In the grand scheme of things, a single human lifetime is a drop in the bucket. Even if we don’t like to acknowledge it, we all know the meter is running so to speak. Yet you’re still squandering your precious time on this Earth by reading Hackaday instead of doing something constructive. Of course nobody is burning up more time on this site than those of us who are writing it all, so don’t feel too bad.

To remind us that life is fleeting, [Dries Depoorter] has designed the Shortlife: a device that counts down until your expected departure date. Before you get too excited, it can’t predict the future. The gadget is programmed with the vital statistics for the individual user, and data provided by the World Health Organization is used to calculate how much of your estimated life expectancy has already elapsed. Some would find this information depressing, while others will no doubt look at it as a source of inspiration. Us? We just think its a slick piece of gear.

The Shortlife is made up of a custom PCB mounted to a marbled block of recycled plastic. On the board there’s an ATmega328 microcontroller, a MAX7219 LED driver, and of course the red LED segment displays. Three of them are the classic seven count, while the rightmost display sports fourteen segments for a bit of added accuracy. All the user has to do if they want to watch their remaining time slip away is plug the device into a USB power source and set the current time.

We’ve seen similar mortal countdown clocks in the past, but the Shortlife certainly brings a certain level of elegance to the idea. Plus we also like the fact that you’re just a line of code or two away from having the display tick down to some other date in the future when that whole existential crisis kicks in

source https://hackaday.com/2020/12/21/watch-life-tick-away-one-led-segment-at-a-time/

An Australian radio telescope picked up unusual signals back in 2019 and thinks they originated from Proxima Centauri, a scant 4.3 light years from our blue marble. Researchers caution that it almost certainly is a signal of human or natural origin and that more analysis will probably show it didn’t come from Proxima Centauri. But they can’t yet explain it.

The research is from the Breakthrough Listen project, a decade-long SETI project. The 980 MHz BLC-1 signal, as it’s called, meets the tests that identify the signal as interesting. It has a narrow bandwidth, it drifts in frequency consistent with a signal moving away or towards the Earth, and it disappears when the radio telescope points elsewhere.

The project has been running since 2015 and this was the first signal their algorithms flagged as requiring further analysis. However, the researchers admit the algorithm is intentionally optimistic. After all, you’d rather have false positives to filter out than have any false negatives.

Unfortunately, since the initial set of detections, the team hasn’t found any more signals from the same part of the sky. Proxima Centauri is interesting because it is among our closest neighbors and it is known to have at least two planets, one of which we think could support life.

The 210 foot Parkes radio telescope — better known locally as “the dish” — that detected the signal dates back to 1961 and was the point of reception for the Apollo 11 moon landing. Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) operates the facility and the picture above is courtesy of CSIRO, CC-BY-3.0.

While you might not have room in your backyard for a 210-foot dish, you can build something more modest. We wonder if this signal will remain a mystery like the Wow signal?

source https://hackaday.com/2020/12/21/did-et-finally-call-us/

At one end of the synthesizer world, there stands commercial instruments designed for the ultimate in sound quality and performance, tailored to the needs of professional musicians. On the other, there are weird, wacky prototypes and artistic builds that aim to challenge our conception of what a synth should be. The VOC-25 by [Love Hultén] falls firmly in the latter category.

The synth is built around the Axoloti Core, a microcontroller board set up for audio experimentation. Packing stereo DACs and ADCs, and MIDI input and output, it’s the perfect base for such a project. Loaded up with vocal samples, it’s played by a keyboard in a fairly typical sense. Where things get interesting is the panel containing 25 sets of plastic teeth. The teeth open and close when the user plays the corresponding note, thanks to a solenoid. Along with the clacking sound of the machinery and pearly whites themselves, it adds quite a creepy vibe to the piece.

With its clean pastel enclosure, we can imagine this piece as the star of an avant-garde filmclip, or merely something to terrify children at a Maker Faire. It’s a fun build, to be sure. We’ve seen some other great experimental synths over the years, too – this 48 Game Boy build comes to mind. Video after the break.

source https://hackaday.com/2020/12/21/we-bet-youve-never-seen-a-pink-denture-synth/

Smartphones are portals to an overwhelming torrent of information. Yes, they’re a great way to find out the time, your bus schedule, and the weather, but they’re also full of buzzers and bells going off every three minutes to remind you that your uncle has reposted a photo of the fish he caught ten years ago. Sometimes, it’s better to display just the essentials, and that’s what Weather Note does.

