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Discussion Starter · #1 ·
With the news getting worse about what China could do with a nuke that is specifically made as an EMP weapon, I've been thinking more along the lines of shielding electronic things that would still be useful after such an event that took the electrical grid down for a very long time. Things like solar chargers, LED lights, etc.

We probably all know what a Faraday Cage is. But in doing some reading about EMP, or at least the parts I can comprehend, an EMP is a "line of sight" effect. If a nuke were detonated overhead, the EMP effect would come from overhead. So in order to protect an item from its effect, would it really have to entirely enclosed all the way? Wouldn't something metal over the top of the item being protected be enough? Sort of like the way a tarp or umbrella can protect something from getting wet from falling rain almost as well as putting the item inside an enclosure such as a house. Or am I wrong in the assumption that EMP only travels in a straight line?
 

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Discussion Starter · #4 ·
No, it's not.
Well, it was my understanding. Here's a source that seems to indicate it:

"A weapon of more than 100 kilotons affects everything within line of sight. That means a blast at 60 miles will affect a 700-mile radius. The only spot not affected will be a small area close to ground zero, almost vertically below the explosion, where the Earth's magnetic field creates an "eye of the storm."

This one is better. Page 11 of link:
"A high altitude nuclear explosion (that creates HEMP) produces three major energy components that arrive in sequence, and which have measurably different effects that can be cumulatively damaging to electronic equipment. The first energy component is the initial energy shockwave which lasts about one microsecond, and is similar to extremely intense static electricity that can overload circuitry for every electronic device that is within line of sight of the burst.".
 

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The EM in EMP stands for Electro-Magnetic. Another word for electro-magnetic is radiation. Just like shortwave, AM, FM, CB, TV, microwaves, cell phones, visible light etc.

As such, it acts as a wave, just like sound in the air and waves in the water. And waves can go round corners. Just like you can hear someone around the corner of a building. Or waves propogate around an island regardless of the direction of the waves.
 

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Discussion Starter · #7 ·
The EM in EMP stands for Electro-Magnetic. Another word for electro-magnetic is radiation. Just like shortwave, AM, FM, CB, TV, microwaves, cell phones, visible light etc.

As such, it acts as a wave, just like sound in the air and waves in the water. And waves can go round corners. Just like you can hear someone around the corner of a building. Or waves propogate around an island regardless of the direction of the waves.
Wouldn't an EMP be closer to the radiation of visible light, except that it's not visible? If a light were shining from directly overhead (such as the sun), and I put an object between the light and my eyes, the vast majority would be blocked, although there would definately be scattered light that would still get to my eyes, but would be greatly diminished.

One example of why I thought it might be effective is that it's often said that a modern car parked in a concrete parking garage could survive an EMP. A parking garage is not completely enclosed, but it would provide protection by putting a concrete layer overhead.
 

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Wouldn't an EMP be closer to the radiation of visible light, except that it's not visible? If a light were shining from directly overhead (such as the sun), and I put an object between the light and my eyes, the vast majority would be blocked, although there would definately be scattered light that would still get to my eyes, but would be greatly diminished.

One example of why I thought it might be effective is that it's often said that a modern car parked in a concrete parking garage could survive an EMP. A parking garage is not completely enclosed, but it would provide protection by putting a concrete layer overhead.
There is no one frequency of an EMP, nor a narrow 'range' of frequencies.

Your examples are slightly misguided. The higher frequencies of an EMP do not need the medium of an atmosphere to propogate around a corner.

And while a car parked in a concrete garage does garner some protection (both from the concrete and the steel rebar encased within), it is still no guarantee it will not be harmed. A strong enough pulse can find it's way to it.

What causes the damage is the EMP creates an induced voltage in electronic circuits. If the voltage and resultant current are high enough, it can arc between the tiny gaps between the various components of electronic circuits. This arc can either 'burn off' a part of a conductor, creating an 'open circuit', or bring melted conductive material along the path and create an unintentional path between the parts... a 'short circuit'.

It doesn't take much voltage to do this as electronics are designed to operate on very low voltage levels. Yes, your TV may plug into your house's main power supply, but there's transformers and voltage converters that bring that voltage down to a level that is 'safe' for the micro-electronics to use.
 

