Are your jellybeans getting stale? [lcamtuf] thinks so, and his guide to choosing op-amps makes a good case for rethinking what parts you should keep in stock.

For readers of a certain vintage, the term “operational amplifier” is almost synonymous with the LM741 or LM324, and with good reason. This is despite the limitations these chips have, including the need for bipolar power supplies at relatively high voltages and the need to limit the input voltage range lest clipping and distortion occur. These chips have appeared in countless designs over the nearly 60 years that they’ve been available, and the Internet is littered with examples of circuits using them.

For [lcamtuf], the abundance of designs for these dated chips is exactly the problem, as it leads to a “copy-paste” design culture despite the far more capable and modern op-amps that are readily available. His list of preferred jellybeans includes the OPA2323, favored thanks to its lower single-supply voltage range, rail-to-rail input and output, and decent output current. The article also discussed the pros and cons of FET input, frequency response and slew rate, and the relative unimportance of internal noise, pointing out that most modern op-amps will probably be the least thermally noisy part in your circuit.

None of this is to take away from how important the 741 and other early op-amps were, of course. They are venerable chips that still have their place, and we expect they’ll be showing up in designs for many decades to come. This is just food for thought, and [lcamtuf] makes a good case for rethinking your analog designs while cluing us in on what really matters when choosing an op-amp.

Good news this week from the Sun’s far side as the Parker Solar Probe checked in after its speedrun through our star’s corona. Parker became the fastest human-made object ever — aside from the manhole cover, of course — as it fell into the Sun’s gravity well on Christmas Eve to pass within 6.1 million kilometers of the surface, in an attempt to study the extremely dynamic environment of the solar atmosphere. Similar to how manned spacecraft returning to Earth are blacked out from radio communications, the plasma soup Parker flew through meant everything it would do during the pass had to be autonomous, and we wouldn’t know how it went until the probe cleared the high-energy zone. The probe pinged Earth with a quick “I’m OK” message on December 26, and checked in with the Deep Space Network as scheduled on January 1, dumping telemetry data that indicated the spacecraft not only survived its brush with the corona but that every instrument performed as expected during the pass. The scientific data from the instruments won’t be downloaded until the probe is in a little better position, and then Parker will get to do the whole thing again twice more in 2025.

Good news too for Apple users, some of whom stand to get a cool $100 as part of a settlement into allegations that Siri-enabled devices “unintentionally” recorded conversations. The $95 million agreement settles a lawsuit brought by users who were shocked — SHOCKED! — to see ads related to esoteric subjects they had recently discussed, apparently independently of uttering the “Hey, Siri” wake phrase. Apple seems to acknowledge that some recordings were made without the wake word, characterizing them as “unintentional” and disputing the plaintiffs’ claims that the recordings were passed to third parties for targeted advertising. The settlement, which may be certified in February, would award the princely sum of $20 to claimants for each Apple device they owned over a ten-year period, up to five devices total.

In related news, Apple is also getting some attention for apparently opting users into its Enhanced Visual Search system. The feature is intended to make it easier to classify and search your photos based on well-known landmarks or points of interest, so if you take a selfie in front of the Eiffel Tower or Grand Canyon, it’ll recognize those features visually and record the fact. It does so by running your snapshots through a local AI algorithm and then encrypting the portion of the image it thinks contains the landmark. The encrypted portion of the image then goes to the cloud for analysis, apparently without getting decrypted, and the suggested location goes back to your device in encrypted form. It’s possible to turn the feature off, but you have to know it’s there in the first place, which we imagine not a lot of Apple users do. While there’s no sign that this new feature leaks any user data, there are a lot of moving pieces that sure seem ripe for exploitation, given enough time.

Are you as sick of counting the numbers of bridges or traffic lights in potato-vision images or trying to figure out if that one square has a few pixels of the rear-view mirror of a motorcycle to prove you’re human? We sure are, and while we’d love to see CAPTCHAs go the way of the dodo, they’re probably here to stay. So, why not have fun with the concept and play a round of DOOM on nightmare mode to prove your non-robotness? That was Guillermo Rauch’s idea, and we have to say it’s pretty cool. You’ve got to kill three monsters to solve the puzzle, and we found it pretty difficult, in part because we’re more used to the WASD layout than using the arrow keys for player movement. Just watch out if you give it a try with headphones on — it’s pretty loud.

