A DIY Stun Gun You Probably Shouldn’t Build

March 16, 2020 by Tom Nardi 36 Comments

In these troubled times, when a trip to the grocery store could turn into a brawl over toilet paper, you might be inclined to build yourself a low-cost electroshock weapon. Or at least, that’s what [Alex Zidros] did. We don’t necessarily recommend you follow in his footsteps, and we’re certainly not advocating testing it on a loved one. We just bring you this information, you have to decide what you do with it.

So what does it take to build an improvised stun gun? Not a whole lot, it turns out. As you might have guessed, the star of the show is a high voltage transformer which supposedly puts out 400 kV. Just looking at it (and the price) we’re going to go out on a limb and say the performance specs are way overrated, but in this case that might actually be a good thing.

Beyond the transformer, there’s a simple 9 V battery holder and electrodes made from the prongs of a hacked up travel adapter. To deliver the lightning, [Alex] is using a pink arcade button. Just because you might be fighting for your life doesn’t mean you can’t have a little fun, right? Everything is packed into a simple 3D printed enclosure, but you could easily replace that with any suitably sized box. Something made out of wood might be a good idea, considering.

If you’d like to see another person shocked by a cobbled together high-voltage weapon, and potentially even learn something in the process, check out the “tutorial” video [Mehdi Sadaghdar] did back in 2014. We did mention you definitely shouldn’t do this at home, right?

Visualizing Energy Fields With A Neon Bulb Array

March 4, 2020 by Tom Nardi 20 Comments

Everyone knows that one of the coolest things to do with a Tesla coil is to light up neon or fluorescent tubes at a distance. It’s an easy and very visual way to conceptualize how much energy is being pumped out, making it a favorite trick at science museums all over the world. But what would it look like if you took that same concept and increased the resolution? Replace that single large tube with an array of smaller ones. That’s exactly what [Jay Bowles] did in his latest video, and the results are impressive to say the least.

From a hardware standpoint, it doesn’t get much simpler. [Jay] knew from experience that if you bring a small neon indicator close to a Tesla coil, it will start to glow when approximately 80 volts is going through it. The higher the voltage, the brighter the glow. So he took 100 of these little neon bulbs and arranged them in a 10×10 grid on a piece of perfboard. There’s nothing fancy around the backside either, just all the legs wired up in parallel.

When [Jay] brings the device close to his various high-voltage toys, the neon bulbs still glow like they did before. But the trick is, they don’t all glow at the same brightness or time. As the panel is moved around, the user can actually see the shape and relative strength of the field by looking at the “picture” created by the neon bulbs.

The device isn’t just a cool visual either, it has legitimate applications. In the video, [Jay] explains how it allowed him to observe an anomalous energy field that collapsed when he touched the base of his recently completed Tesla coil; an indication that there was a grounding issue. He’s also observed some dead spots while using what he’s come to call his “High-Voltage Lite-Bright” and is interested in hearing possible explanations for what he’s seeing.

We’ve been fans of [Jay] and the impressively produced videos he makes about his high-voltage projects for years now, and we’re always excited when he’s got something new. Most hardware hackers start getting sweaty palms once the meter starts indicating more than about 24 VDC, so we’ve got a lot of respect for anyone who can build this kind of hardware and effectively communicate how it works to others.

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Pavlok Gets A Literally Shocking Teardown

February 2, 2020 by Tom Nardi 36 Comments

Apparently, there is a wrist-mounted device that delivers electric shocks to the wearer when it receives the appropriate command over Bluetooth. No, it’s not part of some kind of house arrest program. If you can believe it, the gadget is actually intended to help break bad habits or wake up exceptionally deep sleepers. We don’t know which of those problems [Becky Stern] has, but we’re glad to see she decided to take hers apart before the 21st century self-flagellation started.

Called the Pavlok and available for $180 USD from various online retailers, the device looks like a chunky fitness tracker. But in place of the screen that would show you how many steps you’ve taken or your current heart rate, there’s a lighting bolt button that you can press when you want to shock yourself. With the smartphone application, you can control the device remotely with a handy desktop widget that allows you to select the intensity of the shock. No, we aren’t making any of this up. Check out the video after the break to see it in action.

When [Becky] tried to take the Pavlok apart, she found that it was nearly impossible to handle it without inadvertently triggering a shock. So until she could get the case open and physically disconnect the battery, all she could do was turn the intensity down in the application and work through the occasional jolts from the device. We can only hope that more devices don’t adopt a similar sense of self-preservation.

Once inside she found mainly the same kind of hardware you’d expect in a standard, non-masochistic, fitness wearable. There’s a nRF52832 Bluetooth SoC, a MMA8451Q accelerometer, a PCF85063A I2C RTC, and a FXAS21002C gyroscope. What you’re somewhat less likely to find inside your FitBit however is the LPR6235 coupled inductor and beefy capacitors which are used to build up a high-voltage charge from the standard 3.7 V LiPo battery.

