Survivalist Forum

Advertise Here

Go Back   Survivalist Forum > Survival & Preparedness Forum > Urban Survival
Articles Chat Room Classifieds Donations Gallery Groups Links Store Survival Files



Urban Survival Urban survival and disaster preparedness including hurricanes, earthquakes, floods and anything else.

Advertise Here
Reply
 
Thread Tools Display Modes
Old 08-27-2012, 01:23 PM
Mr2005 Mr2005 is offline
Prepared
 
Join Date: Oct 2010
Posts: 322
Thanks: 47
Thanked 274 Times in 110 Posts
Default Emp...would it kill my flashlights/ Batteries?



Advertise Here

Emp...would it kill my flashlights/ Batteries?

Is so, would they survive inside a metal safe?
Old 08-27-2012, 01:34 PM
Yehudi's Avatar
Yehudi Yehudi is offline
Stranded on Earth
 
Join Date: May 2010
Location: Wyoming
Age: 67
Posts: 3,412
Thanks: 1,656
Thanked 4,354 Times in 1,646 Posts
Default

Consider what an EMP is. It is an electromagnetic pulse. When any magnetic or electromagnetic wave crosses a wire, it will induce a current into that wire. Whatever is attached to that wire will then be subject to that current. Electronic devices have coiled wire components, and when a wave crosses all those winding, the current is increased, the more winding, the more current. In addition, the high speed impulse also causes a voltage spike. In order for an EMP to cause damage, it has to induce a high enough voltage with enough current to overload components in the device, i.e. burn them out.

Most flashlights are encased in metal bodies, making them virtually immune to any EMP. Also, if the switch is off, there is almost no wiring that could transmit any voltage to the components.
The Following 3 Users Say Thank You to Yehudi For This Useful Post:
Old 08-27-2012, 01:36 PM
Yehudi's Avatar
Yehudi Yehudi is offline
Stranded on Earth
 
Join Date: May 2010
Location: Wyoming
Age: 67
Posts: 3,412
Thanks: 1,656
Thanked 4,354 Times in 1,646 Posts
Default

One more thing. Most electronics are internally protected against induced voltage spikes. If you are near enough to a nuclear explosion for your device to be damaged by an EMP, you will probably be damaged by the blast.
The Following User Says Thank You to Yehudi For This Useful Post:
Old 08-27-2012, 01:56 PM
MikeK's Avatar
MikeK MikeK is offline
Walking methane refinery
 
Join Date: Jul 2009
Location: Texas
Age: 51
Posts: 47,141
Thanks: 83,273
Thanked 91,217 Times in 30,522 Posts
Awards Showcase
Outstanding Member 
Total Awards: 1
Default

It won't kill the batteries, but it may take out the LED.

Quote:
Originally Posted by Yehudi View Post
One more thing. Most electronics are internally protected against induced voltage spikes. If you are near enough to a nuclear explosion for your device to be damaged by an EMP, you will probably be damaged by the blast.
If it's a blast specifically to create an EMP and take down our grid, it will be high in the atmosphere, where it can cause the most damaging EMP.
__________________
Folks, when starting a thread, please take a moment and consider which forum that thread belongs in. Disaster Preparedness is for disaster preparedness discussions only. There are forums for gun posts, news, politics, general discussion, etc. Please try to start threads in the right forum. This makes the site better for all of us. Thanks.
Old 08-27-2012, 02:48 PM
Yehudi's Avatar
Yehudi Yehudi is offline
Stranded on Earth
 
Join Date: May 2010
Location: Wyoming
Age: 67
Posts: 3,412
Thanks: 1,656
Thanked 4,354 Times in 1,646 Posts
Default

Where in the flashlight is there enough unshielded wire on which an EMP would be able to generate a pulse?

The higher up, the weaker the pulse, by the square of the distance.
Old 08-27-2012, 06:56 PM
seeya seeya is offline
Hunter
 
Join Date: May 2011
Posts: 1,127
Thanks: 1,168
Thanked 1,026 Times in 552 Posts
Default

Quote:
Originally Posted by Yehudi View Post
Where in the flashlight is there enough unshielded wire on which an EMP would be able to generate a pulse?

