Spinning Up A Water Cooled 3D Printed Stirling Engine

March 31, 2021 by Tom Nardi 7 Comments

The Stirling external combustion engine has fascinated gear heads since its inception, and while the technology has never enjoyed widespread commercialization, there’s a vibrant community of tinkerers who build and test their own takes on the idea. [Leo Fernekes] has been working on a small Stirling engine made from 3D printed parts and common hardware components, and in his latest video he walks viewers through the design and testing process.

We’ve seen Stirling engines with 3D printed parts before, but in most cases, they are just structural components. This time, [Leo] really wanted to push what could be done with plastic parts, so everything from the water jacket for the cold side of the cylinder to the gears and connecting rods of the rhombic drive has been printed. Beyond the bearings and rods, the most notable non-printed component is the stainless steel spice shaker that’s being used as the cylinder.

The piston is made of constrained steel wool.

Mating the hot metal cylinder to the 3D printed parts naturally introduced some problems. The solution [Leo] came up with was to design a toothed collar to hold the cylinder, which reduces the surface area that’s in direct contact. He then used a piece of empty SMD component feed tape as a insulator between the two components, and covered the whole joint in high-temperature silicone.

Like many homebrew Stirling engines, this one isn’t perfect. It vibrates too much, some of the internal components have a tendency to melt during extended runs, and in general, it needs some fine tuning. But it runs, and in the end, that’s really the most important thing with a project like this. Improvements will come with time, especially once [Leo] finishes building the dynamometer he hopes will give him some solid data on how the engine’s overall performance is impacted as he makes changes.

If you’ve got a glass test tube laying around, putting together a basic Stirling engine demonstration is probably a lot easier than you might think. Commercial kits are also available if you’re looking for something more substantial, but even those can benefit from some aftermarket modifications. With a little effort, you’ll have a power plant ready for the surface of Mars in no time.

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Web Tool Cranks Up The Power On DJI’s FPV Drone

March 31, 2021 by Tom Nardi 22 Comments

Apparently, if the GPS on your shiny new DJI FPV Drone detects that it’s not in the United States, it will turn down its transmitter power so as not to run afoul of the more restrictive radio limits elsewhere around the globe. So while all the countries that have put boots on the Moon get to enjoy the full 1,412 mW of power the hardware is capable of, the drone’s software limits everyone else to a paltry 25 mW. As you can imagine, that leads to a considerable performance penalty in terms of range.

But not anymore. A web-based tool called B3YOND promises to reinstate the full power of your DJI FPV Drone no matter where you live by tricking it into believing it’s in the USA. Developed by the team at [D3VL], the unlocking tool uses the new Web Serial API to send the appropriate “FCC Mode” command to the drone’s FPV goggles over USB. Everything is automated, so this hack is available to anyone who’s running a recent version of Chrome or Edge and can click a button a few times.

There’s no source code available yet, though the page does mention they will be putting up a GitHub repository soon. In the meantime, [D3VL] have documented the command packet that needs to be sent to the drone over its MODBUS-like serial protocol for others who might want to roll their own solution. There’s currently an offline Windows-only tool up for download as well, and it sounds like stand-alone versions for Mac and Android are also in the works.

It should probably go without saying that if you need to use this tool, you’ll potentially be violating some laws. In many European countries, 25 mW is the maximum unlicensed transmitter power allowed for UAVs, so that’s certainly something to keep in mind before you flip the switch. Hackaday isn’t in the business of dispensing legal advice, but that said, we wouldn’t want to be caught transmitting at nearly 60 times the legal limit.

Even if you’re not interested in fiddling with drone radios, it’s interesting to see another practical application of the Web Serial API. From impromptu oscilloscopes to communicating with development boards and conference badges, clever developers are already finding ways to make hardware hacking easier with this new capability.

[Thanks to Jules for the tip.]

Custom Built 12-Port A/V Switch Keeps CRT Well Fed

March 30, 2021 by Tom Nardi 5 Comments

Classic gaming aficionados who prefer to play on real hardware know the struggle of getting their decades-old consoles connected to a modern TV. Which is why many gamers chose to keep a contemporary CRT TV around for when they want to take a walk down memory lane. Unfortunately those old TVs usually didn’t offer more than a few A/V ports on the back, so you’ll probably need to invest in a A/V switch to keep them all hooked up at once.

