Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Hardware-Layered Keyboard

January 20, 2025 by 6 Comments

You know (or maybe you didn’t), I get super excited when y’all use the links at the bottom of this round-up we call Keebin’ to communicate with your old pal Kristina about your various labors of love. So just remember that.

Case in point: I was typing up this very issue when I heard from [Jay Crutti] and [Marcel Erz]. Both are out there making replacement keyboards for TRS-80s — [Jay] for Models 3 and 4, and [Marcel] for the Model 1. Oooh, I said to myself. This is going at the top.

A TRS-80 Model 4 with a replacement keyboard.
A TRS-80 Model 4. Image by [Jay Crutti] via JayCrutti.com
Relevant tangent time: I remember in the 90s having a pile of computers in my parents’ basement of various vintages, a TRS-80 Model 2 among them. (Did I ever tell you about the time I got pulled over for speeding with a bunch of different computers in the backseat? I was like no, officer, first of all, those are old machines that no one would really want, and I swear I didn’t steal them.)

I think the TRS-80 is probably the one I miss the most. If I still had it, you can bet I would be using [Jay] and [Marcel]’s work to build my own replacement keyboard, which the 40-year-old machine would likely need at this point if the Model 4 is any indication with its failing keyboard contacts.

To create the replacements, [Jay] used Keyboard Layout Editor (KLE), Plate & Case Builder, and EasyEDA. Using the schematic from the maintenance manual, he matched the row/column wiring of the original matrix with Cherry MX footprints. Be sure to check out [Jay]’s site for a link to the project files, or to purchase parts or an assembled keyboard. On the hunt for TRS-80 parts in general? Look no further than [Marcel]’s site.
Continue reading “Keebin’ With Kristina: The One With The Hardware-Layered Keyboard” →

DIY Strontium Aluminate Glows In The Dark

January 20, 2025 by 8 Comments

[Maurycyz] points out right up front: several of the reagents used are very corrosive and can produce toxic gasses. We weren’t sure if they were trying to dissuade us not to replicate it or encourage us to do so. The project in question is making strontium aluminate which, by the way, glows in the dark.

The material grows strongly for hours and, despite the dangers of making it, it doesn’t require anything very exotic. As [Maurycyz] points out, oxygen and aluminum are everywhere. Strontium sounds uncommon, but apparently, it is used in ceramics.

For the chemists among us, there’s an explanation of how to make it by decomposing soluble nitrate salts. For the rest of us, the steps are to make aluminum hydroxide using potassium alum, a food preservative, and sodium hydroxide. Then, it is mixed with nitric acid, strontium carbonate, europium, and dysprosium. Those last elements determine the color of the glow.

A drying step removes the acid, followed by dissolving with urea and water. The heat of the reaction wasn’t enough to form the final product, but it took time with an oxy-propane torch to form blobs of strontium aluminate. The product may not have been pure, because it didn’t glow for hours like commercial preparations. But it did manage to glow for a few minutes after light exposure.

We try to limit our chemistry to less toxic substances, although ferric chloride can make a mess. You could probably track down the impurities with a gas chromatograph. What we really want is a glow-in-the-dark car antenna.

Time-of-Flight Sensors: How Do They Work?

January 20, 2025 by 16 Comments
With the right conditions, this tiny sensor can measure 12 meters

If you need to measure a distance, it is tempting to reach for the ubiquitous ultrasonic module like an HC-SR04. These work well, and they are reasonably easy to use. However, they aren’t without their problems. So maybe try an IR time of flight sensor. These also work well, are reasonably easy to use, and have a different set of problems. I recently had a project where I needed such a sensor, and I picked up a TF-MiniS, which is a popular IR distance sensor. They aren’t very expensive, and they work serial or I2C. So how did it do?

The unit itself is tiny and has good specifications. You can fit the 42 x 15 x 16 mm module anywhere. It only weighs about five grams — as the manufacturer points out, less than two ping-pong balls. It needs 5 V but communicates using 3.3 V, so integration isn’t much of a problem.

At first glance, the range is impressive. You can read things as close as 10 cm and as far away as 12 m. I found this was a bit optimistic, though. Although the product sometimes gets the name of LiDAR, it doesn’t use a laser. It just uses an IR LED and some fancy optics.

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You Can Now Play DOOM In Microsoft Word, But You Probably Shouldn’t

January 20, 2025 by 23 Comments

DOOM used to primarily run on x86 PCs. It later got ported to a bunch of consoles with middling success, and then everything under the sun, from random embedded systems to PDFs. Now, thanks to [Wojciech Graj], you can even play it in Microsoft Word.

