Rŏ̽ta: Counting, With Style

Rǒta counts things. That’s it, really — what a cheap little mechanical counter does with a thumb press, or what you can do by counting on your fingers and toes, that’s pretty much all that Rǒta does. But it does it with style.

OK, that’s being a bit unfair to [Kevin Santo Cappuccio] — Rǒta has a few more tricks up its sleeve than simple counting. But really, those functions are just icing on the cake of how this little gadget looks. Rǒta was built around the unbeatable combination of a rotary telephone dial mechanism and a trio of Nixie tubes. The dial looks like it might have come from an old pay phone, all shiny and chrome and super robust looking. The Nixies sit atop the dial on a custom PCB, and everything, including the high-voltage supply for the tubes, is enclosed in a 3D printed case with a little bit of a Fallout vibe.

But what does this thing do? Actually, quite a lot. It’ll count up and down, using whatever number you dial into it. You can either increment from zero, or enter any three-digit number as the starting count. It keeps track of the score of your golf game, if that’s your thing, and it’s also got a stopwatch function. You can even dial up a display of the current battery voltage. It takes some ingenuity to use just the dial for all these functions, but that’s as easy as dialing the operator used to be — dialing 0 puts it in menu mode, allowing you to access any of the functions printed on the card in the center of the dial. It’s pretty clever — check out the video below.

Is it particularly useful? Perhaps not. But when has that ever been a measure of the worth of a project? Something like this rotary cellphone might be more useful, but sometimes looking great is good enough.

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Sputtering Daguerreotypes, Batman!

The Daguerreotype was among the earliest photographic processes, long before glass plates or film, that relied on sensitizing a thin layer of silver on top of a copper plate. The earliest Daguerreotype plates were made physically, by rolling a copper-silver plate thinner and thinner until the silver layer was just right. Good luck finding a source of Daguerreotype plates made this way in 2022. (There are electroplating methods, but they all end up with chemically contaminated silver.)

On the other hand, magnetron sputtering is a process of depositing pure metal in thin layers using plasma, high voltages, and serious magnets, and [Koji Tokura] is making his own sputtered Daguerreotype plates this way, giving him the best of both worlds: the surreal almost-holographic quality of the Daguerreotype with the most difficult film preparation procedure imaginable.

The star of the show is [Koji]’s sputtering rig, which consists of a Tupperware glass sandwich box as a vacuum chamber and a microwave oven transformer as the high voltage source. In use, he pumps the chamber down, introduces a small amount of argon, and then lights up the plasma. The high voltage accelerates the plasma ions into a sheet of silver, and the silver particles that get knocked free coat the copper plate. A strong magnet creates a local plasma, which accelerates the coating procedure, but since [Koji] only had a relatively small magnet, he scans the plate with the magnet, using a scavenged 2D pen plotter mechanism.

Check out his video on the Hackaday.io page, and his Daguerreotype gallery as well. (We don’t think that they were all made with this procedure.)

The result is a chemically pure Daguerreotype plate produced in a seriously modern way, and we’d love to see the images in person. In these days of disposable images made by the AIs in your cell phone, it’s nice to see some people taking photography in strange directions. For instance, maybe you’d like to make your own ultra-large collodion plates. Or something else? If you do, show us!

Atmospheric High-Voltage Motor Makes Useful Power

While it almost seems like an insane fever dream from an otherwise brilliant inventor, Nikola Tesla’s plan to harvest energy straight out of the atmosphere and essentially give it away is more reality than fiction. It’s usually prohibitively difficult get that energy out of the atmosphere for several obvious reasons, although it is still possible to do as [lasersaber] shows with his most recent atmospheric motor.

To help solve some of the logistical problems of harvesting electricity from the atmosphere, [lasersaber] is using a Van de Graaff generator as a stand-in for the high voltage gradient that can be found when suspending a long wire in the air. He has been experimenting with high-voltage motors like this for a while now and has refined his designs for corona discharge motors like these to be big enough and have enough torque to drive a drill bit. The motors have a conductive rotor with a series of discharge tubes on the stator, and exposing a metal point on the wiring (where the atmospheric wire would attach) to a sufficiently high voltage will cause rotation. In this case, it’s around 30,000 volts but with an extremely low current.

There are a number of videos documenting his latest build, including this follow-up video where he drills an arbitrarily large number of holes in various materials to demonstrate its effectiveness. Even though he is using a Van de Graaff generator in these builds, he does also show them working with a wire suspended by a drone as well for proof-of-concept. He’s also become somewhat of an expert on high-efficiency and low-power motors and has a number of other interesting builds based on these concepts.

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Scrambling Pocket Calculators Made Easy With EMP Box V2

[Rostislav Persion] has for some time been interested in making small, portable EMP devices capable of interfering with nearby electronics. In these EMP devices, high voltage is used to create a portable spark gap generator, whose operation in turn creates electromagnetic pulses capable of resetting or scrambling nearby electronics such as pocket calculators.

