mobile
nthr...@prioritytest.com
www.prioritytest.com

Jennifer DuMond
Inside Sales Representative
Western  Northern United States
jdum...@prioritytest.com

Chelsea Alayne
Inside Sales Representative
Eastern  Southern United States
cala...@prioritytest.com
=-=-= 

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Re: [PSES] Notified Body Opinion vs. Harmonised Standards (RTTED)

[Macy]

--- micha...@acbcert.com wrote:

From: Michael Derby micha...@acbcert.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Notified Body Opinion vs. Harmonised Standards (RTTED)
Date: Thu, 8 Mar 2012 14:44:30 +

...snip...

Even if you meet all the harmonised standards tests…. If your device causes a 
problem in the real world, you’ll need to work to fix it.

...snip...

Michael,

Would you clarify. 

When does the responsibility for a product's susceptibility fall back onto THAT 
Product's manufacturer?

Especially when the only way to stop bothering the 'poorly made' product is to 
NOT operate your 'well made' product?

Regards,

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Re: [PSES] Inductive Chargers

[Macy]

We had to pursue SAR calculations/tests.

from 2008, source of good information
Remcom  1-888-773-6266
315 South Allen Street, Suite 222
State College, PA 16801 
 Tel: 814-861-1299 
 1-888-773-6266 (1-888-7REMCOM) Toll-Free in U.S. and Canada 
 Fax: 814-861-1308 
 1-888-973-6266 (1-888-9REMCOM) Toll-Free in U.S. and Canada 
  http://www.remcom.com


use SAR Models from Hershey Medical Center they contain characteristics of 
tissue versus frequency


--- steve.ost...@acstestlab.com wrote:

From: Steve O'Steen steve.ost...@acstestlab.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Inductive Chargers
Date: Tue, 6 Mar 2012 09:10:34 -0500

I'm considering the compliance path for several devices, one of which is
an inductive charger.  I've located one publication off of the KDB
website, Pub # 680106, which defines when and how either Part 15 or 18
are used.  What about the rest of the world?  As far as CE mark, my
first inclination was EN 301 489-1 and -3 for the EMC portion of the
RTTE Directive but, I'm not sure which radio standard would apply.  The
KDB publication also mentions the possible need for an RF exposure
evaluation.  Would there be an equivalent requirement for CE marking?

Another product I'm looking into is similar to an inductive charging
system but, instead of a charging function this system uses the lower
frequency transmission to power another device in the system to perform
a specific function.  Although both of these systems use very similar
transmission techniques and occupy a similar band the overall function
is different.  Would this affect the compliance path between these two
systems?

Any input would be appreciated.

 

Regards, 

 

Steve O'Steen

EMC Director

Advanced Compliance Solutions, Inc.

sost...@acstestlab.com

770-831-8048 ext. 210

www.acstestlab.com http://www.acstestlab.com/ 

 

ATLANTA, GA   -   MELBOURNE, FL   -   BOCA RATON, FL

 

CONFIDENTIAL  

This e-mail and any attachments may contain information which is
confidential, proprietary, privileged or otherwise protected by law. The
information is solely intended for the named addressee (or a person
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Re: [PSES] Melting BNC connectors

[Macy]

Doug,

Next you'll tell us the component was radioactive, made of some 'surplus' 
material. Like all that gold jewelry that found itself on the market way back 
when.

--- d...@emcesd.com wrote:

From: Doug Smith d...@emcesd.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Melting BNC connectors
Date: Thu, 9 Feb 2012 19:42:14 -0800

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
|  q-( )  |  o  |Email:   d...@dsmith.org
  \ _ /]\ _ / Website: http://www.dsmith.org
---

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Re: [PSES] Wireless Chargers

[Macy]

... and RF Exposure requirements. include SAR calculation/testing processes?

--- bstu...@dlsemc.com wrote:

From: Bill Stumpf bstu...@dlsemc.com
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Wireless Chargers
Date: Fri, 2 Dec 2011 15:46:07 +

For FCC compliance refer to FCC KDB 680106: 
http://gullfoss2.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm?switch=Pid=41701
Compliance should consider Part 15, Part 18 and RF Exposure requirements.

EU requirements are similar. Simply stated, if the device communicates 
wirelessly the RTTE Directive applies. If no wireless communication is 
present, the EMC Directive applies.  In all cases EMF must be considered as 
part of the compliance plan.

Bill Stumpf
D.L.S. Electronic Systems, Inc.
166 South Carter Street
Genoa City WI 53128
Ph: 262-279-0210
Email: bstu...@dlsemc.com


From: Moshe Henig [mailto:moshe.he...@gmail.com]
Sent: Tuesday, November 29, 2011 4:32 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Wireless Chargers

Dear group.


I am looking for

1.   FCC cerification requirement for Wireless Chargers.
2.  EU requirement for Wireless Chargers.
Regards

Moshe

*
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Re: EN60601-1 Susceptibility to magnetic fields from AC mains

[macy]

Brodie,

Thank you very much for your informative reply.

3 A/m translates to 3.8 microTeslas, correct?
10 A/m would then be 12.6 uT

That is indeed benign.  For some reason 2 mT had stuck in
my mind and that would have been hard to deal with,
requiring a block diagram change during prototype design
phase.

Thank you again.  Your answer has allowed me to jump ahead
on the Project as we wait for Purchasing to complete the
spec purchases.  

Regards,
Robert


On Mon, 1 Dec 2008 14:59:16 -0600
 Brodie Pedersen brod...@nonin.com wrote:
 EN 60601-1 points to IEC 60601-1-2 for EMC test
 requirements.  If you
 are making a device for Europe the frequency required at
 3 A/m is 50 Hz.
 If you want to sell the device in the US it is at 60Hz as
 well following
 the method of IEC 61000-4-8, power frequency magnetic
 fields.  If the
 device is life supporting, then the test level is 10 A/m.
  These are
 very benign levels to pass unless you have a hall effect
 sensor built
 into your device.  
 
 Brodie Pedersen Quality Manager Product Development
 Nonin Medical Inc.
 
 
 -Original Message-
 From: m...@california.com [mailto:m...@california.com] 
 Sent: Monday, December 01, 2008 2:53 PM
 To: John Woodgate; emc-p...@ieee.org
 Subject: Re: EN60601-1 Susceptibility to magnetic fields
 from AC mains
 
 Going to, but need to design NOW, or at least make
 certain
 I'm not painted into a corner later.
 
 
 On Mon, 1 Dec 2008 19:35:37 +
  John Woodgate j...@jmwa.demon.co.uk wrote:
  In message web-197812...@california.com, dated Mon, 1
  Dec 2008, m...@california.com writes:
  
  
  What is the requirement for susceptibility to magnetic
  fields from the AC mains as listed in EN60601-1?
  
  It's really dangerous to rely on answers to such
  questions, even from this erudite community. We can't
  tell you everything that the standard says, and we
 don't
  know what is relevant for your product. You DO need to
  buy the standard and study it.
  -- 
  OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and
  www.isce.org.uk
  Either we are causing global warming, in which case we
  may be able to stop it,
  or natural variation is causing it, and we probably
 can't
  stop it. You choose!
  John Woodgate, J M Woodgate and Associates, Rayleigh,
  Essex UK
  
  -
 


  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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 -


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David Heald: 

Re: EN60601-1 Susceptibility to magnetic fields from AC mains

[macy]

Pat,

Thank you for that 'heads up'.
400 A/m is still around 1/2 mT, not the 2 mT I remember.  

Interesting reference will now appear in the 'design'
documentation ...reference spec: 'internet' 

I'm just trying to make certain that when the documents are
all here and we review my design versus specs, I won't have
to start over.  So far all is ok.

Thanks again.  

Regards,
Robert

On Tue, 2 Dec 2008 08:57:54 -0800
 pat.law...@slpower.com wrote:
 Hi Robert,
 
 3 A/m is indeed the test level called out in IEC
 60601-1-2, the standard 
 used for general medical EMC testing.
 
 However, there are many other medical safety standards in
 the IEC 
 60601-2-* series which may have different test levels.
  My favorite is IEC 
 60601-2-24:1998, which calls out a test level of 400 A/m
 !   (Note -- I 
 haven't performed that test, and have no equipment or
 setup 
 recommendations.)
 
 So long as you put in your product spec 'Reference
 specification for 
 power-frequency magnetic field testing: The Internet', I
 think you're 
 covered.   ; )
 
 Pat Lawler
 EMC Engineer
 SL Power Electronics Corp.
 
 emc-p...@ieee.org wrote on 12/01/2008 11:14:27 PM:
  Brodie,
  Thank you very much for your informative reply.
  3 A/m translates to 3.8 microTeslas, correct?
  10 A/m would then be 12.6 uT
 
  That is indeed benign.  For some reason 2 mT had stuck
 in
  my mind and that would have been hard to deal with,
  requiring a block diagram change during prototype
 design
  phase.
 
  Thank you again.  Your answer has allowed me to jump
 ahead
  on the Project as we wait for Purchasing to complete
 the
  spec purchases.
 
  Regards,
  Robert
 
  
  On Mon, 1 Dec 2008 14:59:16 -0600
  Brodie Pedersen brod...@nonin.com wrote:
   EN 60601-1 points to IEC 60601-1-2 for EMC test
   requirements.  If you
   are making a device for Europe the frequency required
 at
   3 A/m is 50 Hz.
   If you want to sell the device in the US it is at
 60Hz as
   well following
   the method of IEC 61000-4-8, power frequency magnetic
   fields.  If the
   device is life supporting, then the test level is 10
 A/m.
These are
   very benign levels to pass unless you have a hall
 effect
   sensor built
   into your device.
  
   Brodie Pedersen Quality Manager Product Development
   Nonin Medical Inc.
  
  
   -Original Message-
   From: m...@california.com
 [mailto:m...@california.com]
   Sent: Monday, December 01, 2008 2:53 PM
   To: John Woodgate; emc-p...@ieee.org
   Subject: Re: EN60601-1 Susceptibility to magnetic
 fields
   from AC mains
  
   Going to, but need to design NOW, or at least make
   certain
   I'm not painted into a corner later.
  
  
   On Mon, 1 Dec 2008 19:35:37 +
John Woodgate j...@jmwa.demon.co.uk wrote:
In message web-197812...@california.com, dated
 Mon, 1
Dec 2008, m...@california.com writes:
   
   
What is the requirement for susceptibility to
 magnetic
fields from the AC mains as listed in EN60601-1?
   
It's really dangerous to rely on answers to such
questions, even from this erudite community. We
 can't
tell you everything that the standard says, and we
   don't
know what is relevant for your product. You DO need
 to
buy the standard and study it.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk
 and
www.isce.org.uk
Either we are causing global warming, in which case
 we
may be able to stop it,
or natural variation is causing it, and we probably
   can't
stop it. You choose!
John Woodgate, J M Woodgate and Associates,
 Rayleigh,
Essex UK
   
-
   
  
 

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EN60601-1 Susceptibility to magnetic fields from AC mains

[macy]

What is the requirement for susceptibility to magnetic
fields from the AC mains as listed in EN60601-1?

The requirement does appear in 60601 doesn't it?  Or is
there a more stringent requirement in another spec?

Is the magnetic field susceptibility to be measured at 2
milliTeslas?  seems a bit high, or is it 2 microTeslas
which is a bit more reasonable?  Gradient, or no gradient.

Aren't there 'performance' Class ratings that are
established by the manufacturer?

Like 
Class A: product still meets spec
Class B: ??
Class C: product recovers without Operator intervention

Robert

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Re: EN60601-1 Susceptibility to magnetic fields from AC mains

[macy]

Going to, but need to design NOW, or at least make certain
I'm not painted into a corner later.


On Mon, 1 Dec 2008 19:35:37 +
 John Woodgate j...@jmwa.demon.co.uk wrote:
 In message web-197812...@california.com, dated Mon, 1
 Dec 2008, m...@california.com writes:
 
 
 What is the requirement for susceptibility to magnetic
 fields from the AC mains as listed in EN60601-1?
 
 It's really dangerous to rely on answers to such
 questions, even from this erudite community. We can't
 tell you everything that the standard says, and we don't
 know what is relevant for your product. You DO need to
 buy the standard and study it.
 -- 
 OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and
 www.isce.org.uk
 Either we are causing global warming, in which case we
 may be able to stop it,
 or natural variation is causing it, and we probably can't
 stop it. You choose!
 John Woodgate, J M Woodgate and Associates, Rayleigh,
 Essex UK
 
 -


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Any restriction in Europe over the band of 90KHz to 250KHz?

[Robert Macy]

Intentional radiator that is narrow band but rather
energetic.

Is there any frequency I can set this transmitter at in
this low frequency range and not accidentally step on a
restriction.

Vaguely remember some military bands down there that forbid
*any* transmitters down there, but can't find any
documentation supporting that memory.

Robert

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Information on operation in the 6.78 MHz ISM Band

[Robert Macy]

Does anyone have experience in this band?
 
Or, have URLs to find limits and required characteristics
to operate in this band?

Robert

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Re: Germanium ITO Window shielding effectiveness

[robert Macy]

Andrew,

My firm has the technology to make optically transparent
magnetic shield.  Optical transparency is better than 65%.

Costs relate to the requirement of how much
  field of view
  reduction of field

Please contact me directly, off the group.

   - Robert -

   Robert A. Macy, PE. . m...@california.com
   408 286 3985. . . . . . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Thu, 16 Sep 2004 08:21:12 +0100
 Price, Andrew P (UK Basildon)
andrew.p.pr...@baesystems.com wrote:
 Hello group.

 Can anyone help with finding information on shielding
 effectiveness of Germanium and ITO coated windows against
 magnetic fields?

 Regards
 Andy

 Andrew Price
 Principal Development Engineer (EMC Specialist)
 BAE SYSTEMS Avionics
 A125
 Christopher Martin Road
 Basildon, Essex
 SS14 3EL

 tel:   +44 (0) 1268 883308
 email: andrew.p.pr...@baesystems.com




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Re: Difference between the HP 8566A and the HP 8566B

[robert Macy]

Alas, all my vintage reference books are in storage.  

As I recall, B refers to lower frequency capability and/or
finer BW resolution, like from 30Hz BW down to 10Hz BW

Simply has extended lower ranges.  

  - Robert -

On Tue, 25 Nov 2003 08:38:30 -0800
 Pettit, Ghery ghery.pet...@intel.com wrote:
 
 Not true.  The 8566 (A or B) goes to 22 GHz.  The 8568 (A
 or B) goes to
 1.5 GHz.
 
 Ghery Pettit
 
 
 -Original Message-
 From: owner-emc-p...@majordomo.ieee.org
 [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of
 Gaby F. Abboud
 Sent: Tuesday, November 25, 2003 6:37 AM
 To: lfresea...@aol.com; emc-p...@ieee.org
 Subject: Re: Difference between the HP 8566A and the HP
 8566B
 
 
 8566A can be used up to 1GHz
 8566B can be used up to 22GHz
 
 I hope this helped.
 