That’s the situation [Thomas Sowell] found himself in, except he couldn’t find one with enough ports. Rather than chain switches together, he decided to build his own custom 12-port console selector. With an integrated amplifier to keep everything looking sharp, a handsome walnut and metal enclosure, and a slick graphical interface that shows the logo of the currently selected console on a Vacuum Fluorescent Display (VFD), the final product is a classic gamer’s dream come true.

To switch the audio [Thomas] is using a pair of ADG1606 16-channel analog multiplexers, while video is shuffled around with four MAX4315 8-channel video multiplexer-amplifiers. The math might seem a bit off at first, but he’s using one ADG1606 for each stereo channel and since the switch is for S-Video, each device has a luminance and color signal that needs to be handled separately. The multiplexers are flipped with a ATmega2561 microcontroller, which is also responsible for reading user input from a rotary encoder on the front of the case and displaying the appropriate console logo on the 140×32 Noritake VFD.

You may be surprised to find that [Thomas] considered himself an electronics beginner when he started this project, and that this is only the second PCB he’s ever designed. Was this a bold second project? Sure. But it also speaks to how far DIY electronics has come over the last years. Powerful open source tools, modular components, and of course a community of creative folks willing to share their knowledge and designs, has gone a long way towards redefining whats possible for the individual hacker and maker.

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Google Calls It Quits With VR, But Cardboard Lives On

March 30, 2021 by Tom Nardi 16 Comments

Google giving up on one of their projects and leaving its established userbase twisting in the wind hardly counts as news anymore. In fact, it’s become something of a meme. The search giant is notorious for tossing out ideas just to see what sticks, and while that’s occasionally earned them some huge successes, it’s also lead to plenty of heartache for anyone unlucky enough to still be using one of the stragglers when the axe falls.

So when the search giant acknowledged in early March that they would no longer be selling their Cardboard virtual reality viewer, it wasn’t exactly a shock. The exceptionally low-cost VR googles, literally made from folded cardboard, were a massive hit when they were unveiled back in 2014. But despite Google’s best efforts to introduce premium Cardboard-compatible hardware with their Daydream View headset two years later, it failed to evolve into a profitable business.

Of course if you knew where to look, the writing had been on the wall for some time. While the Daydream hardware got a second revision in 2017, and Google even introduced a certification program to ensure phones would work properly with the $100 USD headset, the device was discontinued in 2019. On the software side, Android 7 “Nougat” got baked-in VR support in 2016, but it was quietly removed by the time Android 11 was released in the fall of 2020.

With Cardboard no longer available for purchase, Google has simply made official what was already abundantly clear: they are no longer interested in phone-based virtual reality. Under normal circumstances, anyone still using the service would be forced to give it up. Just ask those who were still active on Google+ or Allo before the plug was pulled.

But this time, things are a little different. Between Google’s decision to spin it off into an open source project and the legions of third party viewers on the market, Cardboard isn’t going down without a fight. The path ahead might be different from what Google originally envisioned, but the story certainly isn’t over.

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Bluetooth PS3 Controllers Modernize The Nintendo GameCube

March 29, 2021 by Tom Nardi 19 Comments

While the PlayStation 3 and Gamecube come from opposing sides of the aisle, and in fact aren’t even from the same generation of hardware, this DIY adapter built by [Jeannot] allows Nintendo’s console to use Sony’s Bluetooth controllers with surprisingly little fuss. This might seem unnecessary given the fact that Nintendo put out an official wireless controller for the system, but given how expensive they are on the second-hand market, you’d need to have pretty deep pockets for an untethered four-player session. Plus, there’s plenty of people who simply prefer the more traditional control layout offered by Sony’s pad.

The internals of the 3D printed adapter are actually quite straightforward, consisting of nothing more than an Arduino Nano wired to a MAX3421E USB host shield. A common USB Bluetooth adapter is plugged into the shield, and the enclosure has an opening so it can be swapped out easily; which is important since that’s what the PS3 controller is actually paired to.

A Gamecube controller extension cable must be sacrificed to source the male connector, though if you wanted to fully commit to using Bluetooth controllers, it seems like you could turn this into an internal modification fairly easily. That would let you solder right to the controller port’s pads on the PCB, cutting the bill of materials down ever further.

[Jeannot] says the firmware is the product of combining a few existing libraries with a fair amount of experimentation, but as demonstrated in the video below, it works well enough to navigate the console’s built-in menu system. Future enhancements include getting the stick sensitivity closer to the values for the Gamecube’s standard controller, and adapting the code to work with newer PS4 controllers.