Bridging adjacent holes narrows the spark gap, resulting in more frequent pulses.

His original EMP box designs relied on spark gaps constructed from metal screws threaded into a clear plastic insulator, but this newest design ditches fussy screw adjustments and relies on perfboard. By cutting out a single row of plated perfboard holes and soldering the high voltage terminals to each end, the empty holes in between form the essential parts of a spark gap.

It’s even adjustable: one simply bridges adjacent holes with solder to effectively decrease the gap. As for generating the high voltage itself, a DC voltage multiplier from Amazon takes care of that. Watch the device reset some calculators in the short video below.

Looking for high-voltage experiments that aren’t so sketchy? Get yourself a Van de Graff generator, some metal balls, and a little bit of oil, and make some art.

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The Deadliest Project On The Internet?

Before deciding whether the headline of this article is clickbait, please take a moment to watch the excellent video by [BigClive] below the break. And then, go to your local search engine and search the phrase “fractal burning death”. We’ll wait.

With that out of the way, we have to admit that when we saw the subject “The most deadly project on the Internet” on [bigclivedotcom]’s YouTube channel, we were a bit skeptical. It’s a big claim. But then we watched the video and did some googling. Sadly, there are over 30 documented cases of this project killing people, and more cases of permanent grievous injury.

The results of Fractal Wood Burning with High Voltage

Fractal Burning is a hobby where wood is burned by slathering wood in a conductive slurry and then applying high voltage to either side of the wood, usually using something not rated for high voltage, such as jumper cables. The High Voltage is supplied by an unmodified Microwave Oven Transformer. Other projects using MOT’s typically rip out the high voltage secondary windings and re-wind them as low voltage, high amperage transformers, and are using in Spot Welders and even arc welders.

As laid out by [BigClive], the voltages coming from an unmodified MOT, ranging from 2-3 KV (That’s between two and three thousand Volts) at a very low impedance are right up there in the “Don’t go near it!” territory.

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A Super Simple DIY Ozone Generator

[Advanced Tinkering] needed a source of fresh ozone for some future chemistry related projects, and since buying an off-the-shelf unit would be, well, just plain boring, it was obvious what to do (Video, embedded below).

Wire mesh discharge surfaces separated with a glass tube

The concept of the corona-discharge ozone generator is pretty straightforward — a high-voltage AC potential is presented over a large surface area, such that any O2 in the vicinity has the chance to get a decent dose of electrons ripping it apart and enabling the formation of the desired O3.

The construction is quite simple, just a pair of cylindrical metal wire mesh electrodes, separated by a glass tube, with a second glass tube surrounding the whole assembly. The use of high voltage AC allows the discharge to form by capacitive coupling across the central tube, giving a very simple construction. A pair of 3D-printed PLA end caps complete the reaction vessel, although it is noted in the video that the PLA is not terribly resistant to the corrosive effects of ozone, and time will tell whether these go the whole mileage.

Feed oxygen from an external generator is pumped into one end cap, at the bottom, with ozone-enriched gas passing out the other end, at the top, giving the gas a more complex path through the assembly and maximizing the contact with discharge. It will be interesting to see what the produced ozone will be used for in these future projects.

We’ve not seen a vast number of ozone hacks, but we’re no strangers to high voltage applications, like this interesting hand disinfection device, and this simple hack that generates a six-figure voltage with little more than some glasses of water, well not much more anyway.

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triggered spark gap

Spark Plug And Plumbing Parts Bring Nitrogen Laser Under Control

When it comes to high-speed, high-voltage switching, there are a wealth of components to choose from — MOSFETS, thyristors, IGBTs, and even vacuum tubes like thyratrons. But who needs all that expensive silicon (or glass) when all you need to build a high-voltage switch is some plumbing fixtures and a lathe?

At least that’s the approach that budget-minded laser experimenter [Les Wright] took with his latest triggered spark gap build. We’ve been watching his work for a while now, especially his transversely excited atmospheric (TEA) lasers. These are conceptually simple lasers that seem easy to build, at least compared to other lasers. But they do require a rapid pulse of high voltage across their long parallel electrodes to lase, and controlling the pulse is where this triggered spark gap shines.

The spark gap is made from brass plumbing fittings on either end of a short PVC coupler. [Les] used his lathe to put a thread into one of the caps to accept a spark plug, the center electrode of which pokes through a small hole in the metal cathode. To trigger the spark gap, [Les] built a trigger generator that outputs about 15,000 volts, which arcs from the spark plug electrode to the spark gap cathode in the low-pressure nitrogen environment. Little spark leads to big spark, big spark discharges a capacitor across the laser electrodes, and you’ve got a controlled single-shot laser. Check it out in the video below.

Honestly, the more we see of [Les]’ videos, the more we want to play with lasers and high voltage. From DIY doorknob caps to blasting Bayer arrays off cheap CCD cameras, there’s always something fun — and slightly dangerous — going on in [Les]’s lab.

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