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  • #16
    I remember there is some dude on the Internet that claims electronics CAN be protected by Faraday shielding, and he shows how to construct metal enclosures to protect from an EMP. I think that any seams need to be properly made.

    The EMP Pulse (Electro Magnetic Pulse) is just similar to a extremely strong Radio Wave. Radio is an "Electro Magnetic Wave".

    I think a car might be somewhat protected in a Metal Building. Depends if the Nuke is Russian or Chinese.

    If you have a Pacemaker, wrap yourself in Tin Foil.

    Tom M.

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    • #17
      Wes,
      Thanks for the pointer to that thread, I must have missed it first time around.

      Your writing is nearly the same as the beginning of "A Distant Eden".

      Comment


      • #18
        Poorly researched

        Originally posted by jdunmyer
        Now for the question: why wouldn't a lot of our modern equipment/devices be protected by being inside a metal building or even a metal-reinforced concrete structure?
        Makes for better fiction.

        Over a really tiny volume, I can create a one volt per inch (or so) field by waving a AA battery around. Waving a battery in the air next to the sheetmetal of my car has never done anything to the electronics. Lets say I make 1V/inch field the size of the earth instead of the size of a flashlight battery. That is still not enough to do much to my car, numerous tests have proven it, and also evidence is lightning storms rarely if ever disable cars. However, the 40 mile long high voltage power line in my backyard, at 1 volt per inch of the 40 miles, is basically toast along with everything connected to it.

        The other common and inaccurate fixation in "EMP lit" is that it will be simple binary, the whole continent will be completely wiped out and absolutely nothing will work and that will be the disaster. Knocking out a mere 10% of vehicles in one city will pretty much destroy that city in the ensuing rioting. Knocking out 10% of the entire countries vehicles would pretty much destroy the country economically, might take a few more months to cannibalism but we'd get there just as surely.

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        • #19
          So all the guys that run classic cars with points would be ok ..

          all other electronic stuff would be dead ..

          old radios with valves ...they would work .

          does it just kill mocrochips ..or does it bugger all trasistors as well .

          ive been watching all those films

          the road

          solar attack

          the quiet earth

          doomsday

          atomic cafe

          atomic journeys

          outbreak

          db bunkers

          twilights last gleaming

          the divide

          survivors 1975

          jericho

          the day after

          z for zachariah

          the last train

          they are just some of them .....im no bunker guy .....im just highly entertained by the above ..

          You do pick up what to do it it all happens though .....first thing, is to get your self an arsenal ..me thinks


          all the best.markj

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          • #20
            Originally posted by jdunmyer
            Wes,
            Thanks for the pointer to that thread, I must have missed it first time around.

            Your writing is nearly the same as the beginning of "A Distant Eden".
            How could it be otherwise? Such an event would have predictable beginnings. I merely built upon my experience with simple power loss in the 2003 Northeastern outage. The effect of an overwhelming surge on electrical devices and vehicles is pure speculation.

            I can say that auto manufacturers have been addressing the possible effects of (at least "normal") electromagnetic interference and damage. Some of our products where I work, those containing semiconductors, are required to be tested for static discharge and bulk current injection resistance.

            Some cars should survive an EMP event, but as Vince points out, if a significant number don't, the net effect would be the same.
            Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
            ~Practitioner of the Electromechanical Arts~

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            • #21
              Originally posted by mayfieldtm
              I remember there is some dude on the Internet that claims electronics CAN be protected by Faraday shielding, and he shows how to construct metal enclosures to protect from an EMP.
              I explained above why shielding protects electronics against EMP. Look up MIL-STD-461: Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment.

              Thing is, the Preppers want the end of the world as we know it. Elmer Fudd in the picture I posted (from the Discovery Channel Preppers show) thinks he's going to live like a king
              If you Google "Teotwawki", you get thousands of hits from guys like him. It's a replay of the survivalist fad that was triggered by the '73 gas crisis.
              Last edited by lazlo; 06-04-2012, 10:47 AM.
              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

              Comment


              • #22
                Originally posted by lazlo
                I explained above why shielding protects electronics against EMP. Look up MIL-STD-461: Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment.

