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273 comments on DrumBeat: October 18, 2007

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Black_Dog on October 18, 2007 - 2:45pm Permalink | Subthread | Parent | Comments top

Does your old Rambler have a DC generator? All newer alternators have diodes in them and I suspect that a strong
EMP (50,000 v/cm?) would kill the diodes. Any thoughts?

E. Swanson

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nelsone on October 18, 2007 - 2:57pm Permalink | Subthread | Parent | Comments top

Yes, I think you're right: The EMP will incinerate all nonlinear circuitry.

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Twilight on October 18, 2007 - 3:18pm Permalink | Subthread | Parent | Comments top

Big power diodes are pretty tough, they may survive, depending.

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SacredCowTipper on October 18, 2007 - 4:19pm Permalink | Subthread | Parent | Comments top

EMP produces stuff from DC to about 2.0 GHz and it does obey the inverse square law - double the distance, cut the power by 75%.

I have some knowledge of how radio works but I am no expert in the field, so I welcome correction, but I suspect the following is true: The higher the bomb, the more area it covers, but the greater the distance and attenuation due to distance as well as atmosphere. The longer waves will follow the ground and generate voltages only with things the right size to resonate while the shorter ones are lines of sight. The key to zapping electronics is having something somewhere in the vehicle that is resonant with the energy received.

EMP is not even a little bit funny, but I think the idea that one, high up, gets every bit of the country is not so believable. And no one triggers a nuke in space over the U.S. without getting a little one wrapped up in cobalt set off at a much lower altitude over their own capitol city.

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Apuleius on October 18, 2007 - 7:50pm Permalink | Subthread | Parent | Comments top

This is really a back of the envelope remark, but still: an EMP will have an easier time frying things that are on the grid, since the grid has all these delicious copper loops, and anything that isn't shielded, which car engines generally are.

So it won't be 100% on things like cars.

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Spaceman on October 18, 2007 - 10:15pm Permalink | Subthread | Parent | Comments top

EMP is not even a little bit funny, but I think the idea that one, high up, gets every bit of the country is not so believable

True.
I believe 4 would be necessary.
http://webpal.org/

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NervousRex on October 18, 2007 - 11:45pm Permalink | Subthread | Parent | Comments top

Hi SCT,

This is a good summary article. The NA grids could be shut down with a single high-altitude nuke, and it might take months or years to restart it:

http://www.todaysengineer.org/2007/Sep/HEMP.asp

There was an article in IEEE Spectrum a few years ago on the same subject but I can't find it. I believe it estimated the damage to silicon devices in North America at something around 45 trillion dollars from one HEMP.

re: cars, I'm more pessimistic than before, it appears any cable with less than 100% foil coverage or any bad grounds are, er, "grounds" for failure.

NR

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SacredCowTipper on October 19, 2007 - 12:17am Permalink | Subthread | Parent | Comments top

I guess car survival doesn't matter much if gas stations are all dead :-) I read here every day and I'm still auto-centric :-(

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Eggplant on October 18, 2007 - 9:15pm Permalink | Subthread | Parent | Comments top

Black_dog asked: "Does your old Rambler have a DC generator?"

Yes, it's an old fashioned DC generator without diodes. The voltage regulators are mechanical relay type. The whole setup is electrically very inefficient. However it's based upon heavy gauge copper wire so there's no way an EMP could knock it out.

I'm a member of an old car club and sometimes the other guys suggest that I replace the voltage regulator with a solid state device. However I LIKE driving a car that's uses neolithic technology. I prefer to keep it simple and easy to maintain.

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273 comments on DrumBeat: October 18, 2007

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