Now i am worried!

[RocketTomato]

... The Faraday cage relies on an isolated conductive "shell" to work properly. As someone above said, if you allow something conductive to make contact with the cage... It would actually act as more of an antenna then a protective cage.

The electrical field will always be zero inside a metal shell. No need to insulate.

You also want to ground it to dissipate any electrical charge that may build up but it is not necessary for it to act as a Faraday cage.

 

[Pandorum]

The electrical field will always be zero inside a metal shell. No need to insulate.

You also want to ground it to dissipate any electrical charge that may build up but it is not necessary for it to act as a Faraday cage.

A metal flashlight is not a true faraday cage. The led and switch areas are not covered and is wide open. Also, lots of metal lights use the metal body as part of the circuitry and will conduct the EMP right into the electronics.

 

[RocketTomato]

A metal flashlight is not a true faraday cage. The led and switch areas are not covered and is wide open. Also, lots of metal lights use the metal body as part of the circuitry and will conduct the EMP right into the electronics.

Right. But I never said a flashlight is a Faraday cage. If you look at what I quoted, I was replying to the comment that the flashlight cannot make contact with the inside of the cage or it will act as antenna, which is not correct.

 

[rickypanecatyl]

How do you figure this? Are you an expert on the intentions of national leaders? Have you not heard the threats made by some national leaders?

+2

I, by the way, am an expert on the intentions of the hearts of chief of states AS WELL AS rogue leaders and I say there will be a nuclear blast in the next 14 months. I'm thinkin it'll probably happen on a Monday... could be Thursday, but I'm gonna go with Monday! :wave:

 

[Pandorum]

Right. But I never said a flashlight is a Faraday cage. If you look at what I quoted, I was replying to the comment that the flashlight cannot make contact with the inside of the cage or it will act as antenna, which is not correct.

But that is correct.
If the flashlight is metal and contacts the inside of the faraday cage then the EMP energy can be transmitted to the flashlight and damage its electronics. You do need to insulate the object you're trying to protect.

 

[BobBarker]

The electrical field will always be zero inside a metal shell. No need to insulate.

You also want to ground it to dissipate any electrical charge that may build up but it is not necessary for it to act as a Faraday cage.

The cage only works if the item you are protecting is not making direct electrical contact with the cage. The separation (or insulation) required to achieve this effect is dependent on the strength of the spike. Just putting a flashlight (or anything else with closely spaced electrical traces, like ICs) in the cage (assuming direct aluminum to cage contact, or a spike of sufficient voltage to overcome the insulation) will in fact not protect anything.

Think about it like this. A Faraday cage works as well keeping signals (emp) out as well as it does keeping it in. But if you were to take a transmitter and make a direct electrical contact with the cage, it now becomes a very poorly designed antenna.

This was one of many things stressed to us during the EMP hardening classes I had to take on aircraft avionics.

 

[AnAppleSnail]

Think about it like this. A Faraday cage works as well keeping signals (emp) out as well as it does keeping it in. But if you were to take a transmitter and make a direct electrical contact with the cage, it now becomes a very poorly designed antenna.

I'm interested in aircraft avionics because they operate high up in the atmosphere, and encounter exciting solar flare effects. Nobody has tested a commercial jetliner near the poles in a solar flare due to safety things (As far as I know!).

With flashlights, this is just one more reason to appreciate anodization. Although if you're going to go all-out in having your EDC ready for use, I suggest this procedure based on me making things up before morning coffee.

1. Place flashlight in a ziploc bag. Seal bag, then roll around light. Flashlight is now waterproof.
2. Wrap in fabric to provide an electrical and impact buffer.
3. Wrap in foil, place in gallon ziplock. If you want to be clever about the foil, run a fishing line in the wrappings so you can pull it and 'unzip' the foil wrapping.
4. Place bag someplace secure. The light will probably survive an earthquake or two, and need battery changes every so often.

 

[TEEJ]

Yeah, contact that creates continuity with the metal of the "cage" essentially makes the conductive contact materials PART of the cage, defeating the purpose.

Similarly, if the light uses its body as part of a circuit, the body is not protecting the circuit. After all that, it comes down to a matter of DEGREE. The effective strength of the effect in that orientation, etc, and, the durability relative to that sort of energy involved of the circuit in question, will determine if the effect actually causes any damage.

Remember that solar effects are a regular occurrence, and that EMP exposure to your lights has already occurred many times....so if they work NOW, they already have at least some resistance to this effect.

In addition to your flashlight, the things that charge your cells, operate your car and computer, etc, are also vulnerable. Are you going to wrap your rig, chargers, and computer, etc, in foil when not in use so they also survive?

 

[archimedes]

Hey, wait a minute, isn't the mind an electrical device that would need to be covered in tinfoil, to continue to work during solar flares and what-not ???

Otherwise, how will one remember where all of the "foil-wrapped computers" are buried, after the EMP burst ?

Something like this ought to work nicely -

http://www.youtube.com/watch?feature=player_embedded&v=Ze07J8IbQfA

( Kidding ... :tinfoil: )

 

[DanTSX]

I'm pretty certain that the destructive effects of EMP on electronic components is vastly overstated. Mostly, this is due to worried preparedness types that would rather try to advise as experts, rather than truly understand the issue at hand.

