An IN-12B Nixie tube on a compact driver PCB

Modern Components Enable Cheap And Compact Nixie Driver Circuit

Nixie tubes can add some retro flair to any project, but they can also complicate your electronics quite a bit: after all, you need to generate a voltage high enough to ignite the tube and then switch that between ten separate display segments. Traditionalists may want to stick with chunky mains transformers and those unobtainium 74141 segment drivers, but modern components allow you to make things much more compact, not to mention way cheaper. [CNLohr] took this to an extreme, and used clever design tricks and his sharp online shopping skills to make an exceptionally compact Nixie driver circuit that costs less than $2.50.  (Video, embedded below. You can also skip straight over to his GitHub repo for the project.)

That price doesn’t include the tubes themselves, but [CNLohr] nevertheless bought the cheapest Nixies he could find: a pair of IN-12B tubes that set him back just $20. He decided to generate the necessary 180 volts through a forward converter built around a $0.30 transformer and a three-cent MOSFET, controlled by software running on a CH32V003. This is one of those ultra-cheap microcontrollers that manage to squeeze a 48 MHz RISC-V core plus a bunch of peripherals into a tiny QFN package costing just 12 cents.

The existing toolchain to program these micros left a lot to be desired, so [CNLohr] wrote his own, called
ch32v003fun. He used this to implement all the control loops for the forward converter as well as PWM control of the display segments – a feature that adds a beautifully smooth turn-on and turn-off effect to the Nixie tubes. There’s still plenty of CPU capacity left to implement other features, although [CNLohr] isn’t sure what to put there yet. Turning the tubes into a clock would be an obvious choice, but the basic system is flexible enough to implement almost anything requiring a numeric display.

The compactness of this circuit is impressive, especially if you compare it to earlier solutions. There’s plenty of fun to be had with cheap-yet-powerful micros like the ch32v003, provided you can find them.

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High Voltage Power Supply From USB

Those who work in different spaces may have different definitions of the term “high voltage”. For someone working on the GPIO pins of a Raspberry Pi it might be as little as 5 volts, someone working on a Tesla coil might consider that to be around 20 kV, and an electrical line worker might not reference something as HV until 115 kV. What we could perhaps all agree on, though, is that getting 300 volts out of a USB power supply is certainly a “high voltage” we wouldn’t normally expect to see in that kind of context, but [Aylo6061] needed just such a power supply and was eventually able to create one.

In this case, the high voltages will eventually be used for electrophoresis or electrowetting. But before getting there, [Aylo6061] has built one of the safest looking circuits we’ve seen in recent memory. Every high voltage part is hidden behind double insulation, and there is complete isolation between the high and low voltage sides thanks to a flyback converter. This has the benefit of a floating ground which reduces the risk of accidental shock. This does cause some challenges though, as voltage sensing on the high side is difficult while maintaining isolation, so some clever tricks were implemented to maintain the correct target output voltage.

The control circuitry is based around an RP2040 chip and is impressive in its own right, with USB isolation for the data lines as well. Additionally the project code can be found at its GitHub page. Thanks to a part shortage, [Aylo6061] dedicated an entire core of the microprocessor to decoding digital data from the high voltage sensor circuitry. For something with a little less refinement, less safety, and a much higher voltage output, though, take a look at this power supply which tops its output voltage around 30 kV.

Upgraded Plasma Thruster Is Smaller, More Powerful

When [Jay Bowles] demoed his first-generation ion thruster on Plasma Channel, the resulting video picked up millions of views and got hobbyists and professionals alike talking. While ionic lifters are nothing new, this robust multi-stage thruster looked (and sounded) more like a miniature jet engine than anything that had come before it. Optimizations would need to be made if there was even a chance to put the high-voltage powerplant to use, but [Jay] was clearly onto something.

Fast forward six months, and he’s back with his Mark II thruster. It operates under the same core principles as the earlier build, but swaps out the open-frame design and acrylic construction for a rigid 3D printed structure designed to more effectively channel incoming air. The end result is a thruster that’s smaller and has a lower mass, while at the same time boasting nearly double the exhaust velocity of its predecessor. Continue reading “Upgraded Plasma Thruster Is Smaller, More Powerful”

New Possibilities From Fading Lighting Technology

Like the incandescent bulb before it, the compact fluorescent (CFL) bulb is rapidly fading into obscurity as there are fewer and fewer reasons to use them over their LED successors. But there are plenty of things to do with some of the more interesting circuitry that made these relatively efficient light bulbs work, and [mircemk] is here to show us some of them.

Fluorescent bulbs require a high voltage to work properly, and while this was easy enough for large ceiling installations, it was a while until this hardware could be placed inside a bulb-sized package. When removed, the high voltage driver from the CFL is used in this case to drive a small inductive heating coil circuit, which can then be used to rapidly heat metals and other objects. After some testing, [mircemk] found that the electronics on the CFL circuit board were able to easily handle the electrical load of its new task.

