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Old 01-24-2017, 01:00 PM
emailthepilot emailthepilot is offline
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Are flashlights and in particular, batteries, suseptible to EMP requiring protection from such?
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Old 01-24-2017, 05:06 PM
BigSlick BigSlick is offline
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Batteries, I would think your good. Old school incandescent lamps, I think you are good there as well. LED's, the simple circuit design are probably good too. LED's with the multi-mode circuit, who knows. I would think the construction of the flashlight barrel if it is made with some kind of metal would provide some degree of EMP protection but in the end who knows. Just my 2 cents.
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Old 01-25-2017, 12:44 AM
JLeeS1983 JLeeS1983 is offline
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Here is a thread about the effects of an EMP on batteries. https://www.survivalistboards.com/showthread.php?t=60982 As to a flashlight I remember reading something that during the nuclear bomb tests they found that the smaller and simpler the electronic the less it was effected. Though now the pulse generated would be alot stronger. The strength of a solar flare would be random.
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Old 01-25-2017, 01:03 PM
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great link. thanks
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Old 01-25-2017, 03:52 PM
jaarmstrong44 jaarmstrong44 is offline
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I have done some studying up on EMP's, as an electrical engineer that I am, when it come to semiconductors (and yes LED's fall in this as well). Anything that has a semiconductor in it will fail. what happens is the semiconductor will heat up to the point the the die melts, shorting out the device. So batteries will be fine but the LED's are toast, but if you are using an incandescent bulb in your flashlight you will not have any problems.
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Old 01-25-2017, 04:22 PM
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Originally Posted by emailthepilot View Post
Are flashlights and in particular, batteries, suseptible to EMP requiring protection from such?
GAWD! Why do people keep worrying about the Boogeyman?!?

There are only two ways for an EMP to occur in the real world:

1) A nuclear explosion in your vicinity
or
2) The Earth passing through a massive solar flare.

In the first case, you have a LOT more to be concerned about than whether or not your flashlight works

In the second case, again you have a lot more to worry about - although what you are worrying about is very different.

In the case of the Earth intersecting a massive solar flare (aka coronal mass ejection) at a level to cause anything resembling the boogeyman "EMP" at least half the world will be totally without commercial electrical power because the major power lines (including all the transformers, relays, and electronics that make them work) will all be fried. Smaller devices, such as your home computer, your cell phone, your car, and your flashlight are all much less likely to be damaged by such an EMP unless they happen to be connected to power/phone/cable WIRES. So, yes, your computer will probably be fried, along with your TV, any landline phone, and your cellphone IF you have it on the charger, but your car and your flashlight are probably safe -- even without any of the magic Faraday Cage nonsense favored by the tinfoil hat brigade.

If the Earth does intersect another solar flare at the level of the Carrington Event, I hope you've got at least ten years worth of batteries for that flashlight, because the lights are likely to be out at least that long.
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Old 01-25-2017, 04:26 PM
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I have done some studying up on EMP's, as an electrical engineer that I am, when it come to semiconductors (and yes LED's fall in this as well). Anything that has a semiconductor in it will fail.
All true, from an electrical engineering standpoint.

However all that starts from the presumption that the device is exposed to an Electromagnetic Pulse.

And also presumes that someone gives a damn about the semiconductor immediately after a nuclear explosion (or can still find the semiconductor in the dark after a massive solar flare puts out the entire electrical grid).
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Old 01-25-2017, 05:59 PM
TyMoore TyMoore is offline
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Batteries are good. Incandescent fine. LED probavly. High energy nuclear EMP will have a 10-20 nanosecond rise time. Very, very sharp spike. Solar EMP is a longer wave phenomena: it mainly affects things like power lines and pipelines.
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Old 01-25-2017, 09:29 PM
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Originally Posted by jaarmstrong44 View Post
I have done some studying up on EMP's, as an electrical engineer that I am, when it come to semiconductors (and yes LED's fall in this as well). Anything that has a semiconductor in it will fail. what happens is the semiconductor will heat up to the point the the die melts, shorting out the device. So batteries will be fine but the LED's are toast, but if you are using an incandescent bulb in your flashlight you will not have any problems.
Who the hell gave you a degree in electrical engineering?

First off, semiconductors aren't particularly susceptible to EMP by them selves. Millions if not billions of semiconductors have been been exposed to EMP without damage, The few that get damaged are the ones that are connected to wires that act as antennas. I've seen the USAF lab in Warner Robbins AFB hit semiconductors with pulses thousands of times more powerful than EMP (I think they were running fields 10-20x as strong (500-800 V/m is what I think were zapping them with), and pulses much, much longer), without inducing damage (which is the military goal, electronics that can survive in front of a fire control radar- and in their WRAFB's case, they want to induces the failure so they can take the chip apart and find the failure point.)

