Mysterious Files PH

You could make a clock with three hands spinning about nested central shafts. If you did that, we probably wouldn’t publish it on Hackaday unless you really found a way to make it interesting. Make a clock out of voltmeters, however, and that usually catches our eye. [lcamtuf] has done just that.

The heart of the build is an AVR128DB28 microcontroller, an 8-bit microcontroller that is still currently in production. It runs at 8MHz, and drives a series of three Baomain 65C5 voltmeters to display hours, minutes, and seconds. Each has a custom printed face with the correct number of 13 or 61 divisions as needed. The voltmeters are driven by a continuous stream of 1-bit pulses with a software-controlled duty cycle determining exactly how far the needle moves. Yes, it’s using simple pulse width modulation, coded by hand by [lcamtuf] to do the job. All the components are wrapped up in a beautiful wooden case, with delicately kerf-bent panels to create the attractive curved lines.

We’ve featured similar builds before, too. As it turns out, hackers just really love clocks and old-school dials. Video after the break, which is worth watching for the rollover behaviour alone.

Most consumer-grade night vision devices are basically a standard camera without the usual filter to block near infrared (NIR) light, which are then paired with a NIR light source that’s not visible to the human eye. Unlike the passive night vision provided by a photomultiplier tube, these can’t resolve objects beyond the beam of their illumination source. On the other hand, if, as [Project 326] did, you use an infrared laser to illuminate the scene, you can still get a very long range out of these devices.

[Project 326]’s device consists of a previously-built reflecting telescope focusing a distant scene in to a webcam with the infrared filter removed, with the infrared laser illuminating the scene. Finding a suitable laser took some effort: the first option, a secondhand fiber-coupled industrial laser, was accidentally over-volted and destroyed during testing. The second had a fiber output which proved extremely hard to terminate, and a third laser couldn’t be collimated correctly. The final laser was a Vertical-Cavity Surface-Emitting Laser (VSEL) diode array element driven at about two Watts and collimated by a small lens.

This illumination setup is safe at a long range, but only at a long range. The laser was strong enough to burn cardboard at close range, but out at about 500 meters, the beam had spread until it was less than a hundredth of the standard safety limit. To make sure that nothing else would get in the way of the beam, it was shone down from the top of a tall building. Testing with a power meter also showed that at a long range, the beam was weaker than expected. It turned out that the wavelength used (940 nm) is attenuated by water vapor, to the point that up to 70% of the beam’s strength was lost before reaching the target. Despite this, and despite a rather linear beam profile, a somewhat dark image was still visible at 650 meters.

If you’re looking for a somewhat more versatile long-range night vision device, check out one based on a photomultiplier tube. Another approach is to use a very high-sensitivity camera.

Thanks to [Keith Olson] for the tip!

There are plenty of porous materials out there that we’re all readily familiar with. Fabrics and wood are great examples, allowing liquids or gases to pass through to a certain degree—a property which is useful or problematic depending on the application.

Metals, however, are not something we would readily consider to be porous. They are solid, unyielding, and impermeable. However, with the right techniques, it is possible to produce so-called “breathable” steel, which has particularly interesting applications in the molding industry.

Breathe Into Me And Make Me Real

Imagine you’re making tooling for an injection molding operation. You’re using steel, of course, because you need a hard, resilient material that can deal with the high temperatures and pressures involved. It’s tough, and readily able to be machined into the desired geometry for your application. Of course, it doesn’t let liquid or gas pass, since it’s a solid impermeable material. This means that when you inject your mold full of hot plastic, you need to find somewhere for the air inside to go. Otherwise, the gas in the mold will end up dissolved in the molten plastic, causing voids, surface imperfections, and other irregularities. Chasing away gas porosity defects in finished parts is one of the major jobs of casting engineers the world over, an endless battle against the forces of heat transfer and fluid mechanics.

Traditionally, this is deal by designing a mold with exhaust ports or vacuum hookups to allow the air to vent out as needed. This takes a great deal of work to get right, particularly when it comes to getting your defect rates as low as possible in mass production. If your gas can’t vent fast enough, or if there are areas where it gets trapped, you end up with defects, and you have to go back to the drawing board.

Breathable mold steel attempts to solve this problem by venting gas through the tooling itself. It allows the creation of a steel mold that is full of tiny little pores that allow air to pass through, while still acting largely impermeable to the molten plastic being molded.

