EMP protection

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DrHenley

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There are three components of a Nuclear EMP blast, E1, E2, and E3 which are of different wavelengths and durations, and they affect different types of circuits and components. Shielding designed for one component may be useless against the others. Too much to try to explain here but just do some reading up on them.
 

Kevin L

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There are three components of a Nuclear EMP blast, E1, E2, and E3 which are of different wavelengths and durations, and they affect different types of circuits and components. Shielding designed for one component may be useless against the others. Too much to try to explain here but just do some reading up on them.
Thank you.

I guess that simply sticking electronics in the insulated interior of a sealed metal box isn't enough.

I've tried to toy with the idea of a Faraday Cage nested within a larger Faraday Cage, so I've been playing with the idea of steel pickup truck flatbed lockers within a sealed, steel dumpster that's insulated on the inside with a layer of rubber.

I don't know that I have room for such an answer, or that I'm that dependant upon a huge array of electronics.

I'm interested in storing a DVD player, with DVD's of practical things like gunsmithy, animal husbandry, gardening instructions, medical techniques (like suturing), and so forth.

I would also put aside a box air conditioner, spare electronic components for the solar panels, 3 small to medium flat screen televisions, calculators, diabetic glucometers, battery chargers, radios, and so forth.

I have not figured out how to load Kindle books onto a thumb drive.

Once I get that down, I'll include redundant Kindle E-readers and tablets, with extra specialty rechargable batteries in order to be able to keep reading E-books.

I would--I imagine--be able to amass an electronic library of over 4,000 books . . . that would be more portable than a small laptop.

However, there is no way to repair the infrastructure if a tablet or E-reader got broken in some way. The only answer I've been able to come up with is to have redundant tablets and extra E-readers.
 

DrHenley

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There is a lot of misconceptions about what a Faraday Cage is and how it works. A Faraday Cage doesn't need to be insulated on the inside to behave as a Faraday Cage. LOOK IT UP! But that's not the only kind of shielding you need for an EMP.
A Faraday cage operates because an external electrical field causes the electric charges within the cage's conducting material to be distributed so that they cancel the field's effect in the cage's interior.
 

Captjim_NM

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Bingo! To work correctly you want a clean metal surface on the inside of the cage. Double wrap your electronics in ESDS bags. To function correctly the cage must have a tight fitting lid and a good ground connection, copper strap is best, then braid. That single strand of 16ga green wire will not get the job done.
 

radiogoon

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Bingo! To work correctly you want a clean metal surface on the inside of the cage. Double wrap your electronics in ESDS bags. To function correctly the cage must have a tight fitting lid and a good ground connection, copper strap is best, then braid. That single strand of 16ga green wire will not get the job done.
Ask any ham about proper bonding and grounding...
 

Illini Warrior

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There is a lot of misconceptions about what a Faraday Cage is and how it works. A Faraday Cage doesn't need to be insulated on the inside to behave as a Faraday Cage. LOOK IT UP! But that's not the only kind of shielding you need for an EMP.

you're probably confusing a lot of people - especially the newbies - with a statement like that >>> I cushion & insulate at the same time - my covers are always either a tite fit or crushed down and locked on firmly ...

my larger Faraday cages are stored in my attic - if by the wildest chances I can find any of my attic contents after the house top gets tornado or nuke blasted - I want my cages back with the contents intact .....[/QUOTE]
 

bigpaul

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I think an EMP will do a lot of damage over here or else we wouldnt be talking about it, not many places have faraday shielding in place, I did hear that an EMP would blow all the connectors in the power grid over here and a report said it would take 2 years to replace them, none are made here and have to be shipped from overseas, 2 years without power? thats the end of life as we know it for most people over here, the survivors would not number many and will be well spread out.
most devices and systems here are electrically powered and without electric the country would go dark.
 
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Captjim_NM

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An EMP attack would take out all the power transformers. Right now there is a one year lead time for those big transformers. All silicon junction devices would be destroyed. An EMP attack would take any nation back to 1880's real fast. Life as we know it would vanish.
 

bigpaul

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An EMP attack would take out all the power transformers. Right now there is a one year lead time for those big transformers. All silicon junction devices would be destroyed. An EMP attack would take any nation back to 1880's real fast. Life as we know it would vanish.
yeah thats what I read, over here in the UK we dont make them and they arent kept "on the shelf" so have to be ordered, made and shipped from overseas, each one takes several months so doing the whole system could take anything up to 2 years, thats even if they had the engineers to do it.
I think it would take the UK back to a pre industrial age which would mean an 18th century type existence, not such many people these days could live like that or would want to, except yours truly.
 