EMP resulting from an airburst nuclear detonation is far more localized and limited than it is proclaimed to be. Those that are wrapping everything in layers of tinfoil and burying hand-crank Ford Model T's for their post-apocolyptic fantasy are going to be a bit sore when they realize that their neighbor's iPad and Prius start right up. The most worrisome effects of EMP is immediate effects to distribution infrastructure (that will mostly be blown up anyways), and lingering ionization that will affect all electromagnetic communication for a decreasing period of time. The most worrisome would be sensitive satellite electronics. As correctly pointed out, the sun dishes out similar EM radiation regularly.

In other words, if you are close enough to a blast for your kit to be affected by EMP, it's already a miracle that the heat and blast effects didn't already kill you. The radiation dose you received in that blast will likely kill you before you have a chance unwrap your cell phone from the reynolds wrap though.

This sentiment that a single EMP burst above the continental US as a giant "Off Switch" is pure lunacy, but it gets repeated all over the web. Tinfoil is for wrapping leftovers, not your head and electronics.

 

[Divine_Madcat]

Dan, while i do not count myself as a crazy prepper, i will say that the worries of an EMP are not as overrated as you make it out to be. I would advise reading up on Starfish Prime nd the soviet K Project.. Both demonstrated that a real airburst nuclear blast would do far more EMP damage than expected...

http://en.wikipedia.org/wiki/Starfish_Prime
http://en.wikipedia.org/wiki/The_K_Project

Frankly, most of the country could be disabled with a well placed, decently powerful (5 - 10MT) high atmosphere detonation.. Not to mention fallout effects.

The real question is, do the people who mean to do us harm, have the ability to airburst a nuke over our soil... That is another debate entirely.

 

[lightfooted]

In fact Dan the more immediate concern is not the airburst nuclear emp but rather the cosmic one....the CMEs from the sun which have proven to be several orders of magnitude greater in their intensity than anything we can generate, just look up the Carrington Event. It has come up of late do to increased solar flare activity and the observations of many that we are not equipped to deal with another Carrington class event.

Research is good, mmkay?

 

[127.0.0.1]

Research is good, mmkay?

ok research how big an event has to be to
1) get past the earth magnetic field and
2) cause induction on something as small as a flashlight body

telegraph wires are very long and a very mild field is all that is needed for induction

you would see the forests set aflame before a solar event could cause harm to a flashlight

seriously...this entire thread and discussion is a non-issue. you'll be dead before your flashlight dies

 

[davyro]

We are fast approaching a solar maximum,this is when the Sun produces Solar flares a lot more frequently & usually a lot more powerfully.We(the Earth)actually literally dodged the bullet just last month.A massive X-class solar flare cracked off from the Sun.Luckily for us it wasn't a direct hit.You'll know when a massive one hits the Earth by the Auroras,these will be seen a lot further from the poles heading towards the Equator.The worrying thing about this solar maximum is its forecast to be a once in a lifetime event.Basically the Sun is ram-ping up in a massive way.The reason i say we dodged the bullet is if one of these massive flares gets us with a direct hit the electric grid is toast as well as all unprotected electrical appliances.The frightening outcome is it will take at least 5yrs if we are lucky to get some sort of grid up & running.These facts can be checked out by anyone who is interested in doing a little research.Just research C.M.E's (coronal mass ejections).We would be back in the stone age in a blink of the eye,we're talking no water,food,deliveries of anything & medical equipment would be like gold dust.Your flashlight could well be a life saver all i know is the way to save electronic equipment is if a circuit breaker is used in some way.So i would personally wrap my light up in rubber or some other non conductive material then place it inside a metal container.This way you have a barrier in between your cage,so the circuit is broke.Also you could wrap your light up with electricians tape.

P.S I've just had a look at NASA's space weather site & there is a massive sunspot that is turning head on to be Earth facing as i'm typing this,it blew off an M 5 flare earlier today but we'll just get a glancing blow.The sunspot
harbours the energy & is looking like it could fire off an X-class flare while Earth facing.An X-class is the most powerful,it just depends what type of X-class it is an X-1 is the weakest X-class flare an X-15 & above would be big trouble for us all.

 

[dss_777]

Based on all I've read in this thread, I'd still say this is the best advice:

Wrapping in aluminum foil should do the trick.

Might work with the flashlight, too.

 

[DanTSX]

ok research how big an event has to be to
1) get past the earth magnetic field and
2) cause induction on something as small as a flashlight body

telegraph wires are very long and a very mild field is all that is needed for induction

you would see the forests set aflame before a solar event could cause harm to a flashlight

seriously...this entire thread and discussion is a non-issue. you'll be dead before your flashlight dies

Pretty much this.

The research was done before I spoke.

Additionally, the links that were posted, pretty much had reinforced my point.

I'm not looking to start an argument, but I think that the CPF community is simply too smart of a forum to fall for this EMP "off switch to the stone-age" stuff.

As far as the intentions and capabilities of other nations, coupled with our own aging nuclear power and weapons infrastructure, the prepper inside of me says to instead focus on getting your iodine pills, and read up on the different types of radioactive particles and weather patterns from your nearest nuclear facility.:tinfoil:

 

[127.0.0.1]

we should be worried about
'what is the best and most trusted and reliable pocket radiation detector on the market in 2012, and where can we get some?'
than anything regarding EMP.

seriously, we are in more actual 'it's happening now' danger from loose radioactive particles, from damaged reactors, than EMP