The General Instruments AY-3-8910 was a quite popular Programmable Sound Generator (PSG) that saw itself used in a wide variety of systems, including Apple II soundcards such as the Mockingboard and various arcade systems. In addition to the Yamaha variants (e.g. YM2149), two cut-down were created by GI: these being the AY-3-8912 and the AY-3-8913, which should have been differentiated only by the number of GPIO banks broken out in the IC package (one or zero, respectively). However, research by [fenarinarsa] and others have shown that the AY-3-8913 variant has some actual hardware issues as a PSG.

With only 24 pins, the AY-3-8913 is significantly easier to integrate than the 40-pin AY-3-8910, at the cost of the (rarely used) GPIO functionality, but as it turns out with a few gotchas in terms of timing and register access. Although the Mockingboard originally used the AY-3-8910, latter revisions would use two AY-3-8913 instead, including the MS revision that was the Mac version of the Mindscape Music Board for IBM PCs.

The first hint that something was off with the AY-3-8913 came when [fenarinarsa] was experimenting with effect composition on an Apple II and noticed very poor sound quality, as demonstrated in an example comparison video (also embedded below). The issue was very pronounced in bass envelopes, with an oscilloscope capture showing a very distorted output compared to a YM2149. As for why this was not noticed decades ago can likely be explained by that the current chiptune scene is pushing the hardware in very different ways than back then.

As for potential solutions, the [French Touch] project has created an adapter to allow an AY-3-8910 (or YM2149) to be used in place of an AY-3-8913.

Top image: Revision D PCB of Mockingboard with GI AY-3-8913 PSGs.

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If we asked you to name Alexander Graham Bell’s greatest invention, you would doubtless say “the telephone”; it’s probably the only one of his many, many inventions most people could bring to mind. If you asked Bell himself, though, he would tell you his greatest invention was the photophone, and if the prolific [Nick Bild] doesn’t agree he’s at least intrigued enough to produce a replica of this 1880-vintage wireless telephone. Yes, 1880. As in, only four years after the telephone was patented.

It obviously did not catch on, and is not the sort of thing that comes to mind when we think “wireless telephone”. In contrast to the RF of the 20th century version, as you might guess from the name the photophone used light– sunlight, to be specific. In the original design, the transmitter was totally passive– a tube with a mirror on one end, mounted to vibrate when someone spoke into the open end of the tube. That was it, aside from the necessary optics to focus sunlight onto said mirror. [Nick Bild] skips this and uses a laser as a handily coherent light source, which was obviously not an option in 1880. As [Nick] points out, if it was, Bell certainly would have made use of it.

The photophone receiver, 1880 edition. Speaker not pictured.

The receiver is only slightly more complex, in that it does have electronic components– a selenium cell in the original, and in [Nick’s] case a modern photoresistor in series with a 10,000 ohm resistor. There’s also an optical difference, with [Nick] opting for a lens to focus the laser light on his photoresistor instead of the parabolic mirror of the original. In both cases vibration of the mirror at the transmitter disrupts line-of-sight with the receiver, creating an AM signal that is easily converted back into sound with an electromagnetic speaker.

The photophone never caught on, for obvious reasons — traditional copper-wire telephones worked beyond line of sight and on cloudy days–but we’re greatful to [Nick] for dredging up the history and for letting us know about it via the tip line. See his video about this project below.

The name [Nick Bild] might look familiar to regular readers. We’ve highlighted a few of his projects on Hackaday before.

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[Geoffrey Litt] shows that getting an effective digital assistant that’s tailored to one’s own needs just needs a little DIY, and thanks to the kinds of tools that are available today, it doesn’t even have to be particularly complex. Meet Stevens, the AI assistant who provides the family with useful daily briefs. The back end? Little more than one SQLite table and a few cron jobs.

A sample of Stevens’ notebook entries, both events and things to simply remember.

Every day, Stevens sends a daily brief via Telegram that includes calendar events, appointments, weather notes, reminders, and even a fun fact for the day. Stevens isn’t just send-only, either. Users can add new entries or ask questions about items through Telegram.

It’s rudimentary, but [Geoffrey] already finds it far more useful than Siri. This is unsurprising, as it has been astutely observed that big tech’s digital assistants are designed to serve their makers rather than their users. Besides, it’s also fun to have the freedom to give an assistant its own personality, something existing offerings sorely lack.

Architecture-wise, the assistant has a notebook (the single SQLite table) that gets populated with entries. These entries come from things like reading family members’ Google calendars, pulling data from a public weather API, processing delivery notices from the post office, and Telegram conversations. With a notebook of such entries (along with a date the entry is expected to be relevant), generating a daily brief is simple. After all, LLMs (Large Language Models) are amazingly good at handling and formatting natural language. That’s something even a locally-installed LLM can do with ease.

[Geoffrey] says that even this simple architecture is super useful, and it’s not even a particularly complex system. He encourages anyone who’s interested to check out his project, and see for themselves how useful even a minimally-informed assistant can be when it’s designed with ones’ own needs in mind.

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[Chris Cecil] had a problem. He had a Manncorp/Autotronik MC384V2 pick and place, and needed more feeders. The company was reluctant to support an older machine and wanted over $32,000 to supply [Chris] with more feeders. He contemplated the expenditure… but then came across another project which gave him pause. Could he make Siemens feeders work with his machine?

It’s one of those “standing on the shoulders of giants” stories, with [Chris] building on the work from [Bilsef] and the OpenPNP project. He came across SchultzController, which could be used to work with Siemens Siplace feeders for pick-and-place machines. They were never supposed to work with his Manncorp machine, but it seemed possible to knit them together in some kind of unholy production-focused marriage. [Chris] explains how he hooked up the Manncorp hardware to a Smoothieboard and then Bilsef’s controller boards to get everything working, along with all the nitty gritty details on the software hacks required to get everything playing nice.

For an investment of just $2,500, [Chris] has been able to massively expand the number of feeders on his machine. Now, he’s got his pick and place building more Smoothieboards faster than ever, with less manual work on his part.

