Hackaday Links: November 21, 2021

November 21, 2021 by Dan Maloney 28 Comments

As the most spendiest time of the year rapidly approaches, it’s good to know that your hard-earned money doesn’t have to go towards gifts that are probably still sitting in the dank holds of container ships sitting at anchor off the coast of California. At least not if you shop the Tindie Cyber Sale that started yesterday and goes through December 5. There’s a lot of cool stuff on sale, so it shouldn’t be too hard to find something; to sweeten the deal, Jasmine tells us that there will be extra deals going live on Black Friday and Cyber Monday. But wait, there’s more — follow Tindie on Twitter for bonus discount codes.

Blue is the old black, which was the new blue? At least when it comes to “Screens of Death” it is, since Microsoft announced the Windows 11 BSOD will revert back from its recent black makeover to the more familiar blue theme. You’ll have to scroll down a bit, perhaps three-quarters of the way through the list of changes. Again, the change seems completely cosmetic and minor, but we’d still love to know what kind of research went into making a decision like this.

From the “One Man’s Trash” department, we have a request for help from reader Mike Drew who picked up a bunch — like, a thousand — old tablet computers. They originally ran Windows but they can run Linux Mint just fine, and while they lack batteries and the back cover, they’re otherwise complete and in usable condition, at least judging by the pictures he shared. These were destined for the landfill, but Mike is willing to send batches of 10 — no single units, please — to anyone who can cover the cost of packaging and shipping. Mike says he’ll be wiping the tablets and installing Mint, and will throw in a couple of battery cables and a simple instruction sheet to get you started. If you’re interested, Mike can be reached at michael.l.drew@gmail.com. Domestic shipping only, please. Here’s hoping you can help a fellow hacker reclaim a room in his house.

Answering the important questions: it turns out that Thanos couldn’t have snapped half of the universe out of existence after all. That conclusion comes from a scientific paper, appearing in the Journal of the Royal Society. While not setting out to answer if a nigh-invulnerable, giant purple supervillain could snap his fingers, it’s pretty intuitive that wearing any kind of gloves, let alone a jewel-encrusted metal gauntlet, makes it hard to snap one’s fingers. But the mechanics of snapping is actually pretty cool, and has implications beyond biomechanics. According to the paper, snapping is actually an example of latch-mediated spring actuation, with examples throughout the plant and animal kingdoms, including the vicious “one-inch punch” of the tiny mantis shrimp. It turns out that a properly executed human finger snap is pretty darn snappy — it takes about seven milliseconds to complete, compared to 150 milliseconds for an eye blink.

And finally, it seems like someone over at Id Software is a bit confused. The story began when a metal guitarist named Dustin Mitchell stumbled across the term “doomscroll” and decided that it would make a great name for a progressive thrash metal band. After diligently filing a trademark application with the US Patent and Trademark Office, he got an email from an attorney for Id saying they were going to challenge the trademark, apparently because they feel like it will cause confusion with their flagship DOOM franchise. It’s hard to see how anyone who lived through the doomscrolling years of 2020 and 2021 is going to be confused by a thrash metal band and a 30-year-old video game, but we suppose that’s not the point when you’re an attorney. Trademark trolls gonna troll, after all.

Magic In VR That Depends On Your Actual State Of Mind

November 21, 2021 by Donald Papp 10 Comments

[Cangar]’s excitement is palpable in his release of a working brain-computer interface (BCI) mod for Skyrim VR, in which the magic system in the game is modified so that spell effectiveness is significantly boosted when the player is in a focused mental state. [Cangar] isn’t just messing around, either. He’s a neuroscientist whose research focuses on assessing mental states during task performance. Luckily for us, he’s also an enthusiastic VR gamer, and this project of his has several interesting aspects that he’s happy to show off in a couple of videos.

User wearing VR headset — The Muse 2 fits under the VR headset easily.