It’s built around the Adafruit Feather Huzzah, a devboard built around the venerable ESP8266. It’s a great base for an Internet of Things project like this one, with WiFi built-in and ready to go. The Weather Note talks to a variety of online platforms to scrape weather data and helpful reminders, with the assistance of If This Then That, or IFTTT. Reminders to walk the dog or get some milk are displayed on a small OLED screen, while there’s also a bunch of alphanumeric displays for other information. WS2812 LEDs are used behind a shadowbox to display weather conditions, with cute cloud, rain, and sun icons. It’s all wrapped up in a tidy frame perfect for the mantlepiece or breakfast table.

It’s a great build to learn about programming for the Internet of Things, and with those bright LED displays, it’s probably a viable nightlight too. It’s a rare project that can both tell you about the weather and keep you from stubbing your toe in the kitchen, after all. Those desiring a stealthier build should consider going down the smart mirror route instead. Video after the break.

source https://hackaday.com/2020/12/20/weather-note-tells-you-what-you-need-to-know-and-no-more/

Water droplets are beautiful things, though photographing them can prove difficult without a little help. Precise timing is key, and that’s what led [Alex Pikkert] to build a timing controller to help nail the perfect shot.

It’s a job that’s ideally suited for the average microcontroller. In this case, [Alex] chose the venerable Arduino Uno. Paired with a bunch of buttons and a 16 x 2 character LCD, it has a simple-to-navigate interface for dialling in a shot. The trick to splash and droplet photography is to first open a valve to release a droplet, and then fire a flash a set time after to capture the droplet in flight, after it’s hit the surface of the liquid. [Alex]’s design uses a MOSFET to trigger the water valve, and optoisolators to safely trigger the flash and camera.

[Alex] has gotten some impressive results with the rig, and it would serve as a great starting point for anyone looking to get into the field. We’ve seen similar builds before, too. If you’ve got your own fancy photography rig for those otherwise-impossible shots, be sure to drop us a line!

source https://hackaday.com/2020/12/20/splash-droplet-photos/

If development platforms were people, Google would be one of the most prolific serial killers in history. Android Things, Google’s attempt at an OS for IoT devices, will officially start shutting down on January 5, 2021, and the plug will be pulled for good a year later. Android Things, which was basically a stripped-down version of the popular phone operating system, had promise, especially considering that Google was pitching it as a secure alternative in the IoT space, where security is often an afterthought. We haven’t exactly seen a lot of projects using Android Things, so the loss is probably not huge, but the list of projects snuffed by Google and the number of developers and users left high and dry by these changes continues to grow.

By now you’ve probably heard about the drone operator who was fined a cool $182,000 by the FAA for violations of the rules regarding safe drone operation. It may seem exorbitant, but when you dig a little deeper, it seems like the drone pilot, who goes by the handle “Mikey” on YouTube, pretty much had it coming. He has been operating drones in the Center City area of Philadelphia for a while now, in flagrant disregard for FAA rules like not operating in beyond line of sight, not operating at night, and not flying in restricted areas. Mikey, who by the way doesn’t have a remote pilot’s certificate, did all this and more, and posted everything on YouTube. We normally give the benefit of the doubt and take pity on people who get hassled for just enjoying their hobbies, but after listening to about three minutes of Mikey’s schtick on YouTube, we decided that he probably had it coming.

Still looking for the perfect gift this holiday season? What about the gift of silicon? DIY chip maker Sam Zeloof is auctioning off chips from his first production batch of homemade ICs, cooked up right in his garage. The Z1 chip, which we featured back in 2018 when Sam first announced it, is a dual-differential amplifier with six FETs and a handful of other components, packaged in a 14-pin ceramic DIP. The current bid is up to $315, which seems a fair price considering all the work Sam put into this, plus the fact that proceeds go to keeping Sam’s fab lab running.

We’re normally loathe to bring up anything that has to do with the safety of 3D-printing, as it mostly just devolves into a flame war in the comments section. But what the heck — it’s Christmas! There’s news of a paper, apparently presented at last week’s Society of Risk Analysis annual meeting, that reportedly confirms what most of us intuitively know already: that the fumes from 3D printers aren’t great to inhale. Specifically, the researchers found that emissions from ABS filament were moderately toxic to human lung cells, while minimally toxic to rats. There’s a lot of detail missing here — for example, “lung cells” implies a cell culture, which is not the same thing as observing clinical changes in someone’s lungs, nor is a rat always a good model for what’s going to happen in humans. Still, we’re keen to read the actual paper and dive into the details. Until then, we’ll probably keep on printing — just maybe with the window cracked.