When old technology fades away, there are often a lot of interesting use cases just waiting to be found. [mircemk] reports that he was able to find these light bulbs at an extremely low price due to low demand caused by LEDs, so anyone needing a high voltage driver board for something like a small Tesla coil might want to look at a CFL first.

Playing Music On A Custom Flyback Transformer

We’ve seen a number of people create plasma speakers over the years here at Hackaday, so at first blush, the latest Plasma Channel video from [Jay Bowles] might seem like more of the same. Even his overview of the assembly of the 555 timer circuit at the heart of the setup, as detailed as it may be, is something we’ve seen before.

But the back half of the video, where [Jay] talks about the flyback transformer used in this plasma speaker, really got our attention. You see, frustrated by the limited options on the market for AC flybacks, he set out to put together a custom transformer utilizing a 3D printed secondary former of his own design.

Winding an early version of the secondary with a drill.

Armed with a spare core, [Jay] spent some time in CAD coming up with his secondary. Despite never having built a flyback before, his first attempt managed to produce some impressive sparks — that is, until it arced through the printed plastic and released the critical Magic Smoke. Inspired by this early success, he went back to the digital drawing board and cranked his way through several different iterations until he came up with one that didn’t self-destruct.

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Domesticating Plasma With A Gorgeous Live Edge Table

If you’ve been reading Hackaday for any length of time, you’ll know we don’t often cover woodworking projects here. It’s not because we aren’t impressed with the skill and effort that folks put into them, and truth be told, we occasionally we even feel a pang of envy when looking at the final result. It’s just that, you know…they’re made of wood.

But when [Jay Bowles] of Plasma Channel sent in this live edge wooden table that features not only a pair of custom-made neon tubes but the burned out transistors and ICs from his previous high-voltage exploits — we knew this wasn’t exactly your grandpa’s idea of woodworking. In fact, he wisely offloaded a lot of the dead tree cutting and shaping to the burly gentlemen at the local sawmill so he could better focus his efforts on the sparky bits.

At its core, he’s created what’s generally known as a “river table” — a surface made of two or more pieces of live edge wood (that is, a piece of lumber that features at least one uncut edge) that are linked via a band of colored epoxy which looks like flowing water. It’s not uncommon to embed stones or even fake fish in the epoxy to really sell the underwater effect, but this is Plasma Channel we’re talking about, so [Jay] had other ideas.

The first step was hitting up a local neon supplier who could fabricate a pair of neon tubes which roughly followed the shape of his epoxy river. While he was waiting for them to be finished, [Jay] played around with a clever experimental rig that let him determine how thick he could pour the epoxy over the tubes before he lost the capacitive coupling effect he was going for. By embedding a short length of neon tube off-center in a block of epoxy, he could see how the thickness impacted his ability to manipulate the plasma with a wave of his hand just by flipping it over.

With the tube placed on clear standoffs, he was able to position it at the ideal depth for the final epoxy pours. It was around this time that he scattered the remains of his previous projects on the “bottom” of the river, so they can spend the rest of their days looking up at his latest technical triumph. We’re not sure if this is to punish the fallen silicon for giving up early or to honor their sacrifice in the name of progress, but in either event, we respect anyone who keeps a jar of blown components laying around for ritualistic applications.

Once the table was assembled, all that was left was to power the thing. Given his previous projects, [Jay] had no shortage of existing HV supplies to try out. But not being satisfied with anything in the back catalog, he ended up building a new supply that manages to pump out the required amount of juice while remaining silent (to human ears, at least). The unit is powered by a battery pack cleverly embedded into the legs of the table, and is easy to fiddle with thanks to a pulse-width modulation (PWM) module wired hooked to the input. All the components were then held in place with a wide array of custom brackets courtesy of his newly arrived 3D printer.

There’s a lot to love about this project, and more than a few lessons learned. Whether you’re interested in recreating the Tron-like effect of the neon tubes, or have been contemplating your own epoxy-pour worktable and want to see how a first-timer tackles it, this video is a great resource.

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Another Magnetron Teardown

[Electronoobs] has a healthy respect for the voltages and ceramics inside a microwave oven. But he still found the courage to tear one apart and show us the insides and characterize some of the components. You can see the video of the teardown below.

The danger of the voltage is obvious. However, there is also a ceramic insulator inside. Some of them are made from aluminum oxide, but others are made with beryllium oxide. You probably don’t want to inhale either one, but beryllium oxide, if powdered, can cause serious health problems. Obviously, you need to be careful if you decide to rip your oven open.  Of course, the other danger is if you put the oven back together and try to use it. You need to ensure all the shielding is back in the proper place.

The video shows the operation of several of the components using test equipment and, in some cases, some surrogate components. The animation of an LC oscillator is very easy to understand. However, when he actually cuts into the magnetron with a rotary tool, you can really see how the device works. Some animations make it even clearer.

We haven’t seen a magnetron teardown for a few years. You can do many things with a magnetron from radar to vacuum deposition of films.

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