A child in a red shirt and blue pants balances on a board suspended across two small, green sawhorses. An astroturf hill and blue elephant-esque cart are in the background.

Popup Playground Roams Around

February 4, 2024 by 4 Comments

Going to the park is a time-honored pastime for kids around the world, but what if there isn’t one nearby? COMPA Teatro Trono and the International Design Clinic have designed a park that can come to you.

Working with a group of design students from Bolivia and America, the theatre troupe has iteratively designed a set of playground carts that can be deployed for kids to meet each other and play. El Alto, the city of 1 million where the playground plies the streets, has grown exponentially since its incorporation as an independent town in 1985. Infrastructure has trouble catching up with population jumps of 54% like that experienced from 2000-2010.

Starting with interviews with kids from the city about what was important for a playground, they found a trend of trees, slides, and the color green. Over the course of three summers, the design students went from janky prototypes to the more refined carts now seen roaming El Alto built around the idea of “exaggerated topography.” An elephant and “astroturf bee” are the two hand carts which disassemble into a variety of playground equipment once in place at a destination.

Not a ton of details are given in the article about the construction of the carts themselves, but we think this tactical urbanist approach to parks is a hack in itself. That said, be sure to point us toward some more info on the builds if you’ve found any. Know of another hack, that brings joy to your own neighborhoods? Send it to the tipsline!

 

POP! Goes The Hydrogen Howitzer

February 4, 2024 by 70 Comments

Military models are great 3D printing projects, even more so if they are somewhat functional. [Flasutie] took it a step further by engineering a 3D-printed howitzer that doesn’t just sit pretty—it launches shells with a hydrogen-powered bang.

This project’s secret sauce? Oxyhydrogen, aka HHO, the mix of hydrogen born when water endures the electric breakup of electrolysis. [Flasutie] wanted functional “high explosive” (HE) projectiles to pop without turning playtime into emergency room visit, and 30 mm was the magic size, allowing the thin-walled PLA projectile to rupture without causing injury, even when held in the hand. To set off the gaseous fireworks, [Flasutie] designed an impact fuze featuring piezoelectric spark mechanism nestled within a soft TPU tip for good impact sensitivity.

The howitzer itself is like something out of a miniaturized military fantasy—nearly entirely 3D printed. It boasts an interrupted thread breech-locking mechanism and recoil-absorbing mechanism inspired by the real thing. The breechblock isn’t just for show; it snaps open under spring power and ejects spent cartridges like hot brass.

Watch the video after the break for the build, satisfying loading sequence and of course cardboard-defeating “armor piercing” (AP) and HE shells knocking out targets.

Common Enzyme Breaks Down PLA Fast

February 4, 2024 by 49 Comments

The global issue of plastic waste has prompted scientists to seek innovative solutions for recycling. Single-use plastics, notorious for their environmental impact, require new methods for efficient and sustainable management. For some common plastics, though, salvation could be at hand, with researchers identifying a common enzyme that can be used to break them down fast.

Researchers at King’s College London have discovered an enzyme used in laundry detergents that can break down PLA plastics within 24 hours, using a little heat as an aid. Normally, this is achieved via composting methods that take weeks or months. This method transforms the plastics back into their original chemical components, offering a rapid and eco-friendly recycling process. The monomers can then be reused for manufacturing new plastic items.

One wonders if this could also be used in another way – perhaps in a multimaterial printer, allowing PLA to be used for supports and then broken down. It’s probably not that necessary, given other degradable materials exist, but it’s something to think about.

This project is a significant leap forward in recycling technology, showcasing the potential for enzymes to revolutionize how we handle plastic waste. It could also be a great way to recycle all those errant deformed Pikachus that keep ending up in your hackerspace’s 3D-printing waste basket. In any case, plastic waste is a problem the world needs to solve, and quickly, because it’s not going anywhere any time soon. Video after the break.

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HF In Small Spaces

February 3, 2024 by 21 Comments

Generally, the biggest problem a new ham radio operator will come across when starting out on the high frequency (HF) bands is finding physical space for the antennas. For a quick example, a dipole antenna for the 20 m band will need around 10 m of wire, and the lower frequencies like 80 m need about four times as much linear space. But if you’re willing to trade a large space requirement for a high voltage hazard instead, a magnetic loop antenna might be just the ticket.

Loop antennas like these are typically used only for receiving, but in a pinch they can be used to transmit as well. To tune the antennas, which are much shorter than a standard vertical or dipole, a capacitor is soldered onto the ends, which electrically lengthens the antenna. [OM0ET] is using two loops of coax cable for the antenna, with each end soldered to one half of a dual variable capacitor which allows this antenna to tune from the 30 m bands to the 10 m bands, although he is using it mostly for WSPR on 20 m. His project also includes the use of an openWSPR module, meaning that he doesn’t have to dedicate an entire computer to run this mode.