We feature a lot of one-off projects and home production methods, but it’s nice to also get a look at methods of more serious production in bigger numbers, too. It’s a topic we follow with interest. Video after the break.

[Editor’s note: Siemens is the parent company of Supplyframe, which is Hackaday’s parent company. This has nothing to do with this story.]

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If you’ve worked on a high-end mountain or road bike for any length of time, you have likely cursed the Presta valve. This humble century-old invention is the bane of many a home and professional mechanic. What if there is a better option? [Seth] decided to find out by putting four valves on a single rim.

The contenders include the aforementioned Presta, as well as Schrader, Dunlop and the young gun, Click. Schrader and Dunlop both pre-date Presta, with Schrader finding prevalence in cruiser bicycles along with cars and even aircraft. Dunlop is still found on bicycles in parts of Asia and Europe. Then came along Presta some time around 1893, and was designed to hold higher pressures and be lower profile then Schrader and Dunlop. It found prevalence among the weight conscious and narrow rimmed road bike world and, for better or worse, stuck around ever since.

But there’s a new contender from industry legend Schwalbe called Click. Click comes with a wealth of nifty modern engineering tricks including its party piece, and namesake, of a clicking mechanical locking system, no lever, no screw attachment. Click also fits into a Presta valve core and works on most Presta pumps. Yet, it remains to be seen whether Click is just another doomed standard, or the solution to many a cyclists greatest headache.

This isn’t the first time we’ve seen clever engineering going into a bike valve.

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A dog may be man’s best friend, but many of us live with cats, fish, iguanas, or even wilder animals. And naturally, we like to share our hacks with our pets. Whether it’s a robot ball-thrower, a hamster wheel that’s integrated into your smart home system, or even just an automatic feeder for when you’re not home, we want to see what kind of projects that your animal friends have inspired you to pull off.

The three top choices will take home $150 gift certificates from DigiKey, the contest’s sponsor, so that you can make even more pet-centric projects. You have until May 27th to get your project up on Hackaday.io, and get it entered into Pet Hacks.

Honorable Mention Categories

Of course, we have a couple thoughts about fun directions to take this contest, and we’ll be featuring entries along the way. Just to whet your whistle, here are our four honorable mention categories.

Pet Safety: Nothing is better than a hack that helps your pet stay out of trouble. If your hack contributes to pet safety, we want to see it.Playful Pets: Some hacks are just for fun, and that goes for our pet hacks too. If it’s about amusing either your animal friend or even yourself, it’s a playful pet hack.Cyborg Pets: Sometimes the hacks aren’t for your pet, but on your pet. Custom pet prosthetics or simply ultra-blinky LED accouterments belong here.Home Alone: This category is for systems that aim to make your pet more autonomous. That’s not limited to vacation feeders – anything that helps your pet get along in this world designed for humans is fair game.

Inspiration

We’ve seen an amazing number of pet hacks here at Hackaday, from simple to wildly overkill. And we love them all! Here are a few of our favorite pet hacks past, but feel free to chime in the comments if you have one that didn’t make our short list.

Let’s start off with a fishy hack. Simple aquariums don’t require all that much attention or automation, so they’re a great place to start small with maybe a light controller or something that turns off your wave machine every once in a while. But when you get to the point of multiple setups, you might also want to spend a little more time on the automation. Or at least that’s how we imagine that [Blue Blade Fish] got to the point of a system with multiple light setups, temperature control, water level sensing, and more. It’s a 15-video series, so buckle in.

OK, now let’s talk cats. Cats owners know they can occasionally bring in dead mice, for which a computer-vision augmented automatic door is the obvious solution. Or maybe your cats spend all their time in the great outdoors? Then you’ll need a weather-proof automatic feeder for the long haul. Indoor cats, each with a special diet? Let the Cat-o-Matic 3000 keep track of who has been fed. But for the truly pampered feline, we leave for your consideration the cat elevator and the sun-tracking chair.

Dogs are more your style? We’ve seen a number of automatic ball launchers for when you just get tired of playing fetch. But what tugged hardest at our heartstrings was [Bud]’s audible go-fetch toy that he made for his dog [Lucy] when she lost her vision, but not her desire to keep playing. How much tech is too much tech? A dog-borne WiFi hotspot, or a drone set up to automatically detect and remove the dreaded brown heaps?

Finally, we’d like to draw your attention to some truly miscellaneous pet hacks. [Mr. Goxx] is a hamster who trades crypto, [Mr. Fluffbutt] runs in a VR world simulation hamster wheel, and [Harold] posts his workouts over MQTT – it’s the Internet of Hamsters after all. Have birds? Check out this massive Chicken McMansion or this great vending machine that trains crows to clean up cigarette butts in exchange for peanuts.

We had a lot of fun looking through Hackaday’s back-catalog of pet hacks, but we’re still missing yours! If you’ve got something you’d like us all to see, head on over to Hackaday.io and enter it in the contest. Fame, fortune, and a DigiKey gift certificate await!

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If you’re into electronics you can never have too many digital multimeters (DMMs). They all have different features, and if you want to make multiple measurements simultaneously, it can pay to have a few. Over on his video blog [joe smith] reviews the new Brymen BM788BT, which is a new entry into the Bluetooth logging meter category.

This is a two-part series: in the first he runs the meter through its measurement paces, and in the second he looks at the Bluetooth software interface. And when we say “new” meter, we mean brand new, this is a review unit that you can’t yet get in stores.

According to a post on the EEVblog, this Bluetooth variant was promised five years ago, and back then Brymen even had the Bluetooth module pin header on the PCB, but it has taken a long time to get the feature right. If you scroll through the thread you will find that Brymen has made its protocol specification available for the BM780 series meters.

It looks like some Bluetooth hacking might be required to get the best out of this meter. Of course we’re no strangers to hacking DMMs around here. We’ve taken on the Fluke 77 for example, and these DMM tweezers.