 Gaby,
  
  From: lfresea...@aol.com
  Date: 2003/11/24 Mon PM 11:23:10 EST
  To: emc-p...@ieee.org
  Subject: Difference between the HP 8566A and the HP
 8566B
  
  Hi there,
  
  can anyone tell me the difference between the two
 spectrum analysers?
  
  Thanks,
  
  Derek N. Walton
  Owner, L F Research EMI Design and Test Facility
  Poplar Grove,
  IL 61065
  
  
 
 
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Re: RFID tags

[robert Macy]

My vote..

Passive means to modify the field, this includes harmonic
content.

Active means use the field to generate new frequencies, as
though a battery were attached.  

  - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Thu, 20 Nov 2003 14:38:05 -0500
 djumbdenst...@tycoint.com wrote:
 
 I have heard the term passive used 2 ways, as indicated
 below or as a
 device that actually transponds an independent code from
 that which it
 received from the interrogator, powered off the
 interrogator's field.  Thus
 in the latter it is a function of with or without a
 battery, with = active,
 without = passive.  What is the consensus of the Forum
 for passive
 regarding RFID tags?
 
 Don Umbdenstock
 Sensormatic 
 


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Re: Leakage at Enclosure Seams

[robert Macy]

From vague memory...
there was some work done by Don White (?) that shows tables
of this type of improvement.  Full of practical data and
information.  

 - Robert -

On Mon, 17 Nov 2003 15:21:54 -
 Jeff Chambers j.chamb...@ndirect.co.uk wrote:
 
 I  have been asked to comment on what improvement might
 be expected in
 changing the design of an equipment lid from:
 
 A flat lid sat on the edges of the box, where the gaps
 between fasteners can
 be modelled as a simple aperture, where the attenuation
 decreases linearly
 with log(f) to zero at a half wavelength.
 
 To:
 A stepped lid, with the lid sat on the edges, and with
 the projection
 extending below the inner edge of the box.This removes
 the 'line of sight'
 gap into the enclosure. Does this improve the
 attenuation? Intuitively it
 should, but if the leakage occurs because of the
 interruption in shielding
 conductivity and hence current flow at the seam, it
 won't.
 
 Does anybody have any references to analyses of the
 above, or comments,
 please?
 
 (No emi gaskets are used btw).
 
 Thanks, Jeff Chambers
 


 Dr Jeff Chambers
 Westbay Technology Ltd
 Main St
 Baycliff
 Ulverston
 Cumbria LA12 9RN
 England
 Tel: 01229 869 108
 Fax: 01229 869 108
 http://www.westbay.ndirect.co.uk
 
 
 
 ---
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Re: System test PCs - Are we cops?

[robert Macy]

Isn't it fraud to sell an item that does not meet spec?  As
in, the vendor says the product is compliant when it is
not.  

Don't all the customers then have a legal recourse to
return any/all product?  

Doesn't policing the policy of compliance then become a
non-governmental function?  

As far as competition, it would not be out of line for the
marketing representative of a compliant company to disuade
potential customers from buying noncompliant products by
pointing out that fraud between the other vendor and this
customer sets a bad tone of a business relationship.  One
could stretch this to the point of mentioning complicity.
 g

   - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112
 





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Re: Effective length of half wave dipole

[robert Macy]

From Dave Cuthbert's comments to me regarding a 1/4
wavelength dipole; he said that the current moves down the
rod as the rod becomes thicker, which implies that the
current distribution absolutely determines the effective
length.  Was that effective length or tuned length? hmm

However, the whole thing may start with the conductivity of
real life materials...

Interesting to see the others' comments.

 - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Wed, 29 Oct 2003 16:59:20 +0800
 kcc...@hkpc.org wrote:
 
 
 Dear all
 
 I got confused with the effective length of a half wave
 dipole.
 
 1) It is due to non-constant current distribution, or
 
 2) It is due to the wave velocity in materials different
 from that in
 vacuum.
 
 
 What do you think which one is correct?
 
 Regards
 KC Chan

  


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Re: Help finding Company

[robert Macy]

David,

Just did a search in Rich's Northern California Directory
for both air and modem which showed many companies, but
no results.

Also searched through Reference USA for *any* firm with
modem in their name, again many companies, but no
results.  

If a company has been around for a while and is fairly
large, these lists usually have it.  If new, or small, or
privately owned; a company can get missed.  

If serious about search; make certain of the name, check
the registry of corporations in Sacramento.

Are they looking for Air-Space, an ISM band wireless
modem company made up of the people previously at Metricom
(Ricochet product line)?

- Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Mon, 13 Oct 2003 19:39:19 -0400
 David Seabury d.seab...@worldnet.att.net wrote:
 
 A friend in Europe is trying to obtain contact info on a
 company called
 Air-Modem Inc.  He thinks they are in Northern
 California.  Does anyone
 know where there might be located?  He has a contact
 name, Ashwin Mody??
 
 Thanks,
 
 David Seabury
 


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Re: Corrosion tests - NEBS or Milspec acceleration factors?

[robert Macy]

Gary, 

These were stainless steel wires inside protective polymer
sheathing, extra thick multiple coatings.  

The wires were mounted on a fence and then placed under
tension to make their resonance from wind, etc fairly high
frequency - like the e string on a bass guitar.  

Seems the tension put so much internal stress into the
wires and encouraged so much corrosion that the wires would
only last a year, even 2 miles from an ocean.  

 - Robert -

On Fri, 10 Oct 2003 14:56:39 -0700
 GARY MCINTURFF mcinturff3...@msn.com wrote:
 Robert,
 Thanks for the info. Do you mean stress from normal
 nut/bolt torque or from a press-fit application. Here is
 another small tidbit you might consider - a trick I got
 from an aircraft mechanic. Even if the part is stainless
 steel if you are working around it with non-stainless
 tools you can compromise the stainless part with the
 tool. It is the tool material that could be starting the
 corrosion. In the particular instance I was discussing it
 was stainless steel panels that were being sheared, and
 the shear didn't have stainless shoes or whatever the
 actually shearing components are. These shoes smeared
 onto the stainless parts and viola corrosion. When they
 put stainless shoes on the shear the problem disappeared.
 This was a Boeing 747 crew chief so he certainly has
 the experience to make him believable. Might want to
 check your manufacturing plant just for grins.
 Gary
   - Original Message - 
   From: robert Macy 
   To: GARY MCINTURFF ; emc-p...@ieee.org 
   Sent: Friday, October 10, 2003 12:01 PM
   Subject: Re: Corrosion tests - NEBS or Milspec
 acceleration factors?
 
 
 
   Gary,
 
   From experience with security systems only close to
 the
   seashore (approx 2 miles away) it is best to *NEVER*
 have
   any of the metal parts under stress/tension, else the
   corrosion rates are incredibly accelerated.  
 
   The particular stainless steel part had been tested
 real
   time in worse environments with absolutely no
 degradation
   detectable.  Yet, in the actual application under
 mounting
   stress the stainless steel part repeatably failed
 within 1
   year even that far away from the ocean.   
 
 - Robert -
 
  Robert A. Macy, PE .. m...@california.com
  408 286 3985 . . . .. . . fx 408 297 9121
  AJM International Electronics Consultants
  101 E San Fernando, Suite 402
  San Jose, CA  95112
 
 
 
   On Fri, 10 Oct 2003 09:47:40 -0700
GARY MCINTURFF mcinturff3...@msn.com wrote:
Ernie,
I know you received Naftali's  email so I will
 just
clarify a little more. We test and pass the GR-487
outdoor enclosure requirements for the
 telecommunications
industry but I have a client who is non-telecom.
Telecommunciations customers seem to accept the test,
because past experience has shown in meets the
 equipment
and time needs (20 years). Non-Telecommunications
customers not familiar with the tests kind of expect
 some
sort of acceleration factor for the hours under test
 to
demonstrate how long the equipment will work, rather
 than
a more or less pass fail salt fog test. He wants to
 how
long the equipment can withstand the elements at his
coastal location. Is there any sort of acceleration
 model
used in the salt fog test, or the mixed gasses and
hygroscopic tests?  He is a little unhappy with my
current response (understandably) that experience
 shows
the test satisfies the screening requirements or else
they  would have been changed long ago to something
 that
did meet the equipment and time requirements.
Can you give me a little insight?
Thanks
Gary McInturff
 


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Re: Corrosion tests - NEBS or Milspec acceleration factors?

[robert Macy]

Gary,

From experience with security systems only close to the
seashore (approx 2 miles away) it is best to *NEVER* have
any of the metal parts under stress/tension, else the
corrosion rates are incredibly accelerated.  

The particular stainless steel part had been tested real
time in worse environments with absolutely no degradation
detectable.  Yet, in the actual application under mounting
stress the stainless steel part repeatably failed within 1
year even that far away from the ocean.   

  - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Fri, 10 Oct 2003 09:47:40 -0700
 GARY MCINTURFF mcinturff3...@msn.com wrote:
 Ernie,
 I know you received Naftali's  email so I will just
 clarify a little more. We test and pass the GR-487
 outdoor enclosure requirements for the telecommunications
 industry but I have a client who is non-telecom.
 Telecommunciations customers seem to accept the test,
 because past experience has shown in meets the equipment
 and time needs (20 years). Non-Telecommunications
 customers not familiar with the tests kind of expect some
 sort of acceleration factor for the hours under test to
 demonstrate how long the equipment will work, rather than
 a more or less pass fail salt fog test. He wants to how
 long the equipment can withstand the elements at his
 coastal location. Is there any sort of acceleration model
 used in the salt fog test, or the mixed gasses and
 hygroscopic tests?  He is a little unhappy with my
 current response (understandably) that experience shows
 the test satisfies the screening requirements or else
 they  would have been changed long ago to something that
 did meet the equipment and time requirements.
 Can you give me a little insight?
 Thanks
 Gary McInturff



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PSpice model for 1/4 wavelength antenna

[robert Macy]

Does someone out there have a PSpice model for a 1/4
wavelength antenna? 433.92MHz 

Something that I can change to reflect diameter of the rod,
detuning, etc. 

Or, do you know someone who has such a model? 

Need it fast, please.

  - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


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Re: GFI Question

[robert Macy]

Scott,

How much wire is buried in the wall between the GFI and the
outlet that doesn't cause the problem?  

Does the addition of an extension cord between the present
outlet and the shredder calm it down?  

Do you have metal conduit?  If so, you have a small filter
through your AC mains to the other outlet.  Around 7 to 10
uH common mode choke and some capacitance.  Don't know, but
probably in the order of 50 to 100pF.  Might be just enough
filter components to solve the touchiness.  

Let us know if a 9-12 foot extension cord solves the
problem.  

 - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



 From: Scott Douglas sdoug...@ptcnh.net
 To: EMC-PSTC List emc-p...@majordomo.ieee.org
 Sent: Thursday, September 11, 2003 12:09 PM
 Subject: GFI Question
 
 
 
  Fellow Listees,
 
  It's been bugging me for a long time. So now I have to
 ask you all for
  some wisdom.
 
  Here is the setup:  table top shredder, rated 120V, 60
 Hz, 2.0 A. UL/CUL
  Listed, made in China. It has a 60 inch 3 wire power
 cord with 3 prong
  plug (presumably 3rd wire is PE).
 
  The problem:  The shredder is plugged into the GFI
 outlet in the laundry
  room (nothing else active on circuit). This GFI is the
 protector for 3
  outlets in the laundry  1/2 bath as well as for a 4th
 outlet in the
  upstairs bath. From time to time the GFI trips while
 shredding envelope
  addresses. Not always, just sometimes, it may be a
 length of run time
  related thing but have not been able to verify that as
 yet and it is not
  consistent. There is another outlet 60 inches away
 (down the counter)
  protected by this GFI outlet. If I plug this same
 shredder into the
  distant outlet, the GFI never trips. Never. Note the
 shredder sits
  immediately in front of the GFI outlet on the counter.
 Even if I leave
  it in the same place and just stretch the cord to plug
 into the other
  outlet I get the same results.
 
  That makes me wonder. GFI. Is this some kind of leakage
 from the
  shredder motor? Is this leakage reduced when you
 connect to the distant
  outlet? Are GFI outlets susceptible to EMI of any kind?
 And most
  important, is there an easy fix while leaving the
 shredder where it is
  and plugged into the GFI outlet? I suppose a GFI
 circuit breaker in the
  panel in the basement would do it, but that could be a
 costly item.
 
  Last up, and to the point of this forum, would this
 problem be exhibited
  in any kind of safety or EMC testing that would be
 required on this type
  of product?
 
  Looking forward to your comments, on- or off-line.
 
  Regards,
  Scott Douglas
  Email:  sdoug...@ptcnh.net


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Re: Conformal Coatings

[robert Macy]

Michael,

Back when I used to design coin operated games we had a
problem with intentional ESD doing damage to the
electronics.  

Turns out, that ESD would, every now and then, give a free
game.  Being rewarded with free games, they quickly learned
a damaging ritual - the kids would link arms, up to six of
them, scuff their feet around the carpeting and then
discharge to the machine through a quarter to really blast
the machine.  More than likely they killed the machine, but
what did they care?  

First thing I did was make the electronics extremely robust
for ESD, *THEN* I modified the software so the slightest
(interpret that to mean so low level that it wasn't
damaging) ESD event simply reset the game, even erased
accumulated games.  They lost their money.  Never had
problems after that.  The next time we watched a field
installation, you couldn't believe how the kids protected
those machines from even the most accidental of discharges.
 Like yelling at another kid to keep away while he's
playing the game.  

Anyway, it was one way to get the customer to help protect
your electronics.  It's all in the reward/punishment
system.  

- Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Wed, 3 Sep 2003 10:31:58 -0500 
 Sosnoski, Michael gl...@wmsgaming.com wrote:
 
 Ladies  Gentlemen,
 
 I am wondering if you have ever heard or know of any
 printed circuit board
 conformal coatings that are better than others for
 protecting against ESD?
 Are some just better than others for anything?
  
 Not that we don't use proper grounding, shielding  board
 layout techniques,
 but this industry is concerned with deliberate, and
 intentional
 stimuli to the equipment, and the more robust I can make
 the boards,
 connectors, etc,.. the better.  Also, as in any
 commercial industry--the
 accountants
  
 Thanks,
 Mike
 
 
 
 
 ---
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Re: ESD from wiring

[robert Macy]

Sounds like you just described the triboelectric(sp?)
effect and teflon insulation has one of the highest
electron work functions you will find.  

Mechanical motion causes a separation of the insulation
from and along the conductor.  That mechanical separation
causes a GUARRANTEED charge separation.  Generates a
voltage.  

This effect is the bane of cable makers, that is why the
insulation is so tightly wrapped and stuck to the
conductor.  If not, 1000 feet of cable and the slightest
slippage and you have voltage.  

This principle is used in the security industry to make
buried cables that detect any motion for the cable.  Cables
in walls detect drilling and digging through them.  Cables
buried in the ground detect footsteps of people walking
around above ground.  Yes, it is that sensitive.  

An example of such a cable is a coax made with teflon
insulation, very loosely wrapped around the center
conductor.  So loose that if you grab the center conductor
with pliers and pull, you can pull the whole 20 feet of
center conductor right out of the coax.  