It all starts with the player wearing a Muse 2 meditation device; a type of passive, off-the-shelf electroencephalography (EEG) unit aimed primarily at guiding a user towards better relaxation and focus. [Cangar] reads data using the Brainflow library and processes it into a final value on a scale between “not focused” and “focused”. [Cangar] makes a point of explaining that his system ultimately has the goal of modeling the player’s state of mind, which is different from modeling just the brain activity. As such, motion data is considered as well, and holding still confers a small bonus to the process.

How is this data actually used in the game? In VR, this “focus” value is shown as a small bar on the player’s wrist, and spell effectiveness (for example, damage for attack spells) scales along with the size of the bar. When the bar is full a player would be very powerful, with spells doing double damage. If the bar is empty, spells will do little to no damage.

[Cangar] demonstrates the mod in two videos (both embedded below), but you won’t see him blasting enemies with fireballs. Presumably, VR gamers already know what that looks like, so what he does instead is explain how the system looks and works (first video, cued to 4:12), and in the second, he video demonstrates how the focus meter changes depending on his activity and mental state.

The results look exciting, and the potential uses of a system like this are pretty interesting to think about. Taking a few deep breaths and calming one’s body and mind before launching a magical attack will have a tangible effect in the world, and because things rarely go according to plan, there is also a clear survival benefit to learning to focus while under pressure. But if a brain monitor isn’t your cup of tea, maybe consider a leisurely bike ride through Skyrim, instead.

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Zac shows off his sound diffusion panels

Taking The Bark Out Of Reverb With Wood Scraps

November 21, 2021 by Matthew Carlson 49 Comments

For the past few years, many have become used to having virtual meetings in their homes. Spaces like kitchen tables, couches, spare bedrooms, and hammocks in the yard have all become “offices”. As you can imagine, many of these spaces aren’t well known for their acoustic qualities. [Zac] built a sound diffusion art piece out of scrap pieces of wood to help his office sound better when recording.

Reverb is caused by sound bouncing off hard, flat surfaces like drywall. These reflections are picked up by the microphone and lead to a noticeable drop in perceived sound quality. There are generally two ways to kill reverb in a space: diffusion and absorption. Diffusion is the technique that [Zac] is going for, with thousands of faces at different angles and locations, it breaks up the harsh reflections into millions of tiny reflections. Absorption is usually accomplished with foam and other typically soft substances.

[Zac] happened to have a large pile of offcuts and extra material from past projects of various wood species, making it easy to make a visually interesting piece. He used a table saw to rip them to a consistent width and a drum sander reduced them all to the same depth. Next, the long sticks were cut with a miter saw into 5 different lengths, leaving him with thousands of little pieces of wood. The hard part began when he had to glue several thousand pieces to a plywood backer board with CA glue. Sanding, finishing with poly, and a french cleat made the three pieces ready to hang on the wall.

Overall, the effect is stunning. While we’d love more hard data on the improvement, it certainly does sound better anecdotally. If you’re interested in more woodworking, take a look into making an inlay without a CNC. Video after the break.

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Polymer Discovery Gives 3D-printed Sand Super Strength

November 21, 2021 by Dave Rowntree 29 Comments

Research activity into 3D printing never seems to end, with an almost constant stream of new techniques and improvements upon old ones hitting the news practically daily. This time, the focus is on a technique we’ve not covered so much, namely binder jetting additive manufacturing (BJAM for short, catchy huh?) Specifically the team from Oak Ridge National Laboratory, who have been exploring the use of so-called hyperbranched Polyethyleneimine (PEI) as a binder for jetting onto plain old foundry silica sand (nature, free access.)

The PEI binder was mixed with a 75:25 mix of water and 1-propanol (not to be mixed up with 2-propanol aka isopropanol) to get the correct viscosity for jetting with a piezoelectric print head and the correct surface tension to allow adequate powder bed penetration, giving optimal binding efficiency. The team reported a two-fold increase in strength over previous jetting techniques, however, the real news is what they did next; by infusing the printed part (known as the green part) with common old ethyl cyanoacrylate (ECA, or super glue to us) the structural strength of the print increased a further eight times due to the reaction between the binder and the ECA infiltrate.