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Image by [akavel] via GitHubReader [akavel] was kind enough to notify me about Clawtype, which is a custom wearable chorded keyboard/mouse combo based on the Chordite by [John W. McKown].

First of all, I love the brass rails — they give it that lovely circuit sculpture vibe. This bad boy was written in Rust and currently runs on a SparkFun ProMicro RP2040 board. For the mouse portion of the program, there’s an MPU6050 gyro/accelerometer.

[akavel]’s intent was to pair it with XR glasses, which sounds like a great combination to me. While typing is still a bit slow, [akavel] is improving at a noticeable pace and does some vim coding during hobby time.

In the future, [akavel] plans to try a BLE version, maybe even running off a single AA Ni-MH cell, and probably using an nRF52840. As for the 3D-printed shape, that was designed and printed by [akavel]’s dear friend [Cunfusu], who has made the files available over at Printables. Be sure to check it out in the brief demo video after the break.

Wooden You Like To Use the Typewriter?

Image by [bilbonbigos] via redditI feel a bit late to the party on this one, but that’s okay, I made an nice entrance. The Typewriter is [bilbonbigos]’ lovely distraction-free writing instrument that happens to be primarily constructed of wood. In fact, [bilbonbigos] didn’t use any screws or nails — the whole thing is glued together.

The Typewriter uses a Raspberry Pi 3B+, and [bilbonbigos] is FocusWriter to get real work done on it. it runs off of a 10,000 mAh power bank and uses a 7.9″ Waveshare display.

The 60% mechanical keyboard was supposed to be Bluetooth but turned out not to be when it arrived, so that’s why you might notice a cable sticking out.

The whole thing all closed up is about the size of a ream of A4, and [bilbonbigos] intends to add a shoulder strap in order to make it more portable.

That cool notebook shelf doubles as a mousing surface, which is pretty swell and rounds out the build nicely. Still, there are some things [bilbonbigos] would change — a new Raspi, or a lighter different physical support for the screen, and a cooling system.

The Centerfold: A Keyboard For Your House In Palm Springs

Image by [the_real_jamied] via redditCan’t you feel the space age Palm Springs breezes just looking at this thing? No? Well, at least admit that it looks quite atomic-age with that font and those life-preserver modifier keycaps. This baby would look great on one of those giant Steelcase office desks. Just don’t spill your La Croix on it, or whatever they drink in Palm Springs.

Do you rock a sweet set of peripherals on a screamin’ desk pad? Send me a picture along with your handle and all the gory details, and you could be featured here!

Historical Clackers: the Odell Typewriter

First of all, the machine pictured here is not the true Odell number 1 model, which has a pair of seals’ feet at each end of the base and is referred to as the “Seal-Foot Odell“. Ye olde Seal-Foot was only produced briefly in 1889.

Image via The Antikey Chop

But then inventor Levi Judson Odell completely redesigned the thing into what you see here — model 1b, for which he was awarded a patent in 1890. I particularly like the markings on the base. The nickel-plated, rimless model you see here was not typical; most had gold bases.

These babies cost 1/5th of a standard typewriter, and were quite easy to use to boot. With everything laid out in a line, it was far easier to use a slide mechanism than your ten fingers to select each character. On top of everything else, these machines were small enough to take with you.

No matter their appearance, or whether they typed upper case only or both, Odells were all linear index typewriters. The print element is called a type-rail. There is a fabric roller under the type-rail that applies ink to the characters as they pass. Pinch levers on the sides of the carriage did double duty as the carriage advance mechanism and the escapement.

Round-based Odells went by the wayside in 1906 and were replaced by square-based New American No. 5 models. They functioned the same, but looked quite different.

Finally, John Lennon’s Typewriter Is For Sale

Image via Just Collecting

Got an extra ten grand lying around? You could own an interesting piece of history.

This image comes courtesy of Paul Fraser Collectibles, who are selling this typewriter once owned and used by the legendary Beatle himself. While Lennon composed poems and songs on the machine, it’s unclear whether he secretly wanted to be a paperback writer.

This machine, an SCM (Smith-Corona Marchant) Electra 120, is an interesting one; it’s electric, but the carriage return is still manual. I myself have an SCM Secretarial 300, which looks very much the same, but has a frightening ‘Power Return’ that sends the carriage back toward the right with enough power to shake the floor, depending upon the fortitude of your table.

Apparently Lennon would use the machine when traveling, but gave it to a close friend in the music industry when he upgraded or otherwise no longer needed it. A booking agent named Irwin Pate worked with this friend and obtained the typewriter from him, and Irwin and his wife Clarine held on to it until they sold it to Paul Fraser Collectibles. I find it interesting that this didn’t go to auction at Christie’s — I think it would ultimately go for more, but I’m a writer, not an auction-ologist.

Got a hot tip that has like, anything to do with keyboards? [Help me out by sending in a link or two](mailto:tips@hackaday.com?Subject=[Keebin' with Kristina]). Don’t want all the Hackaday scribes to see it? Feel free to [email me directly](mailto:kristinapanos@hackaday.com?Subject=[Keebin' Fodder]).

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We’re probably all familiar with the Hall Effect, at least to the extent that it can be used to make solid-state sensors for magnetic fields. It’s a cool bit of applied physics, but there are other ways to sense magnetic fields, including leveraging the weird world of quantum physics with this diamond, laser, and microwave open-source sensor.

Having never heard of quantum sensors before, we took the plunge and read up on the topic using some of the material provided by [Mark C] and his colleagues at Quantum Village. The gist of it seems to be that certain lab-grown diamonds can be manufactured with impurities such as nitrogen, which disrupt the normally very orderly lattice of carbon atoms and create a “nitrogen vacancy,” small pockets within the diamond with extra electrons. Shining a green laser on N-V diamonds can stimulate those electrons to jump up to higher energy states, releasing red light when they return to the ground state. Turning this into a sensor involves sweeping the N-V diamond with microwave energy in the presence of a magnetic field, which modifies which spin states of the electrons and hence how much red light is emitted.