I thought we were talking millivolts when I first heard of
such a cable.  So to check signal level, used a scope on
the cable and with a light tap produced over 8 volts!  The
scope is a high impedance load and the cable is a high
impedance source, but still very energetic.  

It is my understanding that this is one of forms of
deterioration for aging cables.  

Alas, the solution is to not let a cable move.  

- Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112




On Sun, 31 Aug 2003 15:49:43 EDT
 lfresea...@aol.com wrote:
 Hi all,
 
 well, I have found myself involved with an interesing
 problem. I'm testing an 
 aircraft system, that only has a few wires... 8 or so,
 that interface with 
 the outside world. 28 volt dc power, an programming loop,
 a manually operated 
 switch and an indicator.
 
 Well, evey time the push button is pressed, I see a 10 to
 50 nS pulse, very 
 consistant. The problem first was noticed during RE
 testing, and I found it 
 easier to hook my scope to the antenna rather than use
 the SA. I have eliminated 
 the EUT operating, since I have disabled the trigger by
 removing the component 
 that allows it to trigger. I did leave in place the 2
 resistors that 
 terminate the push button wire. I have a predictable set
 up.
 
 I remove either of the two reminating components, and the
 signal drops, it 
 almost goes away.
 
 Anyway, after I'd removed the circuit board to make a
 change, I pushed the 
 wire harness and saw a very similar transient! So I
 jiggled the harness and saw 
 many... Cursing a loose connection, I checked, they were
 all sound. Not sure 
 what was going on, I disconnected power, I could still
 got them. So I stripped 
 down to my cotton shorts.. still got them.
 
 One section of the harness is sleeved with heatshrink
 sleeving, it holds the 
 wires tighly. Jiggling that produced no events.
 
 So, I can only conclude, that the wire is generating a
 charge during the 
 movement/jiggling, that when it discharges any one of a
 number of places causes my 
 event. The parasitics of the harness set the ringing
 frequency. When I press 
 my push botton, I believe I also kick the wiring with the
 impulse, again it 
 rings very close to the frequency when I jiggle the
 cables.
 
 My questions are, am I off base with the charging
 supposition? The cable 
 appears to be a teflon type insulation.
 
 If so, how can I get around it. I can't really blame the
 EUT for it.
 
 Opinions very welcome
 
 Thanks,
 
 Derek Walton



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Re: 94V-0 question

[robert Macy]

Kapton comes to mind.

 - Robert -

On Tue, 12 Aug 2003 11:55:25 -0600
 drcuthb...@micron.com wrote:
 
 I need a sheet of plastic that goes between a PCB and a
 metal enclosure. This is to make a creepage spec. What
 plastics are good for this? Will polycarbonate be
 suitable and have a 94V-0 rating? Thanks.
 
Dave Cuthbert
Micron Technology
 
 
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Re: Thanks to EMC-PSTC List!!

[robert Macy]

Muriel,

Congratulations!

Is your thesis in English?  If so, is there a location to
make it available for download?  I'm sure many would be
interested in it.  

   - Robert -

On Mon, 11 Aug 2003 16:19:58 -0300
 Muriel Bittencourt de Liz mur...@eel.ufsc.br wrote:
 
 Hello List-members,
 
 I'm sending this e-mail this e-mail to thank you. Last
 friday, august, 8,
 I've got my doctor degree in electrical enegineering,
 with a thesis about
 reduction of EMI in switched mode power supplies.
 
 This thesis would not be the same without the
 contribution of the members
 from this invaluable list. A lot of topics that were not
 clear to me at the
 beggining became clear with your help, through the list
 or private e-mails
 answering my basic questions.
 
 Be sure that your comments were all referred in my
 bibliographic references
 chapter. I'd like to put some names that help me most,
 but I think that I
 could forget someone! ;-) and it would no be just...
 
 Once again, I'd like to emphasize the importance and
 relevance of this list
 to my work and another works of research world-wide.
 
 Best Regards,
 
 Muriel Bittencourt de Liz
 August, 11, 2003
 Florianópolis, Santa Catarina, Brazil
 Electrical Engineering Department
 Federal University at Santa Catarina (UFSC)
 
 
 
 ---
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Re: Clayton Pauls - Intro to EMC - an error or two? for those that have the text

[robert Macy]

Simple eqn to remember

  (2
skin depth = sqrt ( -- )
  ( w * u * sigma 

w is radians per sec; or 2 pi f, with f in Hz
u is permeability . or . u rel * u free space
   u free space is 4 pi 10-7
sigma is conductivity in S/m
all MKS units so 
skin depth in meters

One important point to remember is that this formula
calculates skin depth, like attenuation versus depth, for a
*PLANAR WAVE*  

If the impinging wave has curvature, like from a close by
radiator; that wave really punches through and there is
not as much attenuation. 

How much?  Depends on curvature, but for close sources the
effective thickness can be reduced to less than half.

Conclusion:. Use thicker material than you think you need.
 

  - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112
 







On Fri, 8 Aug 2003 13:33:24 EDT
 garymcintu...@aol.com wrote:
 My anal-retentive self is having some trouble
 with an occasional 
 example in the text and I need either a confirmation or a
 slap in the forehead.
I was just fiddling around with the text and
 reviewing some of the 
 examples and in section 6.4 he presents a table of skin
 depth for copper, but 
 then in question 6.2 he asks for the skin depth of steel
 - and the numbers for 
 the skin depth are the same. My calculations say
 otherwise and makes sense to me 
 since the permeability is different between the
 materials. copper = 1 and 
 steel is 1000, that and the conductivity is different
 between the two. 
If you have the text and little or nothing else to
 do could you give 
 me the number you come up with? ( in mm's or mils)
When I'm trying to learn or relearn stuff and I'm
 at odds with the 
 various references it just drives me wild and I don't
 have anyone else to confer 
 with up here. One is torn between the I'm right response
 and the author's 
 obvious authority on the subject.
Thanks
Befuddled (Gary)




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Re: Carton box dimension and gross weight to EU

[robert Macy]

Paul,

Forgot to mention, one company years ago added their own
maximum width dimension of less than 30 inches so the boxes
could be put on a two wheel truck and easily wheeled
through a standard door!

   - Robert -

On Tue, 29 Jul 2003 15:41:54 +0800
 Paul Chan ncc...@tuvps.com.hk wrote:
 Dear all,
 
 I have been asked for the max. dimension and weight of
 the carton box [loaded with product].  Do you know any
 requirements/guidelines?
 Thanks in advance
 Paul Chan
 



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Re: Carton box dimension and gross weight to EU

[robert Macy]

Paul,

Sample shippers:

  http://www.ups.com
At UPS website could not find any numbers, only
definitions.  

  http://www.fedex.com
At the FedEx website could not find any weight
restrictions, but did find Maximum length plus girth* per
piece is 300 inches . where *Girth = 2(Width + Height)

Maximum height per piece 70 inches
Maximum length per piece 119 inches

There was a footnote that said anything different could
still be discussed.  


I remember a maximum from old days as either 60, or 70
pounds, essentially what a man could carry.  But I believe
that maximum restriction has been removed.  

Hope that helps

- Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Tue, 29 Jul 2003 15:41:54 +0800
 Paul Chan ncc...@tuvps.com.hk wrote:
 Dear all,
 
 I have been asked for the max. dimension and weight of
 the carton box [loaded with product].  Do you know any
 requirements/guidelines?
 Thanks in advance
 Paul Chan
 



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Re: self blinking LEDs as EMI sources WAS: LED lamps

[robert Macy]

Interesting observation.  You said hum gets louder.
 Implying hum is already there.  What kind of phone?  

Is it only that one telephone instrument?  

Only occurs when LEDs are near the instrument, not near the
phone lines with the phone in another location?  

Is the effect more pronounced at less than 3m?

Are the LEDs turned on/off while appear to be on?  In other
words, LEDs are OFF then come ON OFF ON OFF ON OFF at some
high rate, perhaps near the 50Hz frequency?

Do the LED ckts affect an AM/FM radio held close by?  

  - Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112




On Sat, 26 Jul 2003 11:36:37 +0800
 Wan Juang Foo f...@np.edu.sg wrote:
 
 Dear All,
 I observe recently that some self blinking (and color
 changing) LEDs 'are'
 what seem to be a substantial emitters of radiated
 emission/interference.
 These LEDs are rigged up by hobbyists as decorative
 illuminators and acts
 more or less like the blinking lights for Christmas
 trees.  I observe that
 each of theses circuits can be made to hung like
 Christmas tree ornaments.
 
 I came across a situation where the telephone lines were
 'substantially
 noisier' :-) when several sets of battery operated
 circuits was about 3 m
 away from the telephone.  It is not a very scientific
 method but I did a
 quick check and found by the method of elimination ;-) or
 what some would
 call systematic trials to find the source of the problem.
  It took me by
 surprise that the LEDs had a substantial role to play in
 the interference.
 LED circuits gets connected (on), hum gets louder. LEDs
 circuits gets
 disconnected, hums gets quieter and so on and so forth...
 
 These are very simple circuits with a single resistor and
 the LED in
 series.  The 2 AA sized NiCad battery with holder, single
 resistor and LED
 including wire, total length about 5, tip to tip.  These
 circuits were
 found to (well at any rate, seems to) emit interference
 that cause a
 telephone to pick up (50Hz) hum!  It looks like the mains
 hum was pick up
 and modulated by the 'device' and reradiated or
 broadcasted...
 
 I can see that the blinking action at about 1 Hz have a
 duty cycle and that
 may generate a lot of ringing but what is surprising is
 the interference
 finding its way into the a telephone handset! I find it
 hard to believe
 that how the 'carrier' of the mains hum can eventually
 gets demodulated a
 puzzle.
 
 One wonders what can be observed if I get the circuits to
 a OATS? There
 again, how do I recreate the 50 Hz environment to couple
 the mains into
 these LED circuit? I had the Helmholtz coil in mind but
 can that be
 'treated' as part of a test setup?
 
 Did anyone here have similar observation? One wonders if
 there any 'product
 specific standards' for such battery operated device that
 uses LEDs as
 decorative illuminators.
 
 :-)
 
 One wonders what will happen if there are such gadgets
 line up to 'hit' the
 market this Christmas...
 
 Looks like there will be a lot of testing work coming for
 EMC engineers!
 
 Tim Foo
 
 
 
 
 
 
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Re: MRI-safe test lab

[robert Macy]

In case you have difficulty finding a strong enough field,
there is a company in St. Louis that makes a medical device
that creates 3D fields strong enough to rip a piece of
metal around inside the brain under computer control for
Parkinson surgery.  

Their fields are in excess of 1 to 3 tesla, I believe.
 Anyway the fields are generated using helium cooled
superconducting coils.  

Just in case you have difficulty getting the field strength
you need, you might be able to use their equipment.   

- Robert -

   Robert A. Macy, PE .. m...@california.com
   408 286 3985 . . . .. . . fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Mon, 21 Jul 2003 10:36:58 -0700
 Knudsen, Patricia J. pknud...@alarismed.com wrote:
 
 I am looking to test to ASTM F 2052, Standard test
 method for measurement
 of magnetically induced displacement force on medical
 devices in the
 Magnetic Resonance environment.  It involves applying a
 large magnetic
 force to the EUT to see if it will get pulled inside an
 MRI machine during a
 scan.
 
 Patty
 
 -Original Message-
 From: Peter L. Tarver
 [mailto:peter.tar...@sanmina-sci.com]
 Sent: Monday, July 21, 2003 10:33 AM
 To: emc-p...@majordomo.ieee.org
 Cc: Knudsen, Patricia J.
 Subject: RE: MRI-safe test lab
 
 
 Patricia -
 
 Can you be more specific as to what standards are
 applicable
 and what aspect of such testing you are looking for (EMC,
 safety, operational, other)
 
 
 Regards,
 
 Peter L. Tarver, PE
 Product Safety Manager
 Sanmina-SCI Homologation Services
 San Jose, CA
 peter.tar...@sanmina-sci.com
 -Original Message-
 From: Knudsen, Patricia J.
 Sent: Monday, July 21, 2003 7:33 AM
 
 I am looking for a lab that can test medical products for
 use within an MRI room.  Does anyone know of a test house
 that can do this, preferrably in the U.S. on the west
 coast?
 
 Patty
 Patricia Knudsen
 Sr. Certification Engineer
 Alaris Medical Systems
 Ph:  (858) 458-7280
 Fax: (858) 458-7095
 pknud...@alarismed.com
 
 ---
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Re: Instrument Controller Software

[robert Macy]

John,

If you buy a GPIB card for your laptop *and* your analyzer
has the GPIB interface *and* you get your analyzer's
software manual, you can learn and write all the software
you need for your project in less than 2 hours.  

Ok, ok, more like 6 hours, but still

  - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Tue, 08 Jul 2003 18:29:04 +
 John Cronin croni...@hotmail.com wrote:



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Re: Source of noise

[robert Macy]

Derek,

Most of the PS manufacturers I've dealt with use passive
dummy loads or quiet active loads.  These very handy
quiet active loads provide programmable loading, BUT IN NO
WAY SIMULATE THE SUPPLY'S ACTUAL USE.  In other words, how
many quiet loads do you power?  Almost every load is a
micro or some digital electronics.  

I've been training my clients to inject heavy noise at
their load outputs [common mode and differential mode] to
make certain that their supplies are not transparent to
those variable loads.  Most now test some time during
development with active digital loads to make certain their
supplies don't pass the noise right back through the
supply.  

Above 30MHz does not require a lot of bulk for filtering.
 Most of the bulk is there for the near 150KHz noise.
 You'll find that part selection and layout are more
critical for filtering above 20MHz.  

I always encourage end-users to include operating specs
in their PS purchase agreements to put the burden for
proper design back onto the PS manufacturers.  

  - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Wed, 2 Jul 2003 15:16:22 EDT
 lfresea...@aol.com wrote:
 Hi All,
 
 
 Thanks for the great replies!
 
 looks like the PCI bus is the problem.. But here's the
 quandry..
 
 Now we are adding the cards back in, they should add
 little to the profile, 
 correct? After all, they all have the CE mark on them,
 and some have the FCC 
 sticker too.
 
 This is not happening, in fact some emissions are quire
 strong.. I've also 
 noticed that the Power supply is letting the PC noise
 out. I opened the power 
 supply ( bang goes the warrenty ), and there is the
 minimal of filters.. Are the 
 power supplies tested individually to carry the agency
 sticker?, with a real 
 PC? or just load resistors? Are they designed to suppress
 the PC noise?
 
 Cheers,
 
 Derek N. Walton
 Owner L F Research EMC Design and Test Facility
 Poplar Grove,
 Illinois,  USA
 www.lfresearch.com



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Re: Crest Factor

[Robert Macy]

I use 3, with 10 as worst case.  

  - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


- Original Message - 
From: rehel...@mmm.com
To: emc-p...@majordomo.ieee.org
Sent: Friday, June 13, 2003 3:57 AM
Subject: Crest Factor


 
 I'm trying to spec a power supply. Can someone provide me with a typical
 crest factor that a typical power supply should be able to source without
 distortion.?
 
