Turning A Kombucha Bottle Into A Plasma Tube

March 21, 2025 by Lewin Day 10 Comments

Kombucha! It’s a delicious fermented beverage that is kind to your digestive system and often sold in glass bottles. You don’t just have to use those bottles for healthy drinks, though. As [Simranjit Singh] demonstrates, you can also use them to create your very own plasma tube.

[Simranjit’s] build begins with a nice large 1.4-liter kombucha bottle from the Synergy brand. To make the plasma tube nicely symmetrical, the bottle had its original spout cut off cleanly with a hot wire, with the end then sealed with a glass cap. Electrodes were installed in each end of the tube by carefully drilling out the glass and installing small bolts. They were sealed in place with epoxy laced with aluminium oxide in order to improve the dielectric strength and aid the performance of the chamber. A vacuum chamber was then used to evacuate air from inside the chamber. Once built, [Simranjit] tested the bottle with high voltage supplied from a flyback transformer, with long purple arcs flowing freely through the chamber.

A plasma tube may not be particularly useful beyond educational purposes, but it does look very cool. We do enjoy a nice high-voltage project around these parts, after all.

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Harvesting Water With High Voltage

February 24, 2025 by Maya Posch 50 Comments

Atmospheric water harvesting is a way to obtain fresh water in arid regions, as there is always some moisture in the air, especially in the form of morning fog. The trick lies in capturing this moisture as efficiently as possible, with a range of methods available that start at ancient low-tech methods involving passive fog droplet capture all the way to variants of what are effectively large dehumidifiers.

A less common way involves high-voltage and found itself the subject of a recent Plasma Channel video on YouTube. The inspiration for the build was a 2018 paper by [Maher Damak] et al. (PDF) titled Electrostatically driven fog collection using space charge injection.

One of the two stakes that make up the electrostatic precipitator system for atmospheric water harvesting. (Credit: Plasma Channel, YouTube)

Rather than passively waiting for dew to collect on the collector, as with many of the methods detailed in this review article by [Xiaoyi Liu] et al., this electrostatic approach pretty much does what it says on the tin. It follows the principle of electrostatic precipitators with a high-voltage emitter electrode to ionize the air and grounded collector wires. In the video a small-scale version (see top image) was first constructed, demonstrating the effectiveness. Whereas the passive grid collected virtually none of the fog from an ultrasonic fog maker, with 35 kV applied the difference was night and day. No water was collected with the first test, but with power applied a significant 40 mL was collected in 5 minutes on the small mesh.

With this scale test complete, a larger version could be designed and tested. This simplifies the emitter to a single wire connected between two stakes, one of which contains the 20 kV HV generator and battery. The mesh is placed right below it and grounded (see image). With an extreme fog test inside a terrarium, it showed a very strong effect, resulting in a harvest of 14 mL/Wh for this prototype. With a larger scale version in a real-life environment (i.e. desert) planned, it’ll be interesting to see whether this method holds up in a more realistic scenario.

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Hacking Flux Paths: The Surprising Magnetic Bypass

February 21, 2025 by Heidi Ulrich 6 Comments

If you think shorting a transformer’s winding means big sparks and fried wires: think again. In this educational video, titled The Magnetic Bypass, [Sam Ben-Yaakov] flips this assumption. By cleverly tweaking a reluctance-based magnetic circuit, this hack channels flux in a way that breaks the usual rules. Using a simple free leg and a switched winding, the setup ensures that shorting the output doesn’t spike the current. For anyone who is obsessed with magnetic circuits or who just loves unexpected engineering quirks, this one is worth a closer look.

So, what’s going on under the hood? The trick lies in flux redistribution. In a typical transformer, shorting an auxiliary winding invites a surge of current. Here, most of the flux detours through a lower-reluctance path: the magnetic bypass. This reduces flux in the auxiliary leg, leaving voltage and current surprisingly low. [Sam]’s simulations in LTspice back it up: 10 V in yields a modest 6 mV out when shorted. It’s like telling flux where to go, but without complex electronics. It is a potential stepping stone for safer high-voltage applications, thanks to its inherent current-limiting nature.

The original video walks through the theory, circuit equivalences, and LTspice tests. Enjoy!

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Jeff Dunham next to a Philco Predicta TV

Jeff Dunham Finds A NOS 1958 Philco Predicta

February 8, 2025 by Heidi Ulrich 14 Comments

When you see a ventriloquist like [Jeff Dunham], you probably expect to see him with a puppet. This time – spoilers ahead – you won’t. Besides his fame on stage, [Dunham] is also a collector of vintage tech and a die-hard television enthusiast. In the video below, [Dunham] has gotten his hands on a rarity: an unboxed 1958 Philco Predicta TV. The original tape was still on the box. We get to follow along on his adventure to restore this sleek, retro-futuristic relic!