Building a practical version of this quantum sensor isn’t as difficult as it sounds. The trickiest part seems to be building the diamond assembly, which has the N-V diamond — about the size of a grain of sand and actually not that expensive — potted in clear epoxy along with a loop of copper wire for the microwave antenna, a photodiode, and a small fleck of red filter material. The electronics primarily consist of an ADF4531 phase-locked loop RF signal generator and a 40-dB RF amplifier to generate the microwave signals, a green laser diode module, and an ESP32 dev board.

All the design files and firmware have been open-sourced, and everything about the build seems quite approachable. The write-up emphasizes Quantum Village’s desire to make this quantum technology’s “Apple II moment,” which we heartily endorse. We’ve seen N-V sensors detailed before, but this project might make it easier to play with quantum physics at home.

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There are a number of reasons you might want to build your own smart speaker virtual assistant. Usually, getting your weather forecast from a snarky, malicious AI potato isn’t one of them, unless you’re a huge Portal fan like [Binh Pham].

[Binh Pham] built the potato incarnation of GLaDOS from the Portal 2 video game with the help of a ReSpeaker Light kit, an ESP32-based board designed for speech recognition and voice control, and as an interface for home assistant running on a Raspberry Pi.

He resisted the temptation to use a real potato as an enclosure and wisely opted instead to print one from a 3D file he found on Thingiverse of the original GLaDOS potato. Providing the assistant with the iconic synthetic voice of GLaDOS was a matter of repackaging an existing voice model for use with Home Assistant.

Of course all of this attention to detail would be for not if you had to refer to the assistant as “Google” or “Alexa” to get its attention. A bit of custom modelling and on-device wake word detection, and the cyborg tuber was ready to switch lights on and off with it’s signature sinister wit.

We’ve seen a number of projects that brought Portal objects to life for fans of the franchise to enjoy, even an assistant based on another version of the GLaDOS the character. This one adds a dimension of absurdity to the collection.

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A tornado can be an awe-inspiring sight, but it can also flip your car, trash your house, and otherwise injure you with flying debris. If you’d like to look at swirling air currents in a safer context, you might appreciate this tornado tower build from [Gary Boyd].

[Gary]’s build was inspired by museum demonstrations and the tornado machine designs of [Harald Edens]. His build generates a vortex that spans 1 meter tall in a semi-open cylindrical chamber. A fan in the top of the device sucks in air from the chamber, and exhausts it through a vertical column of holes in the wall of the cylinder. This creates a vortex in the air, though it’s not something you can see on its own. To visualize the flow, the cylindrical chamber is also fitted with an ultrasonic mist generator in the base. The vortex in the chamber is able to pick up this mist, and it can be seen swirling upwards as it is sucked towards the fan at the top.

It’s a nice educational build, and one that’s as nice to look at as it is to study. It produces a thick white vortex that we’re sure someone could turn into an admirable lamp or clock or something, this being Hackaday, after all. In any case, vortexes are well worth your study. If you’re cooking up neat projects with this physical principle, you should absolutely let us know!

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A major bottleneck with high-frequency wireless communications is the conversion from radio frequencies to optical signals and vice versa. This is performed by an electro-optic modulator (EOM), which generally are limited to GHz-level signals. To reach THz speeds, a new approach was needed, which researchers at ETH Zurich in Switzerland claim to have found in the form of a plasmonic phase modulator.

Although sounding like something from a Star Trek episode, plasmonics is a very real field, which involves the interaction between optical frequencies along metal-dielectric interfaces. The original 2015 paper by [Yannick Salamin] et al. as published in Nano Letters provides the foundations of the achievement, with the recent paper in Optica by [Yannik Horst] et al. covering the THz plasmonic EOM demonstration.

The demonstrated prototype can achieve 1.14 THz, though signal degradation begins to occur around 1 THz. This is achieved by using plasmons (quanta of electron oscillators) generated on the gold surface, who affect the optical beam as it passes small slots in the gold surface that contain a nonlinear organic electro optic material that ‘writes’ the original wireless signal onto the optical beam.

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Amazing as volumetric displays are, they have one major drawback: interacting with them is complicated. A 3D mouse is nice, but unless you’ve done a lot of CAD work, it’s a bit unintuitive. Researchers from the Public University of Navarra, however, have developed a touchable volumetric display, bringing touchscreen-like interactions to the third dimension (preprint paper).

At the core, this is a swept-volume volumetric display: a light-diffusing screen oscillates along one axis, while from below a projector displays cross-sections of the scene in synchrony with the position of the screen. These researchers replaced the normal screen with six strips of elastic material. The finger of someone touching the display deforms one or more of the strips, allowing the touch to be detected, while also not damaging the display.

The actual hardware is surprisingly hacker-friendly: for the screen material, the researchers settled on elastic bands intended for clothing, and two modified subwoofers drove the screen’s oscillation. Indeed, some aspects of the design actually cite this Hackaday article. While the citation misattributes the design, we’re glad to see a hacker inspiring professional research.) The most exotic component is a very high-speed projector (on the order of 3,000 fps), but the previously-cited project deals with this by hacking a DLP projector, as does another project we’ve covered.

While interacting with the display does introduce some optical distortions, we think the video below speaks for itself. If you’re interested in other volumetric displays, check out this project, which displays images with a levitating styrofoam bead.

[Thanks to Xavi for the tip!]

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There’s something cool about the visual design language used in the aviation world. You probably don’t get much exposure to it if you’re not regularly flying a plane, but there are other ways you can bring it into your life. A great example would be building an aviation-themed clock, like this stylish timepiece from [oliverb.]

The electronic heart of the build is an ESP32. This wireless-capable microcontroller is a popular choice for clock builds these days. This is because it can contact network time servers out of the box, which allows you to build an incredibly capable and accurate clock without any additional parts. No real-time-clock needed—just have the ESP32 buzz the Internet for an accurate update on the regular!

