Electronics Q for y'all...

J

joeshredd

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May 8, 2002
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In reading many of the BOB lists, extra batteries are a significant must have...

My question is this: in the ultimate SHTF scenario - a nuke goes off in the back yard (ala the new series (?) on TV-Jericho(?)), isn't an EMP going to render your batteries useless??? Not being a technically minded sort, I'm curious what one would use for light afterwards, besides fire.. Are there any other options? For instance, would one of those shakelights work? What about a wind-up style light? Or, what about solar-powered stuff?

Just curious if any of y'all know or think about this subject...

Thanks in advance! :)
 
The chance of a real nuclear EMP is a matter of debate given the complexities of getting a big enough one up high into orbit. There are a few major world governments who could do it, but the risk of that happening is pretty small--versus some terrorist group popping off a small yield nuclear device in a city with limited exposure.

I think, "bigger things to worry about."

But should it happen, it isn't the batteries that will be affected, but the microprocessors inside the equipment. Batteries are effectively two lumps of chemicals: connecting their wiring causes them to pass current. Pretty passive things.

The microprocessor is however subject to electrical issues. An EMP is like rubbing your feet against a carpet and touching a device that isn't grounded. The microprocessor just goes poof.

An EMP is basically that. Even if you change the batteries, the device still won't work, even though the batteries are still fine.
 
Unless your radio, GPS, etc. are protected by a Faraday cage. This is essentially a metal grid which absorbs the transient electrical impulses of EMP. An example of an unintentional yet effective Faraday cage is a metal shop building. It absorbs the radio waves that work your cell phones, radios, GPS, etc. There are battlefield EMP weapons that don't use a nuculear yield to achieve the effect. So if you wanted to line a stash box with metallic mesh just in case, no big deal. Just hope you aren't wearing a pacemaker at the time an EMP goes off. Or depend on ITE/HAs like me (hearing aids).

But... if you are close enough to a blast to be effected by EMP, I would think that your energizers would be low on your list of concerns. And being nuked is rather low on my list of concerns.

From Wikipedia, the free encyclopedia
A Faraday cage is an enclosure designed to exclude electromagnetic fields. It is an application of Gauss's law, one of Maxwell's equations. Gauss's law describes the distribution of electrical charge on a conducting form, such as a sphere, a plane, a torus, etc. Intuitively, since like charges repel each other, charge will "migrate" to the surface of the conducting form. The application is named after physicist Michael Faraday, who built the first Faraday cage in 1836, to demonstrate his finding.

Codger
 
Faraday cages are difficult, but not impossible, for the amateur to build. Don't get me wrong: if you have electronics or electrical engineering experience, you can do it. I wouldn't say it's as easy as lining a box with mesh. It has to be the right kind of mesh installed very specifically.

But it would be awkward at best to carry stuff in, as transporting it frequently would damage it and defeat the effect. Here's a small but all inclusive one. And here's a smaller one, but as you see it doesn't do much but kill radio reception.

That said, Codger is correct on all counts. They are home-buildable! And the EMP may indeed be the least of your worries.
 
Just how much would it cost to change a van into a Faraday cage ? L:O:L

Are there basic battery powered devices (other than flashlights) that would work after an E:M:P ?

As has proabably been said we would proabably have bigger things to worry about in that case .

Knowledge is always useful .
 
1. Just how much would it cost to change a van into a Faraday cage ?
A: figure the number of feet of welded 1/2" wire mesh it would take to line the interior on all sides, top and bottom. 48" wide rolls are most common. The cage shouldn't be grounded to the van, and the protected items shouldn't contact the inside of the cage.

2. Are there basic battery powered devices (other than flashlights) that would work after an E:M:P ?
A: Yes. Small electric motors, and anything else that does not have electronic circuitry. The pulse, if strong enough, could blow the flashlight bulbs, or burn motor windings.

I keep a small shortwave radio in a metal ammo box. It is waterproof and shockproof. It also acts as a Faraday cage, but that is incidental.
 
I realize a lack of light may be the least of my worries if a nuke does go off! :eek: But, I was still curious...

Codger_64: concerning your radio in a box.. Wouldn't the radio be touching the metal of the box, therefore negating any "farady" style protection?

And I guess what I was heading towards, which I think you have all proven wouldn't survive, was whether or not a solar-powered light, like the Sollight, http://www.sollight.com/products/lightcap.cfm , would function? Oh well, like y'all said, I should worry about a few other things after a nuke event! :o

Thanks again!
 
There are other sources of EMP. Like a massive solar flare. And no, the foam in the box keeps the radio etc. from touching. If the solar light has circuitry, it would not survive unless protected in a box or cage.
 
A close lightning strike can fry electronics !! Remember that when they assemble electronics handling MOSFETs requires that you be grounded so that no static charges are there . A static charge will easily fry a fragile MOSFET !!
 
mete said:
A close lightning strike can fry electronics !! Remember that when they assemble electronics handling MOSFETs requires that you be grounded so that no static charges are there . A static charge will easily fry a fragile MOSFET !!
Click to expand...

