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Joined: Jul 2004
Posts: 625
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The current thread about radios causing havoc with GFCIs and other electrical equipment got me to wondering about something.

There is currently talk that there is a very real danger of terrorists using a nuclear device in this country, either in the immediate future, or in the longer term. Nuclear detonations generate an "EMP" (electromagnetic pulse) that can destroy unprotected electronic equipment for at least hundreds, if not thousands, of miles outside the blast area.

How do you go about protecting equipment from EMP? I've heard that it can be done, but I've never seen anything at all about how to go about actually doing it.

It seems like this is really important to do in any sort of emergency facility, like hospitals and emergency control centers. It's clearly of extreme importance that the radios of emergency responders continue to operate after a nuclear "event." The same applies to the huge amount of medical electronics that ambulances and hospitals rely on to keep people alive.

[This message has been edited by SolarPowered (edited 12-01-2004).]

Joined: Jan 2003
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Here is a link that has some info along with more links.

http://www.unitedstatesaction.com/emp_and_faraday_cages.htm

That one is a little technical I like the layman's version.

http://zapatopi.net/afdb.html

They say it is for protection against mind control but it should help against EMP. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Jan 2003
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If you are not familiar with EMP here is a basic explanation of it along with more links.

http://science.howstuffworks.com/e-bomb.htm/printable


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Dec 2003
Posts: 886
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Dunno. If protection is as simple as wrapping a piece of equipment with foil or some other conductive material and grounding it, wouldn't the steel enclosure used on most computers and other equipment do the same thing? It should be grounded through the line cord.

I really have little knowledge in this area and I always assumed there was little hope for non-military equipment in the event of EMP exposure.

-Hal

Joined: Nov 2000
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Look at this Air Force document on EMP protection for buidlings . Note it is a large PDF file.
Don


Don(resqcapt19)
Joined: Dec 2003
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That document relates to TEMPEST which I very vaguely remember something about. It's a RF shielding system designed to keep "spies" from evesdropping via RF leakage from computer and other equipment.

The only mention of EMP is where the document states that the system [TEMPEST]contrasts with high altitude EMP (HEMP) shielding which protects against nuclear electromagnetic effect infiltration into sensitive electronic equipment.

It's also 14 years old.

-Hal

Joined: Oct 2003
Posts: 6
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Something very interesting about an EMP is that silicon IC devices (transistors) are much more succeptable to failure from an EMP than the good old vacuum tube.

The avionics in a soviet MIG-25, a modern jet fighter make heavy use of vacuum tubes. One theory is that this is to harden the machine to EMP caused by nuclear fallout. You can read more about this and other EMP hardening techniques here:
http://www.globalsecurity.org/wmd/library/report/1984/ERD.htm

So keep that all american-5 Philco radio up and running in case of emergency!!

-vars

Joined: Dec 2003
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You can fire up your "All American 5" but what are you going to listen to? Broadcasting stations went solid state long ago also.

-Hal

Joined: Dec 2003
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On topic- I remember about a year ago that law enforcement was testing a device to stop fleeing cars and put an end to high speed chases. With one method, the fleeing car would be followed and a skateboard type antenna would be fired by explosive charge so as to go under the car. Tethered by a cable to the chase vehicle, a strong EMP would then be directed at the car which would disable the engine computer as well as the ignition system and other electronics.

Kill their 2000 watt sound system and they will be dead in the water. [Linked Image]

-Hal

Joined: Oct 2003
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I worked with EMP shielding for the military while I was at MCI. Most of the pratical know-how info is classified. For the most part it is shielding the equipment building and equipment in a metal mesh or sheet plating, and multi-ground the shield to earth for a building, or skin of an aircraft. Any conductors power and signal that enter have a TVSS device on steroids installed in a specified location where they can be integrated into the building sheild. Some of the concepts are discussed in the sites mentioned earlier, but the most of the specs are classified.

[This message has been edited by dereckbc (edited 12-02-2004).]


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