The higher up, the weaker the pulse, by the square of the distance.


I could see it taking out the power level ic in most led flashlights. This is located right at the front of the light there is almost no shielding there. Led bulb should be a fine , heck it’s a diode
Old 08-27-2012, 07:34 PM
Yehudi's Avatar
Yehudi Yehudi is offline
Stranded on Earth
 
Join Date: May 2010
Location: Wyoming
Age: 67
Posts: 3,412
Thanks: 1,656
Thanked 4,354 Times in 1,646 Posts
Default

Ok, what mechanism would be in effect to take out the IC? Remember, EMP induces current in wires. That is why a wide area nuclear detonation can take out the power grid, because it is inducing current into tens of thousands of miles of exposed wiring. It is highly unlikely that an EMP pulse would be able to induce a measurable amount of current or voltage into an IC.
Old 08-27-2012, 07:54 PM
Insneaker Insneaker is offline
Trapper
 
Join Date: Feb 2011
Location: Nordic
Posts: 782
Thanks: 714
Thanked 649 Times in 371 Posts
Default

Higly sensitive for emp are antennas, telephone lines and power lines. Emp will also destroy devices what is attached to this kind of lines....
If you have small insulated devices, emp might not effect them at all.
Way to protect your devices is keep them in metal box and insulate it from the ground.

Edit: This is almost only information what i have read in multiple military manuals... That is also only answer what i can give and what is surely correct...

There is also emp bomb what will effect only in smaller area... And ofcourse emp can destroy other devices also!
Military manuals tell you mainly to secure radio devices and antennas, but we have to remember, multiple nuclear manuals have been writing during cold war... So there was not so much electronic in military than there is now!
So let just wait to updated manual and there might be some information and research about other devices also!
The Following User Says Thank You to Insneaker For This Useful Post:
Old 08-27-2012, 08:13 PM
technoprepper technoprepper is offline
Hiker
 
Join Date: May 2012
Posts: 691
Thanks: 45
Thanked 817 Times in 377 Posts
Default

Quote:
Originally Posted by Yehudi
One more thing. Most electronics are internally protected against induced voltage spikes. If you are near enough to a nuclear explosion for your device to be damaged by an EMP, you will probably be damaged by the blast.
Internal protection is often inadequate. And, as MikeK has already pointed out, a high altitude EMP bomb can affect most of the country with no harm from blast and negligible radiation risk. City destroying nuclear blasts, on the other hand, have limited EMP range.

Quote:
Originally Posted by Yehudi
Where in the flashlight is there enough unshielded wire on which an EMP would be able to generate a pulse?

The higher up, the weaker the pulse, by the square of the distance.
Question will be answered further below. The statement is not true. Inverse square law does not apply to a wide apparent source and EMP is very much a wide apparent source. Even though the blast may seem like a point source, the EMP is generated over a very large area of the earths atmosphere by the radiation emanating from that blast. The earth's magnetic field also shapes the EMP so the strongest field may not be under the blast; this kind of ducting also invalidates the inverse square law. In fact for 50kiloton EMP weapon the voltage on the ground at ground zero goes up as you increase altitude from 60 to 300km in addition to affecting a much wider area.

As far as I know, there have not been any unclassified tests on the effect of EMP on flashlights and flashlights vary considerably in their design.

Solar "EMP" would be unlikely to affect any flashlights that were not connected to a charger and very few that were connected to a charger. Those that would be affected would probably be affected by the normal spikes that happen any time there is a power outage rather than due to the direct effects of the EMP. Solar EMP and the similar E3 component of nuclear EMP is measured in small numbers of volts or tens of volts per mile instead of tens of thousands of volts per meter.

Most metal flashlights which are not connected to a charger would probably not be damaged by nuclear EMP (though I will explain a number of reasons why the could be) but those which are connected to a charger would be vulnerable. Note, however, that the cases on metal flashlights were not designed for shielding. Corrosion, aluminum oxide, rust, anodizing, paint, and o-rings may compromise the shielding effectiveness.

