Making A Split-Anode Magnetron

September 26, 2024 by Dave Rowntree 3 Comments

YouTuber The Science Furry has been attempting to make a split-anode magnetron and, after earlier failures, is having another crack at it. This also failed, but they’ve learned where to focus their efforts for the future, and it sure is fun to follow along.

The magnetron theory is simple enough, and we’ve covered this many times, but the split anode arrangement differs slightly from the microwave in your kitchen. The idea is to make a heated filament the cathode, so electrons are ejected from the hot surface by thermionic emission. These are forced into a spiral path using a perpendicular magnetic field. This is a result of the Lorentz force. A simple pair of magnets external to the tube is all that is needed for that. Depending on the diameter of the cavity and the gap width, a standing wave will be emitted. The anodes must be supplied with an alternating potential for this arrangement to work. This causes the electrons to ‘bunch up’ as they cross the gaps, producing the required RF oscillation. The split electrodes also allow an inductor to be added to tune the frequency of this standing wave. That is what makes this special.

The construction starts with pre-made end seals with the tungsten wire electrode wire passing through. In the first video, they attempted to coat the cathode with barium nitrate, but this flaked off, ruining the tube. The second attempt replaces the coiled filament with a straight wire and uses a coating paste made from Barium Carbonate mixed with nitrocellulose in a bit of acetone. When heated, the nitrocellulose and the carbonate will decompose, hopefully leaving the barium coating intact. After inserting the electrode assembly into a section of a test tube and welding on the ends, the vacuum could be pulled and sealed off. After preheating the cathode, some gasses will be emitted into the vacuum, which is then adsorbed into a nearby titanium wire getter. At least, that’s the theory.

Upon testing, this second version burned out early on for an unknown reason, so they tried again, this time with an uncoated cathode. Measuring the emission current showed only 50 uA, which is nowhere near enough, and making the filament this hot caused it to boil off and coat the tube! They decide that perhaps this is one step too many and need to experiment with the barium coating by making simpler diode tubes to get the hang of the process!

If this stuff is over your head, you need a quick history lesson about the magnetron. Next check out this teardown. Finally, we have covered DIY magnetrons before, like this excellent DIY magnetron-powered plasma sputtering device. Yes, you read that correctly.

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An Espresso Machine For The DIY Crowd

September 15, 2024 by Donald Papp 29 Comments

Want to build your own espresso machine, complete with open-source software to drive it? The diyPresso might be right up your alley.

diyPresso parts, laid out and ready for assembly.

It might not be the cheapest road to obtaining an espresso machine, but it’s probably the most economical way to turn high-quality components (including a custom-designed boiler) and sensors into a machine of a proven design.

Coffee and the machines that turn it into a delicious beverage are fertile ground for the type of folk who like to measure, modify, and optimize. We’ve seen DIY roasters, grinders, and even a manual lever espresso machine. There are also many efforts at modifying existing machines with improved software-driven controls but this is the first time we’ve seen such a focused effort at bringing the DIY angle to a ground-up espresso machine specifically offered as a kit.

Curious to know more? Browse the assembly manual or take a peek at the software’s GitHub repository. You might feel some ideas start to flow for your next coffee hack.

Building A Multi-Purpose Electrochemistry Device

September 13, 2024 by Dave Rowntree 12 Comments

We don’t get enough electrochemistry hacks on these pages, so here’s [Markus Bindhammer] of YouTube/Marb’s lab fame to give us a fix with their hand-built general-purpose electrochemistry device.

The basic structure is made from plyboard cut to size on a table saw and glued’n’screwed together. The top and front are constructed from an aluminium sheet bent to shape with a hand-bender. A laser-printed front panel finishes the aesthetic nicely, contrasting with the shiny aluminium. The electrode holders are part of off-the-shelf chemistry components, with the electrical contacts hand-made from components usually used for constructing stair handrails. Inside, a 500 RPM 12 V DC geared motor is mounted, driving a couple of small magnets. A PWM motor speed controller provides power. This allows a magnetic stirrer to be added for relevant applications. Power for the electrochemical cell is courtesy of a Zk-5KX buck-boost power supply with a range of 0 – 36 V at up to 5 A with both CV and CC modes. A third electrode holder is also provided as a reference electrode for voltammetry applications. A simple and effective build, we reckon!

Over the years, we’ve seen a few electrochemical hacks, like this DIY electroplating pen, a DIY electrochemical machining rig, and finally, a little something about 3D printing metal electrochemically.

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Portable Router Build: Finding An LTE Modem

August 19, 2024 by Arya Voronova 8 Comments

Ever want your project equipped with a cellular interface for a data uplink? Hop in, I have been hacking on this for a fair bit! As you might remember, I’m building a router, I told you about how I picked its CPU board, and learned some lessons from me daily-driving it as a for a bit – that prototype has let me learn about the kind of extra hardware this router needs.