As for the display itself, three gauges show hours, minutes, and seconds on aviation-like gauges. They’re 3D-printed, which means you can build them from scratch. That’s a touch easier than having to go out and source actual surplus aviation hardware. Each gauge is driven by a NEMA17 stepper motor. There’s also an ATMEGA328 on hand to drive a 7-segment gauge on the seconds display, and a PIR sensor which shuts the clock down when nobody is around to view it.

It’s a tidy build, and one with a compelling aesthetic at that. We’ve seen some similar builds before using real aviation gauges, too. Video after the break.

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The C64 Mini is a beautiful and functional replica of the most popular computer ever made, except at 50% size and without a working keyboard. For maximum nostalgia, it was modeled after the brown breadbox C64 case which so characterized the model. However, [10p6] wanted to build a tiny C64C instead, so set about making a conversion happen.

The build is primarily about the case design. [10p6] created a nice 50% scale duplicate of the C64C, with an eye to making it work with the internals of the popular C64 Mini. The case was paired with a custom PETSCII keyboard PCB and keycaps designed by [Bleugh]. This was a key element, since it wouldn’t really feel like a functional C64C without a functional keyboard. The build also scored a bonus USB hub for more flexibility. For the best possible finish, the case, power button, and keycaps were all printed using a resin printer, which provides a more “production-like” result than FDM printers are capable of.

It’s funny how retro computers remain popular to this day, particularly amongst the hacker set. In contrast, we don’t see a whole lot of people trying to replicate Pentium II machines from the mid-1990s. If you do happen to have a crack at it, though, the tipsline is always open. Video after the break.

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The best kind of Hackaday posts are the ones where there was some insurmountable problem with an elegant solution devised through deep analysis of the problem and creativity. This is not one of those posts. I’m sure you are familiar with bit rot. You know, something works for a long time and then, for no apparent reason, stops working. Well, that has been biting me, and lacking the time for the creative, elegant solution, I decided to attack it with a virtual chainsaw.

It all started with a 2022 Linux Fu about using autokey.

The Problem

I use autokey to give me emacs-style keystrokes in Web browsers and certain other programs. It intercepts keystrokes and translates them into other keystrokes. The problem is, the current Linux community hates autokey. Well, that’s not strictly true. They just love Wayland more. One reason I won’t switch from X11 is that I haven’t found a way to do something like I do with autokey. But since most of the powers-that-be have decided that X11 is bad and Wayland is good, X11 development is starting to show cracks.

In particular, autokey isn’t in the normal repositories for my distro anymore (KDE Neon). Of course, I’ve installed the latest version myself. I’m perfectly capable of doing that or even building from source. But lately, I’ve noticed my computer hangs, especially after sleeping for a long time. Also, after a long time, I notice that autokey just quits working. It is running but not working and I have to restart it. The memory consumption seems high when this happens.

You know how it is. Your system has quirks; you just live with them for a while. But eventually those paper cuts add up. I finally decided I needed to tackle the issue. But I don’t really have time to go debug autokey, especially when it takes hours for the problem to manifest.

The Chainsaw

I’ll say it upfront: Finding the memory leak would be the right thing to do. Build with debug symbols. Run the code and probe it when the problem comes up. Try to figure out what combination of X11, evdev, and whatever other hocus pocus it uses is causing this glitch.

But who’s got time for that? I decided that instead of launching autokey directly, I’d launch a wrapper script. I already had autokey removed from the KDE session so that I don’t try to start it myself and then get the system restaring it also. But now I run the wrapper instead of autokey.

So what does the wrapper do? It watches the memory consumption of autokey. Sure enough, it goes up just a little bit all the time. When the script sees it go over a threshold it kills it and restarts it. It also restarts if autokey dies, but I rarely see that.

What’s Memory Mean?

The problem is, how do you determine how much memory a process is using? Is it the amount of physical pages it has? The virtual space? What about shared libraries? In this case, I don’t really care as long as I have a number that is rising all the time that I can watch.

The /proc file system has a directory for each PID and there’s a ton of info in there. One of them is an accounting of memory. If you look at /proc/$PID/smaps for some program you’ll see something like this:

00400000-00420000 r--p 00000000 fd:0e 238814592 /usr/bin/python3.12 Size: 128 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 128 kB Pss: 25 kB Pss_Dirty: 0 kB Shared_Clean: 128 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 128 kB Anonymous: 0 kB KSM: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 0 kB FilePmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB Locked: 0 kB THPeligible: 0 VmFlags: rd mr mw me sd 00420000-00703000 r-xp 00020000 fd:0e 238814592 /usr/bin/python3.12 Size: 2956 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 2944 kB Pss: 595 kB Pss_Dirty: 0 kB Shared_Clean: 2944 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 0 kB . . .

Note that there is a section for each executable and shared object along with lots of information. You can get all the PSS (proportional set size) numbers for each module added together like this (among other ways):

cat /proc/$PID/smaps | grep -i pss | awk '{Total+=$2} END { print Total}'

Building the Chainsaw

So armed with that code, it is pretty easy to just run the program, see if it is eating up too much memory, and restart it if it is. I also threw in some optional debugging code.

#!/bin/bash #- Run autokey, kill it if it gets too big #- what's too big? $MLIMIT MLIMIT=500000 #- how often to check (seconds) POLL=10

#- Print debug info if you want function pdebug { #- comment out if you don't want debugging. Leave in if you do #- echo $1 $2 $3 $4 }

while true # do forever do PID=$(pgrep autokey-qt) # find autokey pdebug "PID",$PID if [ ! -z "$PID" ] # if it is there then # get the memory size PSS=$(cat /proc/$PID/smaps | grep -i pss | awk '{Total+=$2} END { print Total}') pdebug "PSS", $PSS echo $PSS >>/tmp/autokey-current.log # too big? if [ "$PSS" -gt "$MLIMIT" ] then pdebug "Kill" echo Killed >>/tmp/autokey-current.log # save old log before we start another cp /tmp/autokey-current.log /tmp/autokey-$PID.log kill $PID PID= sleep 2 fi fi if [ -z $PID ] then # if died, relaunch pdebug "Launch" autokey-qt & 2>&1 >/tmp/autokey-current.log fi pdebug "Sleep" sleep $POLL done

In practice, you’ll probably want to remove the cp command that saves the old log, but while troubleshooting, it is good to see how often the process is killed. Running this once with a big number gave me an idea that PSS was about 140,000 but rising every 10 seconds. So when it gets to 500,000, it is done. That seems to work well. Obviously, you’d adjust the numbers for whatever you are doing.