We’ve been very interested in the recent projects which are creating custom firmwares for commercially available fitness wearables, as it could be an express route to a hacker-friendly smartwatch. While the Pavlok has some compelling hardware, and the programming header [Becky] identified looks interesting, we don’t like the idea of being one misplaced if statement away from riding the lightning.

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Mr. Carlson Gets Zapped By Snow

January 25, 2020 by Dan Maloney 47 Comments

As a Canadian, [Mr. Carlson] knows a thing or two about extreme winter weather. Chances are good, though, that he never thought he’d get zapped with high voltage generated by falling snow.

[Mr. Carlson]’s shocking tale began with a quiet evening in his jam-packed lab as a snowstorm raged outside. He heard a rhythmic clicking coming from the speakers of his computer, even with the power off. Other speakers in the lab were getting into the act, as was an old radio receiver he had on the bench. The radio, which was connected to an outdoor antenna by a piece of coax, was arcing from a coil to the chassis in the front end of the radio. The voltage was enough to create arcs a couple of millimeters long and bright blue-white, with enough current to give [Mr. Carlson] a good bite when he touched the coax. The discharges were also sufficient to destroy an LED light bulb in a lamp that was powered off but whose power cord was unlucky enough to cross the antenna feedline.

Strangely, the coil from which the arc sprang formed a 36-ohm shunt to the radio’s chassis, giving the current an apparently easy path to ground. But it somehow found a way around that, and still managed to do no damage to the sturdy old radio in the process. [Mr. Carlson] doesn’t offer much speculation as to the cause of the phenomenon, but the triboelectric effect seems a likely suspect. Whatever it is, he has set a trap for it, to capture better footage and take measurements should it happen again. And since it’s the Great White North, chances are good we’ll see a follow-up sometime soon.

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Drive A Plasma Ball With An ATV Ignition Coil And A 555

December 9, 2019 by Gerrit Coetzee 7 Comments

[Discrete Electronics Guy] sends in his short tutorial on building a high voltage power supply from simple things.

The circuit is a classic, but we love the resourcefulness shown. The ignition coil comes from a three wheeler, the primary power supply is a ATX supply from a computer and the oscillator is powered by a 9V battery. We do wonder whose vehicle stopped working though.

He gives a great explanation of how the circuit works and was constructed and then moves on to build his own Plasma bulb. Despite expecting something more complicated the end result was achieved by putting a lightbulb on a stick. Fantastic. The circuitry was nearly packaged into a takeaway food container and the entire construction was called complete.

All in all it shows what someone can accomplish if they’re resourceful and understand the basics. However, it’s probably that you don’t electroBoom yourself to death if you can avoid it.

Simple Acrylic Plates Make Kirlian Photography A Breeze

November 30, 2019 by Dan Maloney 1 Comment

We know, we know – “Kirlian photography” is a term loaded with pseudoscientific baggage. Paranormal researchers have longed claimed that Kirlian photography can explore the mood or emotional state of a subject through the “aura”, an energy field said to surround and emanate from all living things. It’s straight-up nonsense, of course, but that doesn’t detract from the beauty of plasma aficionado [Jay Bowles]’ images produced by capacitive coupling and corona discharge.

Technically, what [Jay] is doing here is not quite Kirlian photography. The classic setup for “electrophotography” is a sandwich of photographic film, a glass plate, and a metal ground plate. An object with a high-voltage, high-frequency power supply attached is placed on top of the sandwich, and the resulting corona discharge exposes the film. [Jay]’s version is a thin chamber made of two pieces of solvent-welded acrylic and filled with water. A bolt between the acrylic panes conducts current from a Tesla coil – perhaps this one that we’ve featured before – into the water. When something is placed on the acrylic, a beautiful purple corona discharge streams out from the object.

It’s an eerie effect, and it’s easy to see how people can see an aura and attribute mystical properties to it. In the end, though, it’s not much different than touching a plasma globe, and just about as safe. Feeling a bit more destructive? Corona discharge is a great way to make art, both in wood and in acrylic.

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Build Your Own Plasma Ball

October 25, 2019 by Sharon Lin 20 Comments

The simple plasma ball – it graces science museums and classrooms all around the world. It shares a place with the Van de Graaf generator, with the convenient addition of spectacular plasma rays that grace its spherical surface. High voltage, aesthetically pleasing, mad science tropes – what would make a better DIY project?

For some background, plasma is the fourth state of matter, often created by heating a neutral gas or ionizing the gas in a strong electromagnetic field. The availability of free electrons allows plasma to conduct electricity and exhibit different properties from ordinary gases. It is also influenced by magnetic fields in this state and can often be found in electric arcs.

[Discrete Electronics Guy] built a plasma bulb using the casing from an old filament bulb and an ignition coil connected to a high voltage power supply. The power supply is based on the 555 timer IC. It uses a step-up transformer (the ignition coil) driven by a square wave oscillator circuit at a high frequency working as AC voltage. The square wave signal boosts the current into the power transistor, increasing its power.

The plasma is produced inside the bulb, which contains inactive noble gases. When touching the surface of the bulb, the electric arc flows to the point of contact. The glass medium protects the skin from burning, but the transparency allows the plasma to be seen. Pretty cool!

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