electric demolition - wipe out a building

[ProdigyChild]

'EMP-bombs' are easily found on the internet, but all this seems to me like a discussion, what one could do with a nuclear bomb if he had one. But no one does.

So let's forget about EMP fairy tales and discuss what is really feasible for an amateur.
I've done lots of experiments with spark gaps recently and noticed the following:

a) My electronic equipment is not affected by air-transmitted pulses at all, not even if as close as 20cm. Allthough thousands of amps are switched through coils of a few uH. Read: I don't believe in EMP bombs other than nuclear ones.

b) I had trouble with the wires more often than not, i.e. even an average current of 0.1A heated up cables :eek: Probably because of skin effect and massive pulsing (P = R*Iav^2 =/= Integrate R*I(t)^2 dt )

So my idea is: provided I have access to the sockets within a building, can't I destroy some/all electronic equipment? Preferably without making too much noise or leaving traces?

A few examples:

Almost every computer has some varistors in its power supply. Destruction of the electronics seems hard at first glance to me but can can happen between mains voltage an varistor. Some supplies have a fuse in between. This is the point, where one could attack. Another approach see below.

Other equipment has an transformer only (radios, etc...) and too much series resistance to be destroyed easily. A possible attack would be RF to heat up the transformer. Any other ideas?

Simple equipment is only a resistor (coffee machine), maybe a filter between mains voltage and resistor. These are hard to attack, because they take pulses very easily besides beeing switched off (disconnected) most of the time.

Motors typically have capacitors inside, some motors even electrolytic bipolar ones. I don't know, if electrolytic caps have a self-healing property like MP ones?? Once one half of them is shout through, the elco explodes from electrolytic decomposition? :D

Power lines could be heated between 2 sockets by plugging a RF short circuit (capacitor) in one socket and introducing high power RF on the other (fed by the power lines of course). Skin effect produces much higher resistance, so considerable power is dissipated. Eventually, the cable insulation melts and the cable hopefully shorts.


As the total load of the power lines one sees a mix of all this equipment. Some of it is switched off. Most attractive targets would be computers and TV's and thanks to 'standby mode' and ATX they're in contact with the power lines at all times, hahahaha.
Pity, they have the varistors inside, that eat up HV pulses one would wish to feed into the power lines.

On the other side, access to a plug gives access to quite a lot power. A varistor has high power dissipation, because of the high voltage it shorts (like a Z-diode). So permanently feeding in moderate overvoltage pulses would heat up and explode that bastard! Once the varistors are all gone, one could apply high voltage pulses to the mains voltage to destroy all over-voltage sensitive equipment, including the computer switching power supplies.
As a last step we would like to destroy the houses main fuses by overheating with RF power without them triggering......
Pity, there's a zero crossing of AC power, so one can't maintain (as a final demolition step) a permanent arc-over of the fuses thus creating a 'less local' power fail.

Building a over-voltage feedback device is simple compared to building an conventional EMP-device (if such exists at all). A few diodes, a few caps, inductors and spark gaps and a controlling electronic.
Basically, one can multiply mains voltage, charge up a cap and feed that voltage back into the power lines via spark gap. It always results in a RF oscillation of the LC circuit formed by the cap and the inductance of the power lines. 50 or 60 discharges per second can release some power!

Would be a nice way to make you neighbours stop complaining about your chemical work and care about their own sh1t for a while :D

[Marvin]

Making an EMP bomb is far from trivial but its certainly feasable. How far it would reach for the effort involved is another matter.

If you have access to a mains socket in the building there is no need for high power destroying energies. The object of the attack would not be to damage as much equipment in one go, its risky, its unsubtle. If you have access to a power point how about this idea... You build a small circuit that runs off mains and periodically on a random number delivers a few ma to earth. It could be fitted inside of a mains socket, or inside a plug and noone would know. Say a timer for a week or so after its installed it starts and all the place knows is every 3 hours or so randomly or once a week the breaker trips. If its a buisness the effects would be even more phenominal. Computers go down, everyone loses files the routers go down. The engineers turn up and find no problems with the system, then maybe later they start replacing the breakers. If this was planned more carefully than Ive thought about it, it could disrupt a buisness for weeks or more rarely for months. Make it look like an april fools joke, or someones revenge after being fired. For a more local problem and a rare setting the fault is easier to find if its in a socket, but in a plug thats always on it might take months to attribute the fault to 1 device and a lot of money in engineer bills.

[Jacks Complete]

Spread a few around the place, on different plug sockets, with different times to trip (or just totally random) and you would destroy the company! It would cost a fortune, and eventually they would have to check every last socket and plug, etc. as there would be no pattern at all.