We’ve seen a fair amount of projects dedicated to the Gamecube’s official wireless controller, the Wavebird. From reverse engineering its RF communications protocol to adapting it for use with Nintendo’s latest console. There’s little debate that the Wavebird is a fine piece of engineering, but with how cheap and plentiful PlayStation controllers are, they tend to be the one hackers reach for when they want a dual-stick interface for their latest creation.

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NVMe Boot Finally Comes To The Pi Compute Module 4

March 29, 2021 by Tom Nardi 4 Comments

Since the introduction of the Raspberry Pi Compute Module 4, power users have wanted to use NVMe drives with the diminutive ARM board. While it was always possible to get one plugged in through an adapter on the IO Board, it was a bit too awkward for serious use. But as [Jeff Geerling] recently discussed on his blog, we’re not only starting to see CM4 carrier boards with full-size M.2 slots onboard, but the Raspberry Pi Foundation has unveiled beta support for booting from these speedy storage devices.

The MirkoPC board that [Jeff] looks at is certainly impressive on its own. Even if you don’t feel like jumping through the hoops necessary to actually boot to NVMe, the fact that you can simply plug in a standard drive and use it for mass storage is a big advantage. But the board also breaks out pretty much any I/O you could possibly want from the CM4, and even includes some of its own niceties like an RTC module and I2S DAC with a high-quality headphone amplifier.

Once the NVMe drive is safely nestled into position and you’ve updated to the beta bootloader, you can say goodbye to SD cards. But don’t get too excited just yet. Somewhat surprisingly, [Jeff] finds that booting from the NVMe drive is no faster than the SD card. That said, actually loading programs and other day-to-day tasks are far snappier once the system gets up and running. Perhaps the boot time can be improved with future tweaks, but honestly, the ~7 seconds it currently takes to start up the CM4 hardly seems excessive.

NVMe drives are exciting pieces of tech, and it’s good to see more single-board computers support it. While it might not help your CM4 boot any faster, it definitely offers a nice kick in performance across the board and expands what the system is capable of. Continue reading “NVMe Boot Finally Comes To The Pi Compute Module 4” →

Triton AR Headset Blends Stock And Printed Parts

March 28, 2021 by Tom Nardi 4 Comments

Augmented reality (AR) and natural gesture input provide a tantalizing glimpse at what human-computer interfaces may look like in the future, but at this point, the technology hasn’t seen much adoption within the open source community. Though to be fair, it seems like the big commercial players aren’t faring much better so far. You could make the case that the biggest roadblock, beyond the general lack of software this early in the game, is access to an open and affordable augmented reality headset.

Which is precisely why [Graham Atlee] has developed the Triton. This Creative Commons licensed headset combines commercial off-the-shelf components with 3D printed parts to provide a capable AR experience at a hacker-friendly price. By printing your own parts and ordering the components from AliExpress, basic AR functionality should cost you $150 to $200 USD. If you want to add gesture support you’ll need to add a Leap Motion to your bill of materials, but even still, it’s a solid deal.

The trick here is that [Graham] is using the reflectors from a surprisingly cheap AR headset designed to work with a smartphone. By combining these mass produced optics with a six inch 1440 x 2560 LCD panel inside of the Triton’s 3D printed structure, projecting high quality images over the user’s field of view is far simpler than you might think.

If you want to use it as a development platform for gesture interfaces you’ll want to install a Leap Motion in the specifically designed socket in the front, but otherwise, all you need to do is plug in an HDMI video source. That could be anything from a low-power wearable to a high-end gaming computer, depending on what your goals are.

[Graham] has not only provided the STLs for all the 3D printed parts and a bill of materials, but he’s also done a fantastic job of documenting the build process with a step-by-step guide. This isn’t some theoretical creation; you could order the parts right now and start building your very own Triton. If you’re looking for software, he’s also selling a Windows-based “Triton AR Launcher” for the princely sum of $4.99 that looks pretty slick, but it’s absolutely not required to use the hardware.

Of course, plenty of people are more than happy to stick with the traditional keyboard and monitor setup. It’s hard to say if wearable displays and gesture interfaces will really become the norm, of they’re better left to science fiction. But either way, we’re happy to see affordable open source platforms for experimenting with this cutting edge technology. On the off chance any of them become the standard in the coming decades, we’d hate to be stuck in some inescapable walled garden because nobody developed any open alternatives.