And finally, if you feel like your life is missing in-depth knowledge of the inner workings of a Boeing 777’s auxiliary power unit, we’ve got good news for you. We stumbled across this playlist of excellent animations that shows every nook and cranny of the APU, and how it operates. For the uninitiated, the APU is basically a gas turbine engine that lives in the tail of jetliners and provides electrical and pneumatic power whenever the main engines aren’t running. It sounds simple, but there’s so much engineering packed into the APU and the way it integrates into the aircraft systems. We’ve always known that jets have a lot of redundancy built into them, but this series really brought that home to us. Enjoy!

And finally finally, we generally don’t like to plug the Hack Chat here in this space, but we thought we’d make an exception since we’re kicking off the 2025 series in a big way with Eben Upton! The co-founder and CEO of Raspberry Pi will stop by the Hack Chat on January 15 at noon Pacific time, and we just want to get the word out as soon as possible. Hope to see you there!

There’s a paradox in amateur radio: after all the time and effort spent getting a license and all the expense of getting some gear together, some new hams suddenly find that they don’t have a lot to talk about when they get in front of the mic. While that can be awkward, it’s not a deal-breaker by any means, especially when this Pi Pico SSTV decoder makes it cheap and easy to get into slow-scan television.

There’s not much to [Jon Dawson]’s SSTV decoder. Audio from a single-sideband receiver goes through a biasing network and into the Pico’s A/D input. The decoder can handle both Martin and Scottie SSTV protocols, with results displayed on a TFT LCD screen. The magic is in the software, of course, and [Jon] provides a good explanation of the algorithms he used, as well as some of the challenges he faced, such as reliably detecting which protocol is being used. He also implemented correction for “slant,” which occurs when the transmitter sample rate drifts relative to the receiver. Fixing that requires measuring the time it took to transmit each line and adjusting the timing of the decoder to match. The results are dramatic, and it clears up one of the main sources of SSTV artifacts.

We think this is a great build, and simple enough that anyone can try it. The best part is that since it’s receive-only, it doesn’t require a license, although [Jon] says he’s working on an encoder and transmitter too. We’re looking forward to that, but in the meantime, you might just be able to use this to capture some space memes.

Thanks to [CJay] for the tip.

We’ve always found the various methods for adding text and graphics to 3D prints somewhat underwhelming. Embossed or debossed characters are fuzzy, at best, and multi-color printers always seem to bleed one color into the next. Still, the need for labels and logos is common enough that it’s worth exploring other methods, such as this easy toner transfer trick.

Home PCB makers will probably find the method [Squalius] describes in the video below very familiar, and with good reason. We’ve seen toner transfer used to mask PCBs before etching, and the basic process here is very similar. It starts with printing the desired graphics on regular paper using a laser printer; don’t forget to mirror the print. The printed surface is scuffed up a bit, carefully cleaned, and coated with a thick layer of liquid acrylic medium, of the kind used in paint pouring. The mirrored print is carefully laid on the acrylic, toner-side down, and more medium is brushed on the back of the paper. After the print dries, the paper is removed with a little water and some gentle friction, leaving the toner behind. A coat of polyurethane protects the artwork reasonably well.

[Squalius] has tested the method with PLA and PETG and reports good results. The text is clear and sharp, and even fine text and dithered graphics look pretty good. Durability could be better, and [Squalius] is looking for alternative products that might work better for high-wear applications. It looks like it works best on lightly textured surfaces, too, as opposed to surfaces with layer lines. We’d love to see if color laser prints work, too; [Squalius] says that’s in the works, and we’ve seen examples before that are reason for optimism.

Thanks to [greg_bear] for the tip.

If there’s anything more annoying to an amateur radio operator than noise, we’re not sure what it could be. We’re talking about radio frequency noise, of course, the random broadband emissions that threaten to make it almost impossible to work the bands and pick out weak signals. This man-made interference is known as “QRM” in ham parlance, and it has become almost intolerable of late, as poorly engineered switch-mode power supplies have become more common.

But hams love a technical challenge, so when a nasty case of QRM raised its ugly head, [Kevin Loughlin (KB9RLW)] fought back. With an unacceptable noise floor of S8, he went on a search for the guilty party, and in the simplest way possible — he started flipping circuit breakers. Sure, he could have pulled out something fancier like a TinySA spectrum analyzer, but with his HF rig on and blasting white noise, it was far easier to just work through the circuits one by one to narrow the source down. His noise problem went away with the living room breaker, which led to pulling plugs one by one until he located the culprit: a Roomba vacuum’s charging station.

