Looking Mains Voltage In The Eye And Surviving

It is often a surprise to see how other people react to mains electricity when they encounter it in a piece of equipment. As engineers who have dealt with it both personally and professionally for many years it is easy to forget that not everyone has had that experience. On one hand we wince at those who dive in with no fear of the consequences, on the other we are constantly surprised at the number of people who treat any item with more than a few volts in it as though it was contaminated with radioactive anthrax and are scared to even think about opening it up.

We recently had a chat among the Hackaday writers about how we could approach this subject. The easy way out is to be all Elf-and-Safety and join the radioactive anthrax crowd. But the conclusion we came to was that this site is a resource for hackers and makers. Some of you are going to lift the lid on boxes containing significant voltages no matter what, so we thought we’d help you do it safely rather than just listen for the distant screams.

So here follows the first in a series on how to approach electronic devices containing high voltages, and live to tell the tale. By “high voltages” we mean anything up to mains voltages, and those directly derived from them such as the few hundred volts rectified DC you’ll find in a switch-mode PSU. For multi-kilovolt EHT you’ll have to wait for another article, because that is an entire subject in itself. We’ll mention these higher voltages in passing, but their detail is best left for a Hackaday colleague with more pertinent experience.

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Teslaphoresis: Tesla Coil Causes Self-Assembly In Carbon Nanotubes


This significant discovery in nanotechnology could also be the first practical use of a Tesla coil in modern times that goes beyond fun and education. A self-funded research team at Rice University has found that unordered heaps of carbon nanotubes will self-assemble into conductive wires when exposed to the electric field of a strong Tesla coil. The related paper by lead author and graduate student [Lindsey R. Bornhoeft], introduces the phenomenon as “Teslaphoresis”. Continue reading “Teslaphoresis: Tesla Coil Causes Self-Assembly In Carbon Nanotubes”

Inside A Circuit Breaker With MikesElectricStuff

High voltage is  not something we usually tinker with at home. In fact, most of us are more comfortable working with non-lethal, low current, low voltage DC signals. When we do venture into the world of high voltage, we prefer to do it vicariously thru someone with more safety training and/or experience.

[Mike] shows us the inner workings of a 240VAC circuit breaker and explains how the different safety features in the device work. In proper MikesElectricStuff form, [Mike] finds out what it takes to destroy the device. Or in this case multiple devices, [Mike] uses his “Destruct-o-tron” to create catastrophic failure in more than one breaker. You can check out the video embedded after the break to learn a bit about how a circuit breaker works, and of course witness the carnage.

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It’s a Bird, It’s a Plane, No… It’s High Voltage EPROM Man!

At Hackaday, we cover some pretty high-tech builds. Sometimes, though, you see something simple, but it still makes you feel happy to see it. That’s pretty much the case with [ProtoG’s] High Voltage EPROM Man.

The parts probably came out of a junk box, but the good news is that they don’t have to work, and you can freely substitute anything you have. According to [ProtoG], the “robot” head is a bulb socket with a crystal for the visor. The arms are fuses with fuse clips for the hands. The knees are adjustable caps, and the feet are TO-220 transistors.

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Extreme Wire Buzz Game

Remember that old buzz wire game? Kinda like Operation, where you have to do a dexterous task without touching the walls… Well here’s a fun twist on it — what if you throw a 4 million volt stun gun into the mix?

That’s right, [Mike] was given a taser flashlight, and he had this brilliant idea to make a game out of it. The game features three metal wire sections which get progressively harder, with higher risk too! Using the handle, you have to guide an eye-bolt along the wire sections. But be careful — the circuit is live, and if you touch the metal, you’re going to get quite the shock!

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Portable, DIY Radiography

[Matt] has a background in radiation, electronics, and physics, which means building a device to generate X-rays was only a matter of time. It’s something not everyone should attempt, and [Matt] discourages anyone from attempting anything like this, but if you’re looking for a project with a ‘because it’s there’ flair to it, building your own X-ray machine can be a fun and rewarding project.

Despite being scary and mysterious, X-rays are a rather old technology that date back to some of the first purposeful experiments in electronics. Most X-ray devices today are built around the same parts they were 100 years ago, namely, a Coolidge tube. Apply a high enough voltage to the Coolidge tube and electrons whizz from cathode to anode, and slam into a heavy metal target. This produces Bremsstrahlung radiation – breakingbraking X-rays – that can be directed to film or an X-ray intensifier screen that fluoresces in visible light when being struck by X-rays.

Aside from a cheap Coolidge tube, [Matt] constructed the rest of his X-ray generator with a voltage multiplier made out of sufficiently derated Chinese caps, a flyback transformer, and a transformer driver originally made for induction heating applications. The electronics were installed in a Tupperware container and insulated with mineral oil.

Being able to generate X-rays is one thing, viewing them is another matter entirely. For this, [Matt] is using an old X-ray intensifier screen from the 60s or 70s. This screen fluoresces blue, not the easiest color to photograph in low-light settings, but enough to capture images of the inside of tools sitting around his workbench. Following in the footsteps of [Roentgen], [Matt] also took an X-ray image of his hand. This is something he doesn’t recommend, and something he won’t do again, but it is a very cool example of what you can do with sufficient knowledge and respect for what can kill you.

Let’s Blow Up an Explosive Lightning Arrestor

Lightning is some nasty stuff. Luckily, it doesn’t have a very long lifespan. [BigClive] decided to tear down an 11KV lighting arrestor used in power distribution systems. The fiberglass core has silicone rubber water-shedding disks that make the unit look sort of floppy, but inside is some serious hardware.

To protect the circuit, metal oxide varistors shunt high voltage from a lightning strike to ground as you’d expect. The interesting part is how the device deals with failure. It would be a disaster if the device shorted the 11KV power line to ground for any length of time due to a fault. To prevent that problem, a resistor heats up when struck by lightning and triggers an explosive charge that disconnects the ground wire and releases a flag to indicate the failure.

[BigClive] triggered the charge in the video below. So if you like to see things explode in a bucket of water, you’ll enjoy the video.

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