Cooking Up A Batch Of Homebrew Welding Gas

September 21, 2021 by Dan Maloney 31 Comments

You know the feeling — you’re making good progress on a weekend project, you’re really in the groove, things are going right. Right up until you run out of That One Thing™ that you can’t do without, the only store that sells it is closed, and you get a sudden case of whiplash as your progress hits a virtual brick wall.

Of course, every challenge holds the opportunity to hack your way around it, which is how [Lucas] ended up building this carbon dioxide generator. The “IG” in MIG welding stands for the “inert gas” that floods the weld pool and keeps the melted metal — the “M” in MIG — from rapidly oxidizing and ruining the weld. Welders often use either straight CO₂ or a mix of CO₂ and argon as a MIG shielding gas, which they normally get from a commercial gas supplier, generally on non-weekend days.

[Lucas] turned to grade-school chemistry for his CO₂ generator, using the vigorous reaction of baking soda and vinegar to produce the gas. Version one was sketchy as all get-out; the second iteration still had some sketch factor thanks to the use of ABS pipe, but the inclusion of a relief valve should prevent the worst from happening. After some fiddling with how to get the reagents together in a controlled fashion, [Lucas] was able to generate enough CO₂ to put down a decent bead — a short one, to be sure, but the video below shows that it worked.

Could this be scaled up to something for practical use? Probably not. But it’s cool to see what’s possible, and something to file away for a rainy day. And maybe [Lucas] can use this method to produce CO₂ for his homemade laser tube. But again, probably not.

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Mini Wireless Thermal Printers Get Arduino Library (and MacOS App)

September 21, 2021 by Donald Papp 24 Comments

[Larry Bank]’s Arduino library to print text and graphics on BLE (Bluetooth Low Energy) thermal printers has some excellent features, and makes sending wireless print jobs to a number of common models about as easy as can be. These printers are small, inexpensive, and wireless. That’s a great mix that makes them attractive for projects that would benefit from printing out a hardcopy.

It’s not limited to simple default text, either. Fancier output can be done using Adafruit_GFX library-style fonts and options, which sends the formatted text as graphics. You can read all about what the library can do in this succinct list of concise functions.

But [Larry] hasn’t stopped there. While experimenting with microcontrollers and BLE thermal printers, he also wanted to explore talking to these printers from his Mac using BLE directly. Print2BLE is a MacOS application that allows dragging image files into the application’s window, and if the preview looks good, the print button makes it come out of the printer as a 1-bpp dithered image.

Small thermal printers make for neat projects, like this retrofitted Polaroid camera, and now that these little printers are both wireless and economical, things can only get easier with the help of a library like this. Of course, if that’s all starting to look a little too easy, one can always put the thermal back in thermal printing by using plasma, instead.

Bringing The Quake Flicker To Life With A Hacked Light

September 21, 2021 by Tom Nardi 14 Comments

If you ever feel a pang of shame because you’ve been reusing the same snippets of code in your projects for years, don’t. Even the big names do it, as evidenced by the fact that code written to govern flickering lights back in 1996 for Quake is still being used in AAA titles like 2020’s Half-Life: Alyx. In honor of this iconic example of digital buck-passing, [Rodrigo Feliciano] thought he’d port the code in question over to the Arduino and recreate the effect in real-life.

Since the Quake engine has been released under the GPLv2, it’s easy to pull up the relevant section of the code to see how the lighting was configured. Interestingly, lighting patterns were implemented as strings, where the letters from a to z referenced how bright the light should appear. So for example, a strobe light that goes between minimum and maximum brightness would be written as “aaaaaaaazzzzzzzz”, while a flickering light could be represented with the string “nmonqnmomnmomomno“.

An emergency light provided the LEDs and enclosure.

This ended up being very easy to implement on the Arduino in just a few lines, as [Rodrigo] simply had to assign each letter in the string a numerical value between 0 and 255 using map, and then use the resulting number to set the LED brightness with analogWrite.

With the code written, [Rodrigo] then had to put the hardware together. He stripped down a basic emergency light to get an array of white LEDs and a handy enclosure. He also wired up a simple transistor circuit on a scrap of perfboard so the Arduino Pro Mini could control all the LEDs from a single GPIO pin. Combined with a long USB cable to power it, and he’s got a perfect desk accessory for late-night gaming sessions.