To run DOOM inside Microsoft Word, you must enable VBA macros, and ignore security warnings, to boot. You’ll need a modern version of Word, and it will only work on Windows on an x64 CPU. As you might imagine, too, the *.DOCM file is not exactly lightweight. It comes in at 6.6 MB, no surprise given it contains an entire FPS. It carries inside it a library called doomgeneric_docm.dll and the whole doom1.wad data file. Once the file is opened, a macro then extracts all the game data and executes it.

If you think that Microsoft Word doesn’t really have a way of displaying live game graphics, you’d be correct. Instead, that DLL is creating a bitmap image of the game state for every frame, which is then displayed inside Word itself. It uses the GetAsyncKeyState function to grab inputs from the arrow keys, number keys, and CTRL and space so the player can move around. It certainly sounds convoluted, but it actually runs pretty smoothly given all the fuss.

While this obviously works, you shouldn’t get in the habit of executing random code in your word processor. It’s just not proper, you see, like elbows on the dinner table! And, you know. It’s insecure. So don’t do that.

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Innovative Clock Uses Printed Caustic Lens

January 20, 2025 by 13 Comments

Hackers and makers have built just about every kind of clock under the sun. Digital, analog, seven-segment, mechanical seven-segment, binary, ternary, hexadecimal… you name it. It’s been done. You really have to try to find something that shocks us… something we haven’t seen before. [Moritz v. Sivers] has done just that. 

Wild. Just wild.

Meet the Caustic Clock. It’s based on the innovative Hollow Clock from [shiura]. It displays time with an hour hand and a minute hand, and that’s all so conventional. But what really caught our eye was the manner in which its dial works. It uses caustics to display the clock dial on a wall as light shines through it.

If you’ve ever seen sunlight reflect through a glass, or the dancing patterns in an outdoor swimming pool, you’ve seen caustics at play. Caustics are the bright patterns we see projected through a transparent object, and if you shape that object properly, you can control them. In this case, [Moritz] used some GitHub code from [Matt Ferraro] to create a caustic projection clockface, and 3D printed it using an SLA printer.

The rest of the clock is straightforward enough—there’s some WS2812 LEDs involved, an Arduino Nano, and even an RP2040. But the real magic is in the light show and how it’s all achieved. We love learning about optics, and this is a beautiful effect well worth studying yourself.

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Bone Filament, For Printing Practice Bones

January 19, 2025 by 9 Comments

Of course there is bone-simulation filament on the market. What’s fun about this Reddit thread is all of the semi-macabre concerns of surgeons who are worried about its properties matching the real thing to make practice rigs for difficult surgeries. We were initially creeped out by the idea, but now that we think about it, it’s entirely reassuring that surgeons have the best tools available for them to prepare, so why not 3D prints of the actual patient’s bones?

[PectusSurgeon] says that the important characteristics were that it doesn’t melt under the bone saw and is mechanically similar, but also that it looks right under x-ray, for fluorscopic surgery training. But at $100 per spool, you would be forgiven for looking around for substitutes. [ghostofwinter88] chimes in saying that their lab used a high-wood-content PLA, but couldn’t say much more, and then got into a discussion of how different bones feel under the saw, before concluding that they eventually chose resin.

Of course, Reddit being Reddit, the best part of the thread is the bad jokes. “Plastic surgery” and “my insurance wouldn’t cover gyroid infill” and so on. We won’t spoil it all for you, so enjoy.

When we first read “printing bones”, we didn’t know if they were discussing making replacement bones, or printing using actual bones in the mix. (Of course we’ve covered both before. This is Hackaday.)

Thanks [JohnU] for the tip!

Robotics Class Is Open

January 19, 2025 by 5 Comments

If you are like us, you probably just spin up your own code for a lot of simple projects. But that’s wasteful if you are trying to do anything serious. Take a robot, for example. Are you using ROS (Robot Operating System)? If not — or even if you are — check out [Janne Karttunene] and the University of Eastern Finland’s open-source course Robotics and ROS 2 Essentials.

The material is on GitHub. Rather than paraphrase, here’s the description from the course itself:

This course is designed to give you hands-on experience with the basics of robotics using ROS 2 and Gazebo simulation. The exercises focus on the Andino robot from Ekumen and are structured to gradually introduce you to ROS 2 and Docker.

No prior experience with ROS 2 or Docker is needed, and since everything runs through Docker, you won’t need to install ROS 2 on your system beforehand. Along the way, you’ll learn essential concepts like autonomous navigation and mapping for mobile robots. All the practical coding exercises are done in Python.

Topics include SLAM, autonomous navigation, odometry, and path planning. It looks like it will be a valuable resource for anyone interested in robotics or anything else you might do with ROS.

If you want a quick introduction to ROS, we can help. We’ve seen a number of cool ROS projects over the years.