Looking for a fun project to while away some time between Christmas and New Year? You could do worse than by trying to tune into slow-scan TV broadcasts from the International Space Station. The ARISS program, or Amateur Radio aboard the ISS, has been operating from on high for 20 years now, and to celebrate they’ve scheduled SSTV broadcasts from December 24 to December 31. SSTV is an amateur radio mode that transmits low-def, static images on amateur bands that can be received with simple equipment, and without a license. If you want to give it a shot, you should check out Jenny’s how-to article for the basics on getting an RTL-SDR hooked up and getting the right software installed. You also need an antenna — this simple v-dipole should do the trick. Happy watching!

source https://hackaday.com/2020/12/20/hackaday-links-december-20-2020/

A lighthouse beams light out to make itself and its shoreline visible. [Daniel’s] lighthouse has the opposite function, using lasers to map out the area around itself. Using an Arduino and a ToF sensor, the concept is relatively simple. However, connecting to something that rotates 360 degrees is always a challenge.

The lighthouse is inexpensive — about $40 — and small. Small enough, in fact, to mount on top of a robot, which would give you great situational awareness on a robot big enough to support it. You can see the device in action in the video below.

This lighthouse uses a common solution to the rotating connection problem: a slip ring. While these are mechanical, commercial units can be relatively reliable. To route all the signals, the slip ring needs six wire capsules meaning there are six wires that logically pass through the rotating part. The drive motor spins at 60 RPM, but there are two sensors 180 degrees apart to double the scanning rate. The 3D printed housing uses PLA and looks great.

Of course, the real trick will be using all this data meaningfully in your robot or whatever is listening to the lighthouse. That, however, is a different topic. If you think two ToF sensors are good, why not try three?

 

source https://hackaday.com/2020/12/20/lidar-house-looks-good-looks-all-around/

All this ongoing forced togetherness is great, but sometimes you just need to be able to pretend you’re alone so you can get some work done. So, how do you keep family members out of your home office? Our own [Bob Baddeley]’s free/busy indicator is about as simple as it gets.

The best part is that the status can been seen on both sides of the door so you don’t forget to keep it updated. Or maybe it’s the super-low part count. There’s no BLE, LoRa, or Wi-Fi, just two sets of red and green LEDs, a three-way switch, and a power source. Well, and current-limiting resistors of course.

[Bob] already had all the components on hand, including the nifty enclosure, which is another great thing about this build. Like [Bob] says, you could house the control side of this circuit in just about anything you’ve got lying around.

Young children might abuse this one, but this status indicator that lets the family request your presence with the push of a button.

source https://hackaday.com/2020/12/20/status-display-lets-them-know-you-cant-play/

All this ongoing forced togetherness is great, but sometimes you just need to be able to pretend you’re alone so you can get some work done. So, how do you keep family members out of your home office? Our own [Bob Baddeley]’s free/busy indicator is about as simple as it gets.

The best part is that the status can been seen on both sides of the door so you don’t forget to keep it updated. Or maybe it’s the super-low part count. There’s no BLE, LoRa, or Wi-Fi, just two sets of red and green LEDs, a three-way switch, and a power source. Well, and current-limiting resistors of course.

[Bob] already had all the components on hand, including the nifty enclosure, which is another great thing about this build. Like [Bob] says, you could house the control side of this circuit in just about anything you’ve got lying around.

Young children might abuse this one, but this status indicator that lets the family request your presence with the push of a button.

source https://hackaday.com/2020/12/20/status-display-lets-them-know-you-cant-play/

All this ongoing forced togetherness is great, but sometimes you just need to be able to pretend you’re alone so you can get some work done. So, how do you keep family members out of your home office? Our own [Bob Baddeley]’s free/busy indicator is about as simple as it gets.

The best part is that the status can been seen on both sides of the door so you don’t forget to keep it updated. Or maybe it’s the super-low part count. There’s no BLE, LoRa, or Wi-Fi, just two sets of red and green LEDs, a three-way switch, and a power source. Well, and current-limiting resistors of course.