In the video below you can see the final result, which [Rodrigo] has even synced up to footage from the classic 1996 shooter. The light makes for an interesting conversation piece, but we think the logical next step is to work this technique into an ambilight-like system to really make it feel like you’re wandering down those dimly lit corridors.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Grabbity Gloves

September 21, 2021 by Kristina Panos 14 Comments

I keep saying I need to stay away from auction sites, but then I wouldn’t have as much fodder for Hackaday, would I? As I write this, I’m waiting on a Dell AT101W, which will be my first keeb with Alps switches. Well, hopefully it has Alps SKCM salmon or black switches — according to Deskthority, it might have rubber domes. If it doesn’t keyboard, I will probably salvage the switches and build something more ergonomic. Either way, I’m thinking we need a post about Alps switches, because some people think they’re even better than Cherry MX switches.

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Researchers monitor calves as they use the MooLoo, a special pen for urination.

Toilet-Training Cows Is No Bull

September 21, 2021 by Kristina Panos 28 Comments

Human activity may be the main cause of climate change, but all these cows milling and mooing about don’t help, either. Everyone knows that cows produce methane-laden flatulence, but there’s another problem — their urine contains ammonia. The nitrogen leeches into the soil and turns into nitrous oxide, which is no laughing matter. So what’s the answer, giant diapers? No, just train them to use a toilet instead of the soil-let.

A pair of researchers from the University of Auckland traveled to a research institute’s farm in Germany with the hope of training a group of 16 calves to do their business in a special pen. The “MooLoo” is painted bright green and carpeted with artificial turf so it’s less weird for the cows. First they left the calves in the pen until they peed, and then gave it a reward of sugar water. From there, they started extended the animals’ distance from the MooLoo. Whenever the calves thought outside the box, they would be sprayed with water for three seconds. The results are kind of surprising: within an average of 15-20 urination sessions, 11 of the 16 cows had been trained successfully and were using the MooLoo 75% of the time. Watch a calf earn some sugar water after the break.

German cows mostly live in barns, but millions of other cows spend much of their time outside. So, how would that work? The researchers believe that cows could be trained to go when they gather for milking time. Makes sense to us, but how do you train cows on a large scale? Maybe with bovine VR?

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Mechanisms Behind Vaccine Side-Effects: The Science That Causes That Sore Arm

September 21, 2021 by Maya Posch 85 Comments

After receiving a vaccination shot, it’s likely that we’ll feel some side-effects. These can range from merely a sore arm to swollen lymph nodes and even a fever. Which side-effects to expect depend on the exact vaccine, with each type and variant coming with its own list of common side-effects. Each person’s immune system will also react differently, which makes it hard to say exactly what one can expect after receiving the vaccination.

What we can do is look closer at the underlying mechanisms that cause these side-effects, to try and understand why they occur and how to best deal with them. Most relevant here for the initial response is the body’s innate immune system, with dendritic cells generally being among the first to come into contact with the vaccine and to present the antigen to the body’s adaptive immune system.

Key to the redness, swelling, and fever are substances produced by the body which include various cytokines as well as prostaglandin, producing the symptoms seen with inflammation and injury.

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Interactive Clips For Game Boy: Sit Back And Watch Or Take Control

September 21, 2021 by Kristina Panos 4 Comments

How often does this happen to you? You find yourself describing something that happened in a game to someone, and they’re not sure they know what part of the map you’re talking about, or they’ve never gotten that far. Wouldn’t it be cool to make a bookmark in a video game so you can jump right to the beginning of the action and show your friend what you mean using the actual game?

That’s the idea behind [Joël Franusic] and [Adam Smith]’s fantastic Playable Quotes for Game Boy — clip-making that creates a 4-D nugget of gameplay that can either be viewed as a video, or played live within the bounds of the clip. The system is built on a modified version of the PyBoy emulator.

Left: the full game ROM. Right: a bookmarked slice of the game ROM with the rest set to zero.

Basically, a Playable Quote is made up of a save state and all that entails, plus a slice of the game’s ROM that includes just enough game data to recreate an interactive clip. Everything is zipped up and steganographically encoded into a PNG file. Here’s a Tetris quote you can play (or watch) right now — you might recognize it from the post thumbnail. You’ll find the others on the games site, which allows people to create and share and build on each other’s work.

There’s so much more that can be done with this type of immersive and interactive tool outside the realm of games, and we’re excited to see where this leads and what people do with it.

Haven’t heard of PyBoy before? Let us introduce you.