To further bestow the virtues of the PEI binder/ECA mix, it turns out to be water-soluble, at least for a couple of days, so can be used to make complex form washout tooling — internal supports that can be washed away. After a few days, the curing process is complete, resulting in a structure that is reportedly stronger than concrete. Reinforce this with carbon fiber, and boy do you have a tough building material!

Not bad for some pretty common materials and a simple printing process.

We covered a similar binder jetting process for using sawdust a little while ago, and a neat way of printing with metal powder by carrying it in a stream of argon and cooking it with a laser, but there is an opening for a DIY effort to get in on the binder jetting game.

Thanks [Victor] for the tip!

A Trackball So Good You Can’t Buy It

November 21, 2021 by Jenny List 21 Comments

The projects we feature on Hackaday are built to all standards, and we’d have to admit that things have left our own benches as bundles of wire and tape. Sometimes we see projects built to such a high standard that we’re shocked that they aren’t a high-end manufactured product, such as [jfedor2]’s two-ball trackball project. It combines a pair of billiard balls and a couple of buttons with a beautifully-designed 3D-printed case that looks for all the world as though it came from a premium peripheral brand.

Inside are a pair of PMW3360 optical sensors on PCBs mounted with a view into the billiard ball sockets, and for which the brains come courtesy of an RP2040 microcontroller. There are five PCBs in all, each having a set of purpose-built stand-offs to hold it. The result appears to be about as good a trackball as you’d hope to buy, except of course that you can’t. All the files to make your own are in the GitHub repository though, so all is not lost.

Over the years we’ve brought you a variety of trackball designs, including at least one other build using a billiard ball.

Light-Tracking BEAM Robot Can See The Light

November 21, 2021 by Lewin Day 14 Comments

BEAM robotics, which stands for Biology, Electronics, Aesthetics, and Mechanics, is an ethos that focuses on building robots with simple analog circuits. [NanoRobotGeek] built a great example of the form, creating a light-tracking robot that uses no batteries and no microcontrollers.

The robot aims to track the brightest source of light it can see. This is achieved by feeding signals from four photodiodes into some analog logic, which then spits out voltages to the two motors that aim the robot, guiding it towards the light. There’s also a sound-detection circuit, which prompts the robot to wiggle when it detects a whistle via an attached microphone.

The entire circuitry is free-formed using brass wire, and the result is an incredibly artful build. Displayed in a bell jar, the build looks like some delicate artifact blending the past and future. Neither steampunk nor cyberpunk, it draws from both with its combination of vintage brass and modern LEDs.

It’s a great build that reminds us of some of the great circuit sculptures we’ve seen lately. Video after the break.

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PSSST! Here’s A Novel SSB Radio Design With Only Seven Transistors

November 20, 2021 by Ryan Flowers 45 Comments

When [Pete Juliano] sat down to design a sideband transceiver for the 20 Meter (14 MHz) ham radio band, he eschewed the popular circuits that make up so many designs. He forged ahead, building a novel design that he calls Pete’s Simple Seven SSB Transceiver, or PSSST for short.

What makes the PSSST so simple is not only its construction, but the low component count. The same circuit using four 2N2222A’s is used on both transmit and receive. On transmit, an extra three components step in to amplify the microphone input and build output power, which is 2.5-4 Watts, depending on the final output transistor used. The best part is that all of the transistors can be had for under $10 USD! [Pete] shows where radio components such as the RF mixers and the crystal filter can be purchased, saving a new constructor a lot of headaches. The VFO and IF frequencies are both provided by the venerable si5351a with an Arduino at the helm.

Many simple transceivers are designed to demonstrate a minimum viable radio, with performance not really a goal. On the other hand, the PSSST was modeled stage-by-stage in LTSpice, ensuring great transmit audio and nice receiver performance. Be sure to check out the demonstration below the break!

[Pete] has painstakingly documented the entire project on his website, and the code for the VFO is available by request via email. We appreciate this contribution to the homebrew ham radio community, and we’re sure this will provide many nights of solder smoking enjoyment for radio amateurs around the world.

Continue reading “PSSST! Here’s A Novel SSB Radio Design With Only Seven Transistors” →