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monkeylizard

Building a Faraday cage

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Omega    1,729

The problem I see with long term storage of electronic devices such as cell phones, tablets or PCs is that they need to be charged pretty regularly.  So burying them, and storing in layers upon layers of metal boxes will become tedious, and sooner or later maintaining them will fall by the wayside killing the batteries.  I don't know the max shelf life of new batteries, but for those with electronics with removable batteries may want to consider a couple of spares.

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mikegideon    7,933

The problem I see with long term storage of electronic devices such as cell phones, tablets or PCs is that they need to be charged pretty regularly.  So burying them, and storing in layers upon layers of metal boxes will become tedious, and sooner or later maintaining them will fall by the wayside killing the batteries.  I don't know the max shelf life of new batteries, but for those with electronics with removable batteries may want to consider a couple of spares.

 

I revived an old iphone that had been in the drawer for years. The battery was deader than Bernie Sanders' pecker. You don't need battery to retain the information. I have a solar charger for cell phones. 

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Jonnin    1,343

So, is a steel gun safe not enough shielding?

 

It could be, depending on the safe, and whether you grounded it or not, and how far from the metal the electronics are stored, and whether there is any powder inside (its gonna spark, bet on it).   This is expensive solution if what you are protecting is commonplace items like a couple of phones or a laptop etc.   If you already have one and there is room ... it can work.

Edited by Jonnin
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peejman    2,775

So, is a steel gun safe not enough shielding?


Maybe. If it was grounded. If the EMP was very low strength or released a long way off. But again, a big EMP is gonna kill so many other things, I'm guessing you'll have bigger worries than whether or not your electronics got fried.

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mikegideon    7,933

and whether there is any powder inside (its gonna spark, bet on it)

 

I wouldn't bet in that

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Jonnin    1,343

I wouldn't bet in that

 

Depends on how well the safe stops the current I guess.   If it arcs between the safe wall and a gun or knife or whatever with a keg of powder in the middle, it could.  If the safe stops it, its fine.   Loaded ammo I would think is going to go if it arcs.  

 

That brings up the 2nd issue with making one.. there really isn't a good way to test it.

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Obiwan    148

Concerning the gun safe... wouldn't an EMP fry the keypad on an electronic keypad safe?

 

It all depends, but yes, it may fry it, just like it may fry other electronics. A good ole mechanical dial safe should be safe. (sorry, couldn't resist the pun).

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xtriggerman    180

This Gov web page can give about a one day heads up on mass coronal ejections. I believe they are the culprit that will test the efectivness of your Faraday cage in that likely event. I liked the old web page much better since they scaled it on a grid. A quick glance told you if there was an alert level issue hour by hour.

http://www.swpc.noaa.gov/products/alerts-watches-and-warnings

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East_TN_Patriot    1,075

I've done some reading on this topic and many sources that seem to be reliable indicate that the risk for EMP damage to most electronics can be mitigated fairly easily with a basic faraday box of some sort.  The reason is that modern electronics are actually fairly well-shielded from electronic interference and power overload, so as long as the devices are not powered on and they are in a reasonably shielded location, even inside of a car, they will likely survive.  Also, the effect of an EMP blast can vary greatly based on the strength of the device, the altitude of detonation, and the distance one is from the blast.  Of course, as others have mentioned, this is all total speculation because we simply don't have access to the data nor do we really know for sure what EMP capabilities our enemies have on hand.  

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Wingshooter    1,885
On 5/20/2016 at 2:06 PM, xtriggerman said:

This Gov web page can give about a one day heads up on mass coronal ejections. I believe they are the culprit that will test the efectivness of your Faraday cage in that likely event. I liked the old web page much better since they scaled it on a grid. A quick glance told you if there was an alert level issue hour by hour.

http://www.swpc.noaa.gov/products/alerts-watches-and-warnings

Digging up an old thread, but that's an interesting link

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bruiser09    42

I had a thought on how to construct a relatively simple but theoretically effective cage.

First, find an ammo can that is roughly 30-50% larger than the items you want to protect.

Next, construct a box from copper or aluminum that is about 1” smaller than the ammo can in height, length and depth. 

Think of a simple shoe box type of construction having a four sided bottom and snug fitting top.

Apply one to three lines of expanding foam to the inside bottom of the ammo can.

Press inner box into foam and hold until the foam is firm enough to hold inner box.

Apply foam between walls of inner box and ammo can leaving room for inner box lid to fit.

That’s it. This box does not have to be grounded.

 

    note: searching Amazon “aluminum box” offers several ready made options.

5983f8a0cbd39_Aluminumboxes.thumb.jpg.06b9d64075ffcdffe4ea99b5252dd21b.jpg

Something like this could be slipped into the ammo can using a layer of bubble wrap.

 

If you are curious, the reasoning behind this construction method follows:

An EMP, or electromagnetic pulse, has a wide frequency spectrum ranging from VLF (very low frequency) to UV (ultraviolet). As such, the design of an “EMP Cage” would need to protect from frequencies spanning from about 3 Hz (Hertz) to 10 PHz (Petahertz), or just beyond visible light.

The properties of the shielding material need to be just as varied as the frequencies they offer protection from. Different metals offer protection at different frequencies. Low frequency magnetic fields require a metal of more ferrous properties (or that have high permeability) Steel works for lower frequencies with lower carbon steel (often referred to as “mild steel”) being more effective because of it’s higher permeability and saturation point..

Copper is widely used over the RF range. Aluminum also works in the RF range but usually needs to be about twice as thick as copper for the same level of affect. 

The layers of metal are isolated to minimize galvanic decay. The corrosion is real but minimal and is only an issue over time.

Aluminum boxes.jpg

Edited by bruiser09
double photo
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