high voltage

236 Articles

I Love The Smell Of ABS Plastic In The Morning

July 23, 2019 by 17 Comments

One lesson we can learn from the Vietnam War documentary Apocalypse Now is that only crazy people like terrible smells just for fun. Surely Lt. Col. Kilgore would appreciate the smell of 3D printers as well, but for those among us who are a little less insane, we might want a way to eliminate the weird (and not particularly healthy) smell of melting ABS plastic.

While a simple solution would be a large fume hood or a filter to prevent inhaling the fumes, there are more elegant solutions to this problem. [Mark]’s latest project uses an electrostatic precipitator (ESP) to remove the volatile plastic particles from the air. Essentially it is a wire with a strong voltage applied to it enclosed in a vessel of some sort. The voltage charges particles, which then travel to a collecting electrode. Commercial offerings also include an X-ray generator to help clean the air, but [Mark] found this to be prohibitively expensive.

The ESP is built into a small tube through with the air can flow, and the entire device itself is housed in the printing enclosure. The pictures show the corona discharge in the device, and [Mark] plans to test it over the next few months to determine its effectiveness. He does note, however, that the electrostatic discharge creates ozone, which has its own set of problems, so he recommends against building one on your own. Ozone at least still smells like victory.

A Lot Of Volts For Not A Lot

July 13, 2019 by 23 Comments

There was a time when high voltage in electronic devices was commonplace, and projects driving some form of vacuum or ionisation tube simply had to make use of a mains transformer from a handy tube radio or similar. In 2019 we don’t often have the need for more than a few volts, so when a Geiger–Müller tube needs a bit of juice, we’re stumped. [David Christensen] approached this problem by creating his own inverter, which can produce up to 1 kV from a 12 V supply.

Instead of opting for a flyback supply he’s taken a traditional step-up approach, winding his own transformer on a ferrite core. It has a centre-tapped primary which he drives in push-pull with a couple of MOSFETS, and on its secondary is a voltage multiplier chain. The MOSFETs take their drive at between 25 kHz and 50 kHz from a 555 timer circuit, and there is no feedback circuit.

It’s fair to say that this is a somewhat hair-raising circuit, particularly as he claims that it is capable of delivering that 1 kV at 20 W. It’s usual for high-voltage supplies driving very high impedance loads to incorporate a set of high-value resistors on their outputs to increase their internal impedance such that their danger is reduced. We’d thus exercise extreme care around this device, though we can see a lot of value in his description of the transformer winding.

We can’t criticise this circuit too much though, because some of us have been known to produce far hackier high voltage PSUs.

A Field Guide To Transmission Lines

June 11, 2019 by 122 Comments

The power grid is a complicated beast, regardless of where you live. Power plants have to send energy to all of their clients at a constant frequency and voltage (regardless of the demand at any one time), and to do that they need a wide array of equipment. From transformers and voltage regulators to line reactors and capacitors, breakers and fuses, and solid-state and specialized mechanical relays, almost every branch of engineering can be found in the power grid. Of course, we shouldn’t leave out the most obvious part of the grid: the wires that actually form the grid itself.

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Old Nixie Display Rides Again As 3D-Printer Filament Meter

May 9, 2019 by 9 Comments

We’re not sure about the name of this Nixie tube filament meter that [Scott M. Baker] built. He calls it a “filadometer”, perhaps a portmanteau of “filament” and “odometer”, in which case it makes sense. It may not flow trippingly from the tongue and we can’t come up with anything better, but whatever moniker you use it’s actually a pretty cool build.

The filadometer started life as something completely different and utterly typical for Nixie tube projects – a temperature and humidity gauge. [Scott] decided to recycle the eight-tube display to keep track of his Prusa, and in doing so he reveals a pretty remarkable degree of forethought in his design process. The original Nixie display has all the usual trappings – the driver chips, the shift registers, and the high voltage power supply. What stands out is the modularity of his design: the tube sockets and drivers live on a backplane PCB, with a Raspberry Pi and a separate HV supply board plugging into it. The original display had a Model B Pi, so there was plenty of room for a new Zero W. A new printed case and a little programming to capture the filament use from Octoprint is all it took to put this nifty little build back in action. The video below shows the details.

We’re always excited to see new videos from [Scott] because we learn so much from looking over his virtual shoulder. If you haven’t checked out his stuff, take a look at his homage to the 8″ floppy or his dual-port memory hack for retro gaming.

