Tracking The ISS Made Easy

April 7, 2025 by Elliot Williams 3 Comments

If you made something blink, and now it’s time for you to make something move, something like a point-to-a-satellite tracker is a great idea. [Farid Rener] made this moving arrow that always points at the ISS, and documented it nicely to boot.

And there’s a little bit of everything here, from orbital mechanics and fetching the two-line elements (TLE) from the web, to writing the code to translate that into the tabletop machine’s coordinate system. It looks like [Farid] hadn’t done much 3D CAD before, so he got a chance to stretch those muscles too. Finally, it served as an introduction to resource-constrained programming: “This was the first time I’ve had to think about the size of a compiled binary – the most frustrating part was figuring out that using a C++ stringstream was adding too much code to my binary.”

[Farid] is learning a lot here, and you might too. For instance, using pencil lead (graphite) as a lubricant on sliding 3D-printed parts is new to us, but makes sense. We’ll have to try that out.

And while this is a simple desktop tracker, with a lot more mechanical design, the same basics could be put to real use for pointing a receiver dish. Of course, who says you need fancy motors and computers to point a satellite dish anyway? If you work on your arm muscles a bit, you could become the satellite pointer.

Command And Conquer Ported To The Pi Pico 2

April 6, 2025 by Tom Nardi 9 Comments

A couple of months back, Electronic Arts did something uncharacteristically benevolent and released several of the old Command and Conquer games under the GPLv3. Logically, we knew that opened the doors up to the games being ported to new operating systems and architectures, but we admit that it was still a little surprising to see Command and Conquer: Red Alert running on the Raspberry Pi Pico 2.

[Charlie Birks] documented the process of getting the 1996 game up and running on the microcontroller in a series of Mastodon posts spanning a few days in March. Seeing the incremental progress made each day makes for interesting reading, as he moves from the game just barely starting up to being able to complete missions and eventually even get multiplayer going between two Picos.

As [Charlie] clarifies, he’s technically using the Pimoroni Pico Plus 2 W, which takes the RP2350B from the official Pico 2, adds 8 MB of PSRAM, and bumps the onboard flash to 16 MB. The upgraded specs and an SD card are required to get the game running, as content that would have originally been held in RAM on the computer must instead be pulled from flash.

For an even more streamlined experience, he eventually slaps the Pico Plus 2 W into the Pimoroni Pico VGA Demo Base — which provided not only an integrated SD card slot, but (as the name implies) VGA output.

It’s still early days, but [Charlie] has been pushing all of his code changes into his fork of Red Alert on GitHub for anyone who wants to play along at home. If you get his fork compiled and running on your own Pico, we’d love to hear about it in the comments.

A Very Trippy Look At Microsoft’s Beginnings

April 3, 2025 by Tom Nardi 38 Comments

It’s not often you’ll see us singing the praises of Microsoft on these pages, but credit where credit is due, this first-person account of how the software giant got its foot in the proverbial door by Bill Gates himself is pretty slick.

Now it’s not the story that has us excited, mind you. It’s the website itself. As you scroll down the page, the text and images morph around in a very pleasing and retro-inspired way. Running your cursor over the text makes it flip through random ASCII characters, reminding us a bit of the “decryption” effect from Sneakers. Even the static images have dithering applied to them as if they’re being rendered on some ancient piece of hardware. We don’t know who’s doing Billy’s web design, but we’d love to have them come refresh our Retro Edition.

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The Magic Touch: A 555 Touch Switch

April 2, 2025 by Al Williams 14 Comments

There seems to be nothing a 555 can’t do. We’ve seen it before, but [electronzapdotcom] reminds us you can use a 555 and a few parts to make a reasonable touch switch in this video, embedded below.

The circuit uses some very large resistors so that noise from your body can overcome the logic level on the trigger and threshold inputs. You can easily adapt this idea if you need a simple touch switch. Though we imagine this circuit wouldn’t work well if you were in a quiet environment. We suspect 50 or 60 Hz hum is coupling through your finger and triggering the pins, but it could be a different effect.

