EMC Shielding Demo

On 1/13/2015 Jerry greatly enjoyed demonstrating shielding effects and challenges to UIC students in Professor Danilo Erricolo’s class ECE 423 on EMC . http://www.ece.uic.edu/bin/view/ECE/ECE423

27 MHz Radio controlled toy car or 460 MHz FRS handi-talkies
were the sources and receptors sending their waves through a shielding “pot” and its variations . The car receiver was modified to excite an acoustical alert sounder, while the ordinary speaker of the handi-talkie “spoke” evidence of reception action.

First the lid , a single disk shield plate (far right in photo) , was held between the transmitter joy stick controller (in Jerrys hand) and the race car (red 2nd from right in photo ) . That was shown to be totally ineffective.
Thus one could initially hypothesize that radio waves at these frequencies do not behave like rays of light traveling in straight lines , to be blocked or reflected by “opaque” objects. Rather they behave more like acoustic or fluidic analogues flowing around ( diffracting ? ) or bouncing off other nearby objects.

Second , the solid metal open “cup-shape” or pot (in photo behind “shielding demo” white paper sheet) completely covered the race car with the open side facing away from the transmitter. It was also ineffective (for the same reasons) .

For maximum performance , one needs a fully enclosed “Gaussian shell” . It was demonstrated that huge shielding degredations occur from even Slight corruptions of the shell enclosure by modifying the fit / contact quality of the soup-pot lid against the pot opening. It was more remarkable at 460 MHz vs. 27 MHz.

A strainer version of the pot made of perforated metal (near Jerry’s hand) with ~5 mm diameter holes and using the same tight fitting lid , was effective at 27 MHz but largely ineffective at 460 MHz (why ? HINT Wave-guide beyond cutoff attenuation. Also handi-talkies have much more transmit power and receive much lower signal levels than 27 MHz toys , thus requiring more shielding attenuation to block transmission)

When an insulated ~12″ long wire penetrated a hole in the sealed strainer pot (as might be used to power the car within) , attenuation at 27 MHz was severely degraded. It acted like a receiving antenna to the transmitter outside the shield then the current it carried caused a re-radiated emission within the enclosure. However, when the wire was filtered with a sufficiently low impedance shunt capacitor, as a simple filter ( 2 nF not enough 10 nF enough) , shielding effectiveness was restored , as the current it was carrying was attenuated by diversion (bypassing) in to the shield structure.

Enjoy doing your own extensions and variations. Lets hear from you !

Jerry at JDM LABS 1/14/2015

Note : the inspiration for this demo was Dr. Amy Pinchuk of http://infieldscientific.com/eng/about.html
who demonstrated it at the IEEE EMC Society 2004 Symposium in Santa Clara .
Hey see you all in Santa Clara for the EMC Symposium this
March 16-20 http://www.emc2015usa.emcss.org/

JDM 1/23/2015

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JDM LABS 2013 Summary

Hello loyal fans & followers .
2013 has been a busy year for JDM LABS
As I popped into many tents along the midway I was treated to a lot of new and old situations . Here’s a brief overview of what went on.

** Corrected FCC Part 15 Radiated Emissions issues in VHF range on consumer product, used for linking Wireless acquired data to the Internet.
* FIX = Discrete Common-Mode choking / isolation of device from its connection to AC mains power source .
* Start-up company – housed in a Midwest University Industrial Park Incubator using KickStarter funding model.

** Reduced Radiated & Conducted Emissions in LW, MW & VHF ranges of in-vehicle 10 kW class AC mains battery charger.
* FIX = Extensive common-mode filtering on all I/O , plus external cable shields, plus careful routing of internal wiring to minimize coupling to near-field noise sources.
* Well established North-East power-conversion company adapting new technologies to new markets.

** Performed Design Review and bench-top analysis of “interface tool” to connect in-vehicle data busses to maintenance service tools.
* ACTION = Identified HF & VHF emissions risks & mediation approaches. Recommended PCB improvements.
* Medium sized South-East region specialty transportation electronics company, a repeat Client.

** Performed Design Review and Bench-Top Radiated Emissions analysis & mitigation identification on “manufacturing cell” using multiple VFD / Servo BLDC motor controls. Issues in the LW, MW and VHF regions affecting EU requirements.
* FIX = multiple common mode “cores” on all internal communications and power distribution cables . Ground-bond “clamps” on all external shielded motor cables.
RF gasketing of metallic enclosure seams & doors. .
* Large multinational company, headquartered in Midwest.

** Identified and reduced radiated emissions in HF & VHF regions from serial buss of battery monitor electronics for electric motor augmented personal-transportation.
* FIX = Common mode choke in serial data port .
* Small Midwest start-up, seeded by University researchers, using on-site manufacturing.

