Lessons Learned From A High-Voltage Power Supply

January 18, 2024 by Dan Maloney 8 Comments

When you set out to build a 60,000-volt power supply and find out that it “only” delivers a measly 50,000 volts, you naturally have to dive in and see where things can be improved. And boy, did [Advanced Tinkering] find some things to improve.

First things first: if you haven’t seen [Advanced]’s first pass at a high-voltage supply, you should go check that out. We really liked the design of that one, and were particularly impressed with the attention to detail, all of which seemed to be wisely geared to the safe operation of the supply. But as it turns out, the margin of safety in the original design wasn’t as good as it could be. Of most concern was the need to physically touch the supply to control it, an obvious problem should something go wrong anywhere along the HV path, which includes a ZVS-driven flyback and an epoxy-potted Crockcroft-Walton voltage multiplier.

To make things a little more hands-off, [AT] added a pneumatically actuated switch to the supply, along with some indicator lights to help prevent him from leaving the supply powered up. He also reworked the low-voltage DC supply section, replacing a fixed-voltage supply and a DC-DC converter with a variable DC supply. This had the side benefit of providing a little bit more voltage to the ZVS driver, which goosed up the HV output a bit. The biggest change, though, was to the potted part of the HV section, which showed signs of arcing to the chassis. It turns out that even at 100% infill, 3D printed PLA isn’t a great choice for HV projects; more epoxy was the answer to that problem. Along with rewinding the primary on the flyback transformer, the power supply not only hit the 60-kV spec, but even went a little past that — and all without any of that pesky arcing.

We thought [Advanced Tinkering]’s first pass on this build was pretty slick, but we’re glad to see that it’s even better now. And we’re still keen to see how this supply will be put to use; honestly, the brief teaser at the end of the video wasn’t much help in guessing what it could be.

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An Adjustable High-Voltage Power Supply Built With Safety In Mind

January 6, 2024 by Dan Maloney 11 Comments

It’s not entirely clear why [Advanced Tinkering] needs a 50,000-volt power supply, but given the amount of work he put into this one, we’re going to guess it will be something interesting.

The stated specs for this power supply are pretty simple: a power supply that can be adjusted between 20kV and 50kV. The unstated spec is just as important: don’t kill yourself or anyone else in the process. To that end, [Advanced] put much effort into making things as safe as possible. The basic architecture of the supply is pretty straightforward, with a ZVS driver and an AC flyback transformer. Powered by a 24-volt DC supply and an adjustable DC-DC converter, that setup alone yields something around 20kV — not too shabby, but still far short of the spec. The final push to the final voltage is thanks to a three-stage Cockcroft-Walton multiplier made with satisfyingly chunky capacitors and diodes. To ensure everything stays safe in the high-voltage stage, he took the precaution of potting everything in epoxy. Good thing, too; tests before potting showed arcing in the CW multiplier despite large isolation slots in the PCB.

Aside from the potting, some really interesting details went into this build, especially on the high-voltage side. The 3D-printed and epoxy-filled HV connector is pretty cool, as is the special wire needed to keep arcs at bay. The whole build is nicely detailed, too, with care taken to bond each panel of the rack-mount case to a common ground point.

It’s a nice build, and we can’t wait to see what [Advanced Tinkering] does with it. In the meantime, if you want to get up to speed on handling high voltage safely, check out our HV primer.

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Enjoy The Beauty Of Corona Discharge With This Kirlian Photography Setup

October 12, 2022 by Dan Maloney 12 Comments

In our age of pervasive digital media, “pics or it didn’t happen” is a common enough cry that most of us will gladly snap a picture of pretty near anything to post online. So if you’re going to take a picture, it may as well be as stunning as these corona discharge photographs made with a homebrew Kirlian photography rig.

We know, Kirlian photography has a whole “woo-woo” vibe to it, associated as it has been with paranormal investigations and the like. But [Hyperspace Pirate] isn’t flogging any of that; in fact, he seems way more interested in the electronics of the setup than anything else. The idea with Kirlian photography is basically to capacitively couple a high-voltage charge across a dielectric, which induces an electrostatic discharge to a grounded object. The result is a beautiful purple discharge, thanks to atmospheric nitrogen, that outlines the object being photographed.

[Pirate]’s first attempt at a Kirlian rig used acrylic as a dielectric, which proved to be susceptible to melting. We found this surprising since we’ve seen [Jay Bowles] successfully use acrylic for his Kirlian setup. Version 2 used glass as a dielectric — right up until he tried to drill a fill port into the glass. (Important safety tip: don’t try to drill holes in tempered glass.) Version 3 used regular glass and a 3D-printed frame to make the Kirlian chamber; filled with saltwater and charged up with a homebrew Tesla coil, the corona discharge proved enough to char fingertips and ignite paper. It also gave some beautiful results, which can be seen starting at around the 7:40 mark in the video below.

We loved the photos, of course, but also appreciated the insights into the effects of inductance on the performance of this setup. And that first homebrew flyback transformer [Hyperspace Pirate] built was pretty cool, too.

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Simple Induction Heater Helps With Homebrew Shrink-Fitting

October 26, 2020 by Dan Maloney 14 Comments

Machinists have a lot of neat shop tricks, but one especially interesting one is shrink-fitting tools. Shrink-fitting achieves an interference fit between tool and holder by creating a temperature difference between the two before assembly. Once everything returns to temperature, the two parts may as well be welded together.

The easiest way to shrink-fit machine tooling is with induction heating, and commercial rigs exist for doing the job. But [Roetz 4.0] decided to build his own shrink-fitting heater, and the results are pretty impressive. The induction heater itself is very simple — a 48 volt, 20 amp power supply, an off-the-shelf zero-voltage switching (ZVS) driver, and a heavy copper coil. When the coil is powered up, any metal within is quickly and evenly heated by virtue of the strong magnetic flux in the coil.

