Low-End Parts Make Tesla Coil with a High-End Look

We all know the saying: cheap, fast, or good — pick any two. That rule seems to apply across the spectrum of hackerdom, from software projects to hardware builds. But this DIY Tesla coil build might just manage to deliver on all three.

Cheap? [Jay Bowles]’ Tesla coil is based on a handheld bug zapper that you can find for a couple of bucks, or borrow from the top of the fridge in the relatively bug-free winter months. The spark gap is just a couple of screws set into scraps of nylon cutting board — nothing fancy there. Fast? Almost everything needed to build this is stuff lying around the house, and depending on the state of your junk bin you may not even have to order the polypropylene caps [Jay] recommends. Good? That’s a relative term, of course, and if you define it as a coil capable of putting out pumpkin-slaying lightning bolts or playing “Yakkity Sax”, you’ll likely be disappointed. But there’s no denying that this Tesla coil looks good, from its Lexan base to the door-pull top load. And running off a couple of AA batteries, it’s safe to use too.

[Jay] put a lot of care into winding and dressing the secondary coil neatly, and the whole thing would look great as a desktop toy. Not into the winding part? You can always etch a PCB Tesla coil instead.

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Catching 30 kilowatts with Thor’s Hammer

Can you really catch lightning with Mjolnir, the mythical hammer of Thor? If you’re [James Hobson] you can get pretty darn close. He’s a long time writer at Hackaday who’s been building an epic following on his YouTube channel by making the digital effects of blockbuster movies into practical effects. Today he released a video showing how he channeled a jolt of lightning with hammer held high.

The lightning source for this hack is a huge Tesla coil held overhead by a telescoping lift. Humans and high voltage mix poorly, which is why you can’t actually tell this is [James]. He’s wearing a full body suit of grounded chainmail which serves as a Faraday cage, safely directing the current around him to avoid a literally heart-stopping moment. Check out the antics in the video after the break.

Longtime readers will remember [Caleb Kraft’s] take on Mjolnir, a build that placed the Tesla coil in the hammer itself. [James]’ version is undeniably more impressive, with the tradeoff that it’s wholly unportable. While we’re on the topic of mythical hammers, our other most favorite build is the delightful prank build which makes the hammer unliftable except by the recognized owner.

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The Nixie Tube Killer That Never Was

With the wealth of Nixie projects out there, there are points at which Hackaday is at risk of becoming Nixieaday. Nixie clocks, Nixie calculators, Nixie weather stations, and Nixie power meters have all graced our pages. And with good reason – Nixie tubes have a great retro look, and the skills needed to build a driver are a cut above calculating the right value for a series resistor for an LED display.

But not everyone loved Nixies back in the day, and some manufacturers did their best to unseat the venerable cold cathode tubes. [Fran Blanche] came across one of these contenders, a tiny cathode ray tube called the Nimo, and after a long hiatus in storage, she decided to put the tube to the test. After detailing some of the history of the Nimo and its somewhat puzzling marketing — its manufacturer, IEE, was already making displays to compete with Nixies, and seven-segment LEDs were on the rise at the time — [Fran] goes into the dangerous details of driving the display. With multiple supply voltages required, including a whopping 1,700 V DC for the anode, the Nimo was anything but trivial to integrate into products, which probably goes a long way to explaining why it never really caught on.

If you happen to have one of these little bits of solid unobtanium, [Fran]’s video below will go a long way to bringing back its ghostly green glow. You might say that [Fran] has a thing for oddball technologies of the late 60s — after all, she’s recreating the Apollo DSKY electroluminescent display, and she recently helped a model Sputnik regain its voice.

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Ben Franklin’s Weak Motor and Other Forgotten Locomotion

Most of the electric motors we see these days are of the electromagnetic variety, and for good reason: they’re powerful. But there’s a type of motor that was invented before the electromagnetic one, and of which there are many variations. Those are motors that run on high voltage, and the attraction and repulsion of charge, commonly known as electrostatic motors.

Ben Franklin — whose electric experiments are most frequently associated with flying a kite in a thunderstorm — built and tested one such high-voltage motor. It wasn’t very powerful, but was good enough for him to envision using it as a rotisserie hack. Food is a powerful motivator.

What follows is a walk through the development of various types of these motors, from the earliest ion propelled ones to the induction motors which most have never heard of before, even an HV hacker such as yours truly.

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Portable Jacob’s Ladder for When…You Know… You Need a Portable Jacob’s Ladder

When do you need a portable Jacob’s Ladder? We don’t know, but apparently [mitxela] doesn’t want to leave home (or the laboratory) without one. So he built a portable unit that works for a few minutes on a battery. In the video (see below), he says he wouldn’t presume to claim it was the smallest Jacob’s Ladder ever, but he thought it might be a contender.

The battery is a LiPo cell and although it might last up to four minutes, [mitxela] points out that the transistors probably wouldn’t survive that much on time, despite the heat sinks he put in place. The whole device is 45mm square and 17mm thick. Of course, the wires add some height (about 150mm total).

We were hoping to see more of the insides, but we presume this uses one of the cheap high voltage modules you can procure from the usual Far East sources–or, at least–it could. The rest is just laser cutting and workmanship.

If you haven’t encountered them before (outside of old monster movies), a Jacob’s Ladder lets high voltage ionize the air down at the bottom of the narrow gap. The ionized air is hot and rises, and the current flows through it, despite the electrodes getting further apart. Of course, that means you shouldn’t put on in your zero-gee space station.

You might think a portable Jacob’s ladders is unique. Turns out, it isn’t. If you want something easy (and perhaps not as portable), you can’t get much easier than this one.

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BAMF: Hard Drive Platter Launcher Among All-Time Favorites

The hard drive platter launcher that [Krux] built has been among my all-time favorite builds and I am so excited that he is showing it off at this year’s Bay Area Maker Faire. At its core the concept is quite simple; dump a large amount of current through a coil all at once, and the magnetic current generated spontaneously repels the aluminum hard drive platter. The devil is in the details and this is where [Krux’s] work really shines.

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Little eBay Tesla Coil Gets an Upgrade

Like so many of the projects we feature, this one started with a cheap eBay module purchase. In this case, it was a little Tesla coil that made decent sized arcs but wasn’t quite good enough. The result was a super-sized solid state Tesla coil with better results and room to grow.

As [GreatScott!] discovered, the little eBay Tesla coil has a pretty neat design. The exciter is a Slayer circuit, a super simple one-transistor design. His reverse engineering revealed that the primary coil is simply a loop trace on the PCB under the secondary coil. Sadly, his attempt to replace the primary and reproduce the Slayer exciter resulted in anemic performance. What’s a hacker to do in that case except build a bigger coil? Much bigger — like “build your own winding jig” bigger. Twelve hundred secondary turns and an appropriately menacing-looking primary later, the results were — still anemic. It turns out the Slayer is just not up to the task. He turned to an inverter circuit that was previously used in a wireless energy transfer circuit, and we finally get to see a little of the Tesla coil magic. But wait! There’s more to come, as future videos will tweak the circuit and optimize the coil for better performance.

It’s no surprise that Tesla coils are a popular project around here, especially the musical kinds, from the tiny to the large. Music doesn’t seem to be on [GreatScott!]’s mind, though, and we’ll be watching with interest to see where he takes this build.

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