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From 200 to 400 miles altitude, line of sight is really pretty far.
Triple wrap your electronics with a doubled layer of aluminum foil. Put a HD plastic (4 mil) between all three layers. fold all seams 2 or 3 times and squeeze the folds very tightly. If you've ever made tim foil dinner, hobo stew, etc., you know what I mean. And if you are really concerned still everything in a metal garbage can and use foil tape to seal it
 

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Discussion Starter · #11 ·
From 200 to 400 miles altitude, line of sight is really pretty far.
Triple wrap your electronics with a doubled layer of aluminum foil. Put a HD plastic (4 mil) between all three layers. fold all seams 2 or 3 times and squeeze the folds very tightly. If you've ever made tim foil dinner, hobo stew, etc., you know what I mean. And if you are really concerned still everything in a metal garbage can and use foil tape to seal it
That leads me to another question about which metal containers to use. I've been doing quite a bit of reading lately and found information that seems to contradict others. One big one is about the type of metal to look for. On older forum posts, like back around 2013, people were saying that ANY metal container will do. But later posts say steel isn't a good enough conductor of electricity. At the same time, the galvanized steel trash can is highly spoken of. So I'm confused about that.

I have some metal coffee cans that I was thinking of making use of. A couple of others I already have in use is one upside down on top of another upright one to form a big space where I have an oatmeal container that's wrapped in aluminum foil. I figure that's a 2 layer system of 2 different metal types. But do the steel coffee cans do any good at all?

Another design I thought could work is to simply take one metal coffee can and form a lid over it out of aluminum foil. That way I can remove the foil lid easily to get to the contents, and slip it back on afterwards. I'd use a rubber band to hold the foil against the can. Of course, the can would be lined with cardboard to insulate the items from the can.

What do you think of all these ideas?
 

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From 200 to 400 miles altitude, line of sight is really pretty far.
Triple wrap your electronics with a doubled layer of aluminum foil. Put a HD plastic (4 mil) between all three layers. fold all seams 2 or 3 times and squeeze the folds very tightly. If you've ever made tim foil dinner, hobo stew, etc., you know what I mean. And if you are really concerned still everything in a metal garbage can and use foil tape to seal it
Yeah my 6 or 7k worth of electrical and computer based medical equipment is a big one. Got a radio station too.
What about our generator? I didn't think there was a part we can pull and protect? Got to cover the whole thing around and up off the ground.....can pull the electronics off of a well pump and then it would be if the wiring was ok?
What better way to kill everybody that believed them the most and lived totally artificial? Except of course the multi millionaires...
 

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Please remember an EMP will affect micro and subminiture electronics. Transistors, SCRs or chips. Unless your generator is an inverter type or has a lot of elctronics to make it run, you'd probably be safe. If the generator is controlled electronically, which so many are today, go thru your parts manual to see if the electronics are replacable. They most likely are. You could order a spare control system or remove the existing one and store it away in a Faraday cage to protect it. The early electronics on the bombers that dropped the nukes for tests, were all old style, electron tube with no transistors or the like. Those old boat anchor devices were not effected by the EMP of the nearby nuke detonation.

One of the biggest things to remember with any tin can, garbage can, ammo can used for a Faraday cage is metal to metal contact between parts. I've used gallon paint cans (old ones with metal lid) and cookie tins. But the can should be sanded or wire brushed to get rid of any paint or varnish where the pieces meet or overlap. I use the triple wrap with plastic for insulation between the layers, method. And then those packages go into the garbage can which is sealed with alluminum metal tape. My really important electronics get triple wrapped and go into a separate garbage can with copper foil tape sealing the top to the can. I found the can had a few open rivets (eyelets would be a better discription) holding handles in place, so I soldered them closed and also touched up a few crimped seams with solder. Copper is best and is used in commercially build Faraday cages because of conductivity. Aluminum is next. Steel is better than nothing. But with the triple wrap aluminum foil packages I feel relatively safe. I've seen people who built a Faraday cage for generators and large items. It was a wooden frame covered in copper or aluminum screen. The tighter the mesh, the better, and overlap any seams by 3-4 inches (my guess).
Some of you may have seen or heard of using an old microwave oven as a Faraday cage because a cell phone won't work in a microwave. While it is one, it not that great. Take a regular battery AM radio and tune to a close, strong station. Turn it on and put it in the microwave. No change, it will work just fine. Hell, as a demonstration, I took my cell phone, put it in an empty Cheetos bag, folded it closed 3 times, and it didn't work, either. But it's a trick, the cell phone tower loses track of the phone in about 3-5 minutes and won't even put the call thru because it thinks you are out of range or turned the phone off. In all fairness, I needed 2 Cheetos bags, once. But I was very close to a tower. If you want more info, PM me. If you have or have access to MS PowerPoint, I can send you the narrated presentations I use for our group, via email. But be warned, they are 200 to 400MB in size due to all the video and images. The series isn't very long but is divided into 6 parts.

This home made aluminum screen Faraday cage looks like it has aluminum frame.
Tire Wheel Automotive tire Wood Rectangle

Below is a garbage can with copper tape.
Cylinder Fluid Gas Drink Tin

Below is a commercially build Faraday cage.
Wood Fixture Wood stain Hardwood Gas
 
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