Second if you knew anything about nuclear electromagnetic pulse, it's not the power that causes the problem, it's the voltage- there really isn't that much power. In a high altitude nuclear detonation, most (99%) of the energy isn't released as gammas. Most of gammas (75%) don't travel towards the earth. Very little of the energy is turned into non ionizing radiation. SO there isn't enough power to be melting silicon across the entire united states. What does happen if you couple enough of the nanosecond pulse into a semiconductor, it hits a high impedance junction and the voltage can blow a hole in the microscopic junction layer (in CMOS, you get reversible effects first.). Under any normal conditions that takes a conductor feet or inches long to collect enough energy, especially under real world conditions.

The e3 pulse which is kind of disturbance in the earths magnetic field, can generate high currents, but only on extremely long wires, especially on grounded systems.

Not that I'm pround of it, but I accidentally exposed my iphone, and Motorola HT (and unfortunately retina, and gonads) to a 6 million watt peak ERP radar signal at 40' a few years ago. Iphone, HT, and eyes are doing fine.

BTW, a 50,000 V/m EMP pulse is is 663W/ cm^2. That's a lot of power. But it only lasts for 100 nS or so at that level. That's ten millionth's of a second. So our energy is .63 mW-S/cm, or .63 mJ/cm^2. Not melting a semiconductor die at that power level. Over a second, that's less power than from a cell phone. And that's assuming the chip somehow focused the energy from a full square cm on the die, and the die absorbed all of the energy.

And you realize EMP peaks in the HF band. What hams call the 160 meter to 30 meter bands. They are called that due to the wavelength. You need antennas 1/2 of that wavelength to efficiently capture energy. so an antenna about 20 to 80 meters is going get the strongest signal per foot. And the leads on your semiconductor are millimeters, and the ones in a flashlight are centimeters long (also in a coaxial (metal shell) or parallel (plastic body)arrangement which makes for a really poor antenna arrangement.) But they are also hundreds of times too short. Or put another way, the frequency they might couple well (say 500 Mhz) is where EMP has dropped 1/50 of it's levels at low frequencies. (I'm thinking 1/50 works for a 6 CELL Maglite, for a surefire sized light, maybe 1/200 the power)

While it's a wild guess what EMP would do to our society, or even the power grid, it's not had to know what it does to a cell phone, laptop, electronic lock, watch, flashlight, etc (assuming non of the above is connected to a power or data cable- that's makes it hard to make generalizations.)

Lots of small electronics (such as the Ultra radaic plus radiation meter I have in my desk) are certified to be EMP resistant. I'm sure the same tests were done before the military picked aimpoints or PVS14s, or whatever. I know for a fact they did it on the MAS Hamilton X-07 lock, the DOD "electronic" safe lock.
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Old 01-25-2017, 10:52 PM
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Quote:
Originally Posted by xaunloc View Post
GAWD! Why do people keep worrying about the Boogeyman?!?

There are only two ways for an EMP to occur in the real world:

1) A nuclear explosion in your vicinity
or
2) The Earth passing through a massive solar flare.
So 1's more or less a don't care unless you are installing electronics in blast shelters. The range of possible EMP damage is awefully close to the range where normal buildings are destroyed.

2's not an EMP. Solar EMP is some kind of conservative marketing word at best used to argue for protection of the grid from both nuclear EMP and solar weather.

EMP is a ElectroMagnetic Pulse. its just a pulse of electromagnetic radiation. You could describe sending morse code, or radar as strings of EMPs. Pulse implies something of short duration so a solar storm (or the sun rising) is not properly described as a pulse (and the sun is a hell of a generator of electromagnetic radiation- next month through march, it's going to jam every stationary (geosynchronious) satellite link in the northern hemisphere, and do the same in the southern hemisphere in late march and april- but that's still not EMP.)

When emergency management, or the military, or a well informed pepper, uses the term EMP, they are usually referring to a Nuclear EMP (NEMP), typically a high altitude EMP (HEMP). It could also mean directed energy weapons which can be used to disable electronics at short distances.