Yes, this is a simple trick, but one that’s worth remembering as at least a first pass when QRM problems creep up. It probably won’t help if the source is coming from a neighbor’s house, but it’s a least worth a shot before going to more involved steps. As for remediation, [Kevin] opts to just unplug the Roomba when he wants to work the bands, but if you find that something like an Ethernet cable is causing your QRM issue, you might have to try different measures.

A lot of the projects we feature here on Hackaday engender the classic “build versus buy” argument. We’ve always been puzzled by that; if anyone can appreciate the sheer joy of making something rather than buying it, it should be our readers. But there’s something to be said for buying the stuff you can buy and concentrating your effort on the bespoke aspects of the project. It’s perhaps not as exciting, but needs must, oftentimes.

Let’s not forget there’s a third way though, which [Andy] explores with this ball nut modification project. Keen-eyed readers will recall [Andy]’s recent scratch-built ball screw build, in service of some top-secret, hush-hush project related to world domination and total subjugation of humanity. His homebrew efforts in this regard were a great lesson in how to machine a complex mechanism to work in a constrained space. Still, it left folks wondering why he’d go to all the trouble when he could have just trimmed an off-the-shelf part down to size. So, he decided to give that a try.

After securing a ball nut of the proper pitch and diameter, [Andy] looked for ways to shorten it without ruining it. Unfortunately, ball nuts are usually made of hardened steel, which tends to make the usual subtractive methods difficult. But when all else fails, you pull out the metal shop problem solver: the angle grinder. That had the benefit of shortening the nut while simultaneously annealing the steel around the cut, making it possible to face in the lathe. [Andy] put this happy accident to use twice in the build, and it’s a tip we’ll be filing away for a rainy day.

The whole modification process is presented in the video below, which includes testing the modified ball nut. It turned out pretty well, at least in terms of axial backlash. There are compromises, of course, but far fewer than we expected when the sparks started flying from that precision-machined ball nut.

The early 1990s were an interesting time in the PC world, mainly because PCs were entering the zeitgeist for the first time. This was fueled in part by companies like Intel and AMD going head-to-head in the marketplace with massive ad campaigns to build brand recognition; remember “Intel Inside”?

In 1993, Intel was making some headway in that regard. The splashy launch of their new Pentium chip in 1993 was a huge event. Unfortunately an esoteric bug in the floating-point division module came to the public’s attention. [Ken Shirriff]’s excellent account of that kerfuffle goes into great detail about the discovery of the bug. The issue was discovered by [Dr. Thomas R. Nicely] as he searched for prime numbers. It’s a bit of an understatement to say this bug created a mess for Intel. The really interesting stuff is how the so-called FDIV bug, named after the floating-point division instruction affected, was actually executed in silicon.

We won’t presume to explain it better than [Professor Ken] does, but the gist is that floating-point division in the Pentium relied on a lookup table implemented in a programmable logic array on the chip. The bug was caused by five missing table entries, and [Ken] was able to find the corresponding PLA defects on a decapped Pentium. What’s more, his analysis suggests that Intel’s characterization of the bug as a transcription error is a bit misleading; the pattern of the missing entries in the lookup table is more consistent with a mathematical error in the program that generated the table.

The Pentium bug was a big deal at the time, and in some ways a master class on how not to handle a complex technical problem. To be fair, this was the first time something like this had happened on a global scale, so Intel didn’t really have a playbook to go by. [Ken]’s account of the bug and the dustup surrounding it is first-rate, and if you ever wanted to really understand how floating-point math works in silicon, this is one article you won’t want to miss.

This account of running DOOM on a PCB business card isn’t really about serving the “Will it DOOM?” meme of getting the classic game to run on improbable hardware. Rather, this project has more to do with getting it done right and leveraging work that’s already been done.

We’ll explain. You may recall [rsheldiii]’s previous DOOM keycap build, which was quite an accomplishment for someone who doesn’t fancy himself a hardware hacker. But he made a fair number of compromises to pull that build off, and rather than letting those mistakes propagate, he decided to build a more general platform to serve as a jumping-off point for the DOOM building community. The card is centered on the RP2040, which keeps things pretty simple. The card has a tiny LCD screen along with USB jacks for power and a keyboard, so you can actually play the game. It also has GPIO lines brought out to pads on the edge of the board, in case you want to do something other than play the game, which is shown in the brief video below.

