Effects of EMP on LED Lights?

[AzN1337c0d3r]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

Aren't flashlight bodies usually part of the circuit? Thus they don't act to shield the electronics inside.

 

[Marduke]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

The Inova lights? What's special about those?

The Inova X5 is about as perfect as you can get for an emergency light. It will run on dead batteries that won't even glimmer in other lights, it will run like that for weeks, uses lithium batteries with a 20 year shelf life, extremely reliable and rugged construction, and doesn't contain sensitive regulatory circuitry. It's a simple direct drive light, with only some resistors. For these reasons, it is often lovingly called "bomb proof"

 

[Marduke]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

Oh, and an aluminum body would offer no protection. Only a Faraday cage would offer any sort of protection short of several feet of earth, concrete, or metal.

 

[Skibane]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

The amount of damage that can be produced by HEMP (EMP produced by a high-altitude nuke detonation - the only kind of EMP that is likely to be encountered by anyone living more than a few miles from a high-value military target) - has been GREATLY exaggerated on the internet.

EMP does its damage by inducing a very brief, high-voltage spike in electrical devices. This spike can be strong enough to burn out wiring, "punch through" the thin semiconductor layers in transistors, computer chips and diodes, or cause the software in computer-controlled devices to go haywire.

However, the strength of the electrical spike induced in any electrical device by a HEMP burst is dependent on the length and physical orientation of any conductors connected to the device. Long conductors (i.e., AC power lines, phone lines, big antennas, etc.) receive a significant amount of the EM pulse; short conductors do not.

In devices that aren't connected to any long conductors, virtually no electrical spike is generated due to EMP, and thus the device is unlikely to be damaged. Most small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, flashlights, etc.) would fall into this category - The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them.

Similarly, the short length of the wires present in most vehicles (automobiles, motorcycles, ATVs, etc.) also intercepts very little of the EM pulse - and thus, is unlikely to be damaged. Also the wiring in most vehicles is partially shielded by the vehicle's metal body (thereby further reducing the strength of a voltage spike induced), and all vehicle electrical systems are designed to deal with the high voltage spikes normally produced by the ignition system, motor brushes, relay and solenoid coils, etc.

Several practical examples:

1. During the Starfish Prime high-altitude nuclear test conducted on July 9, 1962, it was reported that EMP effects caused damage to streetlights in Hawaii (some 930 miles away), and yet portable radios located on Johnson Island (directly under the nuclear burst) were undamaged. Explanation: The portable radios lacked any large antennas or other connections to long conductors, and thus didn't receive enough of a spike to be damaged.

2. The American Radio Relay League (ARRL) reprinted a series of articles (originally published for the National Institute of Standards) that described the effects of EMP on various communication equipment:

Intro to EMP
EMP Protection Devices
EMP Implications for Communications
EMP Protection for Communications

These tests demonstrated that even very sensitive equipment is unlikely to be damaged by EMP, provided that the equipment doesn't have any connections to long conductors.

BOTTOM LINE: All of your flashlights stand a good chance of being usable after a HEMP burst, even without taking any special precautions beforehand.

 

[d1337]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

On the bright side if your flashlight does fail after the nuke you will probably glow in the dark for a couple of weeks anyway. :sick2:

 

[Bushman5]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

its really quite simple, line your backpack, clothes, vehicle, and house with mass amounts of tinfoil adn copper mesh, and wear a tinfoil hat!!

:laughing:

 

[Sigman]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

Several like threads merged...

 

[markfinn]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

Thanks to you all (in particular to Skibane!) for the explanations!
At first I was a little afraid that you would make me look like a fool for this question, but again it was a pleasant surprise to see these knowledgeable people here. That's what I like CPF for!!!

 

[Dr Jekell]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

From my understanding of it an EMP is comprised of Electro Magnetic Waves, Which is like TV signals, AM/FM Radio, cell phones, transceivers (Portable Radios), ham radio, microwave transceivers, etc but over many bands instead of just one or two.

This would indicate that if an item were to be damaged it would need to have something either attached or built into it that would act like an antenna (like the one for your TV, car radio, power lines & pylons, phone lines) to attract any of the EMP.

So this would debunk the idea your LED lights (with or w/o electronics) would not survive an EMP as they have very short amounts of wire in them to act as an antenna.

The same could be said for small electronics (exceptions exist) to survive as well.

Items like laptop computers, cell phones, MP3/CD/Tape players, are a toss up as to whether or not it would

A) Develop a Fault that can be fixed or gotten rid of
B) Be damaged or
C) Killed

There is a similar problem that is more widespread & catered for is EMI or electromagnetic interference (if you look on the underside of almost any electronic device & you will see a sticker stating that it has been tested for this, most will be tested to the FCC standards which I believe most countries accept - go ahead & have a look under you desktops keyboard)

This may also provide some protection for items like laptops & cell phones as they may have shielding built into them to reduce EMI.

This is my understanding of EMP theory but it may have errors so take it with a grain of salt.

 

[Mr_Dead]

Re: Tin foil?

I'm pretty sure you are right. Many Americans use the term "tin foil" when they really mean Aluminum foil. People raised in the 40's and 50's called it that and their children probably flunked chemistry.

They still use it to seal the ends on wine bottles (the "capsule", protecting the cork). In fact, that's more likely to be real TIN foil, than the cork is to be a real cork these days, but you might not have noticed unless you look closely.

 

[h_nu]

Re: Tin foil?

They still use it to seal the ends on wine bottles (the "capsule", protecting the cork). In fact, that's more likely to be real TIN foil, than the cork is to be a real cork these days, but you might not have noticed unless you look closely.

I didn't realize the foil was Tin. I did notice a synthetic cork on a bottle of Sangiovese Toscana. It even felt like cork.