Here, let’s talk about LTE modems for high data throughput, finding antennas to make it all work, and give you a few tips that should generally help out. I’d like to outline a path that increases your chances of finding a modem working for you wonderfully – the devices that we build, should be reliable.

Narrowing It Down

If you look at the LTE modem selection, you might be a little overwhelmed: Simcom, Qualcomm, uBlox, Sierra, Telit, and a good few other manufacturers package baseband chipsets into modules and adjust the chipset-maker-provided firmware. The modems will be available in many different packages, too, many of them solderable, and usually, they will be available on mPCIe cards too. If you want to get a modem for data connections for a project, I argue that you should go for mPCIe cards first, and here’s why.

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Cheap DIY Button Pad Uses Neat Punchcard Trick

August 13, 2024 by Lewin Day 16 Comments

A StreamDeck is effectively a really cool box full of colorful buttons that activate various things on your PC. They’re fun and cool but they’re also something you can build yourself if you’re so inclined. [Jason] did just that for his sim racing setup, and he included some nifty old-school tech as well.

An ESP32 is at the core of the build, listening to button presses and communicating with the PC. However, the build doesn’t actually use regular buttons. Instead, it uses infrared sensors wired up in a matrix. This was an intentional choice, because [Jason] wanted the device to be reconfigurable with different paper card overlays. There are ways to do this with regular buttons too, but it works particularly well with the infrared technique. Plus, each button also gets a Neopixel allowing its color to be changed to suit different button maps.

What’s really neat is that the button maps change instantly when a different overlay card is inserted. [Jason] achieved this with an extra row of infrared sensors to detect punched holes in the bottom of the overlay cards.

Once upon a time, even building your own keyboard was an uphill battle. Today, it’s easier than ever to whip up fun and unique interface devices that suit your own exact needs. That’s a good thing! Video after the break.

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Portable Router Build: Picking Your CPU

August 13, 2024 by Arya Voronova 23 Comments

I want to introduce you to a project of mine – a portable router build, and with its help, show you how you can build a purpose-built device. You might have seen portable routers for sale, but if you’ve been in the hacking spheres long enough, you might notice there are “coverage gaps”, so to speak. The Pi-hole project is a household staple that keeps being product-ized by shady Kickstarter campaigns, a “mobile hotspot” button is a staple in every self-respecting mobile and desktop OS, and “a reset device for the ISP router” is a whole genre of a hacker project. Sort the projects by “All Time” popularity on Hackaday.io, and near the very top, you will see an OpenVPN &Tor router project – it’s there for a reason, and it got into 2014 Hackaday Prize semifinals for a reason, too.

I own a bunch of devices benefitting from both an Internet connection and also point-to-point connections between them. My internet connection comes sometimes from an LTE uplink, sometimes from an Ethernet cable, and sometimes from an open WiFi network with a portal you need to click through before you can even ping anything. If I want to link my pocket devices into my home network for backups and home automation, I can put a VPN client on my laptop, but a VPN client on my phone kills its battery, and the reasonable way would be to VPN the Internet uplink – somehow, that is a feature I’m not supposed to have, and let’s not even talk about DNSSEC! Whenever I tried to use one of those portable LTE+WiFi[+Ethernet] routers and actively use it for a month or two, I’d encounter serious hardware or firmware bugs – which makes sense, they are a niche product that won’t get as much testing as phones.

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Better Living Through Hackery

August 10, 2024 by Elliot Williams 11 Comments

Hackaday’s own [Arya Voronova] has been on a multi-year kick to make technology more personal by making it herself, and has just now started writing about it. Her main point rings especially true in this day and age, where a lot of the tech devices we could use to help us are instead used to spy on us or are designed to literally make us addicted to their services.

The project is at the same time impossible and simple. Of course, you are not going to be able to build a gadget that will bolster all of your (perceived or otherwise) personal weaknesses in one fell swoop. But what if you start looking at them one at a time? What if you start building up the good habits with the help of a fun DIY project?

That’s where [Arya]’s plan might just be brilliant. Because each project is supposed to be small, it forces you to focus on one specific problem, rather than getting demoralized at the impossibility of becoming “better” in some vague overall sense. Any psychologist would tell you that introspection and dividing up complex problems are the first steps. And what motivates a hacker to take the next steps? You got it, the fun of brainstorming, planning, and building a nice concrete DIY project. It’s like the ultimate motivation, Hackaday style.

And DIY solutions are a perfect match to personal problems. Nothing is so customizable as what you design and build yourself from the ground up. DIY means making exactly what you need, or at least what you think you need. Iteration, improvement, and the usual prototyping cycle applied to personal growth sounds like the ideal combo, because that’s how the tech works, and that’s also how humans work. Of course, even the coolest DIY gadget can’t instantly make you more mindful, for instance, but if it’s a tool that helps you get there, I don’t think you could ask for more.