high voltage

239 Articles

Ben Franklin’s Weak Motor And Other Forgotten Locomotion

October 3, 2017 by 11 Comments

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

June 9, 2017 by 32 Comments

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

May 20, 2017 by 32 Comments

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

April 30, 2017 by 14 Comments

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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Laser Surgery: Expanding The Bed Of A Cheap Chinese Laser Cutter

April 24, 2017 by 29 Comments

Don’t you just hate it when you spend less than $400 on a 40-watt laser cutter and it turns out to have a work area the size of a sheet of copy paper? [Kostas Filosofou] sure did, but rather than stick with that limited work envelope, he modified his cheap K40 laser cutter so it has almost five times the original space.

The K40 doesn’t make any pretenses — it’s a cheap laser cutter and engraver from China. But with new units going for $344 on eBay now, it’s almost a no-brainer. Even with its limitations, you’re still getting a 40-watt CO2 laser and decent motion control hardware to play with. [Kostas] began the embiggening by removing the high-voltage power supply from its original space-hogging home to the right of the work area. With that living in a new outboard enclosure, a new X-Y gantry of extruded aluminum rails and 3D-printed parts was built, and a better exhaust fan was installed. Custom mirror assemblies were turned, better fans were added to the radiator, and oh yeah — he added a Z-axis to the bed too.

We’re sure [Kostas] ran the tab up a little on this build, but when you’re spending so little to start with, it’s easy to get carried away. Speaking of which, if you feel the need for an even bigger cutter, an enormous 100-watt unit might be more your style.

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Wirelessly Charge Your Phone From High Voltage Power Lines

April 10, 2017 by 103 Comments

Using nothing more than an antenna, a spark plug, a flyback transformer, a diode, and a car phone charger, [Kreosan] have implemented the world’s most dangerous cell-phone charger: wirelessly charging their phone from high voltage power lines. This is a demonstration of a hack that we thought was just an urban legend, but it’s probably best to leave this as just a demo — this one is probably illegal and definitely dangerous.

The charger works by holding an old TV aerial fairly close to high voltage overhead cables, and passing the resulting tiny current through a spark plug and a flyback transformer to ground. To charge the phone, they tapped the transformer, rectified it through a diode, and fed it into a car-plug phone charger. [Kreosan] claims to harvest enough “free” electricity to charge the phone. (Where by “free”, we mean stolen from the electric grid.)

If you regularly find yourself running out of charge and like a bit of danger why not make a power bank that looks like a bomb instead. Sure we don’t advise you take it on a plane but it seems like a much safer option than using overhead power lines.

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How Does A Voltage Multiplier Work?

March 22, 2017 by 43 Comments

If you need a high voltage, a voltage multiplier is one of the easiest ways to obtain it. A voltage multiplier is a specialized type of rectifier circuit that converts an AC voltage to a higher DC voltage. Invented by Heinrich Greinacher in 1919, they were used in the design of a particle accelerator that performed the first artificial nuclear disintegration, so you know they mean business.

Theoretically the output of the multiplier is an integer times the AC peak input voltage, and while they can work with any input voltage, the principal use for voltage multipliers is when very high voltages, in the order of tens of thousands or even millions of volts, are needed. They have the advantage of being relatively easy to build, and are cheaper than an equivalent high voltage transformer of the same output rating. If you need sparks for your mad science, perhaps a voltage multiplier can provide them for you.

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