 Thanks,
 Bob Heller
 3M EMC Laboratory, 76-1-01
 St. Paul, MN 55107-1208
 Tel:  651- 778-6336
 Fax:  651-778-6252
 ===
 
 
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Re: Graphing Software

[robert Macy]

Doesn't Excel work for this?  

If not, I use a simple one called Grafdemo.exe which is
best for plots up to 150 data points *and* has curve
fitting SW for smooth displays and approx formulas.  

Or, Computer Calculus 4.0  CC4  which plots 2D and surface
plots

CC4 has good presentation of 2D with maxima *plus* you can
rotate all the axes around for best view.  

Both have a good price - free.  

  - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112





On Fri, 16 May 2003 12:44:49 EDT
 lfresea...@aol.com wrote:
 Hi All,
 
 I'm looking at plotting the response of devices on a
 polar plot, either 2D or 
 3D. In this cases it's the response of a field probe.
 Several plots will be 
 used for different frequencies.
 
 Does anyone have suggestions of what package to use? I
 know or Origin, but 
 it's very expensive.
 
 Cheers,
 
 Derek N. Walton
 Owner L F Research EMC Design and Test Facility
 Poplar Grove,
 Illinois,  USA
 www.lfresearch.com



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Re: ESD gun verification

[robert Macy]

Most spectrum analyzers don't do very well with a single
event.  The repetitive waveform needs to be there to be
operated upon.  

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112



On Fri, 9 May 2003 08:28:11 -0400
 Chris Maxwell chris.maxw...@nettest.com wrote:
 
 One question that struck me is:  Why isn't a spectrum
 analyzer used to verify the waveform?  Most labs don't
 have a 4Ghz oscilloscope; but they almost all have a
 10Ghz spectrum analyzer.  It seems that the spectrum of
 the waveform should be just as traceable and repeatable
 as the waveform itself.
 
 From my own experience, I use this method to quickly
 verify our EFT generator in our own lab (although I'm
 just a manufacturer, not a third party lab).  We have the
 EFT generator calibrated yearly; and whenever I use it, I
 turn on the spectrum analyzer and read the spectrum just
 to make sure that it's working.
 
 Chris Maxwell | Design Engineer - Optical Division
 email chris.maxw...@nettest.com | dir +1 315 266 5128 |
 fax +1 315 797 8024
 
 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA
 web www.nettest.com | tel +1 315 797 4449 | 
 
 



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Re: FCC Limits

[robert Macy]

Interference from an adjacent/inband radiating source is
likely to cause the receiver's AGC circuitry to limit the
incoming RF signal to the point where the signal you're
trying to receive gets buried in the system's noise.  Or,
the interfering signal is of sufficient magnitude so as to
simply confuse the receiving electronics.  

Ghery, are you Insturment Rated, yet?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Tue, 29 Apr 2003 10:32:20 -0700
 Pettit, Ghery ghery.pet...@intel.com wrote:
 Ken,
 
  
 
 The FCC made the change for several reasons,
 international harmonization
 being foremost.  We do have users of the RF spectrum
 below 450 kHz in the
 US.  The ADF receivers in the airplanes I fly tune in
 non-directional
 beacons below that frequency.  I'd really rather home in
 on one of those as
 opposed to your PC (although there is a rather large
 difference in the
 signals, but...).  The only significant opposition in the
 Rule Making came
 from some interests who wanted even lower limits to lower
 frequencies.  They
 were not successful.  Manufacturers of ITE with
 international markets
 supported the change as they were already testing to the
 CISPR 22 limits and
 this was a non-issue to them.
 
  
 
 Ghery Pettit
 
 Intel Corporation
 


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Re: Low signal switching

[robert Macy]

Don,

It is my understanding that physical switch contacts are
cleaned with current - and use.  

It is probably ok at the lower signal levels since from
time to time you're running the higher levels through the
switches.  

Is there someway you can switch and then verify contact?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Mon, 21 Apr 2003 13:27:38 -0400
 djumbdenst...@tycoint.com wrote:
 
 Hello Friends,
 
 I have an application in which I would like to switch
 system signals on coax
 cables. One system is 80 to 1000 MHz, the other is 1-2
 GHz.  I have found
 coax switches by Narda, DB Products and Dow Key. Dow Key
 indicates that the
 signals should be above -20 dBm to ensure that contact
 resistance doesn't
 cause a problem.  The others do not spec or address low
 signal issues. My
 branches operate at -35 dBm, 0 dBm and 50 dBm.  The 2
 higher values are not
 a problem, just the -35 dBm.  Are there other companies
 that you are aware
 of that make 50 ohm coax switches that are specified to
 operate at low
 signal levels?  Other ideas?
 
 Best regards,
 
 Don Umbdenstock
 Sensormatic
 



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Re: high immunity

[robert Macy]

If GW, wouldn't that voltage be more like 600KV/m, or at
least 30KV/m?

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


On Wed, 26 Mar 2003 17:30:14 -0700
 drcuthbert drcuthb...@micron.com wrote:
 
 With the advent of E-weapons we might need some new
 immunity specs. I read that they can output several GW.
 Testing for equipment survival at over 5000 V/m should be
 fun (and profitable to some).
 
 Dave Cuthbert
 Micron Technology
 


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Re: Help wanted with succinct subject description for non-special ists

[robert Macy]

To me, all this regulation can be synopsized:  

Electronics shall not put out stuff - conducted or radiated

Electronics shall not be upset when stuff comes in -
susceptibility to conducted or radiated.  


Difference in attitude between US and elsewhere:

It is my understanding that in the US the FCC thought not
to complicate the manufacturing process by adding
susceptibility tests to product testing, but rather have
the consumer simply modify their behaviour.  If a product
does not work well because it is easily upset by stuff
coming in, the consumer will buy a different product and/or
complain to the manufacturer, thus automatic control
without FCC intervention.  But in the EC and elsewhere,
they thought to add tests ahead of time in order to
establish a minimum quality standard of performance for the
consumer, like prescreen for the consumer.  


Which is better control?  Arguments go both ways.  

  - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112




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Re: HP 6034L Power supply schematics / repair (was Agilent 6842A)

[Robert Macy]

Being a past employee of HP and having met David Packard and Bill Hewlett
(just as the HP-35 calculator was coming out), it was with great sadness I
watched as the management team headed by Carly F effectively dismantled
everything they had built and stood for despite and in front of Bill's son.


For manual's, I've seen them for printing fee available on the news group:
sci.electronics.repair

If you can find the threads there, you'll find at least two sources I
remember seeing offering them.

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112




From: Kurt M. Marden
To: emc-p...@majordomo.ieee.org
Cc: Michael Taylor ; 'emcp...@aol.com'
Sent: Wednesday, February 05, 2003 8:40 AM
Subject: HP 6034L Power supply schematics / repair (was Agilent 6842A)


On that note of (lack of) support, Agilent has no or will not release
documentation on the
old 6034L power supply.  I recently acquired one which powers up but has no
output
and the front panel display shows 0 volts / amps. Agilent will be happy to
charge me $140
just to look at it. Best effort is all they can guarantee on a repair
(which would be over
and above the $140). Sheesh! Anybody have a owners manual or repair guide /
schematics
 for this model?

Thanks,

Kurt

Michael Taylor wrote:

If you think Carley and the rest of HP / Agilent upper management are really
more concerned about your thoughts - over short term profits,  there are
several of us that would like to interest you in some swamp land in Florida
and a bridge in New Jersey.

Seriously,  I have had several instances lately with Agilent that convince
me that the old HP is gone and the NEW - lean-mean Agilent machine  no
longer values customer loyalty the way the old HP did.  In my case,  the way
I was treated on several issues would have never occurred under the old HP.
The net result is I now consider purchasing test equipment from others -
something I would have never done in the past.

Welcome to the brave new world of bean counting business.

Michael Taylor
(loyal HP test equipment fan)
Frozen in Colorado

From: emcp...@aol.com [mailto:emcp...@aol.com]
Sent: Tuesday, February 04, 2003 11:00 AM
To: emc-p...@majordomo.ieee.org
Subject: Agilent 6842A


I think all of the people that own the Agilent 6842A Harmonic and Flicker
Test System should get together and request Agilent to update their software
for the new standards.  As a loyal HP/Agilent customer, I would expect them
to take care of this issue.  This is why we buy certain brands of test
equipment, and not others.  I feel that we got ripped on this deal since
the 6842A is not a cheap piece of test equipment.

Tim Pierce


--
Kurt M. Marden
Environmental Simulation Manager

Curtis-Straus LLC   kmar...@curtis-straus.com
Laboratory for EMC,Safety   Environmental Simulation Lab
NEBS,SEMI-S2 and Telecom168 Ayer Rd.
527 Great Road  Littleton,  MA   01460
Littleton, MA 01460 voice (978) 486-8880
http://www.curtis-straus.comfax   (978) 486-0806



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Re: CALIBRATION AND CONSTRUCTION OF HELMHOLTZ COILS

[Robert Macy]

Ian,

Contact me off line and I will share with you the SW tools (free on the
internet) that I use to do these calculations.

The first is an antiquated tool that runs on DOS called Computer Calculus
4.0, or CC4  I like it because it's powerful but easy to learn and retain.

The second is a 2D finite element analysis program called femm that is
located at
http://femm.berlios.de/

When you use the SW in asymmetric analysis you get true 3D values, so it's
very powerful.

You can use the program for plotting the B field over whatever effective
area of interest you're after.

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112




From: Gordon,Ian ian.gor...@edwards.boc.com
To: 'IEEE EMC-PSTC GROUP' emc-p...@majordomo.ieee.org
Sent: Thursday, January 23, 2003 7:15 AM
Subject: CALIBRATION AND CONSTRUCTION OF HELMHOLTZ COILS



 All
 I would like to construct a Helmholtz coil to perform magnetic field
 immunity testing at DC frequencies and thus simulate the effect of a
 permanent magnet. There are some details on construction in EN61000-4-8
 which details power frequency magnetic field immunity testing within the
 scope of the EMC directive. However the fields referred to are measured in
 A/m, whereas I need a field of, for example, 5mTesla.
 Can anybody advise me as to how to construct such a coil with a test
volume
 of 0.5 x 0.5 x 0.5m and a field of 5mTesla?
 Thanks
 Ian Gordon






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Re: Measuring AC Line Impedance

[Robert Macy]

Do you have the liberty to share your report - or details and results with
the group?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   101 E San Fernando, Suite 402
   San Jose, CA  95112


- Original Message -
From: Spencer, David H david.spen...@usa.xerox.com
To: emc-p...@majordomo.ieee.org
Sent: Wednesday, October 30, 2002 8:57 AM
Subject: RE: Measuring AC Line Impedance



 Follow up

 Having just completed an ton of work on this using input I got around here
 (thanks to Don Borowski, Patrick Lawler, Joe Randolph and  John Woodgate).
 I believe we have characterized the AC mains of our facility.

 As a sanity check/ technical check can any one comment on process.

 Part one
 1)Open circuit voltage measured.
 2)Resistive load placed in circuit.
 3) Voltage drop and current measured.
 4) Voltage drop divided by current provides  resistance component of AC
 mains.

 Part 2
 1) Open circuit voltage measured.
 2)Reactive load placed in circuit (approximately 120uF!)
 3) Voltage change (increase really) and current measured (phase angle was
 recorded to back check math vectorialy).
 4) Voltage change divided by current provides reactive component of AC
 mains.


 As a side note, I also connected an isolation transformer as the reactive
 load,  the reactive numbers were very very close.

 The resistive number + reactive number then make up the AC line impedance
 for this site:  Ztest if you will.



 My two remaining questions:

 Is this method of characterizing the AC line impedance valid (is there
 something I'm missing)?

 Based on my knowledge of these values, and their ratio to the reference
 impedance(s) specified in EN61000-3-3 and EN61000-3-11, I should be able
to
 calculate and correlate the measured Dmax, Pst, et. al...to the limits
 specified in those standards.
 (REFERENCE section 6.1.3 of EN61000-3-11), using our existing AC mains.


 Any comments or input would be welcome.
 Thanks

 Regards
 David Spencer
 Xerox Corp.


 -Original Message-
 From: John Woodgate [mailto:j...@jmwa.demon.co.uk]
 Sent: Thursday, September 19, 2002 11:56 AM
 To: emc-p...@majordomo.ieee.org
 Subject: Re: Measuring AC Line Impedance



 I read in !emc-pstc that Spencer, David H david.spen...@usa.xerox.com
 wrote (in 052106A55179D611B34300096BB02E3F8B1D@USAMCMS4) about
 'Measuring AC Line Impedance' on Thu, 19 Sep 2002:

 Is anyone familiar with a method to measure and calculate those values.
 The
 generic values I have for short circuit condition (which include 4 wires
in
 a magnetic conduit) come out higher than my measured values, and those do
 not include the motor generator source.

 Put a large capacitor (mains voltage rated) across the mains and measure
 the voltage change; it may actually increase. You need about 50 uF to
 get a decent change on 120 V 60 Hz mains. With that result and the one
 with the resistive load, you can calculate the source impedance as an R
 and L in series.

 I'd be interested to learn the result.
 --
 Regards, John Woodgate, OOO - Own Opinions Only.
http://www.jmwa.demon.co.uk

 Interested in professional sound reinforcement and distribution? Then go
to
 http://www.isce.org.uk
 PLEASE do NOT copy news posts to me by E-MAIL!

 ---
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Need services of Professional (PE) Mechanical Engineer registered in California

[Robert Macy]

Dear group,

A fabricator of shell and tube heat exchangers located in Stafford, Texas
has a requirement for a California PE to perform a structural design check
on supports on two vessels that will be erected at the Shell Oil Plant in
Martinez, California.

Could you recommend a California PE?

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112






---
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Re: Need Drivers Programming Guide for HP8592B

[Robert Macy]

Andy,

About 4 years ago I bought a book called something like Programming Guide
for the ... from HP which cost around $20.  Not sure if it was for this
model or not, but watch out.  Their system had the wrong part number and I
got some unrelated book and it took another 10 days to get the right one.

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


- Original Message -
From: andrew.p.pr...@baesystems.com
To: emc-p...@majordomo.ieee.org
Sent: Tuesday, August 13, 2002 4:33 AM
Subject: Need Drivers  Programming Guide for HP8592B



 Is there anyone who can help?

 I require information on HP8592B Commands and Programming for GPIB
 interface.

 Regards
 Andy

 Andrew Price
 Principal Development Engineer (EMC Specialist)
 BAE SYSTEMS Avionics
 A125
 Christopher Martin Road
 Basildon, Essex
 SS14 3EL

 tel:   +44 (0) 1268 883308
 email: andrew.p.pr...@baesystems.com



 
 This email and any attachments are confidential to the intended
 recipient and may also be privileged. If you are not the intended
 recipient please delete it from your system and notify the sender.
 You should not copy it or use it for any purpose nor disclose or
 distribute its contents to any other person.
 



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Re: Need copies of specs addressing ISM bands in Europe

[Robert Macy]

Bill, Rich,

Just couldn't find out all of what I wanted there.  Did find individual
country's allocation for ISM bands and that was encouraging.  What am I
doing wrong?