Pretty standard stuff, right? Perhaps, but where this project stands out for us is that it stresses the importance of relying on reference circuits. We’ve all seen projects that have been derided for pulling the example circuit from the datasheet, but as [rsheldiii] points out, that seems a little wrongheaded. Component manufacturers put a lot of effort into those circuits, and they don’t do it out of the goodness of their hearts. Yes, they want to make it easier for engineers to choose their parts, but in doing so they’ve done a lot of the work for you. Capitalizing on that work wherever possible only makes sense, and in this case the results were perfect for the task at hand.

A spectrometer is a pretty common lab instrument, useful for determining the absorbance of a sample across a spectrum of light. The standard design is simple; a prism or diffraction grating to break up a light source into a spectrum and a detector to measure light intensity. Shine the light through your sample, scan through the spectrum, and graph the results. Pretty easy.

That’s not the only way to do it, though, as [Markus Bindhammer] shows with this proof-of-concept UV/visible spectrometer. Rather than a single light source, [Marb] uses six discrete LEDs, each with a different wavelength. The almost-a-rainbow’s-worth of LEDs are mounted on circular PCB, which is mounted to a stepper motor through a gear train. This allows the instrument to scan through all six colors, shining each on the sample one at a time. On the other side of the flow-through sample cuvette is an AS7341 10-channel color sensor, which can measure almost the entire spectrum from UV to IR.

The one place where this design seems iffy is that the light source spectrum isn’t continuous, as it would be in a more traditional design. But [Marb] has an answer for that; after gathering data at each wavelength, he applies a cubic spline interpolation to derive the spectrum. It’s demonstrated in the video below using chlorophyll extracted from spinach leaves, and it seems to generate a reasonable spectrum. We suppose this might miss a narrow absorbance spike, but perhaps this could be mitigated by adding a few more LEDs to the color wheel.

Can you use brake cleaner for flux removal on PCBs? According to [Half Burnt Toast], yes you can. But should you? Well, that’s another matter.

In our experience, flux removal seems to be far more difficult than it should be. We’ve seen plenty of examples of a tiny drop of isopropyl alcohol and a bit of light agitation with a cotton swab being more than enough to loosen up even the nastiest baked-on flux. If we do the same thing, all we get is a gummy mess embedded with cotton fibers smeared all over the board. We might be doing something wrong, or perhaps using the wrong flux, but every time we get those results, we have to admit toying with the idea of more extreme measures.

[Toast] went there, busting out a fresh can of brake cleaner and hosing down some of the crustier examples in his collection. The heady dry-cleaner aroma of perchloroethylene was soon in the air, and the powerful solvent along with the high-pressure aerosol blast seemed to work wonders on flux. The board substrate, the resist layer, and the silkscreen all seemed unaffected by the solvent, and the components were left mostly intact; one LED bar graph display did a little melty, though.

So it works, but you might want to think twice about it. The chlorinated formula he used for these tests is pretty strong stuff, and isn’t even available in a lot of places. Ironically, the more environmentally friendly stuff seems like it would be even worse, loaded as it is with acetone and toluene. Whichever formula you choose, proceed with caution and use the appropriate PPE.

What even is flux, and what makes it so hard to clean? Making your own might provide some answers.

It’s a fair bet that most of us have a ton of wireless doo-dads around the house, from garage door remotes to wireless thermometers. Each of these gadgets seems to have its own idea about how to encode data and transmit it, all those dedicated receivers seem wasteful. Wouldn’t it be great to use existing RF infrastructure to connect your wireless stuff?

[Malte Pöggel] thinks so, and this LoRa rain gauge is the result. The build starts with a commercially available rain transmitter, easily found on the cheap as an accessory for a wireless weather station and already equipped with an ISM band transmitter. The rain-collection funnel and tipping-bucket mechanism were perfectly usable, and the space vacated by the existing circuit boards left plenty of room to play, not to mention a perfectly usable battery compartment. [Malte] used an ATmega328P microcontroller to count the tipping of the bucket, either through the original reed switch or via Hall Effect or magnetoresistive sensors. An RFM95W LoRa module takes care of connecting into [Malte]’s LoRaWAN gateway, and there’s an option to add a barometric pressure and temperature sensor, either by adding the BMP280 chip directly to the board or by adding a cheap I2C module, for those who don’t relish SMD soldering.

[Malte] put a lot of work into power optimization, and it shows. A pair of AA batteries should last at least three years, and the range is up to a kilometer—far more than the original ISM connection could have managed. Sure, this could have been accomplished with a LoRa module and some jumper wires, but this looks like a fantastic way to get your feet wet in LoRa design. You could even print your own tipping bucket collector and modify the electronics if you wanted.