[Bob] already had all the components on hand, including the nifty enclosure, which is another great thing about this build. Like [Bob] says, you could house the control side of this circuit in just about anything you’ve got lying around.

Young children might abuse this one, but this status indicator that lets the family request your presence with the push of a button.

source https://hackaday.com/2020/12/20/status-display-lets-them-know-you-cant-play/

You have to be of a certain vintage to remember doing research on microfilm and microfiche. Before the age of mass digitization of public records, periodicals, and other obscure bits of history, dead-tree records were optically condensed onto fine-grain film, either in roll form or as flat sheets, which were later enlarged and displayed on a specialized reader. This greatly reduced the storage space needed for documents, but it ended up being a technological dead-end once the computer age rolled around.

This was the problem [CuriousMarc] recently bumped into — a treasure trove of Hewlett-Packard component information on microfiche, but no reader for the diminutive datasheets. So naturally, he built his own microfiche reader. In a stroke of good luck, he had been gifted a low-cost digital microscope that seemed perfect for the job. The scope, with an HD camera and 5″ LCD screen, was geared more toward reflective than transmissive use, though, so [Marc] had trouble getting a decent picture of the microfiches, even with a white paper backing.

Version 2.0 used a cast-off backlight, harvested from a defunct DVD player screen, as a sort of light box for the stage of the microscope. It was just about the perfect size for the microfiches, and the microscope was able to blow up the tiny characters as well as any dedicated microfiche reader could, at a fraction of the price. Check out the video below for details on the build, as well as what [Marc] learned from the data sheets about his jackpot of HP parts.

With the wealth of data stored on microforms, we’re surprised that we haven’t seen any readers like this before. We have talked about microscopic wartime mail, though.

source https://hackaday.com/2020/12/20/this-expedient-microfiche-reader-illuminates-retro-datasheets/

While things like object oriented computing and model-view-controller are old hat these days, when Smalltalk burst on the scene, many people had never heard of these new ideas. While the little language with roots at Xerox and based on Simula never caught fire, it was very influential in a number of ways. Now Smalltalk luminary [Dan Ingalls] has the Smalltalk Zoo, a collection of Smalltalk-related items including several historical simulations you can run in your browser.

We were especially impressed with the AltoSmalltalk-72 simulation since our chances of running a real Alto are pretty slim. The JavaScript behind it actually implements the Alto’s Nova instruction set. The emulator then runs a 45-year old memory dump from a real Alto. According to [Dan], there’s no file system and the microcoded music and animation instructions are missing, but he hopes someone will add them as a spare-time project.

There are a few other project suggestions for anyone brave enough to dig into this old software. We found it amusing that the Smalltalk-72 Javascript interpreter runs over 500 times the speed of the original and has “nearly unlimited” object storage.

In Smalltalk everything is an object. With things like the turtle graphics object (@) and you can say things like:

@ go 50 turn 90 go 50 turn 90 go 50 turn 90 go 50\

It is less amusing when someone tells you they sent the + message to the 3 object in order to add something to 3, but that’s object-orientation for you. If you don’t know Smalltalk, try the snippets you can find on the right side of the emulator.

source https://hackaday.com/2020/12/20/making-a-little-smalltalk/

Despite the lingering reality that most of us don’t have what it takes to make it to the upper reaches of the Hit Parade, there remain many who still harbour a secret desire to make music. What better way to realise this dream, than by making [Blog Hoskins’] $20 MIDI synth project!

The write-up goes into a staggering level of detail to ensure that it’s accessible at all levels, to the extent that a complete beginner could probably assemble a working synth by following it. For some of the fancier parts of front panel there’s a reliance on a laser cutter, but even without such wizardry the Average Joe with an electric drill could still do a pretty good job.

Behind the panel though it’s not short on features it’s a surprisingly simple design. At its heart is an Arduino Nano, surrounded by potentiometers and switches for user control, and an opto-coupler for the MIDI lines. Sadly for analogue synth fans there’s not much else in the way of circuitry, but the point of a build such as this one is to create a playable instrument with the shortest path to usability. A video full fo those glorious synth sounds is below the break.

MIDI synthesisers are a frequent feature here at Hackaday. A recent favourite is this four-voice instrument that uses servos as its active element.

source https://hackaday.com/2020/12/20/a-synth-of-your-own-for-not-a-lot/

A smart thermostat is nothing new. But making one built a decade or more ago takes a few tricks. If you want to upgrade your thermostat without replacing it, [geektechniquestudios] shares their solution using a Raspberry Pi Zero to smarten up that dumb controller.