 

[Don_Redondo]

Re: Will LED flashlights survive the EMP from a nuclear explosion?

The antenna theory makes sense. My house has gone through quite a few near lightning misses – comes with living near the top of a hill. On two separate misses I had network ports damaged. A couple on a router and one on a workstation. The router and it's replacement got damaged a year apart. Since all the computer outlets are surge protected, no lights flickered, and no other electronic equipment in the house was damaged, it doesn't seem like it was a surge on the AC side. The most likely explanation is that the charge differential before the strikes induced a brief excess voltage in the network cables and fried the ports. The intriguing thing is that the routers only lost a couple ports – each time - and they weren't always the ones with the longest cables attached – the orientation must have played a part – which was mentioned as a factor with the EMPs. (The router was under warranty and replaced – both times. Since the service was more than I expected here's a mini cheer for SMC.) Another interesting thing was that the workstation was only crippled and will only connect at 10mbs instead of the 100mbs before the miss. And yet another weird thing was that a laptop turned itself on at the same time. My assumption was that the pulse in the network cable triggered some "wake-on-lan" function but I never found out the exact reason and it never happened again. It was pretty spooky since I was right next to it at the time.

While this is not the same thing as an EMP, I imagine the effects may be similar – some things damaged and some things OK. As for the effect on lights, all this happened before I had any LED flashlights but to the best of my knowledge, none of my incandescents went .

 

[Confederate]

When I worked with the Navy, a lot of the R&D had to do with hardening electronics from electro-magnetic pulse. Now with intelligence fears of a nuclear detonation over the U.S., everything from computers, televisions, radios and even motor vehicles are threatened.

I believe the circuitry in these small lights also would be affected, but if so, how can they be protected? I've heard of makeshift Faraday boxes, but if the lights can be protected in any other way, I'd like to know about it. I need only protect very small items at this point. I also wonder if batteries would be damaged. I know rechargers and solar power units would be fried.

Thanks for any info!

 

[PhantomPhoton]

Theres been quite a discussion on this before. Unfortunately searching for EMP didn't work for me but I was able to find this recent thread via other methods.

Here

 

[joema]

Discussed extensively here:

(Moderator note: Merged like threads, edited out inactive links - THANKS joema!)

 

[Confederate]

Thanks! Just what the doctor ordered!

 

[Sigman]

Thanks for the links joema...I'm merging the threads & will edit out the inactive ones.

 

[mzzj]

Re: Tin foil?

They still use it to seal the ends on wine bottles (the "capsule", protecting the cork). In fact, that's more likely to be real TIN foil, than the cork is to be a real cork these days, but you might not have noticed unless you look closely.

And orginally "tin foil" was lead, not tin.

 

[democopy]

"Every flashlight I own is an LED based one (and quite a few of the brands you mentioned). As far as any kind of EMP pulse destroying or damaging it, the only type that will is going to be a strike from a e-bomb/HPM (High Powered Microwave) based EMP system, and even with the e-bomb/HMP attack it would be hard pressed to actually damage the unit.. The reason for this is simple, there are no long lines in the circuitry of the flashlight, so HEMP blasts and nearby lightning strikes are not going to "couple" their energy into the unit to destroy or damage anything. Microwaves (what e-bombs/HPMs use) could damage or even destroy them IF enough of the energy was coupled into the circuitry. The fact that most good LED flashlights (like the ones you mentioned) are in a metal (usually aluminum or titanium) case, thereby creating an improvised Faraday cage around the electronics. This further keeps the microwave energy from gaining any ground in the destruction of your flashlights. When I was doing the tests back in the lab (back in the 90's) I carried my CMG Infinity LED flashlight with me always on my keychain. It went through thousands of pulse repetitions og HEMP during those years, and dozens of MHD tests, and I still have it today and use it often. I even used it to provide the light source during some of the "close in" tests that we did with the Vircator and certain military gear.

Given the fact that an e-bomb/HPM attack is a very strategic strike (a few city blocks is maximum effective coverage), they probably are not going to go wasting them around the countryside, but rather use them to strike VERY high importance targets, so unless you are at a military base, or at a major infrastructure point, I would bet that your area will never see a microwave attack.

EMP damage is easy to remember, EMP will only damage things that are connected to wires longer than one half wavelength of their frequency, and even at one full wavelength it is not coupling much of the signal. To find the length of a half wavelength, divide 468 by the frequency in megahertz. For HEMP and other coil-only (HF and lower frequency) based systems, this means long wires. HEMP's (and coil-only EMP's) range is from <100KHz to 18MHz before it starts dropping the power levels quickly, with the majority of the power concentrated below 6MHz. At 6MHz, a half wavelength piece of wire is 78 feet long, at 18MHz, it drops to 26 feet. This is why HEMP will not bother handheld devices or devices that are not connected to long lines, the grid or big antennas. E-bombs and HPMs are much higher in frequency, usually in the 950MHz to ~24GHz (24,000MHz) range. At 950MHz a half wavelength piece of wire is 5.9 inches, and the upper end of 24GHz is only .234" (1/4 of an inch) long. This is why e-bombs and HPM weaponry has the possibility of damaging ANYTHING outside of a Faraday shield, because the electronic component's leads, and the circuit board traces are long enough to couple the energy into the device without the need of long wires or grid connections. The good news is that most of the good flashlights are mostly shielded by their metal cases.

In other words, I would not worry about the possibility of the threat."

 

[h_nu]

I have more realistic things to worry about. That said, I have wondered about something though.

In the 80's, when the public became aware of neutron bombs, many people were surprised that the bomb models were sophisticated enough to allow the designs to be tuned to produce mostly neutrons and limit blast effects. Perhaps there are designs that focus most of the energy produced in the microwave region and the EMP could be substantially higher than ordinary bombs.