Become Very Unpopular Very Fast With This DIY EMP Generator

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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Gutted USB Power Packs run Your TV

With a computer in every pocket, being tethered to large mains-powered appliances is a bit passe. No longer must you be trapped before the boob tube when you can easily watch YouTube on your phone. But you might be jonesing for the big screen experience in the middle of a power outage, in which case learning to build a simple battery bank built from cheap cell-phone power packs might be a good life skill to practice.

Looking more for proof of concept than long-term off-grid usability from his battery bank, [Stephen] cobbled together a quick battery bank from 18650 lithium ion batteries and a small 300W inverter. All the hardware was had on the cheap from an outfit called Cd-r King, a Phillipines-based discount gadgetorium we’d like to see in the states. He got a handful of USB power packs and harvested the single 18650 battery from each, whipped up a quick battery holder from 1/2″ PVC pipe and some bolts to connect the inverter. With four batteries in series he was able to run a flat-screen TV with ease, as well as a large floor fan – say, is that a Mooltipass on [Stephen]’s shelf in the background? And what’s nice about the gutted USB power packs is that they can still be used to recharge the batteries.

As [Stephen] admits, this is a simple project and there’s plenty of room to experiment. More batteries in parallel for longer run times is an obvious first step. He might get some ideas from this laptop battery bank project, or even step up to Tesla Li-ion battery hacking – although we doubt Cd-r King will be of much help with the latter.

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Prototype Sodium Ion Batteries in 18650 Cells

French researchers have announced a prototype of an 18650 sodium-ion battery. If you’ve bought a powerful LED flashlight, a rechargeable battery pack, or a–ahem–stronger than usual LASER pointer, you’ve probably run into 18650 batteries. You often find these inside laptop batteries and –famously– the Tesla electric vehicle runs on a few thousand of these cells. The number might seem like a strange choice, but it maps to the cell size (18 mm in diameter and 65 mm long).

The batteries usually use lithium-ion technology. However, lithium isn’t the only possible choice for rechargeable cells. Lithium has a lot of advantages. It has a high working voltage, and it is lightweight. It does, however, have one major disadvantage: it is a relatively rare element. It is possible to make sodium-ion batteries, although there are some design tradeoffs. But sodium is much more abundant than lithium, which makes up about 0.06% of the Earth’s crust compared to sodium’s 2.6%). Better still, sea water is full of sodium chloride (which we call salt) that you can use to create sodium.

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Hack VersaPak battery modules to reuse laptop cells


If you’re familiar with VersaPak tools you’ll note that while the battery pack in this image looks somewhat familiar, it’s not supposed to have a removable cell. This is [Martin Melchior’s] hack to use laptop 18650 Lithium cells with VersaPak tools.

The original NiCad packs used three cells for a total of 3.6V, so it is possible to substitute a Lithium cell in the same voltage neighorhood. The tools are pretty hard on the battery packs, drawing a lot of current in certain situations. But these cells are being harvested from dead laptop battery packs so it’s not a huge concern if their life is a bit shortened.

The hack places an 18650 battery receptacle inside of the VersaPak battery housing. There’s a bit of careful disassembly to get to this point, but it’s well illustrated in [Martin’s] project log. And of course you’ll need to use a proper Lithium battery charger from here on out.

This form factor has been popping up in a lot of hacks lately. Here’s another one that modifies the Goal Zero Bolt flashlight to use them.

Goal Zero Bolt hack lets your flashlight use non-proprietary batteries


[Harrson] was really excited to get a deal on this Goal Zero Bolt flashlight. It’s and LED flashlight that uses Lithium batteries that are recharged via USB. That’s really handy. But when he cracked it open, like any good hacker does with new toys, he found that it won’t charge standard 18650 Lithium cells. That’s the form factor it’s using, but the proprietary cell that comes with it has both conductors at the top.

So where did [Harrson] start with the project? He called the company to ask about the setup. They were able to confirm that the proprietary cells just have a conductor which brings the bottom contact of the cell up to the top. We’d bet this is to make the flashlight itself easier to manufacture.

He got to work by scavenging a flat Kapton covered conductor from an old laptop battery. This thin strip is manufactured for connecting the cells of a battery, and it’s quite flat so it will be able to bypass the 18650 cell housing inside of the battery compartment. He made a solder connection for the strip inside the recharging compartment, leaving a tail which makes contact with the base of a standard cell.

If you’ve ever cracked open a dead laptop battery you probably found round Lithium cells. These are most commonly the 18650 variant we’ve been talking about. The battery dies when just one cell goes bad, so [Harrson] has a supplies of the good cells which he’ll be able to substitute into his flashlight as needed.

Things to do with your laptop batteries when they’re dead

[Roy] over at GeekDad had a dead laptop battery on his hands, and decided he would disassemble it to see what useful things he could do with the cells inside. He mentions in his article that even though your laptop might be convinced that its battery is toast, more often than not just one or two cells are damaged. This may not be news to all of our readers, but is worth pointing out to those who might not be aware.

With the bad cells separated from the good, [Roy] thought up a couple of different uses for his newly acquired batteries. His initial idea was to power an LED flashlight that was made to run on the 18650 cells he recovered from his laptop – not a stretch of the imagination, but definitely useful. The second use he came up with was to pair two of the cells together in order to simultaneously power an Arduino and some small Lego motors.

[Roy] lays out all of the standard caveats you would expect regarding the care and feeding of the lithium cells, and even suggests rebuilding the laptop battery as an option for the more skilled members of his audience.

Now we understand that dismantling and re-using old laptop cells is not necessarily groundbreaking, but it’s definitely something that’s worth a bit of discussion. [Roy] admits that his two ideas fall far short of the “18650 Things” his article title suggests, so how about adding a few of your own?

If you have stripped down some laptop batteries to salvage the cells, let us know what you did with them in the comments – we would be interested in hearing about it.