Creating A Supersonic Trebuchet

August 9, 2026 by 27 Comments

As awesome as trebuchets are, the fact that medieval engineers didn’t create versions capable of launching supersonic projectiles is a bit of a bummer. Fortunately it’s possible to correct this oversight with modern insights and technologies, as [Tom Stanton] demonstrates in a recent video.

While a traditional trebuchet is fairly straightforward, using a heavy weight moving an arm around a pivot that has the projectile attached to the other side, a few tweaks can make it much more lethal. One change is to have the projectile’s rope wound around the arm, forcing an additional pass around the arm to gain velocity. The other is to use a gearing system which uses the dropping weight’s energy more efficiently.

One complication here is that the arm now takes a few rotations to come up to speed, meaning that the release of the payload has to be controlled exactly, with only about an 0.0025 second release window. The solution was both low-tech and effective: since the arm is attached to a drum that the rope is wound onto, the moment enough rope is unwound from the dropping weight, a latch inside the drum is released to launch the projectile.

In a first test with a 10 kg weight, the projectile reached a velocity of around 528 km/h, which definitely was a good start, but also showed just how not aerodynamic the arm was. Some redesigns later of the entire trebuchet, the entire system was tested again with 10 kg and achieved a projectile velocity of 634 km/h. From there it was time to ramp up the weight to the full 40 kg, which theoretically should hit supersonic speeds.

Unfortunately the first attempt hit a mere 1,152 km/h (716 mph), which is just shy of the sound barrier at 1,235 km/h at 39% system efficiency and some components clearly breaking apart. Some more redesigns later and with a lighter projectile at 4 grams, a 40 kg weight achieved an arm speed of 2,342 rpm. The projectile now left the sling with 346.4 m/s, or 1,249 km/h, with an audible snap as the sound barrier got broken.

Even if the era of trebuchets in warfare is well and truly past, they remain fascinating physics demonstrations, with this case in point.

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Retrotechtacular: A View Of The Moon From 1964

August 9, 2026 by 13 Comments

If you didn’t live through it, it is hard to understand how excited the general public was about the race for the moon. You can capture some of it by watching “Lunar Bridgehead,” a film about JPL monitoring the Ranger spacecraft as it hit, rather hard, on the lunar surface.

The Ranger program had been plagued with problems. The first five didn’t make it to the moon. Ranger 6 hit the moon, but failed to start its cameras. Ranger 7 was the first successful mission. There would be two more successful missions before the end of the program.

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Hackaday Links: August 9, 2026

August 9, 2026 by 8 Comments

Bad news for anyone who was hoping for some relief from the memory shortage — Digitimes is reporting that the production capacity of major players such as Samsung, Micron, and SK Hynix has already been booked for 2027 due to record demand. Their industry sources indicate that what we’re experiencing currently is just a prelude to when things get really ugly, which is why customers are paying a premium to lock in their orders so far out.

Although there’s been no official word from either side of the transaction, the Digitimes article further points out that these sort of agreements are usually 3 to 5 year contracts. If that’s the case, and nothing changes in supply and demand equation, we could be in for a very rough ride. There’s a potential opportunity here for other manufacturers to step in and start producing DRAM, possibly even focusing on lower-performance offerings intended for the consumer market, but setting up those production lines isn’t going to happen overnight. It’s always possible the AI bubble could pop in the next couple of years, but we’re not sure we’d put money on it.

There’s a developing story this weekend about the breach of customer data over at Framework. The maker of modular and repairable computers has recently sent an email out to all customers that their names, email addresses, phone numbers, and physical addresses were leaked due to an upstream zero-day attack against database provider Metabase.

Metabase disclosed the breach on August 3rd, but we were mildly surprised to see that Framework doesn’t seem to have made any public acknowledgement of the event so far. As far as we can tell, the only reason there are copies of the email from them circulating online is because several customers posted it to social media. In their statements to sources such as TechCrunch, Framework reps were also hesitant to give hard details such as how many customers were impacted. While we’re fans of what Framework is trying to do in terms of hardware customization and repairability, we have to admit that being cagey about this sort of thing isn’t a good look.

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The Stages Of Grief In Repairing A Trinitron Found In The Trash

August 9, 2026 by 28 Comments

Sometimes you see a project just staring at you with proverbial puppy dog eyes and you just cannot look away. In the case of a once rather nice Sony TV it was the smooth 32″ Trinitron CRT that gave [Happychoice] that look when he came across it along the side of the road. Naturally he had to beg the owner of the junkyard to please let him adopt the pupp^Wjunked TV and attempted an ill-advised repair.

Some later sleuthing revealed that this poor TV had been sitting on the side of that road for at least six years, exposed to the worst that the Italian weather and local fauna could do to it, so it was no surprise that all he got out of it even after cleaning and some repairs was a sad triple-blink of the power LED. This indicated that something on the control board was very unhappy about the status of the power supply.

Over the course of a few months this project went correspondingly from careful optimism down to the depths of depression, through the fields of bargaining and into the blue skies of acceptance of a likely far more involved repair session than originally assumed. That said, the CRT itself looks to be in pretty good nick, as do the PCBs barring the few sketchy resistors that already got replaced.