Plastic flashlights would be considerably more vulnerable. Plastic shake-up powered flashlights might be particularly vulnerable as the coil used to power them would pick up EMP. Crank powered flashlights may also be somewhat vulnerable due to the poorly shielded coils in the dynamo. 2AA batteries would consititute a conductor 4 inches long (enough to produce a spike larger than needed to damage LED) and the contact which connects the tail end of the flashlight to the LED/bulb is another 4 inches. These two conductors run parallel to each other so there will likely be some significant cancellation of electric fields but they make a loop antenna to pick up magnetic fields.
There is also a coil spring battery contact in many flashlights which is an antenna.

Traces on the circuit boards for multiple LED modules, LED driver boards, internal charger boards, and wires, straps, or contacts are all antennas for EMP. Also, a conductor does not need to resemble a wire to be a problem; a metal surface can also function as a patch antenna. There is little to no shielding in a plastic flashlight.

Cree, the makers of LEDs used in many flashlights, says that one of their lines of LEDs is protected to 2kV ESD. Under a 50kV/meter EMP, this voltage can be induced on a wire or conductor 1.6 inches long. In addition to the LED, better flashlights have an LED driver circuit. This contains additional components that could be damaged by EMP. An efficient driver will use a switching power supply which will have an inductor which may not be well shielded and thus picks up the magnetic component of EMP. The engineer who designs a flashlight can add some additional protection.

The transparent lens on the flashlight can prevent the metal case from functioning as a faraday cage. Some LED flashlights have reflectors, others do not. A typical reflector is an extremely thin metal coating on plastic which may or may not be in contact with the case around the edges. This reflector, if it does not contact the metal case, can act as a patch antenna picking up EMP. If it is connected to the case, it may provide weak shielding (it is not thick enough to provide good shielding). It is even possible that the reflector metalization itself could be damaged by EMP (ever seen what happens when you put a compact disc in the microwave?) but I have not calculated the energy required. In addition, the reflector acts like a parabolic antenna and can concentrate higher frequency EM waves onto the LED. On the plus side, the small aperture of the flashlight lens/window will block lower frequencies (to an extent) where much of the EMP energy is present.

Some flashlights have exposed solar cells. These may be vulnerable to direct damage but they do have some power dissipation ability due to their surface area. However, they can also act as a patch antenna picking up EMP to damage other parts which are more susceptible.

Even if the flashlight is switched off, high voltage from EMP can arc across the switch. Also, on some flashlights (particularly multimode ones), the power is not disconnected by the switch but is continuously connected to the driver circuit.

Incandescent light bulbs are also vulnerable to surges. Based on lamp life formula, which has a very high exponent (a couple sources put it at 12 or 13.1), destruction of a 3V lamp during a 3000V surge is virtually instantaneous (far less than a nano-second). That is over-extrapolating, but does give you an idea.

Some flashlights incorporate lasers. Laser diodes are extremely sensitive to surges and in an unusual way. The optical power density in a laser is high enough at the surface of the silicon that a surge destroys the optical surfaces.

A "metal box" may provide some small amount of protection, though in some cases it can worsen the effect. Most EMP protection solutions you will see mentioned on forums like this one or advertised for sale (other than those with 4 digit price tags from reputable electronics enclosure manufacturers), are not effective faraday cages and cannot be relied on for guaranteed protection. It is difficult for the amateur to get a proper electrical "seal" on a box which has a lid that is easily opened and that seal is critical for a proper faraday cage. Having the devices unplugged from all cables to put them in the box generally provides more protection than the improperly designed box does.
Old 08-27-2012, 08:43 PM
seeya seeya is offline
Hunter
 
Join Date: May 2011
Posts: 1,127
Thanks: 1,168
Thanked 1,026 Times in 552 Posts
Default

Quote:
Originally Posted by Yehudi View Post
Ok, what mechanism would be in effect to take out the IC? Remember, EMP induces current in wires. That is why a wide area nuclear detonation can take out the power grid, because it is inducing current into tens of thousands of miles of exposed wiring. It is highly unlikely that an EMP pulse would be able to induce a measurable amount of current or voltage into an IC.
I think you are mixing up an emp(nuclear) with a solar flare. 50,000 to 200,000 volts per meter emp doesnt take much of a antenna to make 15 volts. Coiled spring makes a great antenna.
Old 08-27-2012, 10:23 PM
The Truth's Avatar
The Truth The Truth is offline
I love this forum
 
Join Date: Dec 2009
Location: Australia
Posts: 3,889
Thanks: 4,602
Thanked 4,541 Times in 1,770 Posts
Default

Yehudi, you're wasting your time with this crowd.