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Breathable mold steel is quite something to behold, behaving quite unlike a normal steel part in this regard.

As you might imagine, it’s quite difficult to make a steel mold with complex geometry that also has lots of tiny contiguous holes that allow gases to pass through. It is possible, however, by using some tricky additive manufacturing techniques.

As outlined in one research paper, it’s possible to produce breathable steel via selective laser melting (SLM) 3D printing techniques. This involves using a high-powered laser to fuse metal powder together, layer by layer, to produce a final part. Combining a foaming agent with the metal powder enables the creation of 3D-printed metal parts with incredibly fine interconnected pores.

The pores need to be particularly small, on the order of 80 micrometers or less, such that they allow gas in the mold to pass freely while blocking the flow of the larger polymer molecules of the injected plastic.

Chromium nitride is one foaming agent typically used, for the fact that the Cr and N released during its decomposition both lend beneficial properties to the steel of the finished product. The foaming agent is mixed in with the steel powder, and melts along with it as the part is being produced. The breakdown of the foaming agent releases gas bubbles which creates pores in the steel part as it is produced in a relatively predictable manner.

The level of porosity can be controlled by the amount of foaming agent mixed in to the steel powder, as well as the laser settings. Lower melt pool temperatures caused by faster scanning speeds or lower laser powers tend to favor more porous structures, due to the fluid mechanics involved and how the cooler liquid steel flows into existing pores.

There have been earlier attempts to vent molds with special breathable steel inserts in the past. These consist of premade rectangular inserts or round bars which have been made with so-called “ventilated steel” like PM-35. This material is made by sintering steel powders together in such a way to create a porosity of 20-30%. However, this process isn’t always great for advanced geometry that one might find in a injection mold. Thus, the creation of breathable rods and bars that can be used as an insert in a larger mold, acting as a localized vent. It’s a useful technique, but comes with more constraints on mold and part geometry than being able to simply create the whole mold itself out of breathable steel.

There are other powder metal techniques that allow the production of more complex vented parts, but they can be expensive and difficult to execute well down to smaller pore sizes, especially compared to the simplicity of SLM printing with an additional foaming agent. The 3D-printing based process has also proven to have more admirable mechanical properties compared to products like PM-35 steel in some cases, with impressive compressive strength as well as hardness and corrosion resistance.

Breathable steel is probably not something you’ll come across in your everyday life unless you happen to work in particular manufacturing fields. Still, if you have the expensive 3D printing hardware on hand to work with metal powders, and you really want to make a complex metal part that’s also porous, this is a great way to go. You could probably use it to make some very weird magic tricks at the very least. Ultimately, it just goes to show that modern material processing techniques can upend everything we think we know about a common material like steel. It’s amazing what can be done!

Small internal combustion engines usually keep things simple, relying on carburetors to handle metering the correct amount of fuel and air. Recently, [Carlos Takeshita] decided his small engine could use an upgrade in the form of electronic fuel injection (EFI).

The build began with a Predator 212, a popular gasoline engine from Harbor Freight. [Carlos] set about kitting it out with a missing tooth trigger wheel to measure the crankshaft position with a hall effect sensor. The engine also scored a custom-built aluminium fuel cell, complete with a high-pressure fuel pump and regulator suitable for driving the solitary fuel injector installed in the custom intake manifold. A Teensy 4.0 is charged with monitoring a manifold air pressure (MAP) sensor and the crank position, and choosing when and how long to fire the injector to dose the engine with the correct amount of fuel. Files are on GitHub for those eager to dive deeper.

It can be quite a job to convert an engine to run with electronic fuel injection, but you’re certain to learn a lot during the install and tuning process. We’ve featured similar builds many times over the years.

Sure, you can buy a portable monitor off your favorite e-tailer, but with perfectly fine displays in devices like laptops being tossed out every single day, why not repurpose those instead? That’s what [ScuffedBits] recently did with the panels  pulled from some old laptops.

A good question with any such salvaged panel is just how practical it is to still use them, with disqualifying features being things like passive-matrix TFTs as well as the use of CCFL backlighting as with one of the three panels demonstrated in the video.