Early Monday morning, while many of us will be putting the finishing touches — or just beginning, ahem — on our Christmas preparations, solar scientists will hold their collective breath as they wait for word from the Parker Solar Probe’s record-setting passage through the sun’s atmosphere. The probe, which has been in a highly elliptical solar orbit since its 2018 launch, has been getting occasional gravitational nudges by close encounters with Venus. This has moved the perihelion ever closer to the sun’s surface, and on Monday morning it will make its closest approach yet, a mere 6.1 million kilometers from the roiling photosphere. That will put it inside the corona, the sun’s extremely energetic atmosphere, which we normally only see during total eclipses. Traveling at almost 700,000 kilometers per hour, it won’t be there very long, and it’ll be doing everything it needs to do autonomously since the high-energy plasma of the corona and the eight-light-minute distance makes remote control impossible. It’ll be a few days before communications are re-established and the data downloaded, which will make a nice present for the solar science community to unwrap.

While Parker has been in a similar position on previous orbits and even managed a fortuitous transit of a coronal mass ejection, this pass will be closer and faster than any previous approach. It’s the speed that really grabs our attention, though, as Parker will be traveling at a small but significant fraction of the speed of light for a bit. That makes us wonder if there was any need for mission planners to allow for relativistic effects. We’d imagine so; satellite navigation systems need to take relativity into account to work, and they don’t move anywhere near as fast as Parker. Time will be running slower for Parker at those speeds, and it sure seems like that could muck things up, especially regarding autonomous operation.

Ever since the seminal work of Cameron, Hamilton, Schwarzenegger, et al, it has been taken as canon that the end of humanity will come about when the moral equivalent of SkyNet becomes self-aware and launches all the missiles at once to blot us out with a few minutes of thermonuclear fire. But it looks like AI might be trying to raise an army of grumpy teenagers if this lawsuit over violence-inciting chatbots is any indication. The federal product liability lawsuit targets Character.AI, an outfit that creates LLM-powered chatbots for kids, for allegedly telling kids to do some pretty sketchy stuff. You can read the details in the story, but suffice it to say that one of the chatbots was none too pleased with someone’s parents for imposing screen time rules and hinted rather strongly about how the child should deal with them. The chat logs of that interaction and others that are part of the suit are pretty dark, but probably no darker than the advice that most teenagers would get online from their carbon-based friends. That’s the thing about chatbots; when an LLM is trained with online interactions, you pretty much know what’s going to come out.

In today’s “Who could have seen that coming?” segment, we have a story about how drivers are hacked by digital license plates and are keen to avoid tolls and tickets. The exploit for one specific brand of plate, Reviver, and while it does require physical access to the plates, it doesn’t take much more than the standard reverse engineering tools and skills to pull off. Once the plates are jailbroken — an ironic term given that license plate manufacturing has historically been a prison industry — the displayed numbers can be changed at will with a smartphone app. The worst part about this is that the vulnerability is baked right into the silicon, so there’s nothing to be patched; the plates would have to be recalled, and different hardware would need to be reissued. We’ve been skeptical about the need for these plates from the beginning and questioned why anyone would pay extra for them (last item). But maybe the ability to dump your traffic cam violations into someone else’s lap is worth the extra $20 a month.

And finally, this local news story from Great Falls, Montana, is a timely reminder of how machine tools can mess up your life if you let them. Machinist Butch Olson was alone at work in his machine shop back on December 6 when the sleeve of his jacket got caught in a lathe. The powerful machine pulled his arm in and threatened to turn him to a bloody pulp, but somehow, he managed to brace himself against the bed. He fought the lathe for 20 whole minutes before the motor finally gave out, which let him disentangle himself and get some help. He ended up with a broken back, four fractured ribs, and an arm that looks “like hamburger” according to his sister. That’s a high price to pay, but at least Butch gets to brag that he fought a lathe and won.

What’s the best way to measure the depth of a well using a smartphone? If you’re fed up with social media, you might kill two birds with one stone and drop the thing down the well and listen for the splash. But if you’re looking for a less intrusive — not to mention less expensive — method, you could also use your phone to get the depth acoustically.