At this site I at least found some numbers:

http://europa.eu.int/comm/enterprise/newapproach/standardization/harmstds/re
flist/radiotte.html

  ETSI EN 300 328-2 V1.1.1 (07-2000) Electromagnetic compatibility and Radio
Spectrum Matters (ERM); Wideband Transmission systems; Data transmission
equipment operating in the 2,4 GHz ISM band and using spread spectrum
modulation techniques; Part 2: Harmonized EN covering essential requirements
under article 3.2 of the RTTE Directive.  ETS 300 328/A1:1997 Date expired
(30.04.2001) Art.3.2
  ETSI EN 300 328-2 V1.2.1 (11-2001) Electromagnetic compatibility and Radio
Spectrum Matters (ERM); Wideband Transmission systems; Data transmission
equipment operating in the 2,4 GHz ISM band and using spread spectrum
modulation techniques; Part 2: Harmonized EN covering essential requirements
under article 3.2 of the RTTE Directive  EN 300

But no documents.


My question is still, What is the equivalent European requirement that
matches FCC Part 15.247 regarding ISM bands?

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



- Original Message -
From: Bill Morse bill...@verifone.com
To: 'Robert Macy' m...@california.com; emc-p...@ieee.org
Sent: Monday, August 12, 2002 12:52 PM
Subject: RE: Need copies of specs addressing ISM bands in Europe



 Try the following URL.

 http://www.ero.dk/

 Technical Staff
 Senior EMC Engineer
 William Morse NCE
 Phone 916.630.2540
 FAX916.630.2501
 EMAILbill...@verifone.com

  -Original Message-
 From: Robert Macy [mailto:m...@california.com]
 Sent: Monday, August 12, 2002 10:07 AM
 To: emc-p...@ieee.org
 Subject: Need copies of specs addressing ISM bands in Europe


 Apologize if duplication of question here.

 Is there a website to get a copy of the European Community's rules
regarding
 ISM bands similar to FCC Part 15.245-9?

 - Robert -

Robert A. Macy, PEm...@california.com
408 286 3985  fx 408 297 9121
AJM International Electronics Consultants
619 North First St,   San Jose, CA  95112





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Need copies of specs addressing ISM bands in Europe

[Robert Macy]

Apologize if duplication of question here.

Is there a website to get a copy of the European Community's rules regarding
ISM bands similar to FCC Part 15.245-9?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112




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Re: NEBS compliance for 100baseT / 1000base T

[Robert Macy]

The people who supply these inbedded filter connectors, Regal Electronics,
can answer this and more.

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112

-Original Message-
From: Muhammad Sagarwala msa...@force10networks.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Date: Monday, July 22, 2002 3:32 PM
Subject: NEBS compliance for 100baseT / 1000base T


Hello Gurus,

I am new to this list so pardon me if my questions sound naive.

The question I had was, for nebs compliance we need to pass power cross
and lightening tests.  For boards with copper ports (100baseT and 100base
T), is it possible to use rj45 connectors with integrated magnetics and
still get pass these tests. Has anybody done that - if yes, is it possible
to share the method.  I believe there are components (e.g. sedactors) one
can use, but

those are capacitve and might impact the signal integrity.  Also, mostly
that kind of stuff is used on the line side of the transformer.  I am just a
little bit hesistant to put in on the secondary side...

Any input would be highly appreciated...

Thanks

Muhammad



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Re: case of units

[Robert Macy]

Still use KHz

For me it's a logical carrier over from
small letter = small value
capital letter = large value

   mOhm   means milli Ohm  NOT   mega Ohm
   mHz   is milliHertz
   KHz is kilo Hertz   (note magnifier is larger than one)
   MHz  is megaHertz
  and so on

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Price, Ed ed.pr...@cubic.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Monday, June 24, 2002 8:24 AM
Subject: RE: case of units





-Original Message-
From: Brent DeWitt [mailto:bdew...@ix.netcom.com]
Sent: Sunday, June 23, 2002 7:04 PM
To: emc-p...@majordomo.ieee.org
Subject: case of units



I've always found it interesting that the small k is the
only lower case
letter used for multipliers greater than unity.  I presume it
is because the
temperature folks got there first with Lord Kelvin's initial.  Too bad
really since kilo has a linguistic meaning for numbers and
Kelvin is just
a name.  Also rather interesting that we have no trouble using
G for both
Giga and Gauss.

Just Sunday evening thoughts.

Brent DeWitt


Brent:

For years, I had always written kiloHertz as KHz. Then, as a hirling, I
bumped up against the Information Technology Group at General Dynamics
Electronics Division. I noticed that all my text came back using kHz.
After a few cycles of this, I decided to follow up on the cause. I found
that they worked to a bureaucratic style manual, which dictated the style
for abbreviations and technical terms. I had the temerity to ask who wrote
the style manual, and why KHz was rendered as kHz. They finally produced a
Mil-Std, which had a list of acronyms and special terms. And, there on the
list, was kHz! No explanation, just kHz. So I asked them if maybe the
Mil-Std was just a typo error, and that shouldn't we allow logic to
prevail?
No, because if they did that, someone might think the abbreviation actually
meant degrees Kelvin Hertz. They won.

Lately, after many more years of continuing to personally use KHz (and
having re-educated my MS Word about my preference), I find that I am
wearying of the explanations, and have started to use kHz. Yup, they won.

Ed




Ed Price
ed.pr...@cubic.com
Electromagnetic Compatibility Lab
Cubic Defense Systems
San Diego, CA  USA
858-505-2780  (Voice)
858-505-1583  (Fax)
Military  Avionics EMC Services Is Our Specialty
Shake-Bake-Shock - Metrology - Reliability Analysis

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Re: Lightning Protection for PA System

[Robert Macy]

Scott,

Not knowing how your system is exactly built makes it difficult to second
guess the lightning.

However, here is one way to protect your amplifiers:  Move the protection
interface out to the edge of your building.  Use rod located there with all
referenced to ground.  At this same location use a 10A AC mains line filter
between the amplifier and the speakers (cheap filtering which should be able
to pass the audio) with AC line towards amp and load towards speakers.
Between filter and speakers place fusing in series (won't do much for truly
high voltage which will jump, but will take care of a lot of nuisance
discharges) place gas discharge tubes there.  [ If you can get a surplus
telephone entry block, the type with the carbon shorts, they work great
here, too. ]  Back side of filter place tranzorbs, then back at amp place
more tranzorbs.

You prevent lightning damage by designing a filtering system which limits
the maximum amplitude that can get into your electronics.  And the most
effective rejection filter is always high impedance in series, low impedance
to ground, high impedance in series and low impedance to ground, ad nauseum.
Just make multiple paths that do this and you can even sustain a direct hit.
Speakers and wires will probably fry though.

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Scott Lacey sco...@world.std.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Saturday, June 15, 2002 9:19 AM
Subject: Lightning Protection for PA System



To the group,

I am seeking advice as to the best methods of protecting a Public Address
system
against recurring lightning damage. The system uses several commercial PA
amplifiers, each driving several speakers at indoor and outdoor locations.
There are
also several locations where microphones can be plugged in. The longest
speaker
wires may be up to 250 yards long. It is believed that the charge is being
coupled to
the speaker wires where it then returns to ground at the amplifier location
within the
building, destroying the solid state devices within the amplifier. A
technician has
added fuses to all external microphone inputs and speaker outputs. While
these
have blown several times during storms without obvious damage to the
amplifiers it
is my belief that fuses are generally too slow to protect semiconductor
devices. I am
seeking advice as to surge suppression devices.
System particulars are as follows:

1) The PA amplifiers have 70 volt outputs. All speakers are transformer
coupled.

2) All microphones use standard XLR connectors. They plug into metallic
conduit
mounted jacks at locations inside and outside the building. The outside
microphones
are unplugged during storms.

3) The amplifiers are located on the second floor of the building. Each
amplifier is
dedicated to a set of speakers at one location. The amplifier driving the
longest wires
is the one which most often has to be replaced.

4) The building is in a location known to be susceptible to lightning
activity. Electrical
appliances have been destroyed on at least two occasions.

5) All protective grounding efforts to date have been made to the conduit. I
am
recommending that this be supplemented by driven rods.

It is pretty easy to buy commercial surge suppression devices for the ac
lines. I feel I
need advice as to the best methods to protect the audio inputs and outputs.

For the 70 volt outputs I am thinking of using gas tubes to earth where the
wires
enter the building supplemented by MOV, Tranzorb, or other devices near the
amplifier location. I welcome suggestions as to device types.

For the microphone inputs I am thinking of using semiconductor transient
voltage
suppressors near the amplifier. Again, any suggestions are welcome.

Thanks in advance for any advice and guidance.

Scott Lacey
sco...@world.std.com




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Re: Side Issue: Proximity Cards in Wallets ...

[Robert Macy]

No

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Doug McKean dmck...@corp.auspex.com
To: EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Thursday, June 13, 2002 11:07 AM
Subject: Side Issue: Proximity Cards in Wallets ... 



A proximity card reading security system is used in 
a company, possibly based on the Wiegand Effect. 
Some of the employees put their security cards in 
their wallets to have them all the time.  When needing 
access to an area that requires a card, users simply 
pull out their wallets, swipe the wallet in front of the 
reader and thus gain access.  For those people with 
cards in their wallets, they do not pull the security card 
out of the wallet and then swipe the reader. They all 
swipe the reader with the wallet. 

A question was posed to me that involved the swamping 
of the card with a magnetic field to identify the card.  The 
electronics in the card generates a series of pulses from 
the pulsed magnetic field that when received by the card 
reader validate or invalidate the card. 

Is this field strong enough to wipe any magnetic strips on 
any credit or bank or any of the other types of cards using 
magnetic strips that may also be in the wallet? 

Regards, Doug McKean 




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Re: ferrite transient voltage/current response

[Robert Macy]

Then why would a 10 A surge change their characteristics?

Unless it cracks it?

- Robert -

-Original Message-
From: Robert Wilson robert_wil...@tirsys.com
To: Robert Macy m...@california.com; emc-p...@majordomo.ieee.org
emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Thursday, June 06, 2002 8:51 AM
Subject: RE: ferrite transient voltage/current response


Soft Ferrites cannot be permanently magnetized. This is precisely why
they are used as beads and cores.

Bob Wilson
TIR Systems Ltd.
Vancouver.

-Original Message-
From: Robert Macy [mailto:m...@california.com]
Sent: June 5, 2002 11:20 PM
To: don_borow...@selinc.com; emc-p...@majordomo.ieee.org
Cc: shbe...@rockwellcollins.com
Subject: Re: ferrite transient voltage/current response


He may have magnetized it.  Degaussing with one of those Radio Shack
thingies would probably brought it back.  Can he try it again?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



-Original Message-
From: don_borow...@selinc.com don_borow...@selinc.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Cc: shbe...@rockwellcollins.com shbe...@rockwellcollins.com
List-Post: emc-pstc@listserv.ieee.org
Date: Wednesday, June 05, 2002 2:52 PM
Subject: RE: ferrite transient voltage/current response





While I was at Agilent in Spokane, one of the engineers or technicians
claimed
that he had changed the RF characteristics of a 6-hole ferrite bead
(wound
with
2 1/2 turns) used on a power supply trace to a noisy assembly. The
normal
current was about 1 amp, but he accidently shorted the power supply
voltage
after the inductor. This caused a current spike as the power supply
filter
capacitor discharged (and then the supply current limited at about 10
amps).
After this, there was a problem with RF leakage from the assembly.
Replacing the
inductor fixed the problem. Apparently the effect was repeatable.

I didn't observe this personally, so I can't guarantee it.

Don Borowski
Schweitzer Engineering Labs


Sorry that I wasn't clear; I typically try to keep my questions general
so
  not to get too detailed about the specific application. And
thanks to
Bob,
  Chris and Mike who have responded ... putting it into Chris's
words
... I
  was just trying to find out if ferrites had ratings to prevent
them
from
  j
  ust plain blowing the ferrite to smithereens.  Also, I was
looking
for a
  shortcut if someone else had faced this question rather than
reading
  through all of the vendor web sites.

 I understand and have used ferrites quite often for typical EMI
suppression; the ferrites typically being rated for the application
currents, voltages, etc.  In this case, the program is trying to
protect a
power supply input from the DO-160 waveform 5B pin injected lightning
pulse
of 300 volts open circuit  300A short circuit.  If the Gas Discharge
Tube
is located past (closer to the supply which was done for packaging
limitations) than the T EMI filter, a question was raised as to
whether
the ferrite properties would be altered by the lightning pulse.  Most
of
the standard literature on the use of ferrites does not address these
types
of transients.


Susan Beard







Robert Wilson robert_wil...@tirsys.com@majordomo.ieee.org on
06/04/2002
02:16:48 PM

Please respond to Robert Wilson robert_wil...@tirsys.com

Sent by:owner-emc-p...@majordomo.ieee.org


To:shbe...@rockwellcollins.com, emc-p...@ieee.org
cc:

Subject:RE: ferrite transient voltage/current response



Your question is not all that clear. It appears to imply that
transients
have an affect on the ferrite beads, but it is the other way around
(maybe that is what you meant). But in general, small ferrite beads
have
little effect, except at very high frequencies (hundreds of MHz),
unless
they are no longer beads (i.e. they are very large).

Have a look at the various magnetics vendors data sheets and app notes.

Magnetics Inc: www.mag-inc.com
Fair-Rite Inc: www.fair-rite.com (whoever came up with THAT name should
be shot!
Steward Inc: www.steward.com
Ferroxcube: www.ferroxcube.com
Epcos (was Siemens): www.epcos.com


Bob Wilson
TIR Systems Ltd.
Vancouver.

-Original Message-
From: shbe...@rockwellcollins.com [mailto:shbe...@rockwellcollins.com]
Sent: June 4, 2002 8:57 AM
To: emc-p...@ieee.org
Subject: ferrite transient voltage/current response


Could someone point me to some good App Note information on the
response
of
and affect on ferrite beads to transient voltage  current waveforms?
The
waveforms are based on the indirect lightning pulses specified in
Section
22 of DO-160.

Thanks in advance,
Susan Beard


This e-mail may contain SEL confidential information.  The opinions
expressed
are not necessarily those of SEL.  Any unauthorized

Re: ferrite transient voltage/current response

[Robert Macy]

He may have magnetized it.  Degaussing with one of those Radio Shack
thingies would probably brought it back.  Can he try it again?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



-Original Message-
From: don_borow...@selinc.com don_borow...@selinc.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Cc: shbe...@rockwellcollins.com shbe...@rockwellcollins.com
List-Post: emc-pstc@listserv.ieee.org
Date: Wednesday, June 05, 2002 2:52 PM
Subject: RE: ferrite transient voltage/current response





While I was at Agilent in Spokane, one of the engineers or technicians
claimed
that he had changed the RF characteristics of a 6-hole ferrite bead (wound
with
2 1/2 turns) used on a power supply trace to a noisy assembly. The normal
current was about 1 amp, but he accidently shorted the power supply voltage
after the inductor. This caused a current spike as the power supply filter
capacitor discharged (and then the supply current limited at about 10
amps).
After this, there was a problem with RF leakage from the assembly.
Replacing the
inductor fixed the problem. Apparently the effect was repeatable.