The hardware is decidedly simple: just a Pi Zero and a pair of relays. The relays act as button presses to the old thermostat. The software, though, is decidedly complex. There’s a React server and a Redis database along with some other bits and pieces.

The project is a work in progress, so you’ll probably have to figure a bit out for yourself. Even better, there is room to contribute back. In fact, the project page has a wish list of additions including Google home integration, scheduled temperature changes, and a few others.

Fake button presses takes a bit of finesse on the software side. After all, the computer can jam a button many times faster than a human with a mechanical switch can, and that’s bound to confuse an old circuit, especially if it denounces the switches.

This project is relatively simple to some others we’ve seen. A Pi Zero is cheap, but we’ve seen similar projects done for even less. For example, a $5 Sonoff box can do the same job.

source https://hackaday.com/2020/12/19/old-thermostat-gets-smarts/

The SDR revolution has completely changed the way radio enthusiasts pursue their hobby, but there is still a space for the more traditional scanning receiver. If you are an American, have you ever noticed that it has a gap in its coverage between 800 and 900 MHz? The curious reason for this is explored by [J. B. Crawford], and it’s a tale of dusty laws relating to a long-gone technology, remaining on the books only because their removal requires significant political effort.

What we might today refer to as “1G” phones used an entirely analogue transmission scheme, with an easily-receivable FM carrier for the voice and extremely low-bandwidth bursts of serial data only for the purposes of managing the call. Listening to these calls was an illegal activity, but for those with the appropriate scanners it became a voyeuristic hobby within a hobby. It even made the world news via the pages of the gossip sheets, when (truthfully or not) it was credited for the leak of a revealing and controversial conversation involving Diana Princess of Wales.

This caused significant worry to the cellular phone companies who understandably didn’t want their product to become associated with insecurity. Thus they successfully petitioned the US Congress to include a clause restricting the capabilities of scanning receivers into another telecoms-related Act, and here we are three decades later with analogue phones a distant memory and the law still on the books. It may be ancient and unnecessary but there is neither the will nor the resources to remove it, so it seems destined to become one of those curious legal oddities that remains on the books for centuries. Whether an RTL-SDR breaks it is something we’ll leave for the lawyers, but the detail in the write-up makes it well worth a read.

Header image: krystof.k (Twitter) & nmuseum, CC BY-SA 3.0.

source https://hackaday.com/2020/12/19/why-your-scanner-has-a-hole-in-it/

Humans often like to monitor their exercise habits with the use of a pedometer, which tracks steps taken during a walk. Such devices are a little cumbersome for smaller creatures however, but no matter. Hamsters tend to get most of their workouts done on a wheel anyway, so it’s simple enough to instrument the equipment instead.

The build is a simple tachometer, using an infrared emitter and sensor pair to read the rotation speed of the hamster wheel. The wheel itself is light-colored plastic, so a strip of black felt is used to create a non-reflective section, creating a pulse one per revolution that can be read by the Adafruit Feather 32U4 running the show. Data on peak speed and total rotations is available for tracking the exercise habits of the hamster in question, output on a set of 14-segment displays.

It’s a fun project, and one that would be a great way to teach kids about pet care and basic embedded systems. Hamster performance could even be uploaded to the cloud with a more advanced build, and training milestones linked to rewards a la Premier League footballers. At the end of the day, a hamster wheel is just an exercise bike for our four-legged friends, and we’ve seen those hacked too. Video after the break.

source https://hackaday.com/2020/12/19/hamster-wheel-tacho-measures-tiny-pet-performance/

Masks are proven tools against airborne diseases, but pathogens — like the COVID-19 virus — can collect in a mask and survive which complicates handling and disposal. [Ilaria Rubino], a researcher at the University of Alberta, recently received an award for her work showing how treating a mask’s main filtration layer with a solution of mostly salt and water (plus a surfactant to help the wetting process) can help a mask inactivate pathogens on contact, thereby making masks potentially re-usable. Such masks are usually intended as single-use, and in clinical settings used masks are handled and disposed of as biohazard waste, because they can contain active pathogens. This salt treatment gives a mask a kind of self-cleaning ability.

