Testing a Trash Can Faraday Cage

Nice to see the results match Dr Arthur Bradley, the OG in the field (no pun intended).

https://www.youtube.com/watch?v=aMct99DiZak

For my money, a triple burrito wrap of foil and ziploc gives 90+ dB attenuation plus moisture and mechanical protection.

Also nitpick, but the E1 pulse doesn't fry beefy transformers, instead it's the long-period E3 pulse (seconds to minutes) that raises the grid voltage and overvolts the transformers.

I did a much lower fidelity experiment this past week with one of my kids.

I have some radios I threw in metal boxes on the off chance something like this happened so we’d have some way to get emergency alerts. To check how well it shielded we threw my phone in it and they called to see if it rang. It did.

So we tried some other things - the microwave (worked), a tool chest (didn’t), a faraday bag (worked), miscellaneous storage boxes (didn’t).

Fortunately, the box with the radio was an old box and some paint had worn from the edges. We made a “seal” out of aluminum foil and tried again. It worked.

This only tested high frequency signals and probably doesn’t reflect real EMP risk in any way, but it was fun to do.

EMPs do not affect small devices that aren't plugged in, they simply don't have the size to couple that much EM energy.

What is potentially affected is large power lines, railways, street lights, copper-networking equipment, some industrial systems, etc..

As a New Englander, I am not surprised WBZ was the strongest AM signal available. Depending on the weather, you would hear callers from the Midwest and South regularly on a Boston-based station.

Technically I'm measuring in the "wrong direction" since I would be very surprised if an EMP were initiated inside a trash can in my basement, but shielding works the same in both directions so this doesn't matter.

It really doesn't, with 1.5GHz you're still in near field regime inside the can.

I use metal cookie tins with lids that seal tightly to store thumb drives and hdds of data, my most recent old phone, emergency crank-and-solar-powered radio, walkie talkies, etc.

I tested it by putting my phone in there, closing the lid, and then calling it. No ring. Then loosened the top and it rang. Tested it with streaming music too.

I tested with the radio too. It played music with top off, and went to static with top on.

On the topic of Faraday cages: is there a way to make one whose "Faradayness" can be turned on and off at will? I remember hearing that you can do so with current, but I haven't found much info since.

Since you already suspect that any EMP will come from above why didn't this guy simply turn the trash can upside down and place it over the test setup?

There would be no need to seal anything since the can has a continuous rolled seam. Just use a standard trash can instead of one of those kitchen trash cans that likely has a plastic bottom for easy clean-up.

When apple started doing mac address randomization on the iphone, we used a metal trash can to test that in a controlled environment. It worked quite well for wifi isolation. We did not tape the lid.

     > It's not totally known what effect an EMP would have on stuff

Sandia wrote a report called, "Did High-Altitude EMP Cause the Hawaiian Streetlight Incident?" - http://ece-research.unm.edu/summa/notes/SDAN/0031.pdf

There's probably a hyper detailed classified study sitting somewhere in a dusty drawer with that data that should probably be declassified. If you'd be down to FOIA it, I'd love to read it!

    > With how quickly AI is going basically all futures are weird in some ways. I've been thinking about how this affects me personally, and "try as hard as possible to keep AI from getting us all killed" is pretty high on the list. For me this mostly looks like donations and pandemic deterrence, but I also put some time into thinking about disasters. There are ways AI might go very well, or very poorly, and then there's the "messy middle" where we muddle through and things might fall apart some in the meantime.
    > 
    > The big things here are making sure you have enough water and food for a while, along with critical medications and the standard "prepping" recommendations. But lately I've been thinking about what you might do for other risks, such as engineered pandemics, mirror bacteria, or fire suppression outages. And today, EMPs.

But based on the post, it seems that your threat model is off. The biggest threat of an EMP blast won't be your electronics acting up, but it would be the critical high voltage transformers being taken offline. These transformers have a lead time of months. Weeks in the best-case scenario.

From the congressional research service, https://sgp.fas.org/crs/homesec/R43604.pdf

     > Most HV transformers are unique and therefore are designed and manufactured to custom specifications for a specific network application. In 2010, the lead time between an HV transformer order and delivery ranged from 5 to 12 months for U.S. manufacturers and 6 to 16 months for foreign manufacturers, although lead times well over 20 months could be required in certain situations.10 This process may include three to four months for the engineering design alone.11 Since manufacturing generally occurs on a single production line with just-in-time component supplies, advanced production scheduling is important for managing delivery.
    > 
    > Physical assembly is labor intensive, requiring manual winding of the copper wire around the transformer core and frequent engineering checks during manufacturing. Extensive testing of completed units also contributes to HV transformer manufacturing time. The installed cost for an HV transformer depends heavily on its configuration and specific design requirements. 
    > 
    > New HV transmission substations can cost well in excess of $10 million, including the cost of transformers and other station equipment. According to the U.S. Department of Energy (DOE), the factory prices for HV transformers typically range from $2 million for a 230 kV unit to $7.5 million for a 765 kV unit, before transportation and installation costs.

It's possible to do that but it's not possible to do that cheaply.

As far as contingencies for EMPs for your personal items go. You can use water as a very effective shielding medium. If you have an average sized backyard swimming pool, and if you can somehow bury something at its exact center i.e. under the pool, then a small box there would survive almost anything. Water is a really, really, really great shielding material.

This is a cool test and a great use of (relatively cheap) rtlsdr dongles. Ignoring the "prepper" aspect a faraday cage is genuinely useful thing to have around if you want to play with radio transmitting without any chance of breaking any laws.

A much better faraday cage is matroiska doll nesting of two different size trash cans with a non-conductive platform supporting inside smaller can. The air gap and double conducting surfaces really help. And with the different circumference of the smaller can's rim there'll be a different resonant freq that gets let in. So while the outside seam may pass ~339 MHz without any attenuation the inner seam might pass ~450 MHz and so both unintentional passbands will get at least the minimum ~20dB attenuation per can.

decadess ago for film canisters they made lead-lined bags to take them through airports

I bet that's a pretty good faraday cage

This kind of prepping is silly. I suppose it's a way for adults to build pillow forts.

AI isn't likely to deliberately kill anyone. It's likely to make them entirely economically uncompetitive.

Today, if people go on strike, the economy grinds to a halt. This gives them a good deal of political power. If the economically useless go on strike, nobody cares.

That leaves violence to make people's voices heard, and the surveillance and police forces that we've been automating should be effective at undermining, dispersal, or suppression.

Automating the economy is the risk to humans, not EMPs.