Building Your Own EMP Faraday Cage

[gil]

I don't think batteries need protection...

Gil.

[WA4STO]

..other than the car battery...which would have been fried...right? Maybe not though as the metal body of the car should actually act as a Faraday cage, right?

Gil's right; there's really no 'electronics' (think of itty bitty current paths within a transistor -- those paths get fried easily) in the automotive battery to GET fried.

As for the 'metal body of the car', you might consider the extreme difficulty that mobile hams have had over the decades trying to come up with an effective 'ground' for their antennas. 

The, uh, rubber meets the road as it were, and makes a piss poor conductor of electricity to ground.  Maybe none.

Wanna make a Faraday cage out of your car?  Better find some new-fangled way to come up with about a bajillion ground rods.  :)

73 de WA4STO

[raybiker73]

It comes with some very old foam padding - some have told me about a website where new custom pads can be ordered, for now what I have works.

If you find replacement foam for these NVG cases, let me know where! I bought a few of them last weekend at Bob's Army & Navy up in Clearfield, PA, and while the cases are like new, the foam is pretty ratty. I'd like to custom-cut some foam so that the box would hold my FT-817, MP-1 antenna, mic, key, cables, motorcycle battery and folding solar panel.

Also, you may want to consider adding some wingnut-release jumpers between the lid and the case. There is not much continuity between them, as the rubber seal keeps them insulated from one another. The latches provide some continuity, but I'm not sure if it's enough. Not sure about the breather valve, but it may need some EMP mods as well.

[White Tiger]

It comes with some very old foam padding - some have told me about a website where new custom pads can be ordered, for now what I have works.

If you find replacement foam for these NVG cases, let me know where! I bought a few of them last weekend at Bob's Army & Navy up in Clearfield, PA, and while the cases are like new, the foam is pretty ratty. I'd like to custom-cut some foam so that the box would hold my FT-817, MP-1 antenna, mic, key, cables, motorcycle battery and folding solar panel.

I think Luck gave me the link...let me look around a bit...ahhh, here it is:

http://www.thepelicanstore.com/Pick-N-Pluck-Foam-Sets-15.aspx

By the way...mind sharing what you paid? I bought two on eBay averaged about $35.00 each.

Also, you may want to consider adding some wingnut-release jumpers between the lid and the case. There is not much continuity between them, as the rubber seal keeps them insulated from one another. The latches provide some continuity, but I'm not sure if it's enough. Not sure about the breather valve, but it may need some EMP mods as well.

Theres that continuity issue that keeps slipping by me - would something similar to what Gil designed for his cookie-tin EMP cage, work on this too?

Also, maybe it's a dumb question...but why wouldn't the metal latches provide enough continuity? Is there a formula for size of the object and how much continuity is needed? As you stated, these are old night vision goggle cases, wasn't loose/spare 'lectricity one reason the boxes were designed in aluminum?

Remember - I literally know next to nothing regarding electricity, or it's preferences/proclivities...!

[Geek]

You might try something like this over the seams.

http://www.amazon.com/Lilly-Miller-715-15-Foot-Corrys/dp/B000QD3BPW/ref=sr_1_1?ie=UTF8&qid=1360409864&sr=8-1&keywords=copper+tape

[White Tiger]

You might try something like this over the seams.

http://www.amazon.com/Lilly-Miller-715-15-Foot-Corrys/dp/B000QD3BPW/ref=sr_1_1?ie=UTF8&qid=1360409864&sr=8-1&keywords=copper+tape

that might work..I wonder of the adhesive would interfere with the continuity?

[Geek]

Part of the problem is how to test it.  You won't know if it works until it is too late.

[White Tiger]

Part of the problem is how to test it.  You won't know if it works until it is too late.

Actually - conceptually - I should be able to use my multi-meter to test for continuity...just not sure how

[raybiker73]

Yes, you can check continuity with your multimeter (mine has an audible continuity tester which makes it even simpler). As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board.  :)  You could also drop in an HT and then see if it receives from an HT outside the cage.

[Geek]

Yes, you can check continuity with your multimeter (mine has an audible continuity tester which makes it even simpler). As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board.  :)  You could also drop in an HT and then see if it receives from an HT outside the cage.

Thanks!  I think I am going to try one with an ammo can and the copper tape.

[White Tiger]

Yes, you can check continuity with your multimeter (mine has an audible continuity tester which makes it even simpler). As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board.  :)  You could also drop in an HT and then see if it receives from an HT outside the cage.

Hah! Ray! That is exactly my style! I'm more of a mutt than a thoroughbred - so simple and elegant suits me (I do like the walkthru on the multi-meter, keep trying to find reasons to use it anyway)!

[Geek]

I had some ammo cans aon order and the vendor just canceled my order because they were out of stock!  Add that to the list of stuff that is hard to get these days.  Looks like it may take awhile to get my Faraday cage test to happen.

[White Tiger]

Look at the bright side Geek - all that money you were going to spend on guns & ammo (and ammo cans) can now be devoted to radio, antenna, and feedline (RG213U coax)!

By the time they have all that other "stuff" back on the shelves (and more reasonably priced), you will have refilled the coffers (and maybe a FCC license to boot)!

[raybiker73]

Plus, there are a lot of things other than ammo cans that can be used effectively. My main "Faraday cages" are a metal filing cabinet that I up-armored and attached to my station ground, and an old surplus rocket case that I welded the vent holes shut on.

The Great Northern Prepper Podcast did a pretty decent show about EMP preparation last week:
http://www.greatnorthernprepper.com/

EMP is pretty low on my STMAH list, but it's easy enough to prepare for, and having a lot of stuff locked away in metal cases is good security against theft and damage as well.

[Geek]

Look at the bright side Geek - all that money you were going to spend on guns & ammo (and ammo cans) can now be devoted to radio, antenna, and feedline (RG213U coax)!

By the time they have all that other "stuff" back on the shelves (and more reasonably priced), you will have refilled the coffers (and maybe a FCC license to boot)!

Excellent point, but the ammo cans were about the only thing I was looking for.  I hope they bring a few back from Afghanistan.  :-)

Raybiker:  EMP is low on my list as well.  I am still at the stage of acquiring things that would be useful in a wide variety of scenarios.  Nonetheless, I would like to protect a few electronic items that aren't in daily use anyhow.  For instance, I acquired a generator, which proved to be a stroke of genius when Hurricane Sandy took out the electrical service for more than a week.  I was without power for about 20 seconds.  :-)  This thing has about 5 minor electronic parts.  I didn't want to learn that the generator needed a part right after the power went out, so I have spares, currently stored in mylar anti-static bags.

The parts would easily fit in an ammo can.  If I really start to prep for an EMP, I would need to start acquiring duplicates of a variety of electronics.  I am not intending to do that any time soon, but storing things that are not in daily use anyhow seems like a worthwhile thing to do.