** Identified cause of Radiated Emissions in UHF region, from “Jumbo-tron”-like color LED image display. Worked on-site outdoors at a Midwest hotel.
* FIX = Firmware micro-code modification to attenuate specific signal components.
* Medium sized international company, experienced in large custom commercial LED image color displays.

** Advised methods & techniques to reduce radiated emissions in LW MW & VHF regions from portable 50+ kW class Diesel Electric generator source.
* FIX = Multiple discrete Common Mode filter elements on key circuit nodes.
* Medium sized Midwest company with a long history of locally manufactured generator-sets for transportation & military applications.

** Identified cause of UHF region RF Field immunity weakness in consumer vehicle entertainment media hub.
* FIX = PCB re-layout optimizing effectiveness of existing Common-Mode filtering elements.
* Midwest division of large multinational component & sub-assembly maker.

** Identified mitigation techniques to improve HF-VHF RF Current Immunity of off-road vehicle access control system.
* FIX = Cable Common-Mode ferrite choking.
* Medium sized Midwest company well-established in off-road vehicle support electronics.

** Identified & reduced RF emissions in LW-MW & VHF regions from switch-mode supply in LED illumination system for heavy vehicle applications.
* FIX = PCB layout optimized to minimize coupling of Differential-Mode signals into Common- Mode structures.
* Medium sized Midwest company with niche expertise in vehicle LED lighting systems.

====Recent Education Services ===
* Completed IEEE EMCS Distinguished Lecturer tour 2011-2012 . Informed & entertained & chapters in Austin & Dallas TX, San Jose CA, Madison WI, Detroit MI, Montreal & Ottawa CAN, Chicago IL.

* Developed and presented Lecture and Hands-on Laboratory on Cables & Shielding , supporting “Introduction to EMC SC071″ a 1.5 CEU continuing education course at Illinois Institute of Technology (IIT). Acting as adjunct Teaching Assistant with fellow IEEE EMC Chicago Chapter colleagues.

*Completed 3rd year of IEEE EMC Society Workshop & Tutorial on
” EMC Consultant’s ToolKit” at the Annual International EMC Symposium
in Denver Colorado. Co-presenters were Key Wyatt of Wyatt Technical
Services http://www.emc-seminars.com , Patrick Andre’ of http://www.andreconsulting.com
and Dr Tom Van Doren, of The Van Doren Company http://www.emc-education.com/.

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EMC MiniSymposium – May 7 – Chicago

Hello All : I want to alert you to a great education and networking event.
For those of you who cannot get to the “big” EMCS annual Symposium,
we’re bringing it home to you, Chicago Style .

15th Annual Chicago IEEE EMC MiniSymposium
Tuesday May 7, 2013
Itasca Country Club, 400 East Orchard, Itasca, IL 60143
Convenient to IL-53 / I-355


“Fundamentals of EMC”

“Critical Infrastructure and the Potential Impacts ,
HEMP EMP IEMI and Geomagnetic Disturbance”

“Very-Near-Field Solutions for Far-Field Problems”

“How Coaxial Cables behave in EMC Environments”

“Multi-Tone Radiated Immunity per IEC Standards
Cut your test time in half (or more)”

NEW ! afternoon parallel segment :
“Hands-on Experiments and Laboratory Demonstrations”
Sponsored by Chicago’s own Education Committee

Your Very Affordable Full Day Program Includes :
Lunch, Breaks / Snacks.
20+ Equipment & Services Vendor / Exhibitors.
Professional Engineers (PE’s) 4 PDH credits
Attendance Certificate
Printed Presentations Booklet.
Valuable Prizes – Drawings, Raffles, EMC-Opoly

We look forward to seeing you at our 15th annual event !
– Frank Krozel, MiniSymposium Chairman –

Advanced Program http://www.emcchicago.org/adv.pdf
Attendee sign-up form http://www.emcchicago.org/aform.doc
Vendor sign-up form http://www.emcchicago.org/vform.doc

Exhibitors and Vendors signed up as of 4/14/2013

Electronic Instrument Associates Central, Inc.
Elite Electronic Engineering
EM Test
DLS Electronic Systems
IEEE EMC 2013 – Denver
EMI Solutions
Associated Research
HV Technologies
TRS Rentalco
Fair-Rite Products Corp
API Technologies-Spectrum Control
Teledyne LeCroy
VTI / Vacuum Technologies lnc.

Please check for additional details and updates

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Ghosts In The Machine ?

