Tomatoes Are Not Guncotton

November 22, 2021 by 14 Comments

[Integza] hates tomatoes, but loves rocketry. Thus, he decided to see if he could process his most-loathed fruit into some sort of rocket fuel, or at least something relatively flammable. The experiment ended poorly, but the science behind it is interesting.

The basic idea is that tomatoes are largely made up of water, sugar, and cellulose. Thus, if you nitrate that cellulose, it becomes nitrocellulose, also known as guncotton. Guncotton is was once used to replace gunpowder in firearms, though today it’s often used by magicians to create ashless flashes of flame.

To achieve this, [Integza] first attempted to make regular guncotton using a 50:50 mixture of nitric acid and sulfuric acid. The cotton was then neutralized with a baking soda and water mixture to remove excess acid, and the cotton dried. Once tested, it burned quickly as you’d expect from guncotton.

After removing the sugars from tomatoes with water, soap, hydrogen peroxide, and bleach, the tomatoes were then dried to remove excess water before also getting the acid treatment. They were then similarly neutralized, dried, and tested. One tomato did burn rather quickly, while the others merely fizzled.

One of the reasons behind this may have been due to the composition of the tomatoes. Tomatoes often consist of a mixture of cellulose, hemicellulose, and lignin, these latter components are known for producing inferior guncotton. The ramshackle preparation may have had some effect on the results. Let’s just say and it’s not advisable to work with fuming acids without protective gear and a fume hood, either.

The video’s title claims that the tomatoes were turned into rocket fuel, which is far beyond the actual results of the experiment. However, with some more advanced chemical processing, we could certainly see the fruit becoming a mite more flammable than it was. You’re probably better off just sticking to straight cotton though, for the best results. Video after the break.

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Arduino Plays The Glasses

November 22, 2021 by 8 Comments

Have you ever been on a city street and seen a busker playing music on glasses? Each glass has a different amount of water and produces a different note when tapped. [Cyberlab] must have seen them and created an Arduino robot to play tunes on glasses. You can see the result in the video below.

If we had done this, we might have had a solenoid per glass or used some linear component like a 3D printer axis to pick different glasses. [Cyberlab] did something smarter. The glasses go in a circle and a stepper motor points at the correct glass and activates a solenoid. The result is pretty good and it is a lot simpler than any of our ideas.

If you aren’t musically inclined, you might wonder how you’d program the songs. There’s an example of taking a music box score from a website — apparently, there are lots of these — and removing any polyphony from it. The site mentioned even has an editor where you can import MIDI files and work with them to produce a music box strip that you could then convert. Then you encode each note as a number from 0 to 6.

Of course, you also have to fill your glasses with the right amount of water. A piano tuning phone app should be useful. We’ve seen this done in a linear fashion before. You can even use a single glass for many notes with a little ingenuity.

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Slick Keyboard Built With PCB Magic

November 21, 2021 by 21 Comments

Sometimes a chance conversation leads you to discover something cool you’ve not seen before, and before you know it, you’re ordering parts for yet another hardware build. That’s what happened to this scribe the other day when chatting on some random discord, to QMK maintainer [Nick Brassel aka tzarc] about Djinn, a gorgeous 64-key split mechanical keyboard testbed. It’s a testbed because it uses the newest STM32G4x microcontroller family, and QMK currently does not have support for this in the mainline release. For the time being, [Nick] maintains a custom release, until it gets merged.

Hardware-wise, the design is fabulous, with a lot of attention to detail. We have individual per-key RGB LEDs, RGB underglow, a rotary encoder, a five-way tactile thumb switch, and a 240×320 LCD per half. The keyboard is based on a three PCB stack, two of which are there purely for structure. This slick design has enough features to keep a fair few of us happy.

Interestingly, when you look at the design files (KiCAD, naturally) [Nick] has chosen to take a mirrored approach to the PCB. That means the left and right sides are actually the same PCB layout. The components are populated on different sides of the PCB depending on which half you’re looking at! By mirroring footprints on both PCB sides, and hooking everything up in parallel, it’s possible to do it all with a single master layout.

This is a simple but genius idea that this scribe hadn’t come across before (the shame!) Secondarily it keeps costs down, as your typical Chinese prototyping house will not deal in PCB quantities below five, so you can make two complete keyboards on one order, rather than needing two orders to make five. (Yes, there are actually three unique PCBs, but we’re simplifying the situation, ok?)

Now, if only this pesky electronics shortage could abate a bit, and we could get the parts to build this beauty!

Obviously, we’ve covered many, many keyboards over the years. Here’s our own [Kristina’s] column all about the things. If you need a little help with your typing skills, this shocking example may be the one for you. If your taste is proper old-school clackers, there’s something for everyone.

This beaded QR code tells a story when scanned.

Beaded QR Code Bracelets Weave A Storytelling Interface

November 21, 2021 by 14 Comments

For centuries, people have been using patterns to communicate information in an eye-catching way. QR codes are no different, although they require a barcode scanner to decode rather than a knowledge of Navajo Native American history.

November is National Native American Heritage Month, and as part of their celebration, [ngaskins] and their students are making seed bead bracelets with QR codes. When scanned, each QR triggers a story written by the student in the form of an audio file, a video clip, or an animation. [ngaskins] says that this project was inspired by eyeDazzler, a beadwork tapestry made with software that generates Navajo weaving patterns.

The students started by designing their bracelets on graph paper, software, or a virtual loom before getting the seed beads and the tweezers out, and decided whether they would use a static or dynamic QR code. Aside from the aesthetics of beadwork, the bead loom is good for teaching math and computational ideas because the beads are laid out in rows and columns. It’s also a good tool for teaching lines of symmetry.

QR codes can hold quite a bit of information. In fact, there’s enough room in a version 40 QR for an executable version of Snake.

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Hackaday Links: November 21, 2021

November 21, 2021 by 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 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 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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