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

March 16, 2026 by Lewin Day 20 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” →

The Shockley 4-Layer Diode In 2026

March 14, 2026 by Jenny List 9 Comments

The physicist William Shockley is perhaps today best known for three things: his role in the invention of the transistor, his calamitous management of Shockley Semiconductor which led to a mass defection of employees and precipitated the birth of the Silicon Valley we know, and his later descent into promoting eugenics. This was not the sum of his work though, and [David Prutchi] has been experimenting with a now-mostly-forgotten device that bears the Shockley name (PDF), after finding one used in an early heart pacemaker circuit. His findings are both comprehensive and fascinating.

The Shockley diode, or 4-layer diode as it later became known, is as its name suggests a two terminal device with a 4-layer NPNP structure. It can be modeled as a pair of complementary transistors in parallel with a reverse biased diode, and the avalanche breakdown characteristics of that diode when a particular voltage is applied to it provide the impetus to turn on the two transistors. This makes it a voltage controlled switch, that activates when the voltage across it reaches that value.

The PDF linked above goes into the Shockley diode applications, and in them we find a range of relaxation oscillators, switches, and logic circuits. The oscillators in particular could be made with the barest minimum of components, important in a time when each semiconductor device could be very expensive. It may have faded into obscurity as it was superseded by more versatile 4-layer devices such as the PUJT or silicon-controlled switch and then integrated circuits, but he makes the point that its thyristor cousin is still very much with us.

This appears to be the first time we’ve featured a 4-layer diode, but we’ve certainly covered the genesis of the transistor in the past.

Pokemon Go Had Players Capturing More Than They Realized

March 12, 2026 by Tom Nardi 40 Comments

Released in 2016, Pokemon Go quickly became a worldwide phenomenon. Even folks who weren’t traditionally interested in the monster-taming franchise were wandering around with their smartphones out, on the hunt for virtual creatures that would appear via augmented reality. Although the number of active users has dropped over the years, it’s estimated that more than 50 million users currently log in and play every month.

From a gameplay standpoint, Go is brilliant. Although the Pokemon that players seek out obviously aren’t real, searching for them closely approximates the in-game experience that the franchise has been known for since its introduction on the Game Boy back in 1996.

But now, instead of moving a character through a virtual landscape in search of the elusive “pocket monsters”, players find them dotted throughout the real world. To be successful, players need to leave their homes and travel to where the Pokemon are physically located — which often happens to be a high-traffic area or other point of interest.

As a game, it’s hard to imagine Pokemon Go being a bigger success. At the peak of its popularity, throngs of players were literally causing traffic jams as they roamed the streets in search of invisible creatures. But what players may not have realized as they scanned the world around them through the game was that they were helping developer Niantic build something even more valuable.

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German Fireball’s 15 Minutes Of Fame

March 11, 2026 by Elliot Williams 20 Comments

Sunday night, around 7:00 PM local time, a bright fireball streaked across the western German sky, exploded, and rained chunks of space rock down on the region around Koblenz. One of the largest known chunks put a soccer-ball-sized hole in someone’s roof, landing in their bedroom. Fortunately, nobody was hurt. But given the apparent size of the explosion, there must be many more pieces out there for the finding, and a wave of hopeful meteorite hunters has descended upon the region.

But if you wanted a piece of the action, where exactly would you start looking? How do scientists find meteorites anyway? And what should you do if you happen to see a similar fireball in the night sky?

Citizen Science

Meteorite video-bombs a boring parking lot in Heerlen, NL.

In the age of always-on dashboard cameras, ubiquitous smartphones, and other video recording devices, it’s hard for a shy meteorite to find a quiet spot out of the public eye. That makes them a lot easier to find than they were in the past. Indeed, the International Meteor Organization, which aggregates amateur meteor observations, received more than 3,200 reports of this one, including several with video documentation. Some are stunning, and others may not even be of the event at all.

By collecting reports from many locations, they can hope to piece together the meteorite’s trajectory. However, if you look at the individual reports, it’s clear that this is a difficult task. Nobody is expecting a bright fireball to streak across the night sky, so many of the reports are reasonably vague on the details and heavy on the awe.