We would like to congratulate [Happychoice] on the acquisition of a fun new repair project and wish him all the luck on bringing this beast of a TV back to life.

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The Chinese Smart Glasses Proving That Smart Glasses Can Be Repairable

August 9, 2026 by 21 Comments

It’s often claimed that wearable devices cannot have user-replaceable batteries or even be serviceable at all due to how compact and waterproof they must be, yet there are plenty of examples belying those claims. So too for smart glasses with their compact size and the need to be fully waterproof. They would be certified e-waste as soon as the built-in battery stops being a battery, assuming these claims were true. Recently [iFixit] bought a few Chinese smart glasses to see just how repairable they are, with the Rokid one being very surprising.

The first nice feature of both two Chinese smart glasses is that they have an external battery that clips on in addition to an internal one. Internally they’re quite similar, both featuring a Qualcomm Snapdragon AR1 Gen 1 SoC with 32 GB of eMMC storage, in addition to micro-LED projectors.

Of the two glasses in the video, the Quark one isn’t that dissimilar from the Ray-Ban and Meta ones, requiring fairly destructive heat and prying to get inside. The Rokid one is however very easy to get into, with very light glue that makes it easy to get into, as well as a very servicing-friendly internal architecture including its battery. This is a pattern that extends to its external battery module, giving a glimpse at what such devices ought to look like in a repair-friendly world.

As is to be expected for an [iFixit] video, a significant part of it is spent lamenting the ills of glued-in batteries, including the recent decision by the EU to exempt many wearable devices from its new right to repair regulations involving built-in batteries. In light of the teardown of the Rokid smart glasses in this video, as well as previous Pixel Watch 4 and Fairbuds teardowns, it certainly seems reasonable to enforce user-replaceable batteries for these wearables as well.

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Transmitting Analog Video Via Frikkin’ Laser Beams

August 9, 2026 by 14 Comments

Transmitting analog video via photons is old hat: that’s how everything started, after all, back in the day with over-the-air TV. Up the frequency of those photons from radio to visible light, though? Well, now that’s rather interesting. [Daniel] aka [milar111]’s LYME 101– which doesn’t seem to stand for anything–laser-video transmitter/receiver pair was a strong contender in the recently-completed Frikken’ Laser Beams challenge, but somehow we missed putting it up on the blog.

The project is documented quite well on GitHub as linked above, as well as on Instructables, and Hackaday.io, and in a YouTube video we’ve embedded below so you can see it in action. In principle it’s pretty simple: a Raspberry Pi is used to generate the composite video signal, which modulates a red laser diode through a 2N2222 NPN transistor and some passives. The reciever is a BPW34 photodiode wired with reverse bias for speed and fed through a LM318N op-amp. To get +9V and -9V for this circuit, [Daniel] makes the easy hack of using a pair of 9V batteries for a noiseless dual supply. It hooks up to a CRT just fine, but a little finessing in the form of a terminator resistor and a DC bias pot on the transmitter were needed to get his USB capture card working with the signal.

It’s not the weirdest way we’ve seen people hack analog video signals– there’s no audio cassettes to be seen,  and the signal isn’t even SECAM, the oddest encoding— but that’s not a slight. Transmitting video with higher-than-normal-frequency photons might not be that weird, but it looks like a lot of fun.

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Continously Extruding 3D Printed Tubes With Compressed Air

August 9, 2026 by 12 Comments

[Jan] of [Roetz 4.0] has a unique approach to multi-material 3D printing: he’s designed an extruder which takes two different materials and extrudes one as a shell around the other. This opens up some interesting possibilities, such as a conductive filament surrounded by an insulating shell; [Jan], however, didn’t have an immediate use for the process, so he moved on to a related technique: extruding plastic tubes with a compressed-air core.

The extruder he used for this was a variation on the dual-material extruder; it takes in two strands of filament, melts them, and extrudes them as a shell around the outlet of a compressed-air line, which was controlled by a high-precision pressure regulator. During testing with PLA, it seemed capable of extruding airtight tubes of filament, though it had a tendency to blow bubbles and form tubes with inconsistent diameters. The low thermal conductivity of the stainless steel extruder also proved problematic; coupled with the cooling effect of the compressed air, filament sometimes solidified inside the extruder.

[Jan] found it almost impossible to get consistent results using only pressure-based control; as the layer of molten plastic around the air gets thinner, it provides less resistance to further ballooning, leading to continuous expansion until the bubble bursts. Controlling the volume of air extruded provided much more consistent results, and in a second video, he built a peristaltic pump to do just that. He also switched to using TPU filament, which greatly improved layer adhesion. When inflated with compressed air, the finished TPU structures expanded slightly, though there were still air leaks. The results look promising, and TU Darmstadt has already carried out some research in this area.

In a separate research project, we’ve seen a similar multi-material co-extrusion approach used to print pneumatic channels. For more on the history of [Jan]’s multi-filament extruder, check out his Minuteman printer. Continue reading “Continously Extruding 3D Printed Tubes With Compressed Air” →