Are Microwave Guns For Real?

October 23, 2017 by Lewin Day 65 Comments

Almost exactly one year ago, [Kreosan] published a video detailing an EM “weapon” built out of three magnetrons, some batteries, and a taser. It all seemed a bit too good to be true, so [Allen] decided to try and replicate the results for himself.

[Kreosan]’s original video was impressive, showing everything from home stereos to a humble moped exploding when in the presence of their powerful device. However, many of those watching the video doubted the footage. Most criticism centered around the nature of the power supply to the magnetron falling short of the usual 700-1000W seen in a microwave oven.

Initial testing with a single magnetron. This setup could light the bulb at a distance of a few centimeters.

[Allen] starts by experimenting with a single magnetron, successfully using it to light a compact fluorescent bulb at a range of a few centimeters. Scaling up to the full triple magnetron setup with a cardboard and foil feedhorn, [Allen] is, at best, able to crash a calculator at a distance of a few feet.

The microwaves cause no explosions, and the device doesn’t seem to have anywhere near the 50-foot range claimed by [Kreosan] for their device. [Allen] puts forth the theory that the explosions seen in the original footage are far more likely to be from small firecrackers rather than any electronic components dying from microwaves.

Overall it’s a solid attempt to recreate someone else’s work to verify the results, a cornerstone of science. We did bristle somewhat at the valiant 18650 being described as a “vape battery”, however. For more microwave goodness, check out this attempt to recreate the TSA’s body scanners .

Pulsed Power And Its Applications

January 11, 2017 by Manuel Rodriguez-Achach 43 Comments

Pulsed power is a technology that consists in accumulating energy over some period of time, then releasing it very quickly. Since power equals energy (or work) divided by time, the idea is to emit a constant amount of energy in as short a time as possible. It will only last for a fraction of a second though, but that instantaneous power has very interesting applications. With this technology, power levels of more than 300 terawatts have been obtained. Is this technology for unlimited budgets, or is this in reach of the common hacker?

Consider for example discharging a capacitor. A large 450 V, 3300 uF electrolytic capacitor discharges in about 0.1 seconds (varies a lot depending on capacitor design). Since the energy stored in it is given by 1/2 CV², which gives 334 Joules of energy, the power delivered will be 3340 watts. In fact a popular hacker project is to build large capacitor banks. Once you have the bank, and a way to charge it, you can use it to power very interesting devices such as:

untitled1 — A portable, 1.25 kJ coilgun by [Jason Murray]

Railguns in particular are subject to serious research. You may have read about the navy railgun, capable of reaching a muzzle speed of more than 4,600 mph (around Mach 6), more than any other explosive-powered gun. Power is provided by a 9-megajoule capacitor bank. The capacitors discharge on two conducting rails, generating an electromagnetic field that fires the projectile along the rails. The rail wear due to the tremendous pressures and currents, in the millions of amperes range, is still a problem to be solved.

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Electromagnetic Pulse: Pure Hollywood?

October 18, 2016 by Bryan Cockfield 61 Comments

Imagine you’re in charge of a major heist. Right as your crew is about to rob the main vault, you need all of the electronics in the building to fail at exactly the right moment with no other collateral damage (except, maybe, to your raggedy panel van). Obviously you will turn to one of the entertainment industry’s tired tropes, the electromagnetic pulse! The only problem is that if you were to use a real one rather than a Hollywood prop either there would be practically no effect, a large crater where the vault used to be, or most of humanity would be in deep trouble. After all, the real world isn’t quite as convenient as the movies make it seem.

Our curiosity into this phenomenon was piqued when we featured an “EMP generator” from [FPS Weapons]. The device doesn’t create an enrapturing movie-esque EMP pulse suitable for taking down a casino or two, but it does spew a healthy amount of broadband electromagnetic interference (EMI) in every direction. It probably also doesn’t send the EMI very far; as we’ve seen in many other projects, it’s hard to transfer energy through the air. It got us wondering, though: what is the difference between being annoying and creating a weapon? And, is there any practical use for a device like this?

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Become Very Unpopular Very Fast With This DIY EMP Generator

October 12, 2016 by Gerrit Coetzee 140 Comments

Taking a break from his book, “How to Gain Enemies and Encourage Hostility,” [FPS Weapons] shows us how to build our own handheld EMP generator which can be used to generate immediate dislike from anyone working on something electronic at the hackerspace.