[Dunham]’s fascination with the Predicta stems from its historical significance and bold design. At a time when television was making its way into American homes, the Predicta dared to be different with its swivel-mounted picture tube and early printed circuit boards. Despite its brave aesthetics, the Predicta’s ambition led to notorious reliability issues. Yet, finding one in pristine condition, sealed and untouched for over six decades, is like unearthing a technological time capsule.

What makes this story unique is [Dunham]’s connection to both broadcasting and his craft. As a ventriloquist inspired by Edgar Bergen — whose radio shows captivated America — [Dunham] delights in restoring a TV from the same brand that first brought his idol’s voice to airwaves. His love for storytelling seamlessly translates into this restoration adventure.

After unboxing, [Dunham’s] team faces several challenges: navigating fragile components, securing the original shipping brace, and cautiously ramping up voltage to breathe life into the Predicta. The suspense peaks in the satisfying crackle of static, and the flicker of a 65-year-old screen finally awakened from slumber.

Have you ever come across an opportunity like this? Tell us about your favorite new old stock find in the comments. Buying these can be a risk, since components have a shelf life. We appreciate when these old TVs play period-appropriate shows. Who wants to watch Game of Thrones on a Predicta?

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Lorentz Cannon Fires Lightning

February 6, 2025 by Al Williams 29 Comments

[Editor’s note: This video disappeared, but it has been archived here. We’re leaving the original links as-were in case they come back up.]

The aptly named [LightingOnDemand] has created a Lorentz cannon that can fire a lightning bolt. Honestly, as you can see in the video below, it looks like something from a bad 1950s science fiction movie. The inspiration was researchers using rockets trailing thin wires to attract lightning.

How does the tiny wire carry that much juice? It doesn’t, really. The wire vaporizes into plasma, and if the pulse is fast enough, the Lorentz force hold the plasma together. The rest is non-trivial high-voltage engineering.

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Taser Ring Is Scary Jewelry You Shouldn’t Build

January 16, 2025 by Lewin Day 38 Comments

Officially, the term “taser” refers to a particular brand of projectile-firing electric stun gun. However, the word is also colloquially used to refer to just about any device intended for delivering electric shocks to an adversary. The taser ring from [Penguin DIY] definitely fits that description, though we’d strictly advise you not to consider building this at home.

The build is a hacky one. An arc generator circuit was pulled out from a jet cigarette lighter, and reconfigured to fit in a small ring-based form factor. It was hooked up with a power switch and a small bank of 30 mAh lithium polymer cell for power, and a compact USB-C charger board was installed to keep the batteries juiced. The electronics were then delicately assembled into a ring-shaped mold, which was injected with resin to produce the final ring. Once cast, a pair of small metal electrodes were installed on the outside. Activating the taser function is as simple as squeezing the ring—easy to do just by making a fist.

We’ve seen projects like these before; our advice is usually to avoid them unless you really know what you’re doing. Whether you end up shocking someone else or accidentally shocking yourself, the results tend to be bad. The latter seems particularly easy to do if you’re wearing this thing on your finger. Given it’s a ring, don’t expect to be able to pull it off in a hurry, either. It’s hard to see how that ends well.

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Electrostatic Puck: Making An Electret

December 1, 2024 by Danie Conradie 26 Comments

You might have heard of electrets being used in microphones, but do you know what they are? Electrets produce a semi-permanent static electric field, similar to how a magnet produces a magnetic field. The ones in microphones are very small, but in the video after the break [Jay Bowles] from Plasma Channel makes a big electret and demonstrates it’s effects.

Electrets have been around since the 1800s, and are usually produced by melting an insulating material and letting it solidify between two high-voltage electrodes. The original recipe used a mix of Carnauba wax, beeswax, and rosin, which is what [Jay] tried first. He built a simple electric field detector, which is just a battery, LED and FET, with an open-ended resistor on the FET’s gate.

[Jay] 3D printed a simple cylindrical mold and stuck aluminum foil to the outer surfaces to act as the electrodes. He used his custom 6000:1 voltage transformer to hold the electrodes at ~40 kV. The first attempt did not produce a working electret because the electrodes were not in contact with the wax, and kept arcing across, which causes the electric charge to drop off. Moving the aluminum electrodes the inner surfaces of the mold eventually produced an electret detectable out to 10 inches.

This was with the original wax recipe, but there are now much better materials available, like polyethylene. [Jay] heated a a block of it in the oven until it turned into a clear blob, and compressed it in a new mold with improved insulation. This produced significantly better results, with an electric field detectable out to 24 inches.

[Jay] also built an array of detectors in a 5×5 grid, which he used to help him visualize the size and shape of the field. He once pulled off a similar trick using a grid of neon bulbs.

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