This is a quick hack that [Practical Engineering Solutions] came up with to measure the distance to the surface of the water in a residential well, which we were skeptical would work with any precision due to its deceptive simplicity. All you need to do is start a sound recorder app and place the phone on the well cover. A few taps on the casing of the well with a hammer send sound impulses down the well; the reflections from the water show up in the recording, which can be analyzed in Audacity or some similar sound editing program. From there it’s easy to measure how long it took for the echo to return and calculate the distance to the water. In the video below, he was able to get within 3% of the physically measured depth — pretty impressive.

Of course, a few caveats apply. It’s important to use a dead-blow hammer to avoid ringing the steel well casing, which would muddle the return signal. You also might want to physically couple the phone to the well cap so it doesn’t bounce around too much; in the video it’s suggested a few bags filled with sand as ballast could be used to keep the phone in place. You also might get unwanted reflections from down-hole equipment such as the drop pipe or wires leading to the submersible pump.

Sources of error aside, this is a clever idea for a quick measurement that has the benefit of not needing to open the well. It’s also another clever use of Audacity to use sound to see the world around us in a different way.

If you want to build semiconductors at home, it seems like the best place to start might be to find a used scanning electron microscope on eBay. At least that’s how [Peter Bosch] kicked off his electron beam lithography project, and we have to say the results are pretty impressive.

Now, most of the DIY semiconductor efforts we’ve seen start with photolithography, where a pattern is optically projected onto a substrate coated with a photopolymer resist layer so that features can be etched into the surface using various chemical treatments. [Peter]’s method is similar, but with important differences. First, for a resist he chose poly-methyl methacrylate (PMMA), also known as acrylic, dissolved in anisole, an organic substance commonly used in the fragrance industry. The resist solution was spin-coated into a test substrate of aluminized Mylar before going into the chamber of the SEM.

As for the microscope itself, that required a few special modifications of its own. Rather than rastering the beam across his sample and using a pattern mask, [Peter] wanted to draw the pattern onto the resist-covered substrate directly. This required an external deflection modification to the SEM, which we’d love to hear more about. Also, the SEM didn’t support beam blanking, meaning the electron beam would be turned on even while moving across areas that weren’t to be exposed. To get around this, [Peter] slowed down the beam’s movements while exposing areas in the pattern, and sped it up while transitioning to the next feature. It’s a pretty clever hack, and after development and etching with a cocktail of acids, the results were pretty spectacular. Check it out in the video below.

It’s pretty clear that this is all preliminary work, and that there’s much more to come before [Peter] starts etching silicon. He says he’s currently working on a thermal evaporator to deposit thin films, which we’re keen to see. We’ve seen a few sputtering rigs for thin film deposition before, but there are chemical ways to do it, too.

Back in the bad old days, dealing with DNA and RNA in a lab setting was often fraught with peril. Detection technologies were limited to radioisotopes and hideous chemicals like ethidium bromide, a cherry-red solution that was a fast track to cancer if accidentally ingested. It took time, patience, and plenty of training to use them, and even then, mistakes were commonplace.

Luckily, things have progressed a lot since then, and fluorescence detection of nucleic acids has become much more common. The trouble is that the instruments needed to quantify these signals are priced out of the range of those who could benefit most from them. That’s why [Will Anderson] et al. came up with DIYNAFLUOR, an open-source nucleic acid fluorometer that can be built on a budget. The chemical principles behind fluorometry are simple — certain fluorescent dyes have the property of emitting much more light when they are bound to DNA or RNA than when they’re unbound, and that light can be measured easily. DIYNAFLUOR uses 3D-printed parts to hold a sample tube in an optical chamber that has a UV LED for excitation of the sample and a TLS2591 digital light sensor to read the emitted light. Optical bandpass filters clean up the excitation and emission spectra, and an Arduino runs the show.

The DIYNAFLUOR team put a lot of effort into making sure their instrument can get into as many hands as possible. First is the low BOM cost of around $40, which alone will open a lot of opportunities. They’ve also concentrated on making assembly as easy as possible, with a solder-optional design and printed parts that assemble with simple fasteners. The obvious target demographic for DIYNAFLUOR is STEM students, but the group also wants to see this used in austere settings such as field research and environmental monitoring. There’s a preprint available that shows results with commercial fluorescence nucleic acid detection kits, as well as detailing homebrew reagents that can be made in even modestly equipped labs.

Does “Pix or it didn’t happen” apply to traveling to the edge of space on a balloon-lofted solar observatory? Yes, it absolutely does.

