How I 3D Printed My Own Lego-Compatible Train Bridges

March 16, 2026 by Lewin Day 37 Comments

Lego train sets have been available for decades, now. The Danish manufacturer long ago realized the magic of combining its building block sets with motors and plastic rails to create real working railways for children and adults to enjoy. Over the years, Lego has innovated through several generations of trains, from classic metal-rail systems to the more modern IR and later Bluetooth-controlled versions. The only thing largely missing over all that time, though…? A bridge!

Yes, Lego has largely neglected to build any bridges for its mainstream train lineup. There are aftermarket solutions, and innovative hacks invented by the community, all with their own limitations and drawbacks. This glaring oversight, though, seemed like a perfect opportunity to me. It was time to fire up the 3D printer and churn out a fully-realized Lego rail bridge of my very own.

Bridges Are Hard

I’ve experimented with building Lego rail bridges before, using standard track and household objects like cardboard, books, and beer. Unfortunately, it can be very difficult to support the track evenly at the joints which occur every 150mm, and derailments are common. Credit: author

There’s actually a good reason Lego bridges aren’t a big thing in the company’s own product lineup, beyond a few obscure historical parts. This is probably because they aren’t very practical. Lego locomotives are not particularly strong haulers, nor do they have excellent grip on the rails, and this makes them very poor at climbing even mild grades. Any official Lego bridge would have to be very long with a shallow slope just to allow a train to climb high enough to clear a locomotive on a track below. This would end up being an expensive set that would probably prove unpopular with the casual Lego train builder, even if the diehard enthusiasts loved it.

There are third-party options available out there. However, most rely on standard Lego track pieces and merely combine them with supports that hold them up at height. This can work in some cases, but it can be very difficult to do cool things like passing a Lego train under a bridge, for example. It can be hard to gain enough height, and the short length of Lego track pieces makes it hard to squeeze a locomotive between supports. Continue reading “How I 3D Printed My Own Lego-Compatible Train Bridges” →

Back To Basics: Hacking On Key Matrixes

March 3, 2026 by Lewin Day 13 Comments

A lot of making goes on in this community these days, but sometimes you’ve just gotta do some old fashioned hacking. You might have grabbed an old Speak and Spell that you want to repurpose as an interface for a horrifyingly rude chatbot, or you’ve got a calculator that is going to become the passcode keypad for launching your DIY missiles. You want to work with the original hardware, but you need to figure out how to interface all the buttons yourself.

Thankfully, this is usually an easy job. The vast majority of buttons and keypads and keyboards are all implemented pretty much the same way. Once you know the basics of how to work with them, hooking them up is easy. It’s time to learn about key matrixes!

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Ask Hackaday: How Do You Digitize Your Documents?

January 29, 2026 by Tom Nardi 89 Comments

Like many of you, I have a hard time getting rid of stuff. I’ve got boxes and boxes of weirdo bits and bobs, and piles of devices that I’ll eventually get around to stripping down into even more bits and bobs. Despite regular purges — I try to bring a car-load of ~~crap~~ treasure to local hackerspaces and meetups at least a couple times a year — the pile only continues to grow.

But the problem isn’t limited to hardware components. There’s all sorts of things that the logical part of me understands I’ll almost certainly never need, and yet I can’t bring myself to dispose of. One of those things just so happens to be documents. Anything printed is fair game. Could be the notes from my last appointment with the doctor, or fliers for events I attended years ago. Doesn’t matter, the stacks keep building up until I end up cramming it all into a box and start the whole process starts over again.

I’ve largely convinced myself that the perennial accumulation of electronic bric-à-brac is an occupational hazard, and have come to terms with it. But I think there’s a good chance of moving the needle on the document situation, and if that involves a bit of high-tech overengineering, even better. As such, I’ve spent the last couple of weeks investigating digitizing the documents that have information worth retaining so that the originals can be sent along to Valhalla in my fire pit.

The following represents some of my observations thus far, in the hopes that others going down a similar path may find them useful. But what I’m really interested in is hearing from the Hackaday community. Surely I’m not the only one trying to save some storage space by turn piles of papers into ones and zeros.

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Creating User-Friendly Installers Across Operating Systems

December 11, 2025 by Maya Posch 44 Comments

After you have written the code for some awesome application, you of course want other people to be able to use it. Although simply directing them to the source code on GitHub or similar is an option, not every project lends itself to the traditional configure && make && make install, with often dependencies being the sticking point.

