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Build an Electromagnetic Pulse Generator

  1. Oct 26, 2008 #1

    jacksonpeeble

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    Gold Member

    I also posted this under Computer Science incorrectly...

    I am curious if anybody knows how to build an Electromagnetic Pulse Generator (aka EMP). I've looked for a guide online, but all of the ones I've seen are far too advanced and/or powerful for my purposes. I'm looking for about a 5' radius using materials that are as simple as possible (and relatively easy to find/inexpensive).

    As a side note - this is not for any harmful purpose. I plan on doing some experimenting of my own, and I assure everyone that I won't be destroying any property of anybody else.
     
  2. jcsd
  3. Oct 26, 2008 #2

    berkeman

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    Re: EMPs

    I went ahead and deleted the duplicate post. Now, about your question, the main problem with experimenting with EMP is that it is illegal unless you have your own anechoic chamber or shielded room. The FCC has explicit rules for how the EM spectrum is used, since it is a shared resource for everybody. That's why most transmitters must be licensed and tested to ensure that they conform to the band that they are allocated in.

    An EMP generator will generate "harmful interference" that will step on all kinds of transmissions in your area (much wider than the 5' area that you want the effect to be moderately strong in). It would not take long before you had some folks knocking on your door to have a chat with you.

    That having been said, if you can come up with some kind of shielded enclosure, and you can verify that the shielding is effective, then you could probably do some experiments inside the shielded enclosure, with things like spark gaps and such.

    You might also consider checking out your local HAM radio groups, and chatting with them some about high-power (licensed) RF transmitters and antennas....
     
  4. Oct 26, 2008 #3

    jacksonpeeble

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    Re: EMPs

    Thank you for the legal advice as well as the deletion of my duplicate post. I was unaware of the implications of using such technology without a license.

    However, I do plan on going through with this project. I obey the law as often as possible, but I live in the middle of nowhere and don't enjoy when legal technicalities get in the way of my curiosity. I will take your advice and consult some HAM operators for some tips, but you sound like a pretty intelligent, informed guy yourself, berkeman. Do you know how to go about constructing an EMP, disregarding the legality of doing so?
     
  5. Oct 26, 2008 #4
    Re: EMPs

    You have to make a << deleted by berkeman >>.
     
    Last edited by a moderator: Oct 26, 2008
  6. Oct 26, 2008 #5

    jacksonpeeble

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    Re: EMPs

    Oh. Really? Are you sure?

    Never mind then, I'm definitely not interested it that's the case.

    (To the C.I.A. agents reading this post - Sorry! I didn't know!)
     
  7. Oct 26, 2008 #6
    Re: EMPs

    Here is the basic idea behind a pinch:
    http://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator
    It's also possible to create one by discharging a capacitor bank into an inductor, but I don't know the specifics, just had a friend who tinkered with the stuff in high school.

    And No, nuclear weapons are not required. Anything you can build at home is likely to have a very short range, BUT if you destroy you computer, car and everything with electronics for a block radius you are liable and people will be less than happy with you.
     
  8. Oct 26, 2008 #7

    berkeman

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    Re: EMPs

    I deleted Pumble's joke -- little too spicy for the EE forum. Anyway, If you make a good EMP generator outside of a shielded enclosure, its effects will propagate a long way. So it doesn't really matter that you live out in the country.

    Talking to the HAMs will get you some good information, and the high power transmitters will definitely interest you. Good luck.
     
  9. Oct 26, 2008 #8
    Re: EMPs

    An electromagnetic pulse can be generated in many ways. But the idea is the same, you need to put alot of watts in the air, and spread the signal in frequency. Power requirements need to be in kilowatts, megawatts or gigawatts range for it to start disabling other devices. I wouldn't bother with it.


    http://science.howstuffworks.com/e-bomb3.htm
     
  10. Oct 26, 2008 #9

    jacksonpeeble

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    Re: EMPs

    Thank you very much for the advice, everyone. The Explosively Pumped Flux Compression Generator link is exactly what I'm looking for. Power consumption and supply won't be much of an issue where I'm working. :-)

    On a somewhat off topic - I do not know much about HAM radios, I just know a couple enthusiasts (not what they do). Can someone give me the general overview?
     
  11. Oct 26, 2008 #10
    Re: EMPs

    Ham radio is a vast topic concerning amateurs talking on the radio in allocated frequency bands. Some amateurs go as far as building their own equipment from scratch, and having fun testing it out. The whole beauty of it is how nice and helpful every ham operator is.
     
  12. Oct 26, 2008 #11
    Re: EMPs

    Well, power supply is not normally a big issue for flux compressors; you just get a big capacitor and store up a bunch of charge, and then dump it into the compressor right before blowing it up. These are, after all, the leading contender for portable EMP weapons.

    While these are neat devices, they don't strike me as very do-able for a hobbyist. You will need all kinds of licenses and permits to even obtain suitable explosives in the first place, and they are quite difficult to build. The basic idea is simple enough, but assembling and detonating the explosives in such a way that the shock wave propagates as intended is a very difficult matter; the people who build these things tend to have doctoral degrees and extensive experience in high explosive materials and nonlinear phenomena, not to mention large budgets at their disposal. Beyond that, testing such devices is a very hairy proposition, what with the explosives and all, and will probably be very difficult to do legally. Even if you do manage to legally obtain the materials and permission for testing, you may still find that you attract a lot of negative attention from the defence/intelligence community. This is not the kind of technology that they want out in the wild.

    Personally, for the small scales you're talking about, I'd consider something like a spark gap. It will be enough of a headache getting suitable capacitors and avoiding trouble with the FCC (probably need a Faraday cage, which isn't cheap) without also introducing explosives that destroy the device. And, anyway, you'll have to master the use of big caps and high power switching techniques before you can even think about building a flux compressor, so that's where I'd start.

    Also note that big caps are dangerous in their own right. Learn and practice proper handling and lock-out techniques when using any high-energy storage devices, or you may not live to regret it.
     
  13. Oct 27, 2008 #12

    berkeman

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    Re: EMPs

    HAM radio bands were created by the FCC for licensed amateurs to use for emergency communication (hurricanes, tornadoes, earthquakes, etc.), and our best use of the spectra has been in support of emergency relief operations.

    The FCC eliminated the Morse Code requirement for HAM licenses recently for a very important practical reason -- Morse (CW) is really only needed for low SNR comm over long distances, not for local emergency real-time comm. The elimination of the CW test for your HAM license has caused an explosion in HAM licenses, and a great growth in my area, which is local emergency preparedness. I live basically right on top of an earthquake fault line (the Hayward Fault) which is way too regular, and scheduled to slip in the next couple of years.

    Our whole emergency response -- CERT (Community Emergency Response Teams), HAM, MRC (Medical Response Corps), MMRS (Medical something something Services), and other teams are based around good communications. From our full-on drills, those comms are going to be HAM radio, along with whatever is left operating after the hit.

    EDIT -- forgot to mention -- HAM comm basically divides into long-distance comm for fun, and local comm for emergency preparedness. PM me if you want more info. 73.
     
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