If it's not clear, if a nuclear device goes off at ground level it will free Compton electrons just like at high altitude, but with billions of trillions of gas molecules per cubic foot, they aren't going far, and the EMP will be insignificant compared to the blast damage (again unless done right outside a hardened shelter, where you MIGHT be able to damage something that doesn't get destroyed seconds latter. For a high altitude NEMP (30km is a figure of merit), the atmosphere is 1000 times thinner, so an electron will travel 1000 times farther, more or less making the current density 1000 times higher. There are other effects that make the pulse stronger, and more coherent also. There's tons of classified and unclassified work on source region EMP, and I've ignored most of it, because unless you design battle ships, tanks, or something similar, it's not particularly relevant.. For a battle ship (OK, they don't exist anymore, so a capital ship of some sort) that might be attacked with a nuclear torpedo or depth charge (subs, I guess), it's relevant.

BTW the above description of high altitude EMP, should make it clear than any ballistic missile can cause an EMP. If it doesn't get in to the ultra thin air, then it's not much of a ballistic missile. The problem is the technology of building a lightweight nuclear device is challenging, and a much simpler bomb, is going to tend to weight tons, and be incompatible with the likely available ballistic missile technology (A Saturn-5 rocket could put Fat Man (5 tons) past 30 miles, but a SCUD ain't gonna get off the ground. A scud missile will carry a Russian designed modern nuclear weapon.)
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Old 01-30-2017, 09:32 AM
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Flashlights and batteries should be fine. An EMP is unlikely to affect devices that are not attached to some sort of long electrical conductor such as telephone, cable or power lines.

An EMP that takes out everything with semiconductors makes great reading and writing -- I did it in my series -- but it's not what would really happen. Granted it would still be a really huge disaster, but flashlights, cars, even computers that are disconnected from power should still work okay.
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Old 01-31-2017, 08:30 PM
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Quote:
Originally Posted by xaunloc View Post
If the Earth does intersect another solar flare at the level of the Carrington Event, I hope you've got at least ten years worth of batteries for that flashlight, because the lights are likely to be out at least that long.
We almost did back in 2012

My favorite part:

"A 2013 study estimated that the economic cost to the United States would have been between $0.6 - 2.6 trillion USD. Ying D. Liu, professor at Chinaís State Key Laboratory of Space Weather, estimated that the recovery time from such a disaster would have been about four to ten years."
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Old 05-25-2018, 06:20 AM
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If you are worried get a metal trash can and lid and copper musician’s tape. Line trash can and lid with cardboard. Place small electronics inside and seal with copper tape.
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Old 05-26-2018, 12:31 AM
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If you are worried get a metal trash can and lid and copper musicianís tape. Line trash can and lid with cardboard. Place small electronics inside and seal with copper tape.
What in the world is copper muscianís tape? It sounds like a cheaper alternative to EMI shielding tape which is probably a $1/ft in copper.
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Old 05-26-2018, 06:04 AM
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It’s tape one can get at a music store at least the one near my apartment had it. I saw something on YouTube where a guy showed that it was conducive even the adhesive so I figured it would work. My dad wouldn’t tell me how much he spent on it. He just said I own him... so my guess is it is expensive
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Old 05-26-2018, 11:26 AM
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Itís tape one can get at a music store at least the one near my apartment had it. I saw something on YouTube where a guy showed that it was conducive even the adhesive so I figured it would work. My dad wouldnít tell me how much he spent on it. He just said I own him... so my guess is it is expensive
I googled it and just came up with gaffers/ duct tape- nothing metallic- will have to stop by a music store.
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Old 07-11-2018, 12:16 PM
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Originally Posted by country_boy View Post
What in the world is copper muscianís tape? It sounds like a cheaper alternative to EMI shielding tape which is probably a $1/ft in copper.


Aluminum h-vac tape works well too and probably less expensive. You can get it at Lowes or Home Depot back in the AC parts area.


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Old 07-11-2018, 12:20 PM
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What in the world is copper muscianís tape? It sounds like a cheaper alternative to EMI shielding tape which is probably a $1/ft in copper.
It's tape used in the control cavities of electric guitars to shield them and help prevent unwanted feedback...

You can get it at luthier supply places like this one https://www.stewmac.com/Pickups_and_...pper_Tape.html
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Old 07-15-2018, 10:04 PM
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It's tape used in the control cavities of electric guitars to shield them and help prevent unwanted feedback...

You can get it at luthier supply places like this one https://www.stewmac.com/Pickups_and_...pper_Tape.html
Tnx, thatís cheaper then McMaster.
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Old 07-17-2018, 01:06 AM
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Antenna area! antenna area! antenna area!.

A flashlight has very little antenna area unless plugged into a charger of some type.

I have a vest type survival kit in a 20mm ammo can with two led flashlights and a solar charger that will work even after a EMP attack.

A military ammo can is a Faraday Cage and is used by the US military to protect electronic fuses and primers from harm.

If the military ammo cans did not protect ammo from EMP the US would lose about 80 of there military stockpiles.
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