Another trick would be to undo a faceplate and wire the live pin to the earth. The instant the socket is turned on, *bang!* and the lights go out. Probably upset the equipment which requires a good earth, too. This would work better on fused boards, rather than ECDs.

[cyclonite4]

EMPs are just not worth the effort.

The amount of money, time, and effort that go into their construction contradicts its practicallity (in most cases, but not all).

I believe Marvin's idea holds the most merit, as it is simple, cheap, and much more effective because of its economical damage, and emotional effect (think what would be going through your mind if you were an employee at an office and the power was going out randomly at extended intervals :D ).

A circuit as described by Marvin could be built smalle enough to fit behind the faceplate of a wall socket, just solder the connections from the inside and nothing will be suspicious, because the socket can still be used as normal.

Very inspiring, thank you Marvin for the great idea :) .

[xyz]

Hmmm... nice idea Marvin, I have a semi-mechanical (hard to describe how it works, but cutting the power won't change it's settings or anything) 240v timer that can switch appliances on or off in 15 minute increments throughout the day.

If it was set up to be active during only one interval, it would mean that there would be 15 minutes of every day where the circuit breaker tripped and would trip again in the event that it was reset within that 15 minute period. While thinking about this, at first I thought that the problem would be that the power outage would occur at the same time each day, but then I remembered that the timer doesn't function without power, but starts again as soon as the power is back on, meaning that the variations in the amount of time that the power was left off by employees would ensure variation in the time that it cut out. It's hard to explain, but the power will cut again 23 hours and 45 minutes after it's turned on, each and every time it's turned back on.

You could also set a few extra 15 minute intervals throughout the day for more frequent power cuts and even more randomness.

It would be best to wire it up in a location where it wouldn't be found easily (if at all) such as inside a roof space or some other concealed location that presents access to the wiring. Yes, I know that rewiring live 240v cabling is risky, but I have experience with that... ;), wear 2 pairs of rubber gloves and use only insulated tools.

EDIT: I just re-read your post and noticed the bit about putting it inside a socket, I assume you mean taking the plastic cover off and putting it into the wall cavity behind? That's a better idea than mine as you only need access to a power point or light switch inside the target building.

[ProdigyChild]

Definitely, Marvin's idea is fantastic! Simulation of someone/some device trickling current to earth requires very low power only, so a tiny device could do. Maybe the new pic-controller (6 pins only, SOIC package) as a random time generator + 1 triac + 1 resistor (to AC power) and a minute power supply .

However, I was in a more dramatic mood when I mad my suggestion!
My assumption was I could get into the building, NOT into every room. And I tried to figure out, if I can harm the WHOLE buildings equipment, even though I can acces 1 socket only, probably somewhere in the cellar. Of course, 'switch off' the heating at random has some demoralizing effect, too. But it wont stop a company from one moment to another.

Marvin, why not suggest a schematic?

[xyz]

Ok, to explain what I'm talking about, I have attached a photo of the timer.

Upon closer inspection, it uses 30 minute time increments, not 15 minute ones like I had thought.

The beige plastic pins are inserted into the little holes for the times that you want things to turn on/off, so two need to be used (I removed one in the photo to show what they look like).

Basically, while power is flowing through the timer, the outer part rotates slowly and switches things on or off as the plastic pins pass the lowermost point.

This eliminates the need for a seperate power supply for the timer, and although this setup is rather bulky in comparison to others, it is simple and reliable, and with a few small modifications could be made to dump up to 10 amps to earth (it's maximum rating). Of course, you don't need to dump that much power, personally I'd just use 1 amp, which is still massive overkill.

It's way too bulky to fit inside a light switch or powerpoint however, so it would need to go somewhere else.

EDIT: Damn, I just realised the stupidity of using this timer, as once the power has been cut, the timer will stop, and when the power is restored it will trigger the circuit breaker again almost immediately, giving the timer no way of running for the 30 minutes that it needs to turn itself off again.

[cyclonite4]

EDIT: I just re-read your post and noticed the bit about putting it inside a socket, I assume you mean taking the plastic cover off and putting it into the wall cavity behind? That's a better idea than mine as you only need access to a power point or light switch inside the target building.

I assume your talking about the part on my post?
I decided to mention it as I did a similar thing at my school, but rather than a power-breaker, I had a nichrome wire wrigged up to the switch with a smoke composition inside.

Based on the photo of the timer you have, I doubt it would be able to fit in the small space behind a wall socket. Look in an Altronics, Jaycar or Dick-Smith (You live in australia, of course :D) store at kits with relays in them, I've seen kits with timed relays, condition-activated relays (conditions such as temperature, etc.), and RF controlled relays (so you can fuck with their power with the press of a button :P).

Then again, you can just build your own circuit based on an astable 555 timer, with a relay or high power transistor connecting the active wire to earth.