What do you do with a four-megapixel monochrome digital camera from the 90s that needed a dedicated PC with a frame grabber card to do anything useful? Easy — you turn it into a point-and-shoot by building your own frame grabber.

At least that’s what [Frost Sheridan] did with a vintage Kodak MegaPlus 4.2i, a camera that was aimed at the industrial and scientific market at a time when everyone was still using film for snapshots. Making this workhorse ride again meant diving into the manual, luckily still available after all these years, and figuring out what pins on the 68 pin connector would be useful. [Frost] worked out the pins for serial commands plus the 10-bit parallel interface, although he settled for the eight most significant bits to make things simpler. A Teensy with some extra RAM and a serial interface chip takes care of sending commands to the camera and pulling pixels off the parallel interface, and a 128×160 LCD provides a much-needed viewfinder.

With a battery pack mounted the whole thing is reasonably portable, if a bit of a chore to use. It’s worth the effort, though; the picture quality is fantastic, with a wide dynamic range and plenty of contrast. Hats off to [Frost] for bringing this beauty back to life without making any permanent modifications to it.

FR4 is FR4, right? For a lot of PCB designs, the answer is yes — the particular characteristics of the substrate material don’t impact your design in any major way. But things get a little weird up in the microwave range, and having one of these easy methods to measure the dielectric properties of your PCB substrate can be pretty handy.

The RF reverse-engineering methods [Gregory F. Gusberti] are deceptively simple, even if they require some fancy test equipment. But if you’re designing circuits with features like microstrip filters where the permittivity of the substrate would matter, chances are pretty good you already have access to such gear. The first method uses a ring resonator, which is just a PCB with a circular microstrip of known circumference. Microstrip feedlines approach but don’t quite attach to the ring, leaving a tiny coupling gap. SMA connectors on the feedline connect the resonator to a microwave vector network analyzer in S21 mode. The resonant frequencies show up as peaks on the VNA, and can be used to calculate the effective permittivity of the substrate.

Method two is similar in that it measures in the frequency domain, but uses a pair of microstrip stubs of different lengths. The delta between the lengths is used to cancel out the effect of the SMA connectors, and the phase delay difference is used to calculate the effective permittivity. The last method is a time domain measurement using a single microstrip with a couple of wider areas. A fast pulse sent into this circuit will partially reflect off these impedance discontinuities; the time delay between the reflections is directly related to the propagation speed of the wave in the substrate, which allows you to calculate its effective permittivity.

One key takeaway for us is the concept of effective permittivity, which considers the whole environment of the stripline, including the air above the traces. We’d imagine that if there had been any resist or silkscreen near the traces it would change the permittivity, too, making measurements like these all the more important.

Ho-hum — another week, another high-profile bricking. In a move anyone could see coming, Humane has announced that their pricey AI Pin widgets will cease to work in any meaningful way as of noon on February 28. The company made a splash when it launched its wearable assistant in April of 2024, and from an engineering point of view, it was pretty cool. Meant to be worn on one’s shirt, it had a little bit of a Star Trek: The Next Generation comm badge vibe as the primary UI was accessed through tapping the front of the thing. It also had a display that projected information onto your hand, plus the usual array of sensors and cameras which no doubt provided a rich stream of user data. Somehow, though, Humane wasn’t able to make the numbers work out, and as a result they’ll be shutting down their servers at the end of the month, with refunds offered only to users who bought their AI Pins in the last 90 days.

How exactly Humane thought that offering what amounts to a civilian badge cam was going to be a viable business model is a bit of a mystery. Were people really going to be OK walking into a meeting where Pin-wearing coworkers could be recording everything they say? Wouldn’t wearing a device like that in a gym locker room cause a stir? Sure, the AI Pin was a little less obtrusive than something like the Google Glass — not to mention a lot less goofy — but all wearables seem to suffer the same basic problem: they’re too obvious. About the only one that comes close to passing that hurdle is the Meta Ray-Ban smart glasses, and those still have the problem of obvious cameras built into their chunky frames. Plus, who can wear Ray-Bans all the time without looking like a tool?

