9 ms·
How to Make a Handheld EMP Jammer
- jaytaylor 10y agoHow would the design need to be changed to make it possible to zap a phone from a distance of 1-10 meters?
- kevinconroy 10y agoYou need 1.21 Gigawatts for that. (Seriously, though, you'll need to square the power source as you double the distance.)
- jaytaylor 10y agoDoes that mean the rest of the system can stay the same? Aassuming minimal adjustments required to wire gauge as power increases.
- anonymousiam 10y agoI built one once. I used supermetalized polypulse capacitors, 1.2 mOhm hexfets in H-bar config, 12:1 planar transformers, and a really big coil. It had a range exceeding 2m.
- jacquesm 10y agoThis won't destroy your phone. Phones are extensively tested when it comes to both creating and withstanding EM interference. Best it could do - maybe - is crash one that is on the edge of its spec and you would probably have to get pretty close for that (fall off as the square (edited) of the distance).
- greenhatman 10y agoWould it disable an annoying car alarm?
- nickpsecurity 10y agoOr stereo or subwoofer? I find that an interesting concept.
- Steeeve 10y agoFor stereos, use an AM transmitter and send your neighbor dora-the-explorer theme music on repeat.
- dotancohen 10y agoCan am AM transmitter be made directional though? Otherwise the power would be forbidding, and the collateral damage would be worse than the cause.
- kec 10y agoSure it can. Phased shifted arrays of monopole antennas are often used to steer broadcast signals in a particular direction (If you've ever seen a group of 2-3 radio towers sitting close together in the country side, that's what they're doing). That said: if you're in the US and transmit outside of the ISM bands or at anything above about a few hundred milliwatts of power, you risk the FCC coming down on you with some hefty fines or jail time.
- jacquesm 10y agoAM is used to describe a frequency range here (the 'AM Band'), but it is actually referring to 'Amplitude Modulation', a way to superimpose the signal on the carrier wave. You can do 'AM' at any frequency and your ability to direct the radio waves goes up as the frequency goes up. AM transmitters at the frequencies associated with the AM band (550-1600 KHz) can be directional, in fact, every antenna is more or less directional. What makes it tricky is that at those low frequencies the antenna elements are very large, and this is what will play havoc with any attempts to make a directional antenna for the AM Band that is still practical to use for the purpose described here. So in all likelihood you'll end up upsetting all your neighbors instead of just the one you're targeting.
- deutronium 10y agoHow about something like an Explosively pumped flux compression generator, I'm thinking there must be bits of EEPROM or equivalent in the phone that hold important info like the imei number, that if damaged, would render it unusable?
- jacquesm 10y agoI'll upvote the article if you build and test it :) (On your phone, in your lab). That has a chance of working due the very fast rise time you might be able to induce a sufficiently large voltage to cause some actual damage, it will be a 'one shot' affair though. But anything involving regular coils and some push button arrangement will likely cause it's own insulation to break down long before it will do damage to a phone. That's one of the reasons the spark gap is there in the first place, without it you'd hit the limits of the coil insulation very quickly. Spark gaps are a pretty nasty way to generate EM interference so there is some truth to the story. But even with my plasma cutter (12.5 KW, so not the smallest in the catalog) and stick welder I never managed to crash a cell phone. The plasmacutter did have the habit of resetting the controller until I properly decoupled all the lines into it.
- bigiain 10y agoA friend of mine did some back of the envelope calculations at Burningman one year when the megaphone guys were being particularly annoying - he came up with (from memory) 1km of fine copper wire wrapped round 100g of plastic explosive in the right configuration would probably let you take out a typical megaphone at 20m... (Note: all memories and calculations are from Burningman a decade or so back - and should be treated with an entire playa-ful of grains of salt.)
- AnimalMuppet 10y agoGive me the 100g of plastic explosives, and I could take out the megaphone without needing the copper wire. (Though it might be a bit rough on the megaphone operator. On the other hand, that copper wire is going to create some pretty nasty shrapnel...)
- blacksmith_tb 10y agoShouldn't the signal fall off with the square of the distance (inverse-square law)?
- filterfish 10y agoYes.
- jacquesm 10y agoYes, apologies.
- mSparks 10y agoaiui. its not linear. either it induces a voltage high enough to cause disruption or it doesnt. the limiting factor is the voltage not the power (power is tiny)
- mSparks 10y agoand what i mean by that, is we are talking about a pulse of high voltage and very very high frequency (maybe even gamma radiation) and its effect on electronics. thats not a case of power falloff. Because interaction with the environment and target is non linear. for example if it blasts a phone to reset from a few centimeters it could easily drop all calls in a 20 meter radius. but upping the power/voltage 4 times may only add milimeters to the range of blasting the phone to reset because so much is absorbed by the case. but upping the power/voltage 5 times could add a meter to blasting the phone to reset because the case now no longer absorbs enough energy to prevent the interference. Also resonance and harmonics play a huge role in the effect. All conjecture. but my point is you cant apply school boy physics to the problem because its not a problem they teach in school.
- filterfish 10y agoThere's a very big difference between EM interference and an EM pulse. One is the by-product of all digital electronics and one is a device specifically designed to induce enough current on a circuit board/IC/etc to damage it. That said, based on the size of that thing in the photo I suspect it wouldn't damage anything!
- jacquesm 10y agoThe biggest difference is the fieldstrength of the primary field used to induce a voltage in the target, the same basic principles apply. It takes a (much) higher fieldstrength to induce voltages that will destroy electronics than what's required to flip the occasional bit without damage. Lightning can cause EMP like effects by inducing voltage in conductors not directly hit by the lightning.