March 22, 2013 . Dothan GA .
After eating dinner , our 2012 Ford Fusion, with doors still locked,
somehow had fully opened driver and passenger door windows and tipped open the sunroof.
This was depite using the keyless entry fob to lock doors and hearing the acknowledge
“horn beep” after arming the security system !!

Do not think its an “EMC problem” ..
Could there be a keyless entry command to open the 3 (of 5) windows
yet keep doors locked ?

Then , its SYNC info-tainment system is “powered by uSoft” & uses Bluetooth .
Any known HACKS for the Bluetooth pathway in ?

Automotive buss architects claim there are no physical connections
between critical comand & control systems and auxillary or option feature buss’.
But I heard tales of buss hubs, portals & bridges for the convenience of design & development ? hummmm

** For more discussions of vehicular electronics “ghosts” see :

LinkedIn Group *EMC Experts*
“Auto Unintended Acceleration still in the news”

“Is Toyota Telling the Truth About Sudden Acceleration?”

OK I’m embarassed – its the old “read the manual” Lesson-Learned 😉
Describes the “global open” function: Hold down the unlock button for 5 seconds.
An easy to explain scenario from mashing keys in pocket or purse. Need to have dealer de-program the “feature” . Thanks to Chris Armstrong of LinkedIn “EMC Experts” for getting it. Now back to our regularly scheduled EMC stories .

Jerry at JDM LABS

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DIY Current Probe Comparison

Hey Everyone . Ever balked at paying $100’s for a “regulation” RF current probe ? Well here’s a comparison between a DIY probe made from a clamp-on ferrite vs. a commercial one by Fischer (FCC) . Thanks to Colleague Ken Wyatt http://design-4-emc.com/ for loaning me his FCC F-33-1 probe.


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EMC Training = Chicago MiniSymposium

Thought you would like to get a day of great & affordable EMC Training .  Just $35 for IEEE members includes generous Lunch & break snacks. Over 20 Exhibitors of the latest EMC equipment, components, software  & services.  Enjoy our EMC-opoly game with prizes as well as  periodic raffle drawings.  A great day of learning & Networking !  See you there !

Tuesday May  8  14th Annual Chicago EMC MiniSymposium  
(Itasca Country Club,  400 East Orchard, Itasca, Il. 60143)          http://www.emcchicago.org/    

 Attendee sign-up   http://www.emcchicago.org/sectfiles/aform.pdf  

Programme :    7:30     Registration
8:00     Welcome – Frank Krozel
8:15     “Fundamentals of EMI / EMC”  – Tom Braxton, Shure Incorporated
9:15     “Tips / Techniques for making EMI measurements with a  Spectrum Analyzer  and Test Receiver”   Lee Hill, Silent Solutions
10:15   Break / Vendor tabletops  

11:15   “Conductive Plastics” – John Perkins, Parker Hannifin
12:15   Lunch
12:45   Break / Vendors
1:30     “The Hype Surrounding the BiConical/LPDA Hybrid Antennas”   – Zhong Chen, ETS-Lindgren 

2:30     Break / Vendors
3:30     “PCB Layout Details for Reduced EMI Issues”
         – Roger Swanberg, DLS Electronic Systems
4:30     “Testing Smartgrid and other Emerging Technologies”
          – Jason Smith, HV Technologies
5:30     Symposium concludes

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All About EMC Consulting – Save The Date

Hello loyal followers.

Its been a while , Life sometimes gets in the way. But I want to share news of a great upcoming event in Long Beach Ca. The IEEE EMC Society annual International Symposium  August 14 thru 19 . Particularly the Friday afternoon Workshop : “EMC Consultant’s Toolkit ”  FR-PM1  http://www.emc2011.org/assets/files/Workshops&Tutorials.pdf

Its important because many companies cannot afford a full-time / on-staff skilled EMC expert to guide or remediate their designs, especially in this economy.  Thus there is a huge opportunity for consultants to help companies on an as-needed basis. The session addresses practical tools & skills across technical , business & interpersonal domains. 

We’ve assembled a world class team with over a century of combined experience. I’m doing the intro & leadoff “Marketing Yourself” . Then Kenneth Wyatt of http://www.emc-seminars.com/index.html  covers “Practical Troubleshooting & Using Social Media” . Henry Ott of http://www.hottconsultants.com/news.html who is a pioneer of EMC consulting in the USA will spin “War Stories” which both teach & entertain.  Patrick  Andre’ of  http://www.andreconsulting.com/  will address”Presenting Yourself Professionally” . Then Daryl Gerke of http://jumptoconsulting.com/ will answer that question ” So you want to be a consultant?” . Finally all 5 of us will do a panel discussion taking questions from the audience.