Bad Chainsaw

There are lots of ways this could have been done. A systemd timer, for example. Maybe even a cgroup. But this works, and took just a few minutes. Sure, a chainsaw is a lot to just cut a 2×4, but then again, it will go through it like a hot knife through butter.

I did consider just killing autokey periodically and restarting it. The problem is I work odd hours sometimes, and that means I’d have to do something like tie it to the screensaver. But I agree there are dozens of ways to do this, including to quit using autokey. What would your solution be? Let us know in the comments. Have you ever resorted to a trick this dirty?

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The ESP32 series of microprocessors with their cheap high-power cores and built-in wireless networking have brought us a wide variety of impressive projects over the years. We’re not sure we’ve quite seen the like of [Jonathan R]’s video walkie talkie before though, a pair of units which as you might guess, deliver two-way video and audio communications.

The trick involves not one but two ESP32s: an ESP32-S3 based camera module, and a more traditional Tensilica ESP32 in a screen module. It’s an opportunity for an interesting comparison, as one device uses the Cheap Yellow Display board, and the other uses an Elecrow equivalent. The audio uses ESP-NOW, while the video uses WiFi, and since the on-board audio amplifiers aren’t great, there’s a small amp module.

The video below has a comprehensive run-down including the rationale behind the design choices, as well as a demonstration. There’s a small lag, but nothing too unacceptable for what is after all an extremely cheap device. Perhaps after all this time, the video phone has finally arrived!

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An occasional series of mine on these pages has been Daily Drivers, in which I try out operating systems from the point of view of using them for my everyday Hackaday work. It has mostly featured esoteric or lesser-used systems, some of which have been unexpected gems and others have been not quite ready for the big time.

Today I’m testing another system, but it’s not quite the same as the previous ones. Instead I’m looking at a piece of hardware, and I’m looking at it for use in my computing projects rather than as my desktop OS. You’ll all be familiar with it: the original Raspberry Pi appeared at the end of February 2012, though it would be May of that year before all but a lucky few received one. Since then it has become a global phenomenon and spawned a host of ever-faster successors, but what of that original board from 2012 here in 2025? If you have a working piece of hardware it makes sense to use it, so how does the original stack up? I have a project that needs a Linux machine, so I’m dusting off a Model B and going down memory lane.

Rediscovering An Old Flame

My first Pi from 2012. The heatsinks are my addition.

It’s fair to say that Raspberry Pi have never had the fastest board on the block, or the highest specification. At any point there’s always some board or other touted as a Pi-killer because it claims to do more, but somehow they never make much impact. The reason for this is simple; alongside your Pi you are also buying the ability to run Raspberry Pi OS, and their achievement in creating a solid and well-supported operating system that still runs on their earliest boards is something their competitors can’t touch. So when I pulled out my Model B I was able to go to the Raspberry Pi downloads page and snag a Debian Bookworm image for its 32-bit processor. I went for the “lite” version; while an early Pi will run a desktop and could even be my desktop daily driver, it would be so painfully slow as to be frustrating.

This is what my word trend analysis tool can do. Everyone was talking about Brexit in the UK in 2016.

My purpose for using the Pi is to run a language analysis package. Aside from fiddling with old cameras and writing about tech, I have a long history in computational language processing, and I have recently returned to my news trend analysis code and made it open-source. It’s a project whose roots go back nearly two decades, so there’s been an element of working out what my younger self was thinking. It builds and processes a corpus of news data over time from RSS feeds, and presents a web-based analysis client. 2000s-era me wrote it in PHP (don’t judge!) and I evolved a corpus structure using a huge tree of small JSON files for fast access. An earlier version of this package ran on my first Pi for many years, sitting next to my router with a USB hard disk.

Firing up an original Pi in 2025 is easy enough, as with any Pi it’s simply a case of writing the image to an SD card, hooking up the Pi to screen and peripherals, and booting it. Raspberry Pi OS is as straightforward to set up as always, and after rebooting and logging in, there I was with a shell.

Remembering, Computers Weren’t Always This Quick

Yes. it’s slow. But it’s got a shell. macrophile, CC BY 2.0.

My main machine is a fairly recent high-end Thinkpad laptop with an Intel Core i7, 32 GB of memory, and the fastest SSD I could afford, equipped with a hefty cache. It’s a supercomputer by any measure from the past, so I have become used to things I do in the shell being blisteringly quick. Sitting at the Pi, it’s evident that I’ll need to recalibrate my expectations, as there’s no way it can match the Thinkpad. As i waited – rather a long time – for apt to upgrade the packages, I had time to reflect. Back in the day when I set up Linux on my 486 or my Pentium machine, I was used to waiting like this. I remember apt upgrade being a go away and have a coffee thing, and I also remember thinking that Pentium was pretty quick, which it was for its day. But stripped of unnecessary services and GUI cruft, I was still getting all the power of the Pi in my terminal. It wasn’t bad, simply visibly slower than the Thinkpad, which to be fair, also applies to all the other computers I own.

So my little Pi 1 model B now sits again hooked up to my router and with a hefty USB drive, again waking up every couple of hours and number-crunching the world’s news. I’ve got used to its relative sloth, and to working again with nano and screen to get things done on it. It’s a useful little computer for the task I have for it, and it can run all day consuming only a couple of watts. As long as the Raspberry Pi people still make the Pi Zero, and I hope for a few years after they stop, it will continue to have OS support, and thus its future as my language processing machine looks assured.

