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Natural EMP?!

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LAN_403

EEYORE

Sat Jun 30 2007, 02:05AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

Hello all,
I may have witnessed the effects of an EMP generated by lightning! My GF's neighbors yard had lightning strike the ground with some SERIOUS force. There happend to be some sorta rusty iron bar stock burried in a zigzag fashion which was hit, and BLOWN apart much like the popular exploding wire demo people do with capactiors. My GF's TV instantly had its screen go nuts with color (Just like when you bring a strong magnet near the screen). It is now damaged in that the color is permanently distorted.

Could the lighting have hit the buried metal, blown it up from the enormous power, and created a nasty EMP that ruined the TV screen? I wish I had it on camera!The lighting hit the neighbors truck, blew off its hubcap, and then hit the metal throwing dirt and mud all over the truck, fence, and yard!

I will take some pics of the devastation if she hasnt fixed it all yet.
Matt

GreySoul

Sat Jun 30 2007, 04:16AM

Registered Member #546 Joined: Fri Feb 23 2007, 11:43PM
Location: Albuquerque, NM
Posts: 239

heh I have a pile of radio equipment (2/3 of my station) that is pretty much toast from EMP from a near lightning strike.... yeah I think it can happen....

on your tv maybe you got some weird induction in the degaussing coils that zapped the mask...or something?

-Doug

EEYORE

Sat Jun 30 2007, 04:24AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

Really dont know what may have happend, but its pretty close to the ultimate EMP generator

Ive always thought about getting lightning to strike a coil of thick wire to see what kinda field strenght one would get, I guess this is as close as I will get to it.

Matt

Dave Marshall

Sat Jun 30 2007, 05:55AM

Registered Member #16 Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554

Of course theres a huge magnetic field associated with lightning. Its millions of volts of electricity at tens of thousands of amps, and it isn't a straight line. It travels a very non linear path, giving it alot of surface area.

Have you tried using a degausser on the TV yet? Any powerful magnetic force can skew the colors, but frequently they'll come back to normal. If it didn't, then I'd wager that some windings on one of the solenoids arced over and you've got a short in there somewhere making one coil less effective than the others.

Its very difficult to tell the difference between true EMP (current induced through the air directly on the TV guts themselves) and direct conduction of the lightning strike, either through induced current on house wiring or transmission lines (still EMP, but more indirect), or an actual secondary strike to a power line/pole or the house itself.

I'd tend to think the secondary strike theory is the most likely one, as cloud to ground strikes (the largest of which are often called 'super bolts') very rarely only strike a single point. I've got video of a bolt striking a tree behind me, with positive stroke leaders jumping off trees a hundred feet in front of me. These strikes tend to be of lesser intensity, leaving less evidence, but causing just as much damage to any puny electronics that happen to be in the way.

Dave

Shaun

Sat Jun 30 2007, 06:48AM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Yea, I'v seen a few positive bolts, and even from a few miles you can easily tell them apart from regular ones, they're just massive, wrath-of-god types strokes.

Once we had an old film camera that had a max exposure time of 60 seconds, and since I always wanted to take pics of lightining we set it up on a tripod during the first summer storm, and actually got some good shots. I'd share them but no longer have them. Anyway my point is we were shocked (pun intended) looking at this one developed picture because the closest strike was about half a mile from us, but a thin leader stroke could clearly be seen running from THE ANTENNA OF MY BUDDY'S CAR 6 FEET AWAY.

His radio was fine, but from then on we took our pictures from out of open house windows. Lightnings scariness factor decreases with the cube of distance. 3 times closer, and it's 27 times scarier, lol.

Marko

Sat Jun 30 2007, 04:25PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Mattrq: are you sure that TV didn't simply blow it's degauss PTC? I mean, the magnetic flux density required to 'gauss' TV shadow mask is still extreme, in range over 1 Tesla or so.

Such magnetic field oscillating at just few tens of Hz would definitely blow all elecronics in that TV much before it manages to do anything to shadow mask.

And third, even if a bolt could generate such a magnetic field it would still be very uniform and damped, so it would more likely actually degauss the shadow mask than cause uniform magnetization.

Check out the PTC in that TV.

3 weeks or so ago a quite big bolt hit a crane about a kilometer from my house. I first heard something exploding quite loudly inside or around my computer, it rebooted, and after few seconds I heard really loud thunder going off.

Computer was fine after that and I assume the thing that blew was a MOV, TVS or other protection device in one of those fused wall plugs.

Alhough the bolt was grounded there was seemingly still more than enough power induced in mains wiring to damage electronics on quite large area.

Grond itself is still far from perfect conductor and current propagnating trough it can induce voltage differences across grounding points in victinity, and this in turn may cause neutral line to jump in potential even if it wasn't directly hit.

We don't have widespread 3-wire system, so this can be really dangerous in some cases.

Electromagnetic pulse effects definitely exist, but I don't know how much role they plays on causing damage to electronics. It doesn't take much power to blow silicon after all.

Sun Jul 01 2007, 05:01AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

we haven't hade any lightning lately, but maybe some of the electricity travveled up the earth wire on your tv and fryed it

EEYORE

Sun Jul 01 2007, 05:07AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

kv wrote ...

we haven't hade any lightning lately, but maybe some of the electricity travveled up the earth wire on your tv and fryed it

The TV is not fried,it actually works just fine except for having the color messed up...
Matt

Sun Jul 01 2007, 06:19AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

oh, i didn't really mean fried as in dead but just screwed it up a bit?

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