So if you have questions for the panel please submit them here & we’ll make every effort to cover them. If it is very time sensitive we’ll get you the answer sooner .

So hope to see you in Long Beach  or we can dialog right now !  

I’ve been helping out a number of clients and the <generalized> case studies will appear here in the coming days & weeks.

Best Regards,  Jerry

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Hi again friends. Before we spotlight the 2 remaining Rings of the Big Top,  I thought it would be helpful to share another popular overview / construct. 

We already discussed SOURCES and that they come in 2 flavors : Conducted & Radiated .  That forms 1 dimension or axis of the MATRIX of EMC.

( No, this is not quite “THE MATRIX” Warscharski brothers’ movie. But alluding to a movie is a surprisingly powerful concept, as in a creative thinking mash-up tool called “Movie-Minds” from  www.solutionpeople.com/movieminds . Yes , mixing work with play & fantasy can be quite productive. But more on that in a later Sideshow .)  

Turning back to the other problem axis or dimension, we noted the physical actors fall into 2 colors :   Sources & Affected Devices. That forms the other *orthogonal* EMC MATRIX axis.

To unify this all using a popular presentation rubric:  Its a 2 by 2 MATRIX or a 4-quadrant world. Thus all EMC problem / challenge phenomena fit into one of those 4 boxes. This just one more way of getting your mind wrapped around the problem . Its not the quick and easy answer,  but it helps the thinking.  

                   ||        Source        |      Affected Device _______________________________________________

Conducted     ||             x           |               y


Radiated       ||             z           |                t

Some examples : A cell phone transmitting can be a Radiated-Source,  z . An automotive control is a Conducted-Affected Device,  y.  A CFL bulb is a Conducted-Source, x . A consumer radio is a Radiated-Affected Device,  t.

Now, yes , as we’ve previously warned , a physical device can exhibit aspects of both flavors – Radiation and Conduction *and* both colors – Source and Affected Device.  Our job as the EMC Engineer is to determine which of the quadrant behaviors  dominates the problem and Pareto rank-order the possibilities down to the most likely root cause & effect in the situation. This is the intersection Art and Science. Where Experience teams up with Analytics . Where you put on those RF-Sunglasses and *visualize* the waves traveling from Source to the Affected Device. Where like Nicoli Tesla, you see the schematic  and drawing of the machine visualizing how the electrons flow around properly  *or not* when the Source is present.

So take the Blue Pill like Neo and follow Morpheus down the (EMC) rabbit hole and see just how far it goes. Don’t be like Switch and regret not taking the Red pill so you could wake up and believe whatever the Matrix wants you to. There is no turning back now anyway. You already swallowed the Blue pill, that’s how you got here.

So relax and have a snow-cone from a midway vendor or a cookie from The Oracle . Come-on and follow me , Top Hat and Microphone into the next spotlighted Ring where we’ll amaze and dazzle you with more of The Greatest EMC Show on Earth .

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I Direct Your Attention To The First Ring, Sources !

Hi it’s me again, the guy in the Top Hat , standing in the spotlight of the First Ring under the Big Top. There see the Lions, Tigers, Bears and Elephants who roar, snarl , growl and trumpet. Their sounds travel well beyond the ring and powerfully impress the audience. The animals  paw and pound the ground under the watchful eyes of their trainers .  If they were to escape , they would wreak havoc on the crowds and the whole circus grounds. Even just their voices and movements already affects some of the audience. These animals are metaphorically the Sources in the EMC Circus.

Sources include the licensed Radio information Broadcasts on frequencies covering  AM,  Short-Wave, FM , Television, Police, Fire , Public Safety , Cellular Phones , 3G, EDGE, WiFi, Bluetooth, GPS, Radar, more… 

Sources also include *unintentional* broadcasts or Emissions that  do not carry information . That includes the 60 Hertz AC power distribution system or the variable frequency drive power to an electric motor in an assembly line or in a hybrid-electric vehicle. There’s the high voltage spark that ignites fuel mixture for internal combustion engines. Even a simple electric motor in a home hair dryer has spark-generating commutator and brushes as well as the myriad of small DC motors in automobiles and toys. The happy Neon Sign or ( CFL ) compact fluorescent lamp has an interrupted voltage and current flow creating the glow from within their glass tubes .

Nature’s Sources includes spectacular Lightning and its weaker cousin Electro-Static Discharge or ESD from those dry days when you rub your feet across the carpet and your finger discharges a spark to the door-knob .

Whenever there is a difference in Voltage or driving force or Potential  across a path-way , then a current will flow . When that path-way includes other unintended devices, they will experience the voltage and current . Additionally the voltage and current flow action will launch a field which will radiate through space , again potentially exciting an unintended device.