Good news for everyone worried about a world being run by LLMs and chatbots. It looks like all we’re going to have to do is wait them out, if a study finding that older LLMs are already showing signs of cognitive decline pans out. To come to that conclusion, researchers gave the Montreal Cognitive Assessment test to a bunch of different chatbots. The test uses simple questions to screen for early signs of impairment; some of the questions seem like something from a field sobriety test, and for good reason. Alas for the tested chatbots, the general trend was that the older the model, the poorer they did on the test. The obvious objection here is that the researchers aren’t comparing each model’s current score with results from when the model was “younger,” but that’s pretty much what happens when the test is used for humans.

You’ve got to feel sorry for astronomers. Between light pollution cluttering up the sky and an explosion in radio frequency interference, astronomers face observational challenges across the spectrum. These challenges are why astronomers prize areas like dark sky reserves, where light pollution is kept to a minimum, and radio quiet zones, which do the same for the RF part of the spectrum. Still, it’s a busy world, and noise always seems to find a way to leak into these zones. A case in point is the recent discovery that TV signals that had been plaguing the Murchison Wide-field Array in Western Australia for five years were actually bouncing off airplanes. The MWA is in a designated radio quiet zone, so astronomers were perplexed until someone had the bright idea to use the array’s beam-forming capabilities to trace the signal back to its source. The astronomers plan to use the method to identify and exclude other RFI getting into their quiet zone, both from terrestrial sources and from the many satellites whizzing overhead.

And finally, most of us are more comfortable posting our successes online than our failures, and for obvious reasons. Everyone loves a winner, after all, and admitting our failures publicly can be difficult. But Daniel Dakhno finds value in his failures, to the point where he’s devoted a special section of his project portfolio to them. They’re right there at the bottom of the page for anyone to see, meticulously organized by project type and failure mode. Each failure assessment includes an estimate of the time it took; importantly, Daniel characterizes this as “time invested” rather than “time wasted.” When you fall down, you should pick something up, right?

“World’s best” is a mighty ambitious claim, regardless of what you’ve built. But from the look of [Marius Hornberger]’s tricked-out miter fence, it seems like a pretty reasonable claim.

For those who have experienced the torture of using the standard miter fence that comes with machine tools like a table saw, band saw, or belt sander, any change is likely to make a big difference in accuracy. Miter fences are intended to position a workpiece at a precise angle relative to the plane of the cutting tool, with particular attention paid to the 90° and 45° settings, which are critical to creating square and true joints.

[Marius] started his build with a runner for the T-slot in his machine tools, slightly undersized for the width of the slot but with adjustment screws that expand plastic washers to take up the slack. An aluminum plate equipped with a 3D printed sector gear is attached to the runner, and a large knob with a small pinion mates to it. The knob has 120 precisely positioned slots in its underside, which thanks to a spring-loaded detent provide positive stops every 0.5°. A vernier scale also allows fine adjustment between positive stops, giving a final resolution of 0.1°.

Aside from the deliciously clicky goodness of the angle adjustment, [Marius] included a lot of thoughtful touches. We particularly like the cam-action lock for the angle setting, which prevents knocking your fine angle adjustment out of whack. We’re also intrigued by the slide lock, which firmly grips the T-slot and keeps the fence fixed in one place on the machine. As for the accuracy of the tool, guest meteorologist and machining stalwart [Stefan Gotteswinter] gave it a thumbs-up.

[Marius] is a veteran tool tweaker, and we’ve featured some of his projects before. We bet this fence will see some use on his much-modified drill press, and many of the parts for this build were made on his homemade CNC router.

If you think sonic booms from supersonic aircraft are a nuisance, wait until the sky is full of planes propelled by up-scaled versions of this interesting but deafening audio resonance engine.

Granted, there’s a lot of work to do before this “Sonic Ramjet” can fly even something as small as an RC plane. Creator [invalid_credentials] came up with the idea for a sound-powered engine after listening to the subwoofers on a car’s audio system shaking the paint off the body. The current design uses a pair of speaker drivers firing into 3D printed chambers, which are designed based on Fibonacci ratios to optimize resonance. When the speakers are driven with a low-frequency sine wave, the chambers focus the acoustic energy into powerful jets, producing enough thrust to propel a small wheeled test rig across a table.