The point of this piece has been to reflect on why we shouldn’t let our older hardware collect dust if it’s still useful. Of course Raspberry Pi want to sell us a new Pi 5, and that board is an amazing machine. But if your task doesn’t need all that power and you still have the earlier model lying around, don’t forget that it’s still a capable little Linux board that you probably paid quite a lot less for. You can’t argue with that.

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Spectroscopy seems simple: split a beam of light into its constituent wavelengths with a prism or diffraction grating, and measure the intensity of each wavelength. The devil is in the details, though, and what looks simple is often much harder to pull of in practice. You’ll find lots of details in [Gary Boyd]’s write-up of his optical scanning spectrometer project, but no devils.

Schematic diagram of [Gary Boyd]’s Czerny-Turner type scanning spectrometer.A scanning spectrometer is opposed to the more usual camera-type spectrometer we see on these pages in that it uses a single-pixel sensor that sweeps across the spectrum, rather than spreading the spectrum across an imaging sensor.

Specifically, [Gary] has implemented a Czerny-Turner type spectrometer, which is a two-mirror design. The first concave mirror culminates the light coming into the spectrometer from its entrance slit, focusing it on a reflective diffraction grating. The second concave mirror focuses the various rays of light split by the diffraction grating onto the detector.

In this case [Gary] uses a cheap VEML 7700 ambient light sensor mounted to a small linear stage from amazon to achieve a very respectable 1 nm resolution in the range from 360 nm to 980 nm. That’s better than the human eye, so nothing to sneeze at — but [Gary] includes some ideas in his blog post to extend that even further. The whole device is controlled via an Arduino Uno that streams data to [Gary]’s PC.

[Gary] documents everything very well, from his optical mounts to the Arduino code used to drive the stepper motor and take measurements from the VEML 7700 sensor. The LED and laser “turrets” used in calibration are great designs as well. He also shares the spectra this device is capable of capturing– everything from the blackbody of a tungsten lamp used in calibration, to a cuvette of tea, to the sun itself as you can see here. If you have a couple minutes, [Gary]’s full writeup is absolutely worth a read.

This isn’t the first spectrometer we’ve highlighted– you might say we’ve shown a whole spectrum of them.

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The PET opened, showing the motherboard. (Credit: Ken Shirriff)

An unavoidable part of old home computer systems and kin like the Commodore PET is that due to the age of their components they will develop issues that go far beyond what was covered in the official repair manual, not to mention require unconventional repairs. A case in point is the 2001 series Commodore PET that [Ken Shirriff] recently repaired.

The initial diagnosis was quite straightforward: it did turn on, but only displayed random symbols on the CRT, so obviously the ICs weren’t entirely happy, but at least the power supply and the basic display routines seemed to be more or less functional. Surely this meant that only a few bad ICs and maybe a few capacitors had to be replaced, and everything would be fully functional again.

Initially two bad MOS MPS6540 ROM chips had to be replaced with 2716 EPROMs using an adapter, but this did not fix the original symptom. After a logic analyzer session three bad RAM ICs were identified, which mostly fixed the display issue, aside from a quaint 2×2 checkerboard pattern and completely bizarre behavior upon running BASIC programs.

Using the logic analyzer capture the 6502 MPU was identified as writing to the wrong addresses. Ironically, this turned out to be due to a wrong byte in one of the replacement 2716 EPROMs as the used programmer wasn’t quite capable of hitting the right programming voltage. Using a better programmer fixed this, but on the next boot another RAM IC turned out to have failed, upping the total of failed silicon to four RAM & two ROM ICs, as pictured above, and teaching the important lesson to test replacement ROMs before you stick them into a system.

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Over on his YouTube channel [Electronic Wizard] has released a video that explains how infrared (IR) remote controllers work: IR Remote Controllers protocol: 101 to advanced.

This video covers the NEC family of protocols, which are widely used in typical consumer IR remote control devices, and explains how the 38 kHz carrier wave is used to encode a binary signal.  [Electronic Wizard] uses his Rigol DS1102 oscilloscope and a breadboard jig to sniff the signal from an example IR controller.

There is also an honorable mention of the HS0038 integrated-circuit which can interpret the light waves and output a digital signal. Of course if you’re a tough guy you don’t need no stinkin’ integrated-circuit IR receiver implementation because you can build your own!

Before the video concludes there is a brief discussion about how to interpret the binary signal using a combination of long and short pulses. If this looks similar to Morse Code to you that’s because it is similar to Morse Code! But not entirely the same, as you will learn if you watch the video!

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Whilst recently perusing the fine wares for sale at the Vintage Computer Festival East, [Action Retro] ended up adopting a 1995 ProStar laptop. Unlike most laptops of the era, however, this one didn’t just have the typical trackpad and clicky mouse buttons, but also a D-pad and four suspiciously game controller looking buttons. This makes it rather like the 2002 Sony VAIO PCG-U subnotebook, or the 2018 GPD Win 2, except that inexplicably the manufacturer has opted to put these (serial-connected) game controls on the laptop’s palm rest.

Sony VAIO PCG-U101. (Credit: Sony)

Though branded ProStar, this laptop was manufactured by Clevo, who to this day produces generic laptops that are rebranded by everyone & their dog. This particular laptop is your typical (120 MHz) Pentium-based unit, with two additional PCBs for the D-pad and buttons wired into the mainboard.

Unlike the sleek and elegant VAIO PCG-U and successors, this Clevo laptop is a veritable brick, as was typical for the era, which makes the ergonomics of the game controls truly questionable. Although the controls totally work, as demonstrated in the video, you won’t be holding the laptop, meaning that using the D-pad with your thumb is basically impossible unless you perch the laptop on a stand.

We’re not sure what the Clevo designers were thinking when they dreamed up this beauty, but it definitely makes this laptop stand out from the crowd. As would you, if you were using this as a portable gaming system back in the late 90s.

Our own [Adam Fabio] was at VCF East this year as well, and was impressed by an expansive exhibit dedicated to Windows 95.