                Thing is, the Preppers want the end of the world as we know it. Elmer Fudd in the picture I posted (from the Discovery Channel Preppers show) thinks he's going to live like a king
                If you Google "Teotwawki", you get thousands of hits from guys like him. It's a replay of the survivalist fad that was triggered by the '73 gas crisis.
                Teotwawki..........interesting ..brings up series called "the walking dead" ..is it anygood.

                all the best.markj

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                • #23
                  Hmmm - another good reason to use Humbucker pickups on your guitar.

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                  • #24
                    Originally posted by lazlo
                    I explained above why shielding protects electronics against EMP. Look up MIL-STD-461: Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment.

                    Thing is, the Preppers want the end of the world as we know it. Elmer Fudd in the picture I posted (from the Discovery Channel Preppers show) thinks he's going to live like a king
                    If you Google "Teotwawki", you get thousands of hits from guys like him. It's a replay of the survivalist fad that was triggered by the '73 gas crisis.
                    Gas crisis makes me think of the movie "mad max from thunderdome". I think that was the name of the movie.

                    Brian
                    OPEN EYES, OPEN EARS, OPEN MIND

                    THINK HARDER

                    BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                    MY NAME IS BRIAN AND I AM A TOOLOHOLIC

                    Comment


                    • #25
                      Originally posted by lazlo
                      I explained above why shielding protects electronics against EMP. Look up MIL-STD-461: Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment.

                      Thing is, the Preppers want the end of the world as we know it. Elmer Fudd in the picture I posted (from the Discovery Channel Preppers show) thinks he's going to live like a king
                      If you Google "Teotwawki", you get thousands of hits from guys like him. It's a replay of the survivalist fad that was triggered by the '73 gas crisis.


                      I have a vest just like that guys. Only mine is filled with candy bars and a I have a holster for a bottle of Yahoo. You know, in case there's a sugar shortage.

                      Comment


                      • #26
                        Originally posted by armedandsafe
                        RF is blocked by any electrically conducting material. However, a strong magnetic pulse will not be stopped by conducting material. If you are using a shielding material that is magnetically attractive, all the pulse does is set up an opposing magnetic field inside the enclosure. There is not much that can be done to shield a people sized interior from a strong magnetic pulse.

                        The magnetic pulse destroys electronics by causing electrical current flow through any conducting material inside the electronic device. These currents are usually very high, compared to the ratings of the device and can be in a reversed flow direction. Pass a magnet past an electrical wire and you will cause current to flow in that wire. Pass an electrical pulse through an electrical wire and you will create a magnetic field around that wire. That is a law of physics you cannot repeal.

                        There are ways to shield the circuitry from the EMP, but those methods have to be applied to each little part of the device. It gets very complicated.

                        Pops
                        Mu metal...

                        Comment


                        • #27
                          Originally posted by armedandsafe
                          RF is blocked by any electrically conducting material. However, a strong magnetic pulse will not be stopped by conducting material. If you are using a shielding material that is magnetically attractive, all the pulse does is set up an opposing magnetic field inside the enclosure. There is not much that can be done to shield a people sized interior from a strong magnetic pulse.

                          The magnetic pulse destroys electronics by causing electrical current flow through any conducting material inside the electronic device. These currents are usually very high, compared to the ratings of the device and can be in a reversed flow direction. Pass a magnet past an electrical wire and you will cause current to flow in that wire. Pass an electrical pulse through an electrical wire and you will create a magnetic field around that wire. That is a law of physics you cannot repeal.

                          There are ways to shield the circuitry from the EMP, but those methods have to be applied to each little part of the device. It gets very complicated.

                          Pops
                          It doesn't work like that. The hypothesis you post flies in the face of physics. A keeper on a magnet would pass the field instead of blocking it. A simple appliance motor would electrify or vibrate all of the cookware in the house. A magnetic compass placed in a steel box would still keep up with magnetic north. I'm not even sure the concept of rotating a magnet in a coil would generate electricity or if a transformer would work if a magnetic pulse would fly out unbounded like that.

