Unlikely Cascade of Failures Leads to Microwave’s Demise

Surely a blown light bulb can’t kill a microwave oven, right? You might not expect it to, but that was indeed the root cause of a problem that [mikeselecticstuff] recently investigated; the cascade of failures is instructive to say the least.

While the microwave that made its way to [mike]’s bench wasn’t exactly engineered to fail, it surely was not designed to succeed. We won’t spoil the surprise, but suffice it to say that his hopes for a quick repair after the owner reported a bang before it died were dashed by an arc across the interior light bulb that put a pulse of mains voltage in places it didn’t belong. That the cascade of failures killed the appliance is a testament to how designing to a price point limits how thoroughly devices can be tested before production runs in the millions are stuffed into containers for trips to overseas markets.

Even though [mike] made his best effort to adhere to the Repair Manifesto, the end result was a scrapped microwave. It wasn’t a total loss given the interesting parts inside, but a disappointment nonetheless unless it forces us to keep in mind edge-case failure modes in our designs.

Continue reading “Unlikely Cascade of Failures Leads to Microwave’s Demise”

Custom Workstation Makes Plasma Cutting a Breeze

A plasma cutter is probably top of every metalworker’s short list of dream tools. From freehand curves to long straight cuts, nothing beats a plasma cutter for getting the creative juices flowing. Unfortunately, there’s also the jet of superheated metal blasting through the workpiece to deal with, which is the reason behind this shop-built plasma cutting workstation.

[Regalzack] looks like he had a couple of design goals in mind for his table. A solid work surface isn’t a great idea for plasma cutting, so he designed the top as a grid of replaceable steel slats. Underneath is a hopper to collect the slag, both for neatness and for fire safety. The table top and hopper live on a custom-built wheeled steel frame, and the lower shelf provides plenty of room for his Lincoln 375 plasma rig. With hooks for cables and a sturdy ground clamp tab, the whole thing is a nicely self-contained workstation. The video below shows the build and some of the fabrication techniques [Regalzack] used; we were especially taken by the clever way he cut the slots for the table slats.

Plasma is versatile stuff – you can use it to make music, cook a burger, or decorate wood. And it’s not too shabby for notching metal tubing either.

Continue reading “Custom Workstation Makes Plasma Cutting a Breeze”

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.

Continue reading “Little eBay Tesla Coil Gets an Upgrade”

Hacked CCFL Inverter becomes an Arc Lighter

[GreatScott!] needs to light off fireworks with an arc rather than a flame, because “fireworks and plasma” is cooler than fireworks and no plasma. To that end, he attempted to reverse engineer an arc lighter, but an epoxy potted high-voltage assembly thwarted him. Refusing to accept defeat, he modified a CCFL inverter into an arc lighter, and the process is pretty educational.

With his usual impeccable handwriting and schematic drawing skills, [GreatScott!] documents that his CCFL inverter is a resonant Royer oscillator producing a sine wave of about 37 kHz, which is then boosted to about 2400 volts. That’s pretty good, but nowhere near the 15 kilovolts needed for a self-sustaining arc across electrodes placed 5 mm apart. A little math told him that he could achieve this by rewinding the transformer’s primary with only 4 turns. After some testing, the rewound transformer was fitted back into the Royer circuit and with a few modifications the arc was struck.

It’s not a finished project yet, and we’re looking forward to seeing how [GreatScott!] puts this to use. For now, we’re grateful for the lesson is Royer oscillators and rewinding transformers. But if you’d rather hack an off-the-shelf arc lighter, there’s always this arc lighter pyrography pen, or this mini plasma cutter.

Continue reading “Hacked CCFL Inverter becomes an Arc Lighter”

Arc Lighter become Plasma Pyrography Pen

Wood burning can be quite a striking art form, but who wants to be stuck using an old-fashioned resistive heating element to char wood? You could go with laser engraving, of course, but that seems to take too much of the human touch out of it. So why not try a mini plasma pen and blow torch powered by a fancy cigarette lighter?

Arc lighters are rechargeable electronic lighters that look like a tiny stun-gun, and [NightHawkInLight] has been coming up with some interesting hacks for them. In this case, he extended the electrode leads out and mounted them to a wooden handle. The spark gap is only about 2mm, but the resulting arc is plenty hot enough to char wood with considerable precision. You’ve got to work fast, though, or the high voltage will start finding interesting paths through the char, producing Lichtenberg figures. And if a micro-scale blow torch is a tool you need, [NightHawkInLight] has got that covered too – a small brass tube with a pinched-off nozzle hooked to an aquarium pump provides the pressure for that.

Might there be other applications for this beyond pyrography? Maybe soldering or desoldering? Of non-ESD sensitive components, naturally.

Continue reading “Arc Lighter become Plasma Pyrography Pen”

Painting the Sky with Shooting Stars

Japanese company ALE has been working on a new type of sky show, artificial shooting stars, literally creating an artificial meteor shower at a height of 40 to 50 miles (60 to 80km). The show will be visible to anyone within a 125 mile diameter area (200km), meaning that people in New York city and Philadelphia or Los Angeles and San Diego can watch the same show. Aptly named, they’re calling the project “Sky Canvas”.

The plan is to have a satellite, containing around 500 to 1000 source particles, discharge the particles with a specially designed device. As the video below shows, by ejecting the particles in a continuous manner, rather than all at once, they’ll create the equivalent of a meteor shower. The particles will travel around 1/3rd the way around the Earth before entering the atmosphere, creating the shower of shooting stars. Different colors will be possible by using different materials for the particles, something this fireball cannon illustrates.

Continue reading “Painting the Sky with Shooting Stars”

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.

Continue reading “It’s a Bird, It’s a Plane, No… It’s High Voltage EPROM Man!”