You'd have to be pretty darn close to an airburst EMP for it to knock out a common flashlight.

Even 50 miles away, your flashlight would not notice the miniscule current going through it, assuming the circuit was complete.

If you're unconvinced by simple electromagnetic concept, then wrap your lights in tinfoil and leave them on the basement floor.

--

A large grid on the other hand, like a national grid, is in a way like a giant antenna, capable of absorbing huge amounts of electromagnetic energy, routing it all to a few points very quickly.

The smaller the device, the smaller its "antenna", and the less it will absorb. Distance takes care of the rest.

Unless an EMP went off directly over my head at under 20,000 feet, I would not be too concerned about my flashlights.
Old 08-27-2012, 10:41 PM
9111315's Avatar
9111315 9111315 is offline
Plan Z: Run!
 
Join Date: Apr 2011
Location: central America
Posts: 12,843
Thanks: 15,132
Thanked 17,897 Times in 7,595 Posts
Default

Batteries will be fine. Heck, it may even top off their charge.

An incandescent bulb should have no problem handling any induces voltage associated with its small size. Put a bulb in a microwave and turn it one. The bulb will light up and just a second or two may not cause any damage.

The LED like any semiconductor is much more susceptible to an EMP pulse then other types of electrical components. Being a power device, the LED should hold up much better than an Intel Microprocessor.

In any case, being the end of the would, you should have a lifetime supply of spare bulbs, regardless of how short that lifetime may be. Store them in a secure protected location.

Also, a High Altitude EMP interacts with the earths magnetic field and the atmosphere producing a much different effect than a ground level blast.
Old 08-28-2012, 12:16 AM
seeya seeya is offline
Hunter
 
Join Date: May 2011
Posts: 1,127
Thanks: 1,168
Thanked 1,026 Times in 552 Posts
Default

Quote:
Originally Posted by The Truth View Post
Yehudi, you're wasting your time with this crowd.




You'd have to be pretty darn close to an airburst EMP for it to knock out a common flashlight.

Even 50 miles away, your flashlight would not notice the miniscule current going through it, assuming the circuit was complete.

If you're unconvinced by simple electromagnetic concept, then wrap your lights in tinfoil and leave them on the basement floor.

--

A large grid on the other hand, like a national grid, is in a way like a giant antenna, capable of absorbing huge amounts of electromagnetic energy, routing it all to a few points very quickly.

The smaller the device, the smaller its "antenna", and the less it will absorb. Distance takes care of the rest.

Unless an EMP went off directly over my head at under 20,000 feet, I would not be too concerned about my flashlights.


Do you think a gps,radio or any other small electronics would survive? Any led flashlight with a high/med/low settings has a ic in it and will fry. Only way for it to be safe would be to use a cheapo on/off led light. Like most things everything is not black or white.
Old 08-28-2012, 02:38 AM
technoprepper technoprepper is offline
Hiker
 
Join Date: May 2012
Posts: 691
Thanks: 45
Thanked 817 Times in 377 Posts
Default

Anything but The Truth is trolling and/or spouting nonsense again.

In a 300km airburst, you would already be 186miles away from the air burst if you were at ground zero and the actual EMP hot spot could be two states away. So much for the "Even 50 miles away" non-sense.
See the two graphs here: http://en.wikipedia.org/wiki/Electromagnetic_pulse
And you can see from one of those graphs that most of the contiguous US could expect to see 25000V/meter or more while those at ground zero (directly under the air burst) see the least.

Most of the sentences in The Truth's post are false, I won't bother to take them apart one by one. Just do yourself a favor and disregard the entire post as misinformation.