                          V=N*B*A/t

                          That equation governs the voltage generated during a pulse type event.
                          N=Number of windings. For any closed circuit other than a coil, N=1.
                          B=The magnetic field. A large EMP is 50 micro Teslas. 10^-6
                          A=Area of the coil.
                          t=Time. For a large EMP it is tens of nanoseconds. 10^-8

                          V only gets interesting for large values of A and small values of t. Microelectronics have tiny values of A. Very tiny. This makes the effect uninteresting. Smaller values of t get less interesting on the power grid because 10^-8 events do not couple real well though transformers and coils engineered to efficiently couple 10^-1 events.

                          If an EMP event occurred, I might have to replace a vintage alarm clock but I'm not even 100% sure that would be the case. The Cold War panic about EMP was simply that radio was the fastest (and sometimes only) means of communications for defense forces. An EMP would cause some long range broadcast difficulties for a bit of time and in an attack that would be well, bad. These days fiber optic strands are the long range communications medium of choice. I'm not terribly sure the optical photons would notice the RF photons wandering by.

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                          • #28
                            In the electronic equipment shelters used by the military the only emp protection used other than the aluminum skin of the shelter are extremely fast surge protectors on all lines that pass through the wall. There they used to use tritium switches to crowbar the lines in case of a surge. That's the real danger of emp, the magnetic pulse travelling through lines creating surges. Other than that simple metal shielding is all that's needed.

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                            • #29
                              Originally posted by Forestgnome
                              In the electronic equipment shelters used by the military the only emp protection used other than the aluminum skin of the shelter are extremely fast surge protectors on all lines that pass through the wall.
                              I was an electrical engineer for the Army Research Laboratory for over a decade, and designed mobile supercomputers for command and control, fire control interfaces for the Paladin howitzer, and ground station electronics for black programs (among many others).

                              Military electronics are heavily shielded, both against EMP Mil-Std-461, and against counter-intelligence (Tempest shielding).
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                              • #30
                                actual test results

                                Originally posted by Weston Bye
                                The effect of an overwhelming surge on electrical devices and vehicles is pure speculation.
                                See testing as referenced at

                                http://www.empcommission.org/reports.php

                                and somewhat more informal discussion at

                                http://www.futurescience.com/emp.html

                                Basically you can zap cars with ridiculous field strength with generally no effect, occasionally the "entertainment stuff" needs a power cycle to work again, and once in a blue moon something actually breaks on some specific model cars.

                                This should be no great surprise... how many times does lightning strike very close to hundreds, even thousands of cars and nothing electrical happens (lightning will ruin the paint job and pop the tires if a direct hit, usually). I've never even heard an anecdote of a lightning storm knocking out a car.

                                Another way of looking at it, is hundreds of millions of cars per year pass by 100 KW class radio transmitters sited right next to the road all the time and nothing happens. In the pre-doppler era we had kilowatt class radars zapping cars and doing nothing.

                                Its somewhat unrealistic that nothing would happen in that it would insta-fail, lets say, every marginal emissions computer simultaneously that would have gradually failed over smoothly over the next year or so. We can (and do) have a survivable transportation infrastructure where perhaps 2% of the vehicles have a failed black box per year and we gradually one at a time tow, replace, and drive away. However an entire years worth, lets say 2%, all failing at 9am on wednesday is a pretty tough logistics problem to solve in less than a year....

                                I used to work directly with telecom outside plant guys, and in medium to high lightning areas like where I live, we have excellent lightning protection and we never lose a tower or a POP due to lightning... Tornados knock down towers, sure, we lose commercial power and the generator fails, sure, flooding, sure, but never down due to lightning damage. Its too cheap to spend $20K hardening up a site when the annual zap would blow up $2M of gear every year (if not more often). On the other hand, a place that never gets lightning (I've heard LA never gets storms?) that would be completely wiped off the map by EMP because no one bothers to ground or protect anything.

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