How exactly does salt help? The very fine salt coating deposited on the fibers of a mask’s filtration layer first dissolves on contact with airborne pathogens, then undergoes evaporation-induced recrystallization. Pathogens caught in the filter are therefore exposed to an increasingly-high concentration saline solution and are then physically damaged by spikes of salt crystals. There is a bit of a trick to getting the salt deposited evenly on the polypropylene filter fibers, since the synthetic fibers are naturally hydrophobic, but a wetting process takes care of that.

The salt coating on the fibers is very fine, doesn’t affect breathability of the mask, and has been shown to be effective even in harsh environments. The research paper states that “salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%).”

Again, the salt treatment doesn’t affect the mask’s ability to filter pathogens, but it does inactivate trapped pathogens, giving masks a kind of self-cleaning ability. Interested in the nuts and bolts of how researchers created the salt-treated filters? The Methods section of the paper linked at the head of this post (as well as the Methods section in this earlier paper on the same topic) has all the ingredients, part numbers, and measurements. While you’re at it, maybe brush up on commercially-available masks and what’s inside them.

source https://hackaday.com/2020/12/19/how-researchers-used-salt-to-give-masks-an-edge-against-pathogens/

Masks are proven tools against airborne diseases, but pathogens — like the COVID-19 virus — can collect in a mask and survive which complicates handling and disposal. [Ilaria Rubino], a researcher at the University of Alberta, recently received an award for her work showing how treating a mask’s main filtration layer with a solution of mostly salt and water (plus a surfactant to help the wetting process) can help a mask inactivate pathogens on contact, thereby making masks potentially re-usable. Such masks are usually intended as single-use, and in clinical settings used masks are handled and disposed of as biohazard waste, because they can contain active pathogens. This salt treatment gives a mask a kind of self-cleaning ability.

How exactly does salt help? The very fine salt coating deposited on the fibers of a mask’s filtration layer first dissolves on contact with airborne pathogens, then undergoes evaporation-induced recrystallization. Pathogens caught in the filter are therefore exposed to an increasingly-high concentration saline solution and are then physically damaged by spikes of salt crystals. There is a bit of a trick to getting the salt deposited evenly on the polypropylene filter fibers, since the synthetic fibers are naturally hydrophobic, but a wetting process takes care of that.

The salt coating on the fibers is very fine, doesn’t affect breathability of the mask, and has been shown to be effective even in harsh environments. The research paper states that “salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%).”

Again, the salt treatment doesn’t affect the mask’s ability to filter pathogens, but it does inactivate trapped pathogens, giving masks a kind of self-cleaning ability. Interested in the nuts and bolts of how researchers created the salt-treated filters? The Methods section of the paper linked at the head of this post (as well as the Methods section in this earlier paper on the same topic) has all the ingredients, part numbers, and measurements. While you’re at it, maybe brush up on commercially-available masks and what’s inside them.

source https://hackaday.com/2020/12/19/how-researchers-used-salt-to-give-masks-an-edge-against-pathogens/

Masks are proven tools against airborne diseases, but pathogens — like the COVID-19 virus — can collect in a mask and survive which complicates handling and disposal. [Ilaria Rubino], a researcher at the University of Alberta, recently received an award for her work showing how treating a mask’s main filtration layer with a solution of mostly salt and water (plus a surfactant to help the wetting process) can help a mask inactivate pathogens on contact, thereby making masks potentially re-usable. Such masks are usually intended as single-use, and in clinical settings used masks are handled and disposed of as biohazard waste, because they can contain active pathogens. This salt treatment gives a mask a kind of self-cleaning ability.

How exactly does salt help? The very fine salt coating deposited on the fibers of a mask’s filtration layer first dissolves on contact with airborne pathogens, then undergoes evaporation-induced recrystallization. Pathogens caught in the filter are therefore exposed to an increasingly-high concentration saline solution and are then physically damaged by spikes of salt crystals. There is a bit of a trick to getting the salt deposited evenly on the polypropylene filter fibers, since the synthetic fibers are naturally hydrophobic, but a wetting process takes care of that.

The salt coating on the fibers is very fine, doesn’t affect breathability of the mask, and has been shown to be effective even in harsh environments. The research paper states that “salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%).”