The main downsides of antennas like these is that they are not omnidirectional, are not particularly good at transmitting, and develop a significantly high voltage across the capacitor as this similar mag loop antenna project demonstrated. But for those with extreme limitations on space or who, like [OM0ET] want a simple, small setup for running low-power applications like WSPR they can really excel. In fact, WSPR is a great mode for getting on the air at an absolute minimum of cost.

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Why Not Try A DIAC?

February 3, 2024 by 31 Comments

There are plenty of electronic components which were once ubiquitous but once the niche which led to their existence has passed, they fade away to remain a junkbox curio. The DIAC is the subject of a recent ElectronicsNotes video, and while it might not quite yet have slid into total obscurity yet it’s definitely not the most common of parts in 2023.

If you’ve encountered one it will almost certainly be in the trigger circuit of a lighting dimmer or motor controller, where its bidirectional breakover makes for symmetrical control of a triac gate. This extremely simple circuit allows for perfect control of AC-powered devices, and could once be found everywhere. Its demise over recent years tells an interesting story of our changing use of electricity, as not only have other devices such as smart lights and brushless motors appeared which preclude traditional dimmers, but also we now demand better RF performance from our lighting controls.

The DIAC is still a handy part to know about, and you can take a look at the video below the break. We would normally try to link to another Hackaday story using a DIAC, but is it telling that we couldn’t find one? If you can, link it in the comments!

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Recovering A Busted Video Capture Device With Firmware Flashing Tricks

February 3, 2024 by 6 Comments

Sometimes, you have a piece of hardware that just up and stops working on you. In today’s fast-paced world, it’s easy to toss something broken and move on. [BuyItFixIt], as you imagine, makes it their purpose to, well, fix things instead. Their latest efforts involved resurrecting a dead AVerMedia Live Gamer 2 Plus capture device sourced off eBay.

The device was advertised as being dead, with no power. Probing around the board when powered up showed that there was some basic activity going on with one of the flash chips, but the device simply wouldn’t spring to life. This suggested that perhaps the flash had become corrupted, which was confirmed when reading the chip mostly returned 0xFF. Sadly, the device was so badly bricked that the usual update methods via SD card simply wouldn’t work.

Eventually, hunting down a debug header provided a way in. [BuyItFixIt] was able to find a way to flash firmware over this connection instead, but there was a problem. The firmware they had was formatted for loading via SD card, and wouldn’t work for the debug mode entry route. Instead, getting the device going would require recovering firmware from a similar working device, and then using that as a guide to assemble a proper workable firmware update to get the device back to an operational state.

It’s a great tale of perseverance and triumph, particularly given many would give up after the first update attempt failed. We’ve seen [BuyItFixIt] pull off some heroic repairs before, too. Video after the break.

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Tricky 3D Printed Joinery Problem? Give Heat Staking A Try

February 3, 2024 by 15 Comments

When you just can’t 3D print something as a monolithic part, you’re going to have to join pieces together. In such cases, most of us instinctively include threaded inserts or nut slots in the design, or even reach for a tube of CA glue. But perhaps you should be thinking more along the lines of heat-staking your printed parts together.

Although you might not be familiar with the term, if you’ve looked inside anything made out of plastic, chances are good you’ve seen a heat-staked joint. As [Richard Sewell] explains, a heat-staked joint is nothing more than the classic mortise-and-tenon made from plastic where the tenon stands proud of the joint face so it can be softened with heat. The tenon spreads out so the joint can’t be pulled apart. A variant on the theme includes a mortise with a generous chamfer so the melted tenon can spread out, providing not only extra resistance to pull-out be also a more flush surface.

To melt the joint, [Richard] simply uses a soldering iron and a little pressure. To spread out both the heat and the force a bit, he uses the barrel of the iron rather than a tip, although we could see a broad chisel tip being used for smaller joints. Either way, a layer of Kapton tape helps keep the iron from getting gunked up with melted plastic. [Richard] lists a host of advantages for this kind of plastic joinery, including eliminating the need for additional hardware. But we think the best feature of this joint is that by avoiding monolithic prints, each aspect of a part can have its layer lines optimized.

While it probably isn’t applicable everywhere, heat-staking looks like a technique to keep in mind. We’d love to see [Stefan] over at CNC Kitchen do some of his testing magic on these joints, like he did for threaded inserts.