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It’s been a while since we’ve dunked on an autonomous taxi foul-up, mainly because it seemed for a while there that most of the companies field testing driverless ride-sharing services had either ceased operation or curtailed them significantly. But that appears not to be the case after a Waymo robotaxi got stuck in a Chick-fil-A drive-through. The incident occurred at the chicken giant’s Santa Monica, California location at about 9:30 at night, when the autonomous Jaguar got stuck after dropping off a passenger in the parking lot. The car apparently tried to use the drive-through lane to execute a multi-point turn but ended up across the entrance, blocking other vehicles seeking their late-evening chicken fix. The drive-through-only restaurant ended up closing for a short time while Waymo figured out how to get the vehicle moving again.

To be fair, drive-through lanes are challenging even for experienced drivers. Lanes are often narrow, curve radii are sometimes tighter than a large vehicle can negotiate smoothly, and the task-switching involved with transitioning from driver to customer can lead to mistakes. Drive-throughs almost seem engineered to make tempers flare, especially at restaurants where hangry drivers are likely to act out at the slightest delay. This is probably doubly so when drivers are stuck behind a driverless car, completely eliminating even the minimal decency that would likely be extended to a human driver who got themselves in a pickle. If people are willing to honk at and curse out the proverbial little old lady from Pasadena, they’re very unlikely to cooperate with a robotaxi and give it the room it needs to maneuver out of a tight spot. Perhaps that argues for a change in programming that accounts for real-world driving experiences as well as the letter of the law.

The big news from space this week was the private Fram2 mission, which took an all-civilian crew on the world’s first crewed polar flight. The four-person crew took off from Florida in a SpaceX Crew Dragon and rather than heading east towards Africa, took off due north and entered a retrograde orbit at 90° inclination, beating the previous record of 65° inclination by Valentina Tereshkova aboard Vostok 6 back in 1963. The Fram2 team managed a couple of other firsts, from the first medical X-rays taken in space to the first amateur radio contacts made from the Dragon.

It’s been a while, but Bill “The Engineer Guy” Hammack is back with a new video extolling the wonders of plastic soda bottles. If you think that’s a subject too mundane to hold your interest, then you’ve never seen Bill at work. The amount of engineering that goes into creating a container that can stand up to its pressurized content while being able to be handled both by automation machines at the bottling plant and by thirsty consumers is a lesson in design brilliance. Bill explains the whole blow-molding process, amazingly using what looks like an actual Coca-Cola production mold. We would have thought such IP would be fiercely protected, but such is Bill’s clout, we guess. The video is also a little trip down memory lane for some of us, as Bill shows off both the two-piece 2-liter bottles that used to grace store shelves and the ponderous glass versions that predated those. Also interesting is the look at the differences between hot-fill bottles and soda bottles, which we never appreciated before.

And finally, if you’ve ever been confused by which logical fallacy is clouding your thinking, why not turn to the most famous fictional logician of all time to clarify things? “Star Trek Logical Reasoning” is a YouTube series by CHDanhauser that uses clips from the Star Trek animated series to illustrate nearly 70 logical fallacies. Each video is quite short, with most featuring Commander Spock eavesdropping on the conversations of his less-logical shipmates and pointing out the flaws in their logic. Luckily, the 23rd century seems to have no equivalent of human(oid) resources, because Spock’s logical interventions are somewhat toxic by today’s standards, but that’s a small price to pay for getting your logical ducks in a row.

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There are no shortage of CNC machines in the DIY space these days, but sometimes you just need to do things your own way. That’s what [Chris Borges] decided when he put together this rock-solid, concrete-filled CNC milling machine.

The concrete body of this machine is housed inside a 3D printed shell, which makes for an attractive skin as well as a handy mold. Within the concrete is a steel skeleton, with the ‘rebar’ being made of threaded rods and a length of square tubing to hold the main column. You can see the concrete being poured in around the rebar in the image, or watch it happen in the build video embedded below.

In goes the concrete, up goes the rigidity.All three axes slide on linear rails, and are attached to lead screws driven by the omnipresent NEMA 17 steppers. The air-cooled spindle, apparently the weak-point of the design, is attached to a pivoting counterweight, but make no mistake: it is on rails. All-in-all, it looks like a very rigid, and very capable design — [Chris] shows it cutting through aluminum quite nicely.

Given that [Chris] has apparently never used a true mill before, this design came out remarkably well. Between the Bill of Materials and 45 page step-by-step assembly instructions, he’s also done a fantastic job documenting the build for anyone who wants to put one together for themselves.

This isn’t the first concrete-filled project we’ve highlighted from [Chris], you may remember seeing his lathe on these pages. It certainly isn’t the first CNC mill we’ve covered, either.

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Spade is an open-source hardware description language (HDL) developed at Linköping University, Sweden.

Other HDLs you might have heard of include Verilog and VHDL. Hardware engineers use HDLs to define hardware which can be rendered in silicon. Hardware defined in HDLs might look like software, but actually it’s not software, it’s hardware description. This hardware can be realized myriad ways including in an FPGA or with an ASIC.

You have probably heard that your CPU processes instructions in a pipeline. Spade has first-class support for such pipelines. This means that design activities such as re-timing and re-pipelining are much easier than in other HDLs where the designer has to implement these by hand. (Note: backward justification is NP-hard, we’re not sure how Spade supports this, if it does at all. If you know please enlighten us in the comments!)

Spade implements a type system for strong and static typing inspired by the Rust programming language and can do type inference. It supports pattern matching such as you might see in a typical functional programming language. It boasts having user-friendly and helpful error messages and tooling.

Spade is a work in progress so please expect missing features and breaking changes. The documentation is in The Spade Book. If you’re interested you can follow development on GitLab or Discord.

So now that you know about the Spade language, are you planning to take it for a spin? You will find plenty of Verilog/VHDL designs at Hackaday which you could re-implement using Spade, such as an easy one like Breathing LED Done With Raw Logic Synthesized From A Verilog Design (see benchmarks) or a much more challenging one like Game Boy Recreated In Verilog. If you give Spade a go we’d love to see what you come up with!

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