The breathtaking views on this page come courtesy of IRIS-2, a compact imaging package that creators [Ramón García], [Miguel Angel Gomez], [David Mayo], and [Aitor Conde] recently decided to release as open source hardware. It rode to the edge of space aboard Sunrise III, a balloon-borne solar observatory designed to study solar magnetic fields and atmospheric plasma flows.

To do that the observatory needed a continual view of the Sun over an extended period, so the platform was launched from northern Sweden during the summer of 2024. It rose to 37 km (23 miles) and stayed aloft in the stratosphere tracking the never-setting Sun for six and a half days before landing safely in Canada.

Strictly speaking, IRIS-2 wasn’t part of the primary mission, at least in terms of gathering solar data. Rather, the 5 kg (11 pound) package was designed to provide engineering data about the platform, along with hella cool video of the flight. To that end, it was fitted with four GoPro cameras controlled by an MPS340 microcontroller. The cameras point in different directions to capture all the important action on the platform, like the main telescope slewing to track the sun, as well as details of the balloon system itself.

The controller was programmed to record 4K video at 30 frames per second during launch and landing, plus fifteen minutes of 120 FPS video during the balloon release. The rest of the time, the cameras took a single frame every two minutes, which resulted in some wonderful time-lapse sequences. The whole thing was powered by 56 AA batteries, and judging by the video below it performed flawlessly during the flight, despite the penetrating stratospheric cold and blistering UV exposure.

Hats off to the IRIS-2 team for this accomplishment. Sure, the videos are a delight, but this is more than just eye candy. Seeing how the observatory and balloon platform performed during flight provides valuable engineering data that will no doubt improve future flights.

It looks like we won’t have Cruise to kick around in this space anymore with the news that General Motors is pulling the plug on its woe-beset robotaxi project. Cruise, which GM acquired in 2016, fielded autonomous vehicles in various test markets, but the fleet racked up enough high-profile mishaps (first item) for California regulators to shut down test programs in the state last year. The inevitable layoffs ensued, and GM is now killing off its efforts to build robotaxis to concentrate on incorporating the Cruise technology into its “Super Cruise” suite of driver-assistance features for its full line of cars and trucks. We feel like this might be a tacit admission that surmounting the problems of fully autonomous driving is just too hard a nut to crack profitably with current technology, since Super Cruise uses eye-tracking cameras to make sure the driver is paying attention to the road ahead when automation features are engaged. Basically, GM is admitting there still needs to be meat in the seat, at least for now.

Speaking of accidents, the results of the first aircraft accident investigation on another world were released this week, and there were a few surprises. Ingenuity, the little helicopter that hitched a ride to Mars in the belly of the Perseverance rover in 2021, surpassed all expectations by completing 71 flights successfully and becoming an integral part of the search for ancient life on Mars. But flight 72 proved to be a bridge too far and ended with a hard landing that terminally damaged its rotor system. At the time it was speculated that the relatively bland terrain it was flying over at the time of the accident was the root cause. This was confirmed by analysis of the flight logs, but the degree to which the flight computer’s down-looking navigation camera was confused by the featureless dunes is new information. As for why the rotor blades broke, it doesn’t appear that it was because they impacted the surface. Rather, as Scott Manley points out, the blades appear to have broken at their weakest point due to extreme flexing induced by the high vertical speed while touching down on a slope, which caused one set of legs to hit the surface before the others.

Also roughly in the realm of space-based failures comes the story of a hapless senior citizen in New York who has been issued thousands of dollars in traffic tickets because of her love for Star Trek. Years ago, Long Island resident Beda Koorey got a New York vanity license plate for her car emblazoned with “NCC-1701,” the registration number of the USS Enterprise. She turned in those plates years ago when she gave up driving, but in the meantime, novelty NCC-1701 plates began popping up on Amazon and other sites. They were clearly not intended to be used on cars, but that didn’t stop some people from putting them on over their real plates in an attempt to defeat traffic cameras. It worked, at least from their point of view, since it left poor Beda with a collection of tickets for speeding and red light violations from as far away as Chicago. She even got a ticket for a violation committed by a motorcycle with a phony plate, which you think would not map to the registration for an automobile, but there you go. We always knew it was hard to be a Trekkie, especially back in the ’70s, but at least it never cost us much money. It did cost us a lot of dates, though.