I knew a guy who used to install and program security card access panels with a copper wire grounded to a pipe and held in his mouth . No flipping way . Let me repeat under no circumstances could you pay me enough to do that .

I have personally seen in the last month a ground wire attached to a water pipe with so much electricity running through it that it glowed . I am not talking a red glow . This was white light that you could have read a book by .

Imagine that cooking your dentures . You,ll never have bad breath again . L:O:L
 
Kevin the grey said:
I knew a guy who used to install and program security card access panels with a copper wire grounded to a pipe and held in his mouth . No flipping way . Let me repeat under no circumstances could you pay me enough to do that .
Click to expand...
Security access control cabling uses extremely low voltage at microscopic amounts of amperage. You don't even feel a tingle, and that's if you put the cabling directly in your mouth.

Grounding would be even less, because the electricity would be flowing out, down the pipe.

That said, I can assure you that what he was doing is not approved practice. The water pipe is okay if there's no better grounding system available, but putting it in his mouth is decidedly unapproved.

Kevin the grey said:
I have personally seen in the last month a ground wire attached to a water pipe with so much electricity running through it that it glowed . I am not talking a red glow . This was white light that you could have read a book by .
Click to expand...
That grounding conductor would not last more than a couple of seconds before it melted and popped. Where did you see this? A copper wire at white hot temperatures is in the thousands of degrees--higher than its own melting point. It wouldn't have lasted.
 
Codger_64 said:
There are other sources of EMP. Like a massive solar flare. And no, the foam in the box keeps the radio etc. from touching. If the solar light has circuitry, it would not survive unless protected in a box or cage.
Click to expand...


Gotcha!
Thanks...

and,

m_calingo; thanks for clearing it up for cheung_victor! :D
 
Watchful said:
Security access control cabling uses extremely low voltage at microscopic amounts of amperage. You don't even feel a tingle, and that's if you put the cabling directly in your mouth.

Grounding would be even less, because the electricity would be flowing out, down the pipe.

That said, I can assure you that what he was doing is not approved practice. The water pipe is okay if there's no better grounding system available, but putting it in his mouth is decidedly unapproved.


That grounding conductor would not last more than a couple of seconds before it melted and popped. Where did you see this? A copper wire at white hot temperatures is in the thousands of degrees--higher than its own melting point. It wouldn't have lasted.
Click to expand...

REPLY :Not only did it last the homeowner did it several times before I got there .

I kid you not . It was a panel ground wire attached to a water pipe . It shed light on a wall three inches away as bright as a mini mag-lite .

I think we can say that generally speaking it would not work . In this specific case it did . There are often things done that are neither evident nor approved .
 
Kevin the grey said:
I think we can say that generally speaking it would not work . In this specific case it did ..
Click to expand...
Well, technically, it was NOT working as a ground, but as a conductor!
 
"isn't an EMP going to render your batteries useless??? " The short answer is no , an EMP can damage solid state devices such as solid state diodes, transistors or integrated circuits but batteriess, many capacitors, incandescent bulbs etc will be unaffected. Grandma's tube radio will likely be unaffected- no transistors.
A relatively good faraday cage can be made by grounding an ammo can. It isn't Mu metal but the iron will act to reduce the electromagnetic radiation, aluminum is a poor subsititue but better than nothing.
People often forget that the pulse is not magic and will not destroy all electronics. It destroys by inducing a high voltage spike into any conductor cutting its path. The longer the conductor (wire/antenna) the bigger the spike and the more damage will be likey. A transistor radio in a footlocker in a basement will likely not be affected. Your CB radio, in the truck will likely be reduced to a door stop as it is connected to an antenna.
An interesting effect of the pulse is that it can be reflected and will bounce between the ground and the ionosphere so that some isolated areas halfway around the world may incurr damage.
Enjoy!
 
He is one of the VERY few Army Nuclear Engineers... and I flunked several math classes! :rolleyes: So thanks for the input guys! I felt kind of embarrassed to ask him! :D
 
Let's go back to the original question, what would you do for light?

OK, so it wasn't an EMP, but, it's a major disruption, batteries are all used up, power grid is still down, no estimated Up time? what to do?

If you are technical enough, maybe you could salvage a solar panel and rig batteries?

Oil lamp, wax candles, propane lantern.

That is where we would be.

Oil lamps are pretty cost effective, cheap units, you can store the oil almost indefinitely (flammable, store it out back in the shed, or take proper precatuions).
Give off tremendous light, compared to candles.

Eventually you will run out of oil, also.

At the very end of the road, you are with candles, dependant upon your knowledge of using animal fats.

At this point Shelter Water and Food would far, far outweigh the need for light. the Food-byproducts, fats and oils, might give you some light.

The old timers went to bed early, at 2000 to 2100 hours??
But awoke at daybreak to utilize the daylight as much as possible.
Daybreak in US Lower 48 is anywhere from 0430 to 0600 depending on latitude and season.

good question. What would we do?
 
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