This report from [Sophie Z], for instance, is typical. She records where she was and roughly the location in the night sky where the meteorite passed, along with the comment “I’ve never seen anything so amazing and large before in my life.” Other amateur observers are more precise. [David C] (“I have a Ph.D in physics”) managed to record the start and the end heading of the meteorite to a couple of decimal places. He must have had a camera.

Continue reading “German Fireball’s 15 Minutes Of Fame” →

The “Tin Blimp” Was A Neither Tin Nor A Blimp: The Detroit ZMC-2 Story

March 10, 2026 by Tyler August 31 Comments

That fireball was LZ37. Nobody wanted to see repeats post-war.
Image: “The great exploit of lieutenant Warnefort 1916 England” by Gordon Crosby, public domain.

After all the crashing and burning of Imperial Germany’s Zeppelins in the later part of WWI – once the Brits managed to build interceptors that could hit their lofty altitude, and figured out the trick of using incendiary rounds to set off the hydrogen lift gas – there was a certain desire in airship circles to avoid fires. In the USA, that mostly took the form of replacing hydrogen with helium. Sure, it didn’t lift quite as well, but it also didn’t explode.

Still, supplies of helium were– and are– very much limited, and at least on a rigid Zeppelin, the hydrogen wasn’t even the most flammable part. As has become widely known, thanks in large part to the Mythbusters episode about the Hindenburg disaster, the doped cotton skin in use in those days was more flammable than some firestarters you can buy these days.

That’s a problem, because, as came up in the comments of our last airship article, rigid airships beat blimps largely on Rule of Cool. Who invented the blimp? Well, arguably it was Henri Griffard with his steam-driven balloon in 1857, but not many people have ever heard his name. Who invented the rigid airship? You know his name: Ferdinand Adolf Heinrich August Graf von Zeppelin. No relation. Probably. Well, admittedly most people don’t know the full name, but Count Zeppelin is still practically a household name over a century after his death. His invention was just that much cooler.

That unavoidable draw of coolness led to the Detroit Airship Company and their amazing tin blimp. The idea was the brainchild of a man named Ralph Upton, and is startling in its simplicity: why not take the all-metal, monocoque design that was just then being so successfully applied to heavier-than-air flight, and use it to build an airship? Continue reading “The “Tin Blimp” Was A Neither Tin Nor A Blimp: The Detroit ZMC-2 Story” →

Secure Communication, Buried In A News App

March 9, 2026 by Lewin Day 28 Comments

Cryptography is a funny thing. Supposedly, if you do the right kind of maths to a message, you can send it off to somebody else, and as long as they’re the only one that knows a secret little thing, nobody else will be able to read it. We have all sorts of apps for this, too, that are specifically built for privately messaging other people.

Only… sometimes just having such an app is enough to get you in trouble. Even just the garbled message itself could be proof against you, even if your adversary can’t read it. Enter The Guardian. The UK-based media outlet has deployed a rather creative and secure way of accepting private tips and information, one which seeks to provide heavy cover for those writing in with the hottest scoops.

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Hiding A Bomb In Plain Sight

March 7, 2026 by Al Williams 38 Comments

You are at war. Trains are key to keeping your army supplied with fuel, ammunition, food, and medical supplies. But, inexplicably, your trains keep blowing up. Sabotage? Enemy attack? There’s no evidence of a bomb or overt enemy attack. This is the situation the German military found itself in during World War II. As you can see in the video below, the hidden bomb was the brainchild of a member of Britain’s SOE.

The idea was to put plastic explosive inside a fake plastic lump of coal. They hand-painted each one, and the color had to match the exact appearance of local coal. Paint and coal dust helped with that. The bomb had to weigh the correct amount as well.

The coal was safe until it got quite hot, so resistance fighters could easily carry the coal and surreptitiously drop the bomb anywhere coal is stored. Eventually, it will be put in a boiler, and at the right temperature, it will do its job. There’s some actual footage of a test in the second video below.

Continue reading “Hiding A Bomb In Plain Sight” →