We featured plenty of stories of start-up tech companies with the next must-have IoT device that fold up shop after a few years and abandon their users by effectively bricking their widgets. Heck, we’ve even suffered that fate ourselves; curse you, Logitech, for killing the SqueezeBox. However, one company recently took IoT bricking to a new low by ending support for a line of AI-powered companion bots for kids. The company was called Embodied, and they hawked $800 AI bots for kids called Moxie, with a cute face and a huggable form factor that kids couldn’t help falling in love with. Embodied couldn’t make a go of it financially and since Moxie uses a cloud-based LLM to interact with kids, the bots are now bricked. This leaves parents who invested in these devices with the quandary of having to explain to young kids that their robot pal is dead. Some of the TikToks of parents breaking the news are heartbreaking, and we can’t help but think that this is a perfect opportunity for someone in our community to reverse-engineer these things and bring them back to life.

And finally, the burning of the Yule Log is an ancient tradition, one that reminds us of the time our grandfather brought an entire telephone pole that had washed up on the beach home and burned it for days on end, feeding it slowly into the fireplace in the living room through the open front door. Good times. Not everyone is blessed with a fireplace in their abode, though, which has given rise to the popularity of video Yule Logs that you can just play on your TV. And now NASA is in on the action with an eight-hour 4K video of the SLS main engines and boosters. Framed by a lovely stone fireplace and replete with crackling wood sound effects over the subdued roar of the four RS-25 engines and twin solid-fuel boosters, it’ll make a nice addition to your holiday festivities. Although given that NASA just announced that the next Artemis missions are delayed until at least 2026, we’re not sure that it’s a great idea to show a rocket that never lifts off. You’ll also want to be careful that the neighbors don’t see the action.

For the amateur radio operator with that on-the-go lifestyle, nothing is more important than having your gear as light and packable as possible. If you’re lugging even a modest setup out into the woods, every ounce counts, which is why we love projects like this packable dipole antenna feedpoint.

At its simplest, a dipole antenna is just two pieces of wire cut to a specific, frequency-dependent length connected to a feedline. In practical terms, though, complications arise, such as keeping common-mode currents off the feedline and providing sturdy mechanical support for the antenna to suspend it safely. [Ham Radio Dude]’s design handles both those requirements while staying as small and packable as possible. The design starts with a bifilar 1:1 current balun, which is wound on an FT82-43 ferrite toroid with 22 AWG magnet wire. One side of the balun is connected to a BNC connector while the other is connected to a pair of Wago splice connectors that are glued together. A loop of paracord for mechanical strain relief is added, and the whole thing gets covered in heat-shrink tubing. The antenna is deployed by attaching a feedline to the BNC, clipping quarter-wave wires into the Wago terminals, and hoisting the whole thing aloft. Full build details are in the video below.

People will no doubt be quick to point out that these Wago terminals are rated for a minimum of 18 AWG wire, making them inappropriate for use with fine magnet wire. True enough, but [Dude] was able to get continuity through the Wagos, so the minimum gauge is probably more of an electrical code thing. Still, you’ll want to be careful that the connections stay solid, and it might pay to look at alternatives to the Wago brand, too.

We haven’t seen [Les Wright] in a while, and with the release of his new video, we know why — he’s been busy growing crystals.

Now, that might seem confusing to anyone who has done the classic “Crystal Garden” trick with table salt and laundry bluing, or tried to get a bit of rock candy out of a supersaturated sugar solution. Sure, growing crystals takes time, but it’s not exactly hard work. But [Les] isn’t in the market for any old crystals. Rather, he needs super-sized, optically clear crystals of potassium dihydrogen phosphate, or KDP, which are useful as frequency doublers for lasers. [Les] has detailed his need for KDP crystals before and even grown some nice ones, but he wanted to step up his game and grow some real whoppers.

And boy, did he ever. Fair warning; the video below is long and has a lot of detail on crystal-growing theory, but it’s well worth it for anyone taking the plunge. [Les] ended up building an automated crystal lab, housing it in an old server enclosure for temperature and dust control. The crystals are grown on a custom-built armature that slowly rotates in a supersaturated solution of KDP which is carefully transitioned through a specific temperature profile under Arduino control. As a bonus, he programmed the rig to take photographs of the growing crystals at intervals; the resulting time-lapse sequences are as gorgeous as the crystals, one of which grew to 40 grams in only a week.

We’re keen to see how [Les] puts these crystals to work, and to learn exactly what a “Pockels Cell” is and why you’d want one. In the meantime, if you’re interested in how the crystals that make the whole world work are made, check out our deep dive into silicon.

Thanks to [Joseph Hopfield] for the tip.