Quote:
Originally Posted by Yehudi
Ok, what mechanism would be in effect to take out the IC?
There are many mechanisms that causes EMP to take out ICs. And ICs are not the only components that can be damaged.

In the case of Cree XLamp LED's, the most commonly seen form of damage from electrical overstress is burning out the really thin gold bond wires that connect from the leads to the IC, damaging encapsulant or phosphor near the bond wires, or damage to the LED chip itself near the bond wires (where current density is highest). You can see pictures here:
http://www.cree.com/~/media/Files/Cr...Overstress.pdf
These are not the only mechanisms which can damage these LEDs, let alone other ICs and semiconductors.

Here are a few ways ICs can be damaged.
- Gate punch-through. The insulating gates of mosfet transistors, widely used in ICs,
are very susceptible to high voltage.
- PN junction punch throug/reverse breakdown. The semiconductor junctions in diodes and bipolar transistors can be damaged by transients
- Latch up - CMOS logic inputs are susceptible to latchup. The input structure is such that there is a parasitic SCR present. Once triggered by a minor overvoltage, it remains on until the device is powered down. The latchup condition can sometimes
result in permanent damage as well. This is a major cause of system upset.
- Localized overheating. Fast pulses can induce heat in a small area of a chip that might be within the long term power dissipation abilities of a chip but builds up faster than it can spread out, causing destruction.
- Illegal operating states. The component can be tricked into an illegal operating state and may remain there. A simple, and very common example, is two transistors in series between the positive power supply and ground. Only one of these two transistors can be on at any one time, except for a brief overlap during switching (which is actually the major cause of power consumption in many ICs). In an illegal operating state, both of these transistors turn on simultaneously and stay on, causing excesive current, not from the EMP but from the normal power source, to flow through them; this can destroy the chip. Latch-up can cause this.
- High DV/DT. Fast rise time pulses can turn mosfet transistors on when they aren't supposed to be. This can result in another illegal state where even a small amount of EMP energy can trigger the release of larger amounts of system energy in a destructive fashion.
- It should be noted that once a transistor is damaged, that also can create permanent illegal states or current paths.
- Power supply overvoltage. Excessive voltage on the power supply rails due to a transient on the power supply can cause considerable damage on the chip. This can also occur if the protection diodes try to divert too much energy from the inputs into the power supply decoupling caps.
- Protection diode overload - These diodes can handle a limited amount of power before they are destroyed
- Protection diode delayed response - protection diodes are designed to handle transients which are slower than EMP E1 transients and thus may not turn on fast enough to protect the transistors they were intended to protect.
- Secondary breakdown. Transistors may be able to handle a specific maximum current and a specific maximum voltage but not both simultaneously

It only takes about 1W to 10W of power for 1 microsecond to damage many ICs (even less for microwave mixer diodes).

Quote:
Remember, EMP induces current in wires. That is why a wide area nuclear detonation can take out the power grid, because it is inducing current into tens of thousands of miles of exposed wiring. It is highly unlikely that an EMP pulse would be able to induce a measurable amount of current or voltage into an IC.
You are confusing solar "EMP" geomagnetically induced currents with EMP. While EMP produces one component that is similar to the solar "EMP" (and thus both can wipe out the power grid) it is the other two components that damage normal electronics.

Nuclear emp consists of three phases, E1, E2, and E3. Solar "EMP" resembles E3. E3 damages high voltage transformers connected to very long lines through a mechanism very different from E1 and E2. It essentially induces DC into the transformer which causes it to go into saturation at which point it is destroyed by the power it is carrying.
E1 and E2 can also potentially damage the electronic systems that control the power grid.

An IC is normally connected to traces on a circuit board which act like small antennas.

E1 and E2 do not require miles of wire. E2 is somewhat similar to surges which are induced by nearby lightning strikes (not direct hits) and some equipment is already protected but E1 happens about a thousand times faster. The combined effect of E1 and E2 can be worse than either alone. E1 and E2 have separate causes but the pulses overlap.