To use the shrinker, [Roetz 4.0] starts with a scrupulously clean tool holder, bored slightly undersized for the desired tool. Inside the coil, the steel tool holder quickly heats to a lovely deep brown color, meaning it has gotten up to the requisite 250-300°C. The tool is quickly dropped into the now-expanded bore, which quickly shrinks back around it. The advantage of this method over a collet or a chuck is clear in the video below: practically zero runout, and the tool is easily released after another run through the heater.

You say you’ve got no need for shrink-fitting tools? How about stuck bolts? Induction heaters work great there too.

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Set Your Nuts (and Bolts) Free With This Induction Heater

May 22, 2019 by Adam Fabio 36 Comments

[Amon] built an induction heater to break stuck bolts loose. If you work on cars, machines, or anything big and metal, sooner or later you’re going to run into stuck nuts and bolts. Getting them unstuck usually involves penetrating oil, heat from a torch, and cheater bars. Heat usually works well, as heating the bolt makes the metal expand, helping it to break free. Torches aren’t exactly precision instruments though, and things can get interesting using one in tight spaces.

Fire isn’t the only way to heat a bolt through. Electricity can do the job as well. But why use a heating coil when you can grab an induction heater. Mechanics have had induction heaters in their toolboxes now for a few years, under names such as Bolt Buster or Mini Ductor. These devices cost several hundred dollars. However, you can purchase a 1000 watt induction heater from the usual sources for around $30. These are open frame Zero Voltage Switching (ZVS) power supplies, with uninsulated copper coils.

[Amon] bought one of these induction heaters, along with a beefy 24V, 40 amp switch mode supply to power it. He built the two into a plastic enclosure. A relay energizes the induction heater, so it isn’t always running. The key to this build is the handle. Rather than mount the induction coil directly on the supply, [Amon] ran two extension wires to a 3d printed gun style handle. This keeps the bulky part of the heater away from the work. The copper tube coil was re-shaped to better work with the gun. Some fiberglass sleeve keeps everything insulated, even at extreme temperatures.

The result is a very useful heater, ready to bust loose some bolts. We’ve seen homebuilt ZVS supplies powering induction coils before. It will be interesting to see how well these commercial units hold up.

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Hacklet 92 – Workbenches And Toolboxes

January 23, 2016 by Adam Fabio 3 Comments

Everyone needs a place to work. While some of us have well equipped labs with soldering stations, oscilloscopes, and a myriad of other tools, others perform their hacks on the kitchen table. Still, some hackers have to be on the go – taking their tools and work space along with them on the road. This week’s Hacklet is all about the best toolbox and workbench projects on Hackaday.io!

We start at the top – in this case, a bench top. [KickSucker] created Mondrian Inspired Work Table as a multi-use tabletop for all kinds of projects. Rather than slap down a piece of plywood, [KickSucker] took a more artistic route. Piet Mondrian was a dutch artist known for painting irregular grids of black and white lines. He’d fill a few of the rectangles up with primary colors, but leave most of them white. Between different off-cuts of wood, and colorful bits of skateboard deck [KickSucker] had the makings of an awesome work surface. The frame of the bench is an IKEA expedite shelf unit. The frame is made from MDF, with the offcuts laid on top of it. The fun part was arranging all the pieces to make lines and colors. The result is a great custom work table, and a heck of a lot less wood scraps lying around the shop. That’s a double win in our book!

Next up is [M.Hehr] with Portable Workbench & mini Lab. [M.Hehr] has wanted a portable electronic workstation for years. We’re betting he’s seen a few of them here on the blog. While cleaning up the lab before Christmas, [M.Hehr] found a couple of wooden IKEA boxes. Each box held some drawers. An idea formed in [M.Hehr’s] head. It was time to put the plan in motion! The boxes were attached and hinged. Custom brackets were cut on a Shapeoko 2 router. Everything – even the screws were recycled. [M.Hehr] created a perfect space for each tool, ensuring that things won’t end up in a tangled mess when the box is carried around. We really love the retractable power point and custom-made power supply!

Next we’ve got [Tim Trzepacz] with Musician’s Road Box with 9 space rack. [Tim’s] sister [Tina] was playing a lot of music on the road, and needed a way to organize her gear. There are plenty of commercial solutions for this, but [Tim] decided to roll the perfect solution. He designed a plywood box with a 9U rack. [Tina’s] mixer and backing sound sources were located on the top, while effects and other modules were located in the rack. [Tim] spent a good amount of time designing the box. He was able to get the cut list down to a single piece of plywood, with room to spare. This is perfect for a 4′ x 8′ router like the ShopBot. When it comes time to hit the road, the case seals up to a rugged package. Standard roadcase corners and twist-latches finish this awesome piece.

Finally we have [Géllo] with protoBox. [Géllo] is into induction heating, which requires a Zero Voltage Switching (ZVS) flyback driver. ProtoBox started life as a place for [Géllo] to store his ZVS. It has evolved to become a small portable electronics lab. [Géllo] powers the box with a set of lithium-ion batteries sourced from old laptops. This particular ZVS design is plenty powerful enough to heat metal red hot, or create some nice arcs. [Géllo] added an Arduino Mega, a Bluetooth radio, and a 2×16 character LCD. The system is controlled with relays. A bluetooth enabled smartphone can be used to enable or disable any feature. [Géllo’s] assembly techniques are a bit scary, especially considering the fact that this is a high power design. However, this is a great proof of concept!

If you want to see more workbench and toolbox projects, check out our new workbench and toolbox list! If I missed your project, don’t be shy! Just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!