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Cold Plasma Torch Produces A Cleansing Flame That Never Consumes

April 28, 2019 by 20 Comments

It’s basically a lightsaber. Except smaller. And with an invisible blade. And cold to the touch. But other than that, this homebrew cold plasma torch (YouTube, embedded below) is just like the Jedi’s choice in elegant weaponry.

Perhaps we shouldn’t kid [Justin] given how hard he worked on this project – seventeen prototypes before hitting on the version seen in the video below – but he himself notes the underwhelming appearance of the torch without the benefit of long-exposure photography. That doesn’t detract from how cool this build is, pun intended. As [Justin] explains, cold plasma or non-equilibrium plasma is an ionized stream of gas where the electron temperature is much hotter than the temperature of the heavier, more thermally conductive species in the stream. It’s pretty common stuff, seen commercially in everything from mercury vapor lamps to microbial sterilization.

It’s the latter use that piqued [Justin]’s interest and resulted in a solid year of prototyping before dialing in a design using a flyback transformer to delivery the high voltage to a stream of argon flowing inside a capillary tube. The quartz tube acts as a dielectric that keeps electrons from escaping and allows argon to be ionized and wafted gently from the tube before it can reach thermal equilibrium. The result is a faint blue glowing flame that’s barely above room temperature but still has all the reactive properties of a plasma. The video shows all the details of construction and shows the torch in action.

Hats off to [Justin] for sticking with a difficult build and coming through it with an interesting and useful device. We’ve no doubt he’ll put it to good use in his DIY biohacking lab in the coming months.

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Nixie Power Supply Shows Ins And Out Of Offshore Manufacturing

April 3, 2019 by 9 Comments

[Tony] built a high-efficiency power supply for Nixie tube projects. But that’s not what this post is about, really.

As you read through [Tony]’s extremely detailed post on Hackaday.io, you’ll be reading through an object lesson in electronic design that covers the entire process, from the initial concept – a really nice, reliable 170 V power supply for Nixie tubes – right through to getting the board manufactured and setting up a Tindie store to sell them.

[Tony] saw the need for a solid, well-made high-voltage supply, so it delved into data sheets and found a design that would work – as he points out, no need to reinvent the wheel. He built and tested a prototype, made a few tweaks, then took PCBWay up on their offer to stuff 10 boards for a mere $88. There were some gotchas to work around, but he got enough units to test before deciding to ramp up to production.

Things got interesting there; ordering full reels of parts like flyback transformers turned out to be really important and not that easy, and the ongoing trade war between China and the US resulted in unexpected cost increases. But FedEx snafus notwithstanding, the process of getting a 200-unit production run built and shipped seemed remarkably easy. [Tony] even details his pricing and marketing strategy for the boards, which are available on Tindie and eBay.

We learned a ton from this project, not least being how hard it is for the little guy to make a buck in this space. And still, [Tony]’s excellent documentation makes the process seem approachable enough to be attractive, if only we had a decent idea for a widget.

Look Ma, No Glue! Electrostatic Adhesion As If By Magic

March 9, 2019 by 26 Comments

One of the projects at the recent Hacker Hotel hacker camp in the Netherlands appeared to have achieved the impossible. A vertical PCB surface was holding pieces of paper as though they were pinned to it as on a notice board, yet there was no adhesive or fixings in sight. Was Harry Potter among the attendees, ready with a crafty bit of magic at a waggle of a wizard’s wand, or was a clever hack at work?

Of course, it was the latter, as [Jana Marie Hemsing], had created an electrostatic adhesion plate because she was curious about the phenomenon. A PCB with extra insulation has an array of conductors on one side that carry a very high voltage. High enough for electrostatic attraction to secure a piece of paper to the PCB.

The voltage is generated from an AC source by a Cockroft-Walton multiplier on the back of the PCB, and the front is coated with Plasti-Dip for insulation. It seems that soldermask is not a reliable insulator at such high voltages.

Using the board, [Jana] was able to attach a piece of paper to it with a shearing force of 5 mN at 3 kV applied voltage, which may not sound like much but appeared to be just enough to carefully pick the contraption up by the piece of paper. The boards are designed for tessellation, so larger arrays could easily be assembled.

We’ve never had a project quite like this one, but we have brought you an electrostatic ping-pong ball accelerator.