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  • sasquatch
    replied
    Asked the "Stoners" who smoke pot in their cave and look into the future,,,

    The husband claims it's not "time" yet, but it is comming soon, but he couldn't put a "date" on it.

    The female, she just rambles on about her garden food supply.

    Leave a comment:


  • loose nut
    replied
    Originally posted by lazlo
    On the bright side, the Prepper's fad has been great for ammo sales, and there's whole cottage industry providing bunkers, supplies, security systems, training.
    Danger, Will Robinson, Danger.

    There appears to be a time warp, forming, that is going back to the "50's.

    Danger.

    Leave a comment:


  • Forestgnome
    replied
    Originally posted by lazlo
    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).
    I worked on some of the same stuff, C3 and Sigint. Very familiar with Tempest. Most of the shielding on individual equipment are Tempest, but use emp resistant technologies, not so much shielding for emp. I would say most of the commercial electronic equipment I work on would survive emp, especially when coupled to line conditioning.

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  • Weston Bye
    replied
    The effect of an overwhelming surge on electrical devices and vehicles is pure speculation.
    Perhaps I should rephrase that.

    The effect of an overwhelming surge on electrical devices and vehicles that I described in the story is pure speculation.

    I was referring to the little story I wrote and submitted in another thread, and referred to in post #13 here.

    Leave a comment:


  • lazlo
    replied
    Originally posted by vincemulhollon
    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.
    Vince, you're killing the fantasy for the Preppers. If you scan through the Google hits for "Teotwawki", this is the leading cause for the end of the world rapture they're hoping happens: a huge EMP pulse that wipes-out all modern electronics.

    Some other random End of the World scenarios I read in a 5 minute scan: "Hyperinflation", the Greek Debt Crisis, the Zombie Apocalypse,... but most of "them" refer to the End of the World scenario as: "SHTF" -- when the "sh!t hits the fan"...

    On the bright side, the Prepper's fad has been great for ammo sales, and there's whole cottage industry providing bunkers, supplies, security systems, training. And of course, Elmer Fudd's body armor

    Leave a comment:


  • vincemulhollon
    replied
    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.

    Leave a comment:


  • lazlo
    replied
    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).

    Leave a comment:


  • Forestgnome
    replied
    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.

    Leave a comment:


  • 2ManyHobbies
    replied
    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.

    Leave a comment:


  • Forestgnome
    replied
    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...

    Leave a comment:


  • Rustybolt
    replied
    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.

    Leave a comment:


  • bborr01
    replied
    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

    Leave a comment:


  • dp
    replied
    Hmmm - another good reason to use Humbucker pickups on your guitar.

    Leave a comment:


  • aboard_epsilon
    replied
    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

    Leave a comment:


  • lazlo
    replied
    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.

    Leave a comment:

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