The device is pretty simple. A DC source, in this case an 18650 lithium battery cell, sends power to an “Ultra High Voltage 1000kV Ignition Coil” (as the eBay listing calls it), when a button is pressed. A spark gap is used to dump a large amount of magic pixies into the coil all at once, which generates a strong enough magnetic pulse to induce an unexpected voltage inside of a piece of digital electronics. This usually manages to fire a reset pin or something equivalent, disrupting the device’s normal operation.

While you’re not likely to actually damage anything in a dramatic way with this little EMP, it can still interrupt an important memory write or radio signal and damage it that way. It’s a great way to get the absolute shock of your life if you’re not careful. Either from the HVDC converter or the FCC fines. Video after the break.

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Don’t Take Photos Of Your Arduino 101 Either, It’s Light Sensitive

May 5, 2016 by Gerrit Coetzee 41 Comments

Wafer level chips are cheap and very tiny, but as [Kevin Darrah] shows, vulnerable to bright light without the protective plastic casings standard on other chip packages.

We covered a similar phenomenon when the Raspberry Pi 2 came out. A user was taking photos of his Pi to document a project. Whenever his camera flash went off, it would reset the board.

[Kevin] got a new Arduino 101 board into his lab. The board has a processor from Intel, an accelerometer, and Bluetooth Low Energy out of the box while staying within the same relative price bracket as the Atmel versions. He was admiring the board, when he noticed that one of the components glittered under the light. Curious, he pulled open the schematic for the board, and found that it was the chip that switched power between the barrel jack and the USB. Not only that, it was a wafer level package.

So, he got out his camera and a laser. Sure enough, both would cause the power to drop off for as long as the package was exposed to the strong light. The Raspberry Pi foundation later wrote about this phenomenon in more detail. They say it won’t affect normal use, but if you’re going to expose your device to high energy light, simply put it inside a case or cover the chip with tape, Sugru, or a non-conductive paint to shield it.

EDIT: [Kevin] also tested it under the sun and found conditions in which it would reset. Videos after the break.

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Photonic Reset Of The Raspberry Pi 2

February 8, 2015 by Brian Benchoff 102 Comments

For the past month, the Raspberry Pi 2 has only been available to the Raspi Foundation, and for about 2 weeks, select members of the media who have worn the Raspi 2 on a necklace like [Flavor Flav] wears a clock. That’s not many people with real, working hardware and when a product is released, the great unwashed masses will find some really, really weird bugs. The first one to crop up is a light-sensitive reset of the Raspberry Pi 2.

[PeterO] on the Raspberry Pi forums took a few pictures – with flash – of a running Raspberry Pi 2. It took a little bit of deduction to realize that a camera flash will either reset or turn the Raspi 2 off. Yes, this is weird, and experiments are ongoing.

A short video from [Mike Redrobe] confirms the finding and a reddit thread offers an explanation. U16, a small chip located in the power supply part of the Raspi 2, is sensitive to light. Putting enough photons will cause the Pi to shut down or restart.

There’s still some research to be done, however, I can confirm a cheap green laser pointer will reset a Raspberry Pi 2 when the beam is directed at the U16 chip. This is the chip that is responsible, and this is not an EMP issue. This is a photon/light issue with the U16 chip. The solution to this bug is to either keep it in a case, or put a tiny amount of electrical tape over the chip.

Thanks [Arko] for staying up until an ungodly hour and sending this to me.

EM Pulser Flings Washers, Side Effects May Include Curing Cancer Or Death

September 24, 2014 by Rich Bremer 57 Comments

Some folks believe that exposure to electromagnetic pulses helps the human body heal itself (one portion of the [Bob Beck] protocol). [Steffan] is one of those folks and was interested in EMP generation but wasn’t crazy about the several-hundred dollar price tag for professional units. As any determined DIYer would do, he set off to make his own.

This whole thing works by straight-out-of-the-wall 110v AC running through a couple 60 watt light bulbs before moving through a rudimentary rectifier circuit. The DC output from the rectifier charges five 130uF camera flash capacitors. An inductor coil is responsible for generating the EMP and is only separated from the capacitors by a single normally-open momentary switch. Although it is possible to wrap your own coil, [Steffan] decided to use an off the shelf 2.5mH unit normally used for speaker system crossovers. Once the momentary switch is pressed, the energy in the capacitors is discharged through the inductor coil and the EMP is created. To demonstrate that the pulser does indeed work, a metal washer was placed on the inductor coil and the unit fired resulting in the washer being thrown into the air.

[Stephan] did deviate from the some of the online designs he had researched, using 7 capacitors instead of the recommended 5. The result was a firecracker-like discharge sound and melting of the 14 gauge wire. Well, back to 5 caps.