It’s fair to ask the obvious question: is the engine producing thrust, or is the test model moving thanks to the vibrations caused by the sound? [invalid_credentials] appears to have thought of that, with a video showing a test driver generating a powerful jet of air. Downloads to STL files for both the large and small versions of the resonating chamber are provided, if you want to give it a try yourself. Just be careful not to annoy the neighbors too much.

Thanks to [cabbage] for the tip via [r/3Dprinting].

While not impossible, replicating the machines and processes of a modern semiconductor fab is a pretty steep climb for the home gamer. Sure, we’ve seen it done, but nanoscale photolithography is a demanding process that discourages the DIYer at every turn. So if you want to make semiconductors at home, it might be best to change the rules a little and give something like this pulsed laser deposition prototyping apparatus a try.

Rather than building up a semiconductor by depositing layers of material onto a silicon substrate and selectively etching features into them with photolithography, [Sebastián Elgueta]’s chips will be made by adding materials in their final shape, with no etching required. The heart of the process is a multi-material pulsed laser deposition chamber, which uses an Nd:YAG laser to ablate one of six materials held on a rotating turret, creating a plasma that can be deposited onto a silicon substrate. Layers can either be a single material or, with the turret rapidly switched between different targets, a mix of multiple materials. The chamber is also equipped with valves for admitting different gases, such as oxygen when insulating layers of metal oxides need to be deposited. To create features, a pattern etched into a continuous web of aluminum foil by a second laser is used as a mask. When a new mask is needed, a fresh area of the foil is rolled into position over the substrate; this keeps the patterns in perfect alignment.

We’ve noticed regular updates on this project, so it’s under active development. [Sebastián]’s most recent improvements to the setup have involved adding electronics inside the chamber, including a resistive heater to warm the substrate before deposition and a quartz crystal microbalance to measure the amount of material being deposited. We’re eager to see what else he comes up with, especially when those first chips roll off the line. Until then, we’ll just have to look back at some of [Sam Zeloof]’s DIY semiconductors.

Those of us who worked in TV repair shops, back when there was such a thing, will likely remember the cardinal rule of TV repair: Never touch the yoke if you can help it. The complex arrangement of copper wire coils and ferrite beads wrapped around a plastic cone attached to the neck of the CRT was critical to picture quality, and it took very little effort to completely screw things up. Fixing it would be a time-consuming and frustrating battle with the cams, screws, and spacers that kept the coils in the right orientation, both between themselves and relative to the picture tube. It was best to leave it the way the factory set it and to look elsewhere for solutions to picture problems.

But how exactly did the factory set up a deflection yoke? We had no idea at the time, only learning just recently about the wonders of automated deflection yoke yamming. The video below was made by Thomson Consumer Electronics, once a major supplier of CRTs to the television and computer monitor industry, and appears directed to its customers as a way of showing off their automated processes. They never really define yamming, but from the context of the video, it seems to be an industry term for the initial alignment of a deflection yoke during manufacturing. The manual process would require a skilled technician to manipulate the yoke while watching a series of test patterns on the CRT, slowly tweaking the coils to bring everything into perfect alignment.

Automating this process would have been a huge competitive advantage for a company like Thomson. Being able to provide correctly aligned CRT assemblies to a manufacturer would have been a productivity booster, especially since Thomson claimed to be able to adjust the process to the customer’s assembly line needs. They also say that the automated yamming process took just 30 seconds per tube thanks to a series of sensors and cameras watching the screen. The human element wasn’t completely eliminated, though; at the 3:50 mark, some unlucky QA tech is shown watching an endless carousel of tubes flashing a few test patterns to confirm the process. And you think your job sucks.

It’s not exactly clear when this video was made. The title suggests it was 1995, and that seems about right from the technology in the video, which includes a computer running a version of Windows from around that timeframe. Ironically, the LCD monitor on that touchscreen display was a harbinger of things to come for Thomson, which was out of the CRT business in the US less than a decade later.