I didn't observe this personally, so I can't guarantee it.

Don Borowski
Schweitzer Engineering Labs


Sorry that I wasn't clear; I typically try to keep my questions general so
  not to get too detailed about the specific application. And thanks to
Bob,
  Chris and Mike who have responded ... putting it into Chris's words
... I
  was just trying to find out if ferrites had ratings to prevent them
from
  j
  ust plain blowing the ferrite to smithereens.  Also, I was looking
for a
  shortcut if someone else had faced this question rather than reading
  through all of the vendor web sites.

 I understand and have used ferrites quite often for typical EMI
suppression; the ferrites typically being rated for the application
currents, voltages, etc.  In this case, the program is trying to protect a
power supply input from the DO-160 waveform 5B pin injected lightning pulse
of 300 volts open circuit  300A short circuit.  If the Gas Discharge Tube
is located past (closer to the supply which was done for packaging
limitations) than the T EMI filter, a question was raised as to whether
the ferrite properties would be altered by the lightning pulse.  Most of
the standard literature on the use of ferrites does not address these types
of transients.


Susan Beard







Robert Wilson robert_wil...@tirsys.com@majordomo.ieee.org on 06/04/2002
02:16:48 PM

Please respond to Robert Wilson robert_wil...@tirsys.com

Sent by:owner-emc-p...@majordomo.ieee.org


To:shbe...@rockwellcollins.com, emc-p...@ieee.org
cc:

Subject:RE: ferrite transient voltage/current response



Your question is not all that clear. It appears to imply that transients
have an affect on the ferrite beads, but it is the other way around
(maybe that is what you meant). But in general, small ferrite beads have
little effect, except at very high frequencies (hundreds of MHz), unless
they are no longer beads (i.e. they are very large).

Have a look at the various magnetics vendors data sheets and app notes.

Magnetics Inc: www.mag-inc.com
Fair-Rite Inc: www.fair-rite.com (whoever came up with THAT name should
be shot!
Steward Inc: www.steward.com
Ferroxcube: www.ferroxcube.com
Epcos (was Siemens): www.epcos.com


Bob Wilson
TIR Systems Ltd.
Vancouver.

-Original Message-
From: shbe...@rockwellcollins.com [mailto:shbe...@rockwellcollins.com]
Sent: June 4, 2002 8:57 AM
To: emc-p...@ieee.org
Subject: ferrite transient voltage/current response


Could someone point me to some good App Note information on the response
of
and affect on ferrite beads to transient voltage  current waveforms?
The
waveforms are based on the indirect lightning pulses specified in
Section
22 of DO-160.

Thanks in advance,
Susan Beard


This e-mail may contain SEL confidential information.  The opinions
expressed
are not necessarily those of SEL.  Any unauthorized disclosure,
distribution or
other use is prohibited.  If you received this e-mail in error, please
notify
the sender, permanently delete it, and destroy any printout.  Thank you.





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Re: Constant for Change of Resistance formula.

[Robert Macy]

Bill,

Big oops.

Measuring the resistance to determine the temperature is not productive
*unless* the resistance dominates the resistance measurement.

Picture three equal valued resistances in a row.  The middle one gets very
hot (more than 100C rise) and increases over 40%, the two on the edges are
heat sinked and barely increase in temperature.  The resulting change in
resistance is 13% which implies the temperature in there has only gone up
around 33C.

Measuring the resistance doesn't tell you much.  At least with transformers
the dominant resistance is pretty much the bulk resistance.

- Robert -


-Original Message-
From: Bill Ellingford bill.ellingf...@motion-media.com
To: 'Robert Macy' m...@global.california.com; emc-p...@majordomo.ieee.org
emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Monday, May 13, 2002 1:56 PM
Subject: RE: Constant for Change of Resistance formula.



Hi Robert / group
OK, Not the best choice of website to demo the answer.  The differing
figures are because the formula has been transposed to give Temp from
change
of R from the original formula which gives R from change of T.  To do this,
another constant (The 234.5 constant) is required.  This is the implied
point of zero resistance for copper on the Celsius scale.  The formula we
use is:

  Rfinal - Rorig
  x (234.5 + Tamb start) -(Tamb finsh - Tamb start)
  Rorig

The Tamb start and finish are the changes (if any) in Room ambient.  If the
room remains at 20c then 234.5 + 20 is the multiplier.

-Original Message-
From: Robert Macy [mailto:m...@california.com]
Sent: 13 May 2002 14:54
To: Bill Ellingford; emc-p...@majordomo.ieee.org
Subject: Re: Constant for Change of Resistance formula.


Bill,

Thanks for the site.

Went there and found the same formula and constant I use.

For copper, Temp Coeff = 3.9 x 10-3

Then I clicked on table of coeff and there was a very long list of
materials, but the temp coeff of copper there was 6.8 x 10-3  ???!!!

Any ideas for this disparity?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Bill Ellingford bill.ellingf...@motion-media.com
To: 'Colgan, Chris' chris.col...@tagmclaren.com;
emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Date: Monday, May 13, 2002 5:38 AM
Subject: RE: Constant for Change of Resistance formula.



Hi Folks
Further to the answer given, here is a little more data.
The constant used is for the change of resistance with temperature.  metals
and alloys (conductors) all exhibit a different constant.  This can be used
for calculating temperature rise or resistance change.  i.e. find the temp
rise from a start and finish test measurement on a winding (for example) at
the begining and end of a on load heat run or, find R for a given temp:
using a table or the formula, resistance at various temperatures can be
pre-determined from a measurement made at one particular temperature.

A website with the formulae can be found at
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html

Where you have a transition from one metal type to another, you must
measure
each metal part individually.  If you have only two metals in contact, you
may be able to apply a combination of the temp coefficient methods and
transposition of the measurement of change of junction voltage formulae
i.e.
Thermocouple laws.

Hope this adds some value:  Bill Ellingford

-Original Message-
From: Colgan, Chris [mailto:chris.col...@tagmclaren.com]
Sent: 13 May 2002 10:28
To: emc-p...@majordomo.ieee.org
Subject: RE: Constant for Change of Resistance formula.



Ned is referring to the constant used in the temperature rise calculated
by
change in resistance formula ie

...

Where dt is the temperature rise, R1 is start resistance, R2 is end
resistance, T1 is start ambient and T2 is end ambient.  234.5 is the
formula
constant for copper.

This formula is used extensively when heat testing transformers and coils.

I'm afraid I don't know the constant for brass but I believe the figure may
be related to the inferred absolute zero of a material.  Try asking a
metallurgist?

Regards

Chris Colgan
Compliance Engineer
TAG McLaren Audio Ltd
The Summit, Latham Road
Huntingdon, Cambs, PE29 6ZU
*Tel: +44 (0)1480 415 627
*Fax: +44 (0)1480 52159
* Mailto:chris.col...@tagmclaren.com
* http://www.tagmclaren.com




 -Original Message-
 From: Robert Wilson [SMTP:robert_wil...@tirsys.com]
 Sent: Friday, May 10, 2002 7:00 PM
 To: emc-p...@majordomo.ieee.org; Ned Devine
 Subject: RE: Constant for Change of Resistance formula.

 What are the units? 234.5 ...what?? Looking at what the units are, will
 basically tell you exactly what the property is related to.



 Nonetheless, you cannot

Re: Constant for Change of Resistance formula.

[Robert Macy]

Bill/group

Let's check all these numbers.

Room temp of 20C?  68F (br).  More like 25C, 77F.

Most people assume room temp is 297K (or is that 298?) which is more like
23.82C, ~75F (seems more reasonable), putting that into the linear equation
gives

  234.5 + 23.82 = 0.00387
error less than 0.7% compared to
0.0039

However the formula is very clear that this is a short range linearity

When you extrapolate to 100C, or 75C rise above ambient, the linear formula
predicts 1.295 times the room temp resistance, but the actual value climbs
more like:

(1+0.0039)^75  = 1.339   (for 1 degree steps)
  error is now more than 3%

My conclusion is to just measure it.

Run current through the contacts, measure the resistance, then stick the
whole thing in a temp chamber and increase temp 'til you read the same
resistance.

Or, lower the temp from ambient, until you read the SAME resistance.  Then
that temperature difference is your rise above ambient.

I know, I know.  The first method does not take into account thermal
gradients that cool parts of the conductors and would suggest less rise than
actually occurs - which could be a large error, say measure 25C rise, but
actually have 35C rise in the hotspots.

The second method is moving into the nonlinear range, but for a temp change
of 25C is only 0.4% error.  Therefore, to more closely approximate the
actual conditions, I'd recommend you cool the connector and reproduce the
resistance measurement made at room temp.


Any idea why their chart (at that website) showed temp coefficient of 0.0068
for copper?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



-Original Message-
From: Bill Ellingford bill.ellingf...@motion-media.com
To: 'Robert Macy' m...@global.california.com; emc-p...@majordomo.ieee.org
emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Monday, May 13, 2002 8:15 AM
Subject: RE: Constant for Change of Resistance formula.


Hi Robert / group
OK, Not the best choice of website to demo the answer.  The differing
figures are because the formula has been transposed to give Temp from
change
of R from the original formula which gives R from change of T.  To do this,
another constant (The 234.5 constant) is required.  This is the implied
point of zero resistance for copper on the Celsius scale.  The formula we
use is:

  Rfinal - Rorig
  x (234.5 + Tamb start) -(Tamb finsh - Tamb start)
  Rorig

The Tamb start and finish are the changes (if any) in Room ambient.  If the
room remains at 20c then 234.5 + 20 is the multiplier.

-Original Message-
From: Robert Macy [mailto:m...@california.com]
Sent: 13 May 2002 14:54
To: Bill Ellingford; emc-p...@majordomo.ieee.org
Subject: Re: Constant for Change of Resistance formula.


Bill,

Thanks for the site.

Went there and found the same formula and constant I use.

For copper, Temp Coeff = 3.9 x 10-3

Then I clicked on table of coeff and there was a very long list of
materials, but the temp coeff of copper there was 6.8 x 10-3  ???!!!

Any ideas for this disparity?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Bill Ellingford bill.ellingf...@motion-media.com
To: 'Colgan, Chris' chris.col...@tagmclaren.com;
emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Date: Monday, May 13, 2002 5:38 AM
Subject: RE: Constant for Change of Resistance formula.



Hi Folks
Further to the answer given, here is a little more data.
The constant used is for the change of resistance with temperature.  metals
and alloys (conductors) all exhibit a different constant.  This can be used
for calculating temperature rise or resistance change.  i.e. find the temp
rise from a start and finish test measurement on a winding (for example) at
the begining and end of a on load heat run or, find R for a given temp:
using a table or the formula, resistance at various temperatures can be
pre-determined from a measurement made at one particular temperature.

A website with the formulae can be found at
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html

Where you have a transition from one metal type to another, you must
measure
each metal part individually.  If you have only two metals in contact, you
may be able to apply a combination of the temp coefficient methods and
transposition of the measurement of change of junction voltage formulae
i.e.
Thermocouple laws.

Hope this adds some value:  Bill Ellingford

Re: Constant for Change of Resistance formula.

[Robert Macy]

Bill,

Thanks for the site.

Went there and found the same formula and constant I use.

For copper, Temp Coeff = 3.9 x 10-3

Then I clicked on table of coeff and there was a very long list of
materials, but the temp coeff of copper there was 6.8 x 10-3  ???!!!

Any ideas for this disparity?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Bill Ellingford bill.ellingf...@motion-media.com
To: 'Colgan, Chris' chris.col...@tagmclaren.com;
emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Monday, May 13, 2002 5:38 AM
Subject: RE: Constant for Change of Resistance formula.



Hi Folks
Further to the answer given, here is a little more data.
The constant used is for the change of resistance with temperature.  metals
and alloys (conductors) all exhibit a different constant.  This can be used
for calculating temperature rise or resistance change.  i.e. find the temp
rise from a start and finish test measurement on a winding (for example) at
the begining and end of a on load heat run or, find R for a given temp:
using a table or the formula, resistance at various temperatures can be
pre-determined from a measurement made at one particular temperature.

A website with the formulae can be found at
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html

Where you have a transition from one metal type to another, you must measure
each metal part individually.  If you have only two metals in contact, you
may be able to apply a combination of the temp coefficient methods and
transposition of the measurement of change of junction voltage formulae i.e.
Thermocouple laws.

Hope this adds some value:  Bill Ellingford

-Original Message-
From: Colgan, Chris [mailto:chris.col...@tagmclaren.com]
Sent: 13 May 2002 10:28
To: emc-p...@majordomo.ieee.org
Subject: RE: Constant for Change of Resistance formula.



Ned is referring to the constant used in the temperature rise calculated by
change in resistance formula ie

...

Where dt is the temperature rise, R1 is start resistance, R2 is end
resistance, T1 is start ambient and T2 is end ambient.  234.5 is the formula
constant for copper.

This formula is used extensively when heat testing transformers and coils.

I'm afraid I don't know the constant for brass but I believe the figure may
be related to the inferred absolute zero of a material.  Try asking a
metallurgist?

Regards

Chris Colgan
Compliance Engineer
TAG McLaren Audio Ltd
The Summit, Latham Road
Huntingdon, Cambs, PE29 6ZU
*Tel: +44 (0)1480 415 627
*Fax: +44 (0)1480 52159
* Mailto:chris.col...@tagmclaren.com
* http://www.tagmclaren.com




 -Original Message-
 From: Robert Wilson [SMTP:robert_wil...@tirsys.com]
 Sent: Friday, May 10, 2002 7:00 PM
 To: emc-p...@majordomo.ieee.org; Ned Devine
 Subject: RE: Constant for Change of Resistance formula.

 What are the units? 234.5 ...what?? Looking at what the units are, will
 basically tell you exactly what the property is related to.



 Nonetheless, you cannot possibly directly determine what the temperature
 change of something as physically and geometrically complex as a
 connector, merely by factoring in what its resistance change is. Among
 other things, the solution is extremely non-linear and iterative. Changing
 resistance will generate more heat, which will increase temperature, which
 will generate even more heat and on and on! Add this to the fact the
 resistance coefficient with temperature is itself non-linear, and you can
 see how this complicates things further. The final temperature that the
 system stabilizes at, is reached when the logarithmically increasing
 (i.e. also very non-linear) heat transfer to the environment caused by
 increasing temperature, balances increased heat being generated.



 To reach a solution, you need to iterate your calculations, where the
 results of one calculation are plugged as variables into the next
 iteration. Typically a thermal analysis program will require several
 hundred iteration before a converged solution results.



 Bob Wilson
 TIR Systems Ltd.
 Vancouver.

 -Original Message-
 From: Ned Devine [mailto:ndev...@entela.com]
 Sent: May 10, 2002 8:29 AM
 To: emc-p...@majordomo.ieee.org
 Subject: Constant for Change of Resistance formula.



 Hi,



 Does any one know how the constant for CoR formula was determined? I know
 the K is 234.5 for copper and 226 for aluminum, but what property is this
 related to?



 I am trying to determine the change in temperature of a connector, based
 on the change of resistance. The connector contacts are made of brass.