Asking the user to install dependencies and set up any filesystem links is an option, but having an installer of some type tackle all this is of course significantly easier. Typically this would contain the precompiled binaries, along with any other required files which the installer can then copy to their final location before tackling any remaining tasks, like updating configuration files, tweaking a registry, setting up filesystem links and so on.

As simple as this sounds, it comes with a lot of gotchas, with Linux distributions in particular being a tough nut. Whereas on MacOS, Windows, Haiku and many other OSes you can provide a single installer file for the respective platform, for Linux things get interesting.

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PCB Design Review: TinySparrow, A Module For CAN Hacking, V2

December 9, 2025 by Arya Voronova 12 Comments

A year ago, I’ve design reviewed an MCU module for CAN hacking, called TinySparrow. Modules are plenty cool, and even more so when they’re intended for remaking car ECUs. For a while now, every car has heavily depended on a computer to control the operation of everything inside it – the engine and its infrastructure, the lights, and Sadly, ECUs are quite non-hackable, so building your own ECUs only makes sense – which is why it’s heartwarming to see modules intended to make this easier on the budding ECU designer!

Last time we saw this module, it was quite a bit simpler. We talked about fixing a number of things – the linear regulator, the unprotected CAN transceiver, and the pinout; we also made the board cheaper to produce by reducing the layer count and instead pushing the clearance/track width limits. This time, we’re seeing TinySparrow v2 , redesigned accounting for the feedback and upgraded with a new MCU – it’s quite a bit more powerful!

For a start, it’s got ESD diodes, a switching-linear regulator chain for clean but efficient power supply, and most importantly, an upgraded MCU, now with USB and one more CAN channel for a total of two! There’s a lot more GPIOs to go around, too, so the PCB now uses all four of its sides for breakout out power, programming, and GPIO pads. Only a tiny bit bigger than its v1, this module packs a fair bit of punch.

Let’s revisit the design, and try to find anything still left to improve – there’s a few noteworthy things I found.

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The Unexpected Joys Of Hacking An Old Kindle

November 24, 2025 by Tom Nardi 23 Comments

In the closing hours of JawnCon 0x2, I was making a final pass of the “Free Stuff for Nerds” table when I noticed a forlorn Kindle that had a piece of paper taped to it. The hand-written note explained that the device was in shambles — not only was its e-ink display visibly broken, but the reader was stuck in some kind of endless boot loop. I might have left it there if it wasn’t for the closing remark: “Have Fun!”

Truth is, the last thing I needed was another Kindle. My family has already managed to build up a collection of the things. But taking a broken one apart and attempting to figure out what was wrong with it did seem like it would be kind of fun, as I’d never really had the opportunity to dig into one before. So I brought it home and promptly forgot about it as Supercon was only a few weeks away and there was plenty to keep me occupied.

The following isn’t really a story about fixing a Kindle, although it might seem like it on the surface. It’s more about the experience of working on the device, and the incredible hacking potential of these unassuming gadgets. Whether you’ve got a clear goal in mind, or just want to get your hands dirty in the world of hardware hacking, you could do far worse than picking a couple of busted Kindles up for cheap on eBay.

If there’s a singular takeaway, it’s that the world’s most popular e-reader just so happens to double as a cheap and impressively capable embedded Linux development environment for anyone who’s willing to crack open the case.

Continue reading “The Unexpected Joys Of Hacking An Old Kindle” →

Lithium-Ion Batteries: WHY They Demand Respect

November 4, 2025 by Arya Voronova 65 Comments

This summer, we saw the WHY (What Hackers Yearn) event happen in Netherlands, of course, with a badge to match. Many badges these days embrace the QWERTY computer aesthetic, which I’m personally genuinely happy about. This one used 18650 batteries for power, in a dual parallel cell configuration… Oh snap, that’s my favourite LiIon cell in my favourite configuration, too! Surely, nothing bad could happen?

Whoops. That one almost caught me by surprise, I have to shamefully admit. I just genuinely love 18650 cells, in all glory they bring to hardware hacking, and my excitement must’ve blindsided me. They’re the closest possible entity to a “LiIon battery module”, surprisingly easy to find in most corners of this planet, cheap to acquire in large quantities, easy to interface to your projects, and packing a huge amount of power. It’s a perfect cell for many applications I and many other hackers hold dear.

Sadly, the 18650 cells were a bad choice for the WHY badge, for multiple reasons at once. If you’re considering building a 18650-based project, or even a product, let me show you what exactly made these cells a bad fit, and how you might be able to work around those limitations on your own journey. There’s plenty of technical factors, but I will tell you about the social factors, because these create the real dealbreaker here. Continue reading “Lithium-Ion Batteries: WHY They Demand Respect” →