How reliable is it? Beats us. The circuit is a bistable, so essentially your finger pumps a signal into a flip-flop. This is old trick, but could be useful. Of course, if you really need a touch switch, you have plenty of options. You can get little modules. Or, directly measure skin resistance.

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A Forgotten Photographic Process Characterised

April 1, 2025 by Jenny List 3 Comments

Early photography lacked the convenience of the stable roll film we all know, and instead relied on a set of processes which the photographer would have to master from film to final print. Photographic chemicals could be flammable or even deadly, and results took a huge amount of work.

The daguerreotype process of using mercury to develop pictures on polished metal, and the wet-collodion plate with its nitrocellulose solution are well-known, but as conservators at the British National Archives found out, there was another process that’s much rarer. The Pannotype uses a collodion emulsion, but instead of the glass plate used by the wet-plate process it uses a fabric backing.

We know so much about the other processes because they were subject to patents, but pannotype never had a patent due to a disagreement. Thus when the conservators encountered some pannotypes in varying states of preservation, they needed to apply modern analytical techniques to understand the chemistry and select the best methods of stabilization. The linked article details those analyses, and provides them with some pointers towards conserving their collection. We look forward to someone making pannotype prints here in 2025, after all it’s not the first recreation of early photography we’ve seen.

Protocol Analyzer Remembered

March 30, 2025 by Al Williams 22 Comments

Anyone will tell you that as hard as it is to create a working system, the real trick is making two systems talk to each other, especially if you created only one or none of them. That’s why tools that let you listen in on two systems talking are especially valuable.

If you were a well-funded lab back in the RS232 days, you might have an HP4957A protocol analyzer. The good news is that if you still use RS232, these kinds of things are now cheap on the surplus market. [IMSAI Guy] got one of these decidedly cool devices and shows it to us in the video below.

The look of these was pretty neat for their time—a folded-up instrument with a cute keyboard and a CRT-100. You can load different interpreters from ROM to RAM, such as the VT-100, which is essentially an application for the device. Of course, now you could rig one of these up in a few minutes with a PC or even a Pi Pico. But it wouldn’t have the same charm, we are sure you would agree.

You can find a lot of old RS232 gear around, from breakout boxes to advanced sniffers like this one. Too bad we couldn’t afford them when we really needed them.

This could be handy if you have a lot of ports. Either real or virtual. Or, do it yourself.

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Contagious Ideas

March 29, 2025 by Elliot Williams 10 Comments

We ran a story about a wall-mounted plotter bot this week, Mural. It’s a simple, but very well implemented, take on a theme that we’ve seen over and over again in various forms. Two lines, or in this case timing belts, hang the bot on a wall, and two motors drive it around. Maybe a servo pulls the pen in and out, but that’s about it. The rest is motor driving and code.

We were thinking about the first such bot we’ve ever seen, and couldn’t come up with anything earlier than Hektor, a spray-painting version of this idea by [Juerg Lehni]. And since then, it’s reappeared in numerous variations.

Some implementations mount the motors on the wall, some on the bot. There are various geometries and refinements to try to make the system behave more like a simple Cartesian one, but in the end, you always have to deal with a little bit of geometry, or just relish the not-quite-straight lines. (We have yet to see an implementation that maps out the nonlinearities using a webcam, for instance, but that would be cool.) If you’re feeling particularly reductionist, you can even do away with the pen-lifter entirely and simply draw everything as a connected line, Etch-a-Sketch style. Maslow CNC swaps out the pen for a router, and cuts wood.

What I love about this family of wall-plotter bots is that none of them are identical, but they all clearly share the same fundamental idea. You certainly wouldn’t call any one of them a “copy” of another, but they’re all related, like riffing off of the same piece of music, or painting the same haystack in different lighting conditions: robot jazz, or a study in various mechanical implementations of the same core concept. The collection of all wall bots is more than the sum of its parts, and you can learn something from each one. Have you made yours yet?

(Fantastic plotter-bot art by [Sarah Petkus] from her write-up ten years ago!)