 Thanks



 Ned





 Ned Devine
 Program Manager
 Entela, Inc.
 3033 Madison Ave. SE
 Grand Rapids, MI 49548
 1 616 248 9671 Phone
 1 616 574 9752 Fax

Re: Constant for Change of Resistance formula.

[Robert Macy]

Ned,

Not familiar with this K term.  For straight resitance changes in
transformers, we always used 0.0039 per C.  Does K somehow include contact
resistance, not just bulk resistance?

This is definitely the time to measure it.

Environmental chamber at -50, 0, 50, 100, and 150.  Make your own curves.



- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112

-Original Message-
From: Ned Devine ndev...@entela.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Date: Friday, May 10, 2002 8:45 AM
Subject: Constant for Change of Resistance formula.


Hi,

Does any one know how the constant for CoR formula was determined?  I
know the K is 234.5 for copper and 226 for aluminum, but what property is
this related to?

I am trying to determine the change in temperature of a connector, based
on the change of resistance.  The connector contacts are made of brass.

Thanks

Ned


Ned Devine
Program Manager
Entela, Inc.
3033 Madison Ave. SE
Grand Rapids, MI  49548
1 616 248 9671 Phone
1 616 574 9752 Fax
ndev...@entela.com e-mail

Entela, Inc. A Certified Woman Owned Business
www.entela.com











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Re: ESD

[Robert Macy]

Slight adjustments

Part I   http://www.pcdmag.com/mag/archives/OEG20010928S0122.html
Part II  http://www.pcdmag.com/online/redux_0701_esd.html

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: John Barnes jrbar...@iglou.com
To: Richard Jones gw0...@ntlworld.com; emc-p...@majordomo.ieee.org
emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Tuesday, April 23, 2002 7:10 AM
Subject: Re: ESD



Richard,
I invite you to read my article Designing Electronic Equipment for ESD
Immunity.  Part I was published in the July 2001 Printed Circuit Design
magazine (vol. 18 no. 7, pp. 18-26).  Part II was published on the
magazine's web site in November 2001.  You can download the entire
article from the Internet:
*  Part I-- http://www.pcdmag.com/story/OEG20010928S0122
*  Part II-- http://www.pcdmag.com/redux/0701_esd.html

I also have a (partially-) annotated bibliography for the article at
   http://www.r-e-d-inc.com/esd-anno.htm
which covers close to 1400 source documents on the subject.

Enjoy!
 John Barnes
 Consultant, Robust Electronic Design, Inc.
 President, dBi Corporation




---
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Re: Marking - Made in XXX

[Robert Macy]

Amund,

I believe it's a law in the US that all products be labeled with their
country of origin.

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112

-Original Message-
From: am...@westin-emission.no am...@westin-emission.no
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Saturday, April 20, 2002 3:08 PM
Subject: Marking - Made in XXX



Is it necessary to describe where a product is manufactured, as in Made in
XXX. I have see this statement/label on many products, but is it only
voluntary ?

Best regards
Amund Westin, Oslo/Norway



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Re: Decoupling - capacitor values

[Robert Macy]

Years ago in ultrasonic echocardiography instrumentation (the ultrasonics
analog is a wide band receiver listening in the 1-10MHz region down to less
than 10uV, so the digital had better be quiet!) which used a bit slice
architecture system containing Schottky logic with a clock of 20MHz for
controlling and manipulating images in real time.  We're talking 4 PCBs
using 10 amps each board, so you can see the opportunity for generating
horrific noise that would be injected into the analog section.  We found
that power distributed using a tree type of distribution where traces were
thick then thinner out at the extremities *and* +5 was over top of GND made
for the quietest distribution.

The tree technique worked much quieter than the recommended grid structure
where +5 distribution on bottom layer goes one direction with GND
distribution on the top going the other.  This structure made little tiny
loop antennas that radiated energy all around inside the box and was awful!
But easier for the layout people.

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: am...@westin-emission.no am...@westin-emission.no
To: ieee pstc list emc-p...@ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Thursday, April 18, 2002 12:49 AM
Subject: SV: Decoupling - capacitor values



Correct, the picture is complex. The PCB is 2-layer with signal, 5V-power
and 0V-ref lines routed on both sides. There is no ground layer/plane.
There
must be a large number of RF current loops because the 0V-lines are routed
up and down and around.
Beside trying to achieve a good decoupling I assume that reducing loop area
is the most important.

Amund



-Opprinnelig melding-
Fra: Cortland Richmond [mailto:72146@compuserve.com]
Sendt: 18. april 2002 00:54
Til: am...@westin-emission.no; ieee pstc list
Emne: Re: Decoupling - capacitor values


Yes, it makes sense. But the goal here is preventing or reducing Vcc drop
during the time the microprocessor is switching. You need not only low
reactance, but *also* enough capacitance to supply the current needed
_while it is switching_. You have not given enough information here to tell
if 820pF is sufficient.

Regards,

Cortland Richmond

Amund Westin wrote:

 Insert a SMD ceramic capacitor of value 820pF in parallel with the
existing
100nF. The reason for the low value 820pF is because the capacitor
self-resonance frequency is approximate 180MHz, and I believe it is
important to choose a Cap value with a resonance frequency higher than the
frequency we would like to decouple.

Does it make sense?







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Re: Faying

[Robert Macy]

Ed,

Thank you.  Especially the part blaming Woodgate.

My grandfather's name was Fay (son of Irish immigrant) and I always wondered
at the origin of that name.

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Price, Ed ed.pr...@cubic.com
To: 'EMC-PSTC List' emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Monday, April 01, 2002 7:13 AM
Subject: Faying



A couple of weeks ago, there was a thread discussing bonding techniques for
ground studs. I suggested that MIL-B-5087 had some nice drawings showing
typical accepted military practices. Of course, MIL-B-5087 has been
superseded by MIL-STD-464, but you can still find electronic copies of
MIL-B-5087.

Jacob Shanker read through all of the 464 sections on Bonding, and then
asked me if I knew what the term faying meant. It seems that MIL-STD-464
uses that term without any definition, as if it's a very common American
English word. IMHO, I consider myself to possess a rather decent
vocabulary.
But faying left me puzzled, even after closely reading the context of the
several citings in MIL-STD-464. It's certainly not in any common usage in
my
part of the world. I certainly wouldn't want to call something faying at
any typical US military base. So, off to the dictionary web sites.

1. Britannica says: not found.
2. Merriam Webster says: Main Entry: fay // Pronunciation: 'fA // Function:
verb
   Etymology: Middle English feien, from Old English fEgan; akin to Old
High
German fuogen to fit, Latin pangere to fasten
   Date: before 12th century : to fit or join closely or tightly
3. Harcourt's Metallurgy Engineering Dictionary says: faying surface //
Metallurgy: the interface between two metallic parts that are to be joined.
4. Finally, turning to Google in desperation for a simple explanation, I
find pictures at:
http://www.offroaders.com/info/tech-corner/reading/bolt-tension/bolt_tensio
n
.htm

So after all this searching, I find that MIL-STD-464 faying is just a
12th
Century Old English way to say facing or mating surfaces. I'm not sure
how he did it, but I suspect John Woodgate is to blame for this.

Regards,

Ed


Ed Price
ed.pr...@cubic.com
Electromagnetic Compatibility Lab
Cubic Defense Systems
San Diego, CA  USA
858-505-2780  (Voice)
858-505-1583  (Fax)
Military  Avionics EMC Services Is Our Specialty
Shake-Bake-Shock - Metrology - Reliability Analysis





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Re: Relative merits of various logic families in not generating RFI

[Robert Macy]

Thank you for the prompt reply.

Yes, faster rise time would lend the signal and its generation to create
energetic RFI, but just in case there were some internal states that blew
power out, or high impedance return paths through the substrate that caused
all the outputs to dance in common mode horror would be examples of the
gotchas I was looking for.

   - Robert -

-Original Message-
From: peter.pou...@invensys.com peter.pou...@invensys.com
To: Robert Macy m...@california.com
List-Post: emc-pstc@listserv.ieee.org
Date: Tuesday, March 19, 2002 8:23 PM
Subject: Re: Relative merits of various logic families in not generating RFI



Robert,

I suggest you have a look at the logic selection guides and application
notes from the major semiconductor logic manufacturers.

As a starting point, check out page 13 to 15 of
http://www.fairchildsemi.com/ms/MS/MS-520.pdf for a rule-of-thumb guide on
how to assess EMI generation from the manufacturer's specs for the logic.

Generally the slower the rise  fall time, the lower the emissions.






Robert Macy
m...@california.com  To:
emc-p...@ieee.org
Sent by:   cc:
owner-emc-pstc@majordomFax to:
o.ieee.org Subject: Relative
merits of various logic families in not
   generating RFI


20/03/02 08:49
Please respond to
Robert Macy







Group,

What are the relative merits of the various logic families HCT, HC, AC, ACT
with regard to generating RFI?

I remember one time we replaced an HCT which made more noise than Schottky
TTL due to an internal overlap in the switching causing a power rail
shorting spike.

I'm sure by now that most IC vendors have addressed the EMC problems
associated with poorly designed chips, but what's the status on these now?

What's the order of preference?  Which one's best?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



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Relative merits of various logic families in not generating RFI

[Robert Macy]

Group,

What are the relative merits of the various logic families HCT, HC, AC, ACT
with regard to generating RFI?

I remember one time we replaced an HCT which made more noise than Schottky
TTL due to an internal overlap in the switching causing a power rail
shorting spike.

I'm sure by now that most IC vendors have addressed the EMC problems
associated with poorly designed chips, but what's the status on these now?

What's the order of preference?  Which one's best?

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



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Re: creepage v breakdown voltage

[Robert Macy]

Doing high voltage power supplies we found we always got in trouble using
20,000 V/in and things worked well when we kept below 10,000 V/in.

Metric that's 790 V/mm and 390 V/mm

This was free air and not some kind of pointy structure.

  - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Roman, Dan dan.ro...@intel.com
To: 'MCA Compliance' bally...@iolfree.ie; Emc-Pstc Post
emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Friday, March 15, 2002 6:49 AM
Subject: RE: creepage v breakdown voltage



I was looking into this a few weeks ago also and found similar results
experimentally as other posters have mentioned.  The only voltage per inch
spec I was able to come up with was in the IPC specs but they were way out
of whack!  0.12 mils per volt or more meaning that 2121 Vdc distance that
the safety standards say should be 2.5 mm the IPC spec is saying you need 5
mm

While the safety standards may be conservative to allow for temperature,
grease, dirt, etc. over time the IPC specs are ultra-conservative.  The
dielectric tables for hermetically sealed material group III is probably
closer to the actual breakdown but I never did find a spec I could use to
predict the ACTUAL breakdown voltage of a gap between traces.  If anyone
finds a rule of thumb or equation I'd like to have it also.

Dan

-Original Message-
From: MCA Compliance [mailto:bally...@iolfree.ie]
Sent: Friday, March 15, 2002 4:54 AM
To: Emc-Pstc Post
Subject: creepage v breakdown voltage



does data exist which correlates creepage distance on a pcb with
hi-potential test voltage it should withstand ?

for example, I know 60950 sugests a test voltage of 1500Vrms for 1 minute
and a creepage of 2.5mm (material group III) for basic insulation.

How did they arrive at 2.5 mm ???

Brian
email: i...@mcac.ie




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Re: Don'r Get Caught Running a Red Traffic Light!

[Robert Macy]

Did you take a look at the people who make traffic light controllers?  , and
the magnetic sensor people?

If you can't find something, I'll see what's in archives around here.  Know
nothing related to your needs, just some of the players' names.

Also, you'd be amazed the information you can get from the city engineers
regarding this stuff - well at least here in San Jose.

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Peter Merguerian pmerguer...@itl.co.il
To: EMC-PSTC (E-mail)  emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Wednesday, March 06, 2002 9:18 AM
Subject: Don'r Get Caught Running a Red Traffic Light!



Dear All,

For an outdoor pole-mounted computerized camera taking pictures of your car
and its license plates when you run over a red light, does anyone have an
objection to the following safety standards for ITE? Is it ok to assume
that
the mains transient voltage for outddor equipment is limited to 2500V?

UL60950:2000]
EN60950:2000
IEC60950:2000

This e-mail message may contain privileged or confidential information. If
you are not the intended recipient, you may not disclose, use, disseminate,
distribute, copy or rely upon this message or attachment in any way. If you
received this e-mail message in error, please return by forwarding the
message and its attachments to the sender.


PETER S. MERGUERIAN
Technical Director
I.T.L. (Product Testing) Ltd.
26 Hacharoshet St., POB 211
Or Yehuda 60251, Israel
Tel: + 972-(0)3-5339022  Fax: + 972-(0)3-5339019
Mobile: + 972-(0)54-838175
http://www.itl.co.il
http://www.i-spec.com





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Re: CCFL light output

[Robert Macy]

Recommend you get a copy of Westinghouse Lighting Handbook

In one table they show lumens output for various fluorescent lamps with
current and volts input required.

for the Preheated
des.len curr. vol. *pwr lumens *lumens/watt
4W   6  0.132 32   4.32  115   26.6
6W   9  0.147 47   6.91  250   36.2
8W  12  0.170 56   9.56  420   43.9
20W 24  0.380 56   21.321220   57.2
30W 36  0.355 98   34.8 2100   60.3
84W 60  1.530 63   96.4 6250   64.8

for the High Output
len*pwr   lumens   *lumens/watt
24 32.8160048.8
48 60  400053.5
72 90.4645071.3
961328 900068.2

for the Super-Hi, Outdoor, and Low temp-jacketed
len*pwr   lumens   *lumens/watt
48 129 6900   53.5
72 19211100   62.5
96 25815500   60.1

*calculated values


Appears to be a nonlinear relationship.

Also, Slimline which come in smaller/different diameters have different
lumens per watt for the same length.


There is another curve rating efficiency (lumens per watt) which ranges from
52 lumens per watt for a natural color lamp to 80 lumens per watt for warm
white lamps.  But it doesn't say which basic tube is used as a reference.
Probably 72inch


Is this enough for you to do your modeling?

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Wani, Vijay (V) vw...@dow.com
To: 'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Wednesday, February 27, 2002 8:27 AM
Subject: CCFL light output



Group:
 I am trying to build a thermal model a cold cathode fluorescent lamp
(CCFL)
for cooling analysis.  CCFL manufacturer showing a chart of light output in
Lumens as a function of lamp length and diameter.  I need to convert lumens
to watts for input into Icepak. I would appreciate any help you can
provide.

thank you in advance.

Vijay Wani




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Re: Use of PCB Traces as Fuse and Voltage suppressor

[Robert Macy]

Jim,

You touch on an important issue concerning a fuse - just how does it blow?

Years ago I discovered by accident that fuses were designed with some
remarkable properties, when we had to make our own transient generator to
verify some telcom equipment's compliance to a BABT power supply transient
spec.

