New Part Day: Raspberry Pi LEGO HAT

The Raspberry Pi Foundation have been busy little bees for the last couple of years producing their own silicon, new boards and now in collaboration with the LEGO Education team a new HAT to connect to the LEGO SPIKE education platform. This new HAT board will work with every Raspberry Pi board with a 40-pin GPIO header.

Based on the RPI2040 microcontroller, it makes an interesting detour away from dumb slave boards, although it looks like the firmware is closed (for now) so you’ll have to make do with the pre-baked capabilities and talk to it with the supplied python library.

According to the documentation, the communication between the Pi and the RPI2040 nestled beneath the HAT PCB is plaintext-over-serial, freeing up the majority of the GPIO pins for other uses. The board uses a surface mount pass-through type header which allows pins from the Pi to protrude through the PCB, allowing stacking more HATs on top. Curiously they decided to mount the PCB with active parts facing down, giving a flat rear surface to park things on. We suspect that decision was made to improve access to the LPF2 connectors, especially if they were surface mount parts.

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Mechanical Linkage CAD For Everyone

As much as some of us don’t like it, building things for real requires some mechanical component. Maybe it is something as simple as an enclosure or even feet for a PCB, but unless you only write software or play with simulators, you’ll eventually have to build something. It is a slippery slope between drilling holes for a front panel and attempting to build things that move. Sometimes that’s as simple as a hinge and a spring, or maybe it is a full-blown robot articulated arm.  That’s why [RectorSquid] built Linkage, a “program that lets you design and edit a two-dimensional mechanism and then simulate the movement of that mechanism” (that quote is from the documentation.

The program has had a few versions and is currently up past 3.15. To get an idea of the program’s capabilities, the first video below shows an older version simulating a ball lift. The second video shows the actual mechanism built from the design. The associated YouTube channel has more recent videos, too, showing a variety of simulations.

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Oculus Go VR Headset Gets Root Access, No Jailbreak Needed

The Oculus Go, Facebook’s first generation standalone VR headset, hit the market back in 2018 but it’s taken until now for owners to get an official unlocked OS build. The release was hinted at by former Oculus CTO John Carmack in a recent Tweet as something he had been pushing for years. This opens the hardware completely, allowing root access without the need for an unofficial jailbreak.

Oculus Go headset [image: WikiMedia Commons]
The Oculus Go is Android-based and has specifications that are not exactly cutting edge by VR standards, especially since head tracking is limited to three degrees of freedom (DoF). This makes it best suited to seated applications like media consumption. That said, it’s still a remarkable amount of integrated hardware that can be available for a low price on the secondary market. Official support for the Go ended in December 2020, and the ability to completely unlock the device is a positive step towards rescuing the hardware from semi-hoarded tech junk piles where it might otherwise simply gather dust.

When phone-based VR went the way of the dodo, millions of empty headsets went obsolete with it for a variety of reasons, but at least this way perfectly-good (if dated) hardware might still get some use in clever projects. Credit where credit is due; opening up root access to old but still perfectly functional hardware is the right thing to do, and it’s nice to see it happening.

Building A Devil’s Toothpaste Rocket Motor

When it comes to weird and wacky homebrew rocket experiments, [Integza] keeps himself fairly busy. He’s now attempted a design repurposing Devil’s Toothpaste for propulsion.

Devil’s Toothpaste is really the same as the famous Elephant Toothpaste experiment, just executed with higher concentration hydrogen peroxide. In this case, [Integza] is using 50% hydrogen peroxide combined with potassium permanganate as a catalyst. When the two are combined, the hydrogen peroxide breaks down into oxygen and water, which [Integza] uses here to propel a skateboard.

The potassium permanganate catalyst is impregnated into 3D printed porous ceramic parts. The peroxide is then  injected into this matrix via a compressed air mechanism, where it decomposes, creating a jet of water and oxygen that then blasts out of a 3D printed rocket nozzle to generate thrust.

It works surprisingly well, even if it’s a messy and unconventional way to build a rocket. It’s also a lot less fiery than most of [Integza]’s previous projects. Video after the break.

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Smokeless Burn Barrel Makes Your Backyard Fire Much Cleaner

Old 55-gallon drums are often repurposed into fire barrels with the simple addition of a few holes cut into the walls. Generally, they’re fit enough for purpose but can have a very smoky output, particularly when overloaded.  However, this design from [Building Stuff Is Fun] combines two drums into one to create a barrel that burns far more efficiently with less smoke! (Video, embedded below.)

Note the vent holes feeding oxygen to the fire just before the barrel outlet.

Through some clever cuts and folding of steel, a single burn barrel is created from the original two that helps eliminate smoke entirely, through two clever design features. First of all, plentiful air is provided to the fire thanks to the intakes at the bottom of the barrel. Secondly, the barrel-in-barrel design, paired with some smart vents, helps provide fresh air to the fire just before it leaves the barrel. This extra oxygen supply helps create secondary combustion at the outlet which burns up all the matter that would normally be passed out as smoke.

The design involves a lot more work than just hacking some holes in an old drum, but the results are undeniably impressive. The output of the smokeless burn barrel looks far hotter and cleaner. We’ve seen similar designs used to supply workshop heat, too. Video after the break.

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Going Forward To The Land: Technology For Permaculture

It’s usual for a Hackaday scribe to read hundreds of web pages over a typical week as we traverse the world in search of the good stuff to bring you. Sometimes they’re obvious Hackaday stories but as you’ll all no doubt understand we often end up on wild tangents learning about stuff we never expected to be excited about. Thus it was last week that I happened upon a GQ piece charting the dwindling remains of the communes set up in rural California by hippies during the counterculture years.

With only a few ageing residents who truly embraced the back-to-the-land dream remaining, these adventurously-designed home-made houses are gently decaying into the forest. It’s a disappearing world, but it’s also close to home for me as someone who crew up on a self-sufficiency smallholding in the 1970s. My parents may not have been hippies in the way those of everyone else in that scene at the time seemed to be, but I learned all my curiosity and hacking skills in the many opportunities presented to a small child by an unruly combination of small farm and metalworking business. There’s part of me that would build a hippy home in a Californian forest in a heartbeat, and throw myself with gusto into subsistence vegetable growing to get me through each winter.

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Announcing The Next Round Of Remoticon Talks

It’s coming up fast — Hackaday Remoticon 2021 is just a few weeks away, and we’re working around the clock to load up the weekend with awesome and inspiring talks that are bound to get the creative juices racing through your crazy straw brain.

Come and practice your neuroplasticity with us on November 19th and 20th. Remoticon is free-as-in-beer this year, unless you want a t-shirt. Even then, $25 is peanuts, because we’re sure that you’ll find a few talks that are priceless, and you’ll have a cool shirt to remember them by. Grab your ticket right now! We’ll wait.

A few days ago we announced mechanical engineering marvel Jeremy Fielding as our second keynote speaker. Passion is paramount to all projects, and Jeremy’s passion is making things move. He’s a renaissance man with a quiver full of self-taught skills, and is sure to bring enthusiasm to his keynote talk, which focuses on building hardware that moves, and how to handle the mechatronic mysteries that arise when trying to scale things up.

For now, let us indulge you with a preview of the second round of talks and speakers that we’ll be showcasing on November 19th and 20th. There’s plenty more where these came from, and we’ll be serving up fresh samples all the way until Remoticon weekend.

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