MOS0231

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An EMP attack would take out all the power transformers. Right now there is a one year lead time for those big transformers. All silicon junction devices would be destroyed. An EMP attack would take any nation back to 1880's real fast. Life as we know it would vanish.
The big transformers, have to be moved via rail.
And as I understand it, some of those rail lines are no longer there.
 

bigpaul

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The big transformers, have to be moved via rail.
And as I understand it, some of those rail lines are no longer there.
they certainly arent over here, ever here of Doctor Beeching? he closed a lot of the branch lines back in the 1960s, there is only one rail line down through my county and into the next and that is on the south coast nowhere near my location.
if there is no power that means no fuel so they cant bring them in by road either. most rail lines are electrified too!!!
 

MNwr786

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To determine if something will function as a faraday cage, I suppose one could start with an understanding of RF currents. I have been using radio for a while so here is my take on it. As some already stated, there are different frequency components to an EMP attack. Lets start with higher frequencies and skin effect. Eddy currents in the metal force the majority of the current to flow within the first few mm of the material. If the metal used in your faraday cage is thin with respect to skin depth, the currents on the outside will be seen on the inside. This issue must be considered for all frequencies you encounter and becomes more of an issue for lower frequencies.

The next thing we must consider are the gaps and seams that are not sealed off. This issue is also one of frequency. In microwave ovens, that door mesh is effective at blocking most of the radiation for two reasons, one, for a metal surface to reflect RF current, ideally, it should be large with respect to a wavelength (like hams bouncing UHF signals off aircraft), which the mesh in the door is, and two, the openings are smaller than 1/20 of a wavelength meaning they cannot act as a slot antenna on that frequency absorbing and re-radiating the energy. Imagine taking a piece of sheet metal and cutting out a 1/2 wave dipole antenna. The piece you removed can be used as an antenna, but in the same way, so can the plate with the slot. The only differences are the method of feeding (for radio) and polarization (of the signal it transmits and receives). Any gaps can act like a slot antenna, absorb and re-radiate, and allow RF current inside a faraday cage. However, in this situation, what is allowed through are the frequencies the slots or holes resonate on and their higher harmonics (which only allows a portion of the spectrum through).

To seal these gaps up does not necessarily require major effort. Some metal foil tape will do just fine. Some might disagree because the sticky side is not making electrical contact, but to that I'd argue capacitive reactance. Those two metal surfaces "not in contact" are so close that the capacitor formed is essentially a dead short to RF signals higher than a few MHz (which is how those cellular antennas that stick to your window transfer signal).

The lower frequencies that can pass through the metal will not be much of a concern either as the conductors in the devices you store inside it will be an insignificant fraction of a wavelength and therefore not couple the energy. most electronics are damaged by electromagnetic pulses because the device is powered on when the pulse hits. The pulse induces a tiny current on the MOSFET and JFET gates (solid state switches) turning them all on at the same time. If a device with power has all of its thousands of semiconductor switches turn on at the same time, the smoke is surely to be let out. I doubt you will store your devices turned on, and again, due to the small size making them inefficient antennas, not enough energy will couple to fry anything if the battery is not connected.

At the end of the day, you could just store your smaller stuff under 10 feet of water in a sealed plastic pipe. As long as the device is not connected to anything that makes an effective antenna on VLF (which is thousands of feet), it will be fine. The water will block the rest.
 

MNwr786

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Then by definition, it is NOT a Faraday Cage!
Although I agree to some extent with that, I think there is a misconception here. Michael Faraday himself acknowledged they have limitations by design, and while some signals may be blocked, others can still pass. Too many people think it must block 100% of everything to earn the name Faraday cage, this is not true. If it were, the device would be theoretical only. For example, slow-moving magnetic fields can get inside something like a sealed propane tank. I was pointing out these design issues so that people have an understanding of what they expect their "metal container" to accomplish. Obviously, if one does a crappy job, they can just call it Faraday Screening. Many scholars and universities use the term Faraday Cage for a variety of enclosures short of theoretical perfection. Sufficient broadband attenuation to achieve a high probability of protecting what's inside is the only criteria I use for describing something as a Faraday Cage. Theoretical perfection is for people with book smarts, a good calculator and zero hands-on experience!
 

EricB1970

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Anyone thinking of using a microwave as a Faraday cage to protect their electronics must ask themselves why people with pacemakers aren't allowed near them.
 

MOS0231

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The only thing I would really want to protect would be my portable speaker, my tablet with a few thousand hours of music, and the means to charge it.

As BigPaul points out, if there is no infrastructure not much use.

Comms, maybe. But am I really going to care about what is going on a 1,000 miles away, or even 100 miles?
 

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