So to the EMC engineer,  the First Ring of Sources is all around us , made up of many different animals . One or another of them can be a threat to the normal functionality of a device. The trick is determining which ones are the likely threats to the device of choice, based upon the nature of the device as well as the likely animal acts in the First Ring when the device must operate. Happily we have Standards which specify which sources are likely to influence a device based on its nature and intended use . The Standards “alphabet soup” as I lovingly refer to it , includes contributions from many agencies of governments and industry such as SAE, IEEE, ISO , EIA, CISPR, VDE, VCC, CE , EU, CSA , … There is even a subdiscipline of EMC Engineering devoted to developing , managing and selecting Standards .  I leave that to those experts.   I personally prefer to look to the physics and product application aspects to guide “design for EMC” efforts. 

So as the spotlight follows me stepping out of the First Ring,  I know I have only tantalized you with a brief story of the Sources. You were hoping to see a lion leaping through a flaming hoop ? All in good time . First we need to visit the other 2 Rings to get the big picture before we can understand how and why to get the lion to jump, let alone thru a hoop and then with fire to boot. Patience Grasshopper ! See you soon..

Copyright 2010 JDM LABS LLC , all rights reserved

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Rosetta Stone : Guide to the EMC Circus

Here I’ll describe a Roadmap, Guide or Rosetta Stone to help you navigate the ongoing EMC discussions.

The Circus Big Top archetype has 3 rings . Here its the over-arching Model , Construct , Analogy or Metaphor to the EMC World. In Ring 1 are the “Noise Sources” such as radio and TV broadcasts; hear the road of the lion ? Ring 2 the “Signal Path” includes the air around us and cables ; watch the high trapeze athletes leap astoundingly and effortlessly from swing to swing. Ring 3 the “Device Affected” could be your laptop or iPod ; watch a clown get wacked with the oversized mallet.  Please note these few examples are not all-inclusive ; we’ll come back again to show you lots more. Also some devices and systems have elements of 2 or all 3 rings within. That gets pretty exciting but we can still deal with it , just keep your head. We’re confident that all EMC problems and physical pieces can be broken down and categorized into those 3 big groups .  Finally under the Big Top the person in the spotlight with the Top Hat and megaphone directs the audience’s attention to the important actions. I’m that guy , so please follow along now and do watch for the elephant droppings.

Surrounding the Big Top are the Sideshows. These small tents accommodate a single performer giving an intimate audience experience. There you can focus on a single skill like card magic or fortune-telling. It’s really up close , fun and personalized with interactions. In the EMC Circus, Sideshows deliver focused lessons; expanding and drilling down into the Big Top’s 3 rings : Source , Path and Affected.  For example, the “Path”  Sideshow will reveal your good or bad fortune , using Dr. Tom VanDoren’s crystal ball of the 4 Coupling mechanisms.   http://emclab.mst.edu/studfac/vandoren.html

Moving on to the Midway there are games of chance & skill . Shooting at moving targets or knocking down <weighted> milk bottles. In the EMC Circus Midway we’ll entertain with examples of applying the skills and principles you learned in the Sideshows but with real-world twists & fun. You can even win gaudy prizes by playing the games over and over.  

Of course there are the Amusement Park Thrill Rides like the Ferris Wheel and Tilt-a-Whirl. We’ll be doing EMC  Demonstrations and Experiments of physical principles that will have you breathlessly hanging on to your inverted seat. The 2010 IEEE EMC Symposium featured a gaggle of such heart-pounders.  http://www.emc2010.org/index.php?id=91

And what would the Circus be without Street Performers wandering the Midway ? Here’s a chance to interact with a Captain Jack Sparrow impersonator . Yes interpersonal skills and communications are part of the EMC craft. If you cannot convince your audience you’ve got the goods on the problem , you’ll never be able to sell the solution. So we’ll give you some perspectives and tools to be most convincing.

Refreshments !  Take a Break. Sip a cool drink and have a “so bad its good” Funnel Cake . We all need a bit of diversion during the tough job of problem solving . A brief change of venue often provides that something to get un-stuck or see the problem in a new and useful light. So here we’ll have some creativity aids and diversions but no time wasting video poker , thank-you.

So there’s a quick guide to the EMC Circus. Grab your stuff , get your season pass admission ticket (sign up on the right-hand column for your RSS Feed) and join me in the Big Top as we direct your attention to the Big 3 phenomena in the ever-moving spotlight .

Hurry! Hurry! Hurry! Step This Way . As ELP Sang ” Welcome back my friends to the show that never ends … come inside , come inside”

Copyright 2010 JDM LABS LLC , all rights reserved

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