Looking up the model number of a panel on a site like panelook.com will tell you the display technology, resolution and other important details before you decide to commit to using it. If it’s using a LED backlight and at least Low-Voltage Differential Signaling (LVDS) but ideally eDP you can likely find a cheap driver board for it that has all the requisite inputs like HDMI and power.

The hardest part is probably the case for the panel, as they’re rather thin and fragile. Here [ScuffedBits] opted to 3D print two different types of cases, with the second variant probably being the best version as it protects most of the panel. Installing these is quite easy: slide the panel into the first half, then add the second half of the case to close it up. Permanently keeping the case in place was left as an exercise to a future [ScuffedBits], while demonstrating why it’s definitely the hardest part of repurposing an old laptop display.

To start things off, we’d like to extend a special thanks to everyone who joined us for Hackaday Europe this weekend in Lecco, Italy. It was 48 hours of fascinating talks, incredible badge hacks, and some of the greatest company you could hope for. For those who couldn’t make it in person, we didn’t forget you — expect to hear more about what went down once we get a chance to catch our collective breath.

That’s not the only thing to keep an eye out for in the coming days. This is your reminder that Amazon will be officially ending support for older Kindles in a few days. After May 20th, any of the megacorp’s e-readers that were introduced before 2012 will be persona non grata, so you should plan accordingly.

The biggest change is that these older devices won’t be able to buy digital books from Amazon, but you can still use them offline, and the fantastic Calibre makes it a breeze to load up content from other sources. To be perfectly honest, we’d advise any Kindle user to decouple their device from the Amazon mothership by using Calibre or even jailbreaking it and installing KOReader, so the end of official support is fine by us. In fact, if a surge of unsupported Kindles brings more attention and users to those projects, that suits us just fine.

We’ve also heard that Microsoft is removing the “Together” feature from Teams on June 30th. We actually had to look this one up — apparently, it was a mode added during the pandemic that made it look like you and the other people in the call were all sitting together in a virtual conference room of sorts. Sounds an awful lot like a dystopian nightmare to us, but to be fair, things got kinda weird there when we were all sheltering in place, so it’s hard to judge. In any event, we don’t think too many people will miss this particular feature in 2026.

While on the subject of products the world seems to have forgotten about, Electrek reports that Tesla has all but given up on their once promising solar roof tiles. The company won’t say just how many installations they’ve completed since the camouflaged panels hit the market in 2016, but estimates suggest the number may be as low as 3,000. It will probably come as little surprise to find that cost seems to be the biggest factor: a roof full of Tesla’s swanky tiles could run you six-figures, while traditional panels are only getting cheaper every year.

From end-of-life to the latest and greatest, today also marks the release of Linux 7.1-rc4. If you’re in the business of running release candidate kernels, you probably don’t need to be told what’s new, but for everyone else, Phoronix has a rundown on some of the changes. Highlights include improvements to hardware support (including a fix for the Framework Laptop 13 Pro), security fixes, and new guidance about the use of AI-generated code.

Finally, if you want a time-waster, there’s Halupedia. According to the site’s GitHub: An infinite, hallucinated encyclopedia. Every link leads to an entry that does not exist yet — until you click it, at which point an LLM pretends it has always existed and writes it for you, in the deadpan register of a 19th-century scholarly press. For example, you can read about “The Ministry of Slightly Wrong Maps,” or, if you prefer, “The Ministry of Terribly Wrong Maps.”

See something interesting that you think would be a good fit for our weekly Links column? Drop us a line, we’d love to hear about it.

Streaming services have enabled many of us to have easy access to the world’s media library at the touch of a screen, but [Coconauts] thinks we’ve lost something along the way. To bring some intentionality back to the listening experience, they built an NFC record player called Minilos.

Like a normal record player, Minilos requires the user to select an album to play on the machine. These were originally decorative coasters with records printed on them, so they are much smaller than even a 45. Each one features an NFC tag that instructs ESP32 microcontroller hidden in the device to play the requested song. Once placed on the record player, it will then play through that album and come to a stop.

In [Coconauts]’s current setup, the ESP32 is connected to a Home Assistant server which then instructs a Google Speaker to play the requested song via Spotify, although we could easily imagine this being used to play music directly from an SD card or other digital storage device instead.

If you want complete control over your music listening while still keeping that authentic vinyl experience, you could always look into cutting your own records with a laser.