EMP from a normal high altitude burst (not a super-EMP, which is worse) can induce as much as 50,000 volts per meter of wire in the worst affected area and 25,000 volts per meter across most of the Contiguous US. You don't need miles of wire to be damaged. Inches of wire can be enough. As I posted above, a popular line of LEDs used in flashlights is only protected to 2000V transients (the intent is to protect against electrostatic discharge during assembly at static controlled work stations). At 25000V/m, 3.2 inches of wire is all you may need to do damage. Small unshielded electronic devices can be damaged just by the voltage induced in the internal wiring. And even shielded devices can be damaged by wires and cables run inside your home or office or worse, ones which connect to the outside world.
Old 08-28-2012, 03:14 AM
Camel's Avatar
Camel Camel is offline
Target Shooter
 
Join Date: Aug 2012
Posts: 446
Thanks: 121
Thanked 376 Times in 192 Posts
Default

Depending on the power of the EMP pulse. I doubt everything will go out from a solar flare, the damage will be heavy on large installations that has lots of coils and wires the power can travel through but a LED flashlight and a car inside a garage with metal framing wil probably survive without any damage at all.

The EMP threat is a bit overrated, it isn't fun but it is not like everything will start to burn from it. If it was to hit the US I believe your sectioning of the power grids will save many of them. The energy won't be able to travel from state to state and the pulse would need to hit the whole continent. The big problem comes from the power of the pulse being able to travel in existing power lines and spreading that way. The pulse will however not be able to travel from Pennsylvania to Ohio and "jumping out" of the system to cause an EMP pulse there as well.
Old 08-28-2012, 12:22 PM
Yehudi's Avatar
Yehudi Yehudi is offline
Stranded on Earth
 
Join Date: May 2010
Location: Wyoming
Age: 67
Posts: 3,412
Thanks: 1,656
Thanked 4,354 Times in 1,646 Posts
Default

Quote:
Originally Posted by The Truth View Post
Yehudi, you're wasting your time with this crowd. .
Roger that. Long ago, I learned that it is pointless to attempt to change the minds of those with diametrically opposed viewpoints in internet discussions. Neither of us is likely to change. The best that can be done is to counter misinformation and provide reasonable arguments for those readers who may be undecided and/or badly misinformed. I post for those silent onlookers who have not yet made up their minds on a subject.

I have worked in electronics for about 40 years. I designed and manufactured circuit boards. I worked on high vulnerability industrial electronic systems and provided surge protection and shielding for them. I also worked with nuclear weapons and radiation monitoring systems. While some out-of-context Google Fruit may appear to support the opinions of the vulnerability of flashlights and other small devices, the mechanisms of EMP interactions do not support that.
Old 08-28-2012, 12:41 PM
Yehudi's Avatar
Yehudi Yehudi is offline
Stranded on Earth
 
Join Date: May 2010
Location: Wyoming
Age: 67
Posts: 3,412
Thanks: 1,656
Thanked 4,354 Times in 1,646 Posts
Default

I also worked with high sensitivity magnetometers which record the fluctuations in the Earth’s magnetic field due to interactions with moving ferromagnetic objects and with electromagnetic wave sources. That also gave me hands on experience with how such interactions affect the Earth’s magnetic field, and how moving electromagnetic and magnetic fields interact with detection devices. Of course that included the design requirements for maximizing the measurement of moving fields, and the opposite of that, minimizing the interactions with the sensor. To give you an indication of the scale, our magnetometers could measure fluctuations in the Earth’s magnetic field down to one millionth of a gauss.
Reply

Bookmarks



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Rayovac batteries and flashlights jetroop2k1 Disaster Preparedness General Discussion 0 11-27-2011 08:31 PM
Flashlights, batteries and the quest for light. Jash Disaster Preparedness General Discussion 23 10-01-2011 12:18 AM
Great Deal on Led Flashlights! 10 for $10 with batteries High Kapacity Urban Survival 42 07-10-2010 07:22 PM
Rechargable Batteries too big for flashlights TheOmegaMan Disaster Preparedness General Discussion 4 03-23-2010 03:59 PM
Surefire Flashlights that run on different batteries etc Reviews and questions 4 10-28-2009 11:47 PM


All times are GMT -5. The time now is 05:10 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Kevin Felts 2006 - 2012,
Green theme by http://www.themesbydesign.net