The BABT spec required that you simulate some very husky power transients.
It was like a short occurs in adjacent electronics followed by the inductive
kick.  The -48 voltage would clamp to around 10 volts then pop up to over
300 volts capable of supplying 500A for something like more than 50mS.  If
you didn't design your protection properly you would have a lot of
unintentional PCB trace fuses.  [  Actually heard that the spec originated
because a workman had dropped his wrench across the 1 inch diameter rods
which supply the -48 to the telco building from the battery building.  After
the wrench evaporated, they found the whole room of equipment was blown,
thus the spec.  Somebody verify that?  ]

The simulator used 4 deep discharge current vehicle batteries supplying the
telcom equipment through 50uH of inductance (that was  cable on a
spool).  Parallel to that you used a starter solenoid to short out a fuse
with a dead short.  Amazingly the larger fuses never produced much kick
back.  They were designed to blow gently away.  Tried all kinds.  Most of
the 8AG didn't do much, other types, nothing, even the 100 amp cartridge
types, nothing,  The absolute best was a 1A 8AG type.  When that went, you'd
get a flash of light, 300 volts trying to drive 500 amps into everything,
and even the coil would jump up off the floor.

Talk about PCB traces acting like fuses.

Anyway, I learned a respect for people who design fuses to make them go away
so gently when there is an incredible potential for some extremely high
voltage transients.

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



-Original Message-
From: Jim Bacher jim.bac...@paxar.com
To: 'Cortland Richmond' 72146@compuserve.com; Chris Maxwell
chris.maxw...@nettest.com; ieee pstc list emc-p...@ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Monday, February 25, 2002 3:04 PM
Subject: RE: Use of PCB Traces as Fuse and Voltage suppressor



Long time ago we found that the traces worked well as fuses when the
batteries were fully charged. However, when the batteries were mostly
discharged, the PC Board traces did not work well as fuses. At lower
battery
charge levels, the traces became very hot and ignited the PC Board rather
than opening the traces up.  I therefore would recommend against using PC
Board traces as fuses.


Jim

Jim Bacher,  Senior Engineer
Paxar Corp.
e-mail: jim.bac...@paxar.com  or  j.bac...@ieee.org
voice: 1-937-865-2020
fax: 1-937-865-2048

-Original Message-
From: Cortland Richmond [mailto:72146@compuserve.com]
Sent: Thursday, February 21, 2002 12:53 AM
To: Chris Maxwell; ieee pstc list
Subject: RE: Use of PCB Traces as Fuse and Voltage suppressor



When do you need a fuse? Level II is the only time you are allowed to lose
functionality, and the requirement for THAT is, it can't catch fire or
explode. I've seen trace fuses tried. The problem comes after the trace
blows.  You are at the mercy of your board shop, and if you use a number of
them, results might not be all that repeatable.  AS i said earlier, I've
had a board catch fire in my hand (though not as a result  of stress, but a
solder splash). It is instructive.

Cortland

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Re: Need Help on Inner PCB plane for RF shielding in isolated circuit

[Robert Macy]

Chris,

Using a PCB layer as an RF shield.  Don't forget you probably have that PCB
layer cut into swiss cheese with vias, unless you used blind vias.


Background:

A microstrip trace will radiate off the board a certain amount - makes sense
since part of its field is out in free space.

A stripline should not radiate anything because it is between two ground
layers, right?  Wrong.  A stripline in a practical PCB layout will only drop
the emission around 14dB, due to all the swiss cheese that got cut into the
PCB.


My point is, knowing the above practical information are you sure that an
RF shield made by a swiss cheese PCB layer will give you that much
shielding?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112

-Original Message-
From: Chris Wells cdwe...@stargate.net
To: EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org
Date: Thursday, February 21, 2002 5:45 AM
Subject: Need Help on Inner PCB plane for RF shielding in isolated
circuit


Hi - I'm looking for some practical advise on using an inner Printed
Circuit Board PCB  plane tied at the corner mounting holes of the chassis
as a shield from RF exposure coming in on an isolated field circuit relative
to another digital logic board.

Questions:
a.. Must my shield layer be the bottom most inner plane to be
effective? Note that the 2 board solder sides face each other.  Layout wise
it is very difficult to do without going to a 6 layer board - I am trying to
stay with 4 if possible.
b.. Would I get some capacitive bypass protection if the grounded
shield plane where the top inner layer of the field circuit and the isolated
field circuit common was the bottom inner plane exposed to the adjacent
board?  I know the field would not be blocked but the capacitive bypass to
the chassis should reduce the RF intensity.
c.. Would the placing of the grounded plane between the top PCB
components and the Isolated common plane disturb the performance of the
field circuitry?  What would this do to the field circuit return path loop
area?
d.. Would a ground pour on the solder side of the adjacent PCB hurt
or help?  It would increase the capacitance between the two boards but it
would reduce the loop area of the traces on the solder side of the adjacent
board too.
e.. PCB clearance issues within a PCB - What are the
clearance/voltage rating issues within a PCB?  What voltages can I support
from:
a.. Surface trace to inner grounded plane - Can 240VAC be
supported.
b.. Electrically hot via passing through the grounded plane -
What inner pad clearance would one use on a 240VAC circuit?
f.. What do the safety standards say? - I see that UL3111 version of
IEC 61010-1 can treat the PCB as a molded void free material and so the
clearance issues are not addressed.  I understand that IPC has a spec on
voltage ratings versus construction - I am looking for it now.

Details:
The circuit worked fine at 10V/M but I am now being asked to take this
to 35V/M and that is somewhat of a challenge.
Testing to ANSI C37.90.2 1995 25-1000 MHz.
My problem area is 400-500 Mhz.
I am trying to keep RF energy on field circuit from coupling over to an
adjacent board and corrupting the bus of some microprocessor based logic.
The two boards are only .200 apart.
I have experimented with an insulated grounded shield plane placed
in-between the two boards and it works great.
I can withstand 50V/M WITH 80% modulation!!!
Unfortunately the shield is very difficult to make for production and
the cost is an issue.

I am trying to put the shield into the 4 layer PCB in the area around
the field circuit.
The solder sides of the two boards face each other.
The field circuitry has lots of through hole PCB type components and so
there are leads and trace pads that are exposed on the bottom of the field
PCB.
I have trimmed the leads and this helps some.
Even with a 6 layer board and the bottom inner layer as a grounded
shield I would have the leads sticking through the shield like holes in
cheese.
The field circuit construction is:
a.. top +5V pour plus a couple traces
b.. top inner layer presently free - this is where I would like to
put the grounded shield plane.
c.. second inner layer (solder side) is the isolated field circuit
common,
d.. Bottom solder side are a number of field circuit traces.
Unfortunately the free plane is not the bottom inner plane but the
second from the top component side.
The two boards have DC:DC and opto signal isolation on the field board
relative to the adjacent logic board.
The two boards and are connected at one edge of the board

Re: Use of PCB Traces as Fuse and Voltage suppressor

[Robert Macy]

Our experience with gas discharge tubes was that they worked according to
spec in the lab.  fired perfectly around 400V like they're supposed to, but
down inside of the PVC oil tank holding the 150KV isolation transformer they
liked to fire at 600V+

Guess they needed photon energy to make the gas trigger or something.

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112



-Original Message-
From: Chris Maxwell chris.maxw...@nettest.com
To: bogda...@pacbell.net bogda...@pacbell.net
Cc: EMC-PSTC Internet Forum emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Wednesday, February 20, 2002 2:15 PM
Subject: RE: Use of PCB Traces as Fuse and Voltage suppressor



Hi Bogdan,

I'm sorry if you thought that my previous message was an endorsement for
using necked down PCB traces as a fuse.  I understand and share the
sentiment that it is an unpredictable and probably not even cost
effective solution.

I was wondering why anyone would shape a PCB trace in such a way (two
triangles pointing at each other with a thin trace between the points).
A fuse is probably not the likely intention.  A reasonable explanation
may be a cut jumper.  The triangles make the trace visible; while the
thin trace provides an easy spot for the trace to be cut with an exacto
knife which permanently removes the jumper.Another reason
(suggested by a colleage) are alignment marks used by the PCB fab house
to help align layers.

Just to be sure... I'm not suggesting the above as design ideas.  I'm
just trying to figure out why anyone would do such a thing.

One solution to the original problem that I haven't seen suggested is
the good old air discharge tube, gas-discharge tube, gas tube
...whatever you want to call them.  Of course, they aren't free (about
$1 each).  They are more predictable than open air terminals, they are
UL/CSA recognized and they can handle some massive breakdown currents.
They are available from Bourns and Sankosha USA... probably some other
manufacturers as well.

Chris



 -Original Message-
 From: bogdan matoga [SMTP:bogda...@pacbell.net]
 Sent: Wednesday, February 20, 2002 4:19 PM
 To: gab...@simex.ca; Chris Maxwell; emc-p...@mahordomo.ieee.org
 Subject: Use of PCB Traces as Fuse and Voltage suppressor

 Gabi:
 I believe that there is a basic rule which is not published anywhere:
 when you design something, then do it right.
 When transient suppressors are needed, then use the correct component,
 which will not depend on Paschen's Law and give predictable
 performance.

 Same for necked down fuses.
 When you want performance, then do it right. The above original
 suggestions are perfect for Mickey-Mouse-engineering.
 Bogdan.





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Re: CM Choke simulation

[Robert Macy]

Derek,

Yes, do it all the time.   As long as you don't get into saturating any
cores, you can pretty much use lumped models and none of the nonlinearities
associated with core material.

Don't forget to include your AC mains cable.  It's a trifilar wound
transformer.  A Belden AC cord looks like a 3 winding transformer with 7uH
core.

You can also model the LISN and the parasitic capacitance in your test
setup.  Very educational.

Why do you ask?

   - Robert -




-Original Message-
From: lfresea...@aol.com lfresea...@aol.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Date: Friday, February 15, 2002 1:42 PM
Subject: CM Choke simulation


Hi all,

I'm trying to model a common mode choke in Micro-sim. Has anyone tried
this? Failing that, any suggestion on how to model one in Spice, possibly
using magnetic models?

Thanks in advance.

Derek.


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Re: Clean class B test bed

[Robert Macy]

Tony,

When we had to test a 100MHz video two board system, weaknesses in grounding 
structures of the PC's became extremely evident.  Two stood out as the best 
(best internal motherboard grounding) Gateway (best) and Dell (very close 2nd 
best).  No other PC's yielded a compliant system.  [ Even had to fuss with 
the grounding plates on the back.]

Sorry, don't know model numbers, but they were large with the proportions of 
the old rack mount types.

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Tony raym...@bellsouth.net
To: emc-p...@ieee.org emc-p...@ieee.org
Date: Friday, February 08, 2002 11:42 AM
Subject: Clean class B test bed


Hello,

I am looking to find a clean Class B test bed (PC) for radiated emission 
testing. If anyone knows of such a thing please post the manufacturer, model 
number, any other information I would need to acquire one for use here.

 

Thanks for the help.

Tony Rayman

 

Re: Teslars???

[Robert Macy]

That's Tesla, which is a weber per sq meter.  It is a measure of the B
field, flux per area.  If you're English, 1 tesla is 10,000 gauss.

I don't believe those numbers.  We have light rail train go by here which is
powered by 600Vac (I believe it's 600 Vac)  I haven't seen the fields from
the motors, only the fields from the disturbance to the earth's field
(approx 50uT) as it is being deflected by the large metal vehicles.  Much
more an effect than from the power source.

If those specs you quoted go down to 50 Hz or 60Hz, than they relate,
otherwise doubt if you'lll easily relate them.  It would be susceptibility
to AC mains magnetic fields.

Might also look at the Swedish MPR II, or is that III now?  The limit for a
monitor radiating is 200nT in this bandwidth.

Underneath high tension wires I've seen fields around 100mG,  which
translates to 10uT!  and those fields are considered big.

Again, I question those specs.  Maybe they meant 0.6 to 1.7 microtesla.

 - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: marti...@appliedbiosystems.com marti...@appliedbiosystems.com
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Thursday, February 07, 2002 3:15 PM
Subject: Teslars???



We have a customer that is concerned about how our product, laboratory
equipment, will respond to electromagnetic disturbances from a high speed
train that runs close to their lab.  The customer states that the
disturbance will be around 0.7-1.2 m Teslar.

Can someone please explain what the unit Teslar is and how that unit
relates, or if it relates, to the immunity tests of EN 61000-4-3 Radiated
immunity, or any other immunity test.

Has anyone ever had a similar concern from a customer dealing with this
type of disturbance?

Your responses are appreciated.

Regards

Joe Martin
EMC/Product Safety Engineer
Applied Biosystems
marti...@appliedbiosystems.com





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Re: Safety Link Offers Classifed Ads to EMC-PSTC members (no-charge)

[Robert Macy]

Agree, worthwhile.

All the newspaper articles in the Career section of the newspapers say that
after being laid off to take off a few weeks, gain bearings, then look for
your new position.  I totally disagree.  I say take 20 minutes, shake your
head, and go for new places as agressively and thoroughly as if looking for
a position were the new job.

Usually, there are severance packages that allow for the following gap in
income.  Any reduction in that gap is free money.  Also, you maintain the
mental advantage of not needing the new position so you'll just have a
different attitude while you're looking, one of more power.

Years ago when I was hiring people, I always was more impressed with the
person who hits the pavement the next day, even better, the same day.
That makes them look like a self starter, agressive, *and* someone who
actually likes to work, wants to be back at work.

Just my two cents here.

   - Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112

-Original Message-
From: Cortland Richmond 72146@compuserve.com
To: Art Michael amich...@connix.com; ieee pstc list emc-p...@ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Tuesday, February 05, 2002 10:52 AM
Subject: Re: Safety Link Offers Classifed Ads to EMC-PSTC members
(no-charge)



Art,

What a nice thing to do! I am just getting ready to pick up my stuff from
the office, and then ... Why wait for the outplacement firm? Forward
momentum!

Cortland

(I cannot speak for Alcatel
They cannot speak for me;
OF all that we might choose to say,
The other now is free!)



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Re: Harmonics measurement instrumentation

[Robert Macy]

Hmmm...measured with a current meter, then measured with a wattmeter and got
different answersHarmonics out of phase? contain no power?

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: gunter_j_ma...@embraco.com.br gunter_j_ma...@embraco.com.br
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Tuesday, January 22, 2002 11:56 AM
Subject: Harmonics measurement instrumentation



List

I would like your precious opinion about a situation regarding harmonic
current measurement (61000-3-2).

First case:
Using a sinusoidal AC power source, with a controlled output voltage
(almost perfect sine, voltage THD lower than the needed, even with load), I
measured the current harmonics using the internal instrument of the power
source.
The 13th and 15th harmonics were right above the limits (Class A limits).

Second case:
I add a digital wattimeter to measure the harmonics.
The harmonic content became 30% lower than the first case (good enough to
pass). And I got this results with the two instruments (the one inside the
power source, and  the wattimeter).

My first thought was the increased impedance due to the wattimeter (Zm).
But I got 50mV of drop voltage in this instrument (peak voltage), that is
lower than the specified in 61000-3-2, Annex B (0,15Vpeak maximum).
And the impedance of its current shunt is only 0,008 ohms (data from its
manual).
This put my first guess down ! Theoretically, the wattimeter couldn't
attenuate so much the harmonics !

Any idea of what could be happening  ?

Thank you again.

Günter J. Maass
Researcher - Power Electronics Development
EMBRACO S.A.



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