- bigiain 10y agoI vividly remember riding a motorcycle next to a lake, when a lightning strike hit the lake maybe 20-30m from where I was. The bike's engine died briefly (maybe 0.5 or 1 sec) then came good again - I'm pretty sure it was the fairly simple electronics driving the ignition getting "zapped". (This was a 1991-vintage bike - its modern enough that it uses hall sensors not points, but the electronics driving the ignition and the advance curves might even be analog instead of microcontroller-driven.)
- deleted 10y ago[deleted]
- phkahler 10y agoI've often thought about using a wok as a dish and putting a magnetron at the focus. High power directed microwaves would probably damage a lot of things. And made from kitchen hardware...
- Thorondor 10y agoProbably safer to let somebody else try this... ;) A couple of Ukrainians made a cool YouTube video recently where they built something similar and used it to blow up some cell phones. https://www.youtube.com/watch?v=FIU8WZR9DNA https://www.youtube.com/watch?v=FIU8WZR9DNA
- smadison 10y agoI think they've been using it on Samsung Note 7s more recently.
- jacquesm 10y agoYou really don't want to microwave a Lithium-Ion battery.
- bigiain 10y agoOh yeah I do! (From a distance. With a camera running...) (It can't be much worse than all the times I've smashed LiPo batteries into the ground (or a tree or another quad) at 80+mph... They only _rarely_ "vigorously discharge" as a result of that. I'm pretty careful the next few times I recharge one after a particularly violent crash...)
- ars 10y agoThey seem to have absolutely no sense of self preservation. Can they really expose their hand to that (below the temperate at which they get a burn) with no internal/hidden damage whatsoever?
- zeroer 10y agoIt's not ionizing radiation, so the only damage is from the heat. So they probably can expose their hand without damage.
- mcguire 10y ago"18650 lithium battery cell" Or, possibly, explode into flaming death.
- mcguire 10y agoOk, so let me put it another way: how much resistance does that circuit have?
- tlarkworthy 10y agoThings like that were used to cheat slot machines http://empjammer.com/how-a-emp-jammer-working http://empjammer.com/how-a-emp-jammer-working
- jacquesm 10y agoMuch cheaper to use an electric gas lighter. That's what we used to test on stuff that was supposed to be reliable and it is amazing how hard it is to defend against it. If you could survive 10 seconds or more without a latch losing state or some other bitflip then it was usually a pretty good job. Even so, this required physical contact to something made of metal on the machine (even if most of it is properly grounded there always is some exposed metal that isn't). I hope the engineering on that product is better than the English, it is barely understandable.
- bigiain 10y agoHeh - showing my age here, but I remember using gas lighters (stolen from school heaters) to zap free game credits into Asteroids machines...
- emmelaich 10y agoSame. And pinball machines and others. Feel pretty bad about it now, because I probably destroyed a few IC boards.
- ars 10y agoWhat did you do? Just heat it up till it does "something"?
- bigiain 10y agoJust zap some of the metal around the coin slot until it either crashed or gave you free games. (These were the piezo spark-ignitors, not pilot flames...)
- ghostDancer 10y ago
- M_Grey 10y agoOr, "How to kill people with pacemakers". Seriously, there are a lot of bad uses for this which have nothing to do with phones.
- subliminalpanda 10y agoOr one of those going off on a plane. Horrible consequences.
- M_Grey 10y agoOh damn it... that's a good point. What would the effect be if you got one into a critical part of a power or transmission station too? Not good I bet.
- subliminalpanda 10y agoKnock out a city block or worse.
- deleted 10y ago[deleted]
- noir_lord 10y agoNot a great deal tbh. Inverse square law means it'll have bugger all range and those kinds of systems are large enough with enough 'capacity' to just soak it up. Next to the control computer maybe but not in a transmission station.
- robryk 10y agoThen you could just as well bring a crowbar and throw it at something to cause a short. Or just smash stuff manually. This device has a very small range.
- M_Grey 10y agoSure, but then someone finds a crowbar, or smashed stuff... what obvious trace would this leave, and could it be scaled up?
- giardini 10y agoWhy a second external coil? It isn't aligned with the first coil and so the induced EMF is minimized (usually such coils are co-axial).
- madengr 10y agoFunny he can build an EMP generator but can't properly bias an LED.
- smoyer 10y agoSweet! ... My EMP generator only works on Samsung Galaxy Note 7s!
- georgeecollins 10y agoThis seems like a device that is possible to cause a lithium battery fire because of the discharge rate.
- madengr 10y agoJust to clarify after seeing several posts below. The magnetic and electric near fields fall off from 1/r^3 to 1/r^2, depending on component. The far fields fall off at 1/r, hence the familiar 1/r^2 for power (not amplitude). http://www.rfcafe.com/references/electrical/near-far-field.htm http://www.rfcafe.com/references/electrical/near-far-field.h... This thing operates in the near field, so it is pretty much useless past a distance of a coil diameter.
- Hasz 10y agoIf you wanted to do this right, you'd match the impedance to the antennae impedance of a typical phone antennae. This gets around the square rule, sort of, and you won't need a suitcase full of batteries to power the thing.
- pervycreeper 10y agoWhat component is failing in order to cause that iphone's screen to fade out in that way?
- jwildeboer 10y agoIt doesn't destroy phones, though. It resets them at max according to the video and tests.
- viggity 10y agothis reminds me of a coworker who tried to create a tiny DC motor with a battery, a magnet, and _non-enameled_ wire. yeah, that didn't work out too well for him. I tried to explain why the wire needed to be enameled, but the cargo-cult science was strong with him.