Again, the salt treatment doesn’t affect the mask’s ability to filter pathogens, but it does inactivate trapped pathogens, giving masks a kind of self-cleaning ability. Interested in the nuts and bolts of how researchers created the salt-treated filters? The Methods section of the paper linked at the head of this post (as well as the Methods section in this earlier paper on the same topic) has all the ingredients, part numbers, and measurements. While you’re at it, maybe brush up on commercially-available masks and what’s inside them.

source https://hackaday.com/2020/12/19/how-researchers-used-salt-to-give-masks-an-edge-against-pathogens/

One of the Holy Grails in the world of electronic badges has been full-colour PCB art as a logical progression from the limited palette of traditional PCB artwork. In the progression towards achieving this goal there have been a variety of techniques applied, and it’s become an expensive commercial possibility rather than an unachievable dream. Has it become practical for mere mortals then? [Tom Clement] has put together a write-up of his progression towards achieving full-colour PCB artwork on a limited production run , and it makes for a fascinating read.

The board in question is the Pixel badge, an improved commercial version of the CampZone 2019 I-Pane badge we reviewed last year. It’s a very bright large multicolour LED matrix that has caught the eye of campgoers at events ever since the original, and has generated enough demand for a new production run. As well as a few electronic enhancements it replaces the original’s dithered monochrome silkscreen rear art with a full-colour design, and it is that with which the write-up is concerned.

It starts with UV printing, and goes through the various iterations of the process until a satisfactory result is achieved. We learn about the effect of reflow temperatures on UV printing inks, it seems that white ink discolours with temperature and the inventive solution is to transfer all the whites to the PCB silkscreen layer. He closes with a discourse on alignment, and we start to appreciate the achievement behind producing this badge. A colour print isn’t necessary for the Pixel’s eye-searing light show, but the point of badges is as much to show off the cutting edge of the art.

As the regular Hackaday reader will know, colour PCB art is a long-time topic of interest here at Hackaday.

source https://hackaday.com/2020/12/19/bringing-full-colour-pcb-art-to-production/

The mechanical keyboard rabbit hole is a deep one, and can swallow up as much money and time as you want to spend. If you’ve become spoiled on the touch and responsiveness of a Cherry MX or other mechanical switch, you might even start putting them on other user interfaces as well, such as this Logitech joystick that now sports a few very usable mechanical keys for the touch-conscious among us.

The Logitech Extreme 3D Pro that [ErkHal] and friend [HeKeKe] modified to accept the mechanical keys originally had a set of input buttons on the side, but these were unreliable and error-prone with a very long, inconsistent push. Soldering some mechanical switches directly on the existing board was a nice improvement, but the pair decided that they could do even better and rolled out an entire custom PCB to mount the keys more ergonomically. The switches are Kailh Choc V2 Browns and seem to have done a great job of improving the responsiveness of the joystick’s side buttons. If you want to spin up your own version, they’ve made the PCBs available on their GitHub page.

While [ErkHal] notes the switches aren’t the best and were only used since they were available, they certainly appear to work much better than what the joystick shipped with originally. In fact, we recently saw similar switches used to make a custom mechanical keyboard made for the PinePhone.

source https://hackaday.com/2020/12/19/logitech-joystick-gets-a-mechanical-sidekick/

Growing fresh vegetables at home is a popular pastime, even moreso in a year when we’ve all been locked inside. However pests can easily spoil a harvest, potentially putting a lot of hard work down the drain. [Matt] of [DIY Perks] isn’t one to give up his tomatoes without a fight, however, and came up with a solution to protect his plants.

The trick is to take advantage of the mildly conductive slime excreted by snails as they travel along the ground. To protect potted plants, [Matt] places two strips of copper tape around the perimeter of the pot, spaced about a centimeter apart. Each strip is connected to one terminal of a 9 V battery. When a snail attempts to cross the strips, it completes a circuit between the two, and the electrical current that flows irritates the snail, forcing it to retreat.

[Matt] notes that no snails were harmed in the making of the video, and that the solution is far kinder to the slimy critters than poisons or traps. He also goes so far as to demonstrate alternative solutions for garden beds, as well. We’ve more commonly seen [Matt] working with lighting, though it’s great to see he has a bit of a green thumb, too. Video after the break.

source https://hackaday.com/2020/12/19/protect-your-tomatoes-with-a-9v-battery/

“Scope creep” is often derided as an obstacle between your idea and the delivery of a finished project. That may be, but sometimes the creep is the whole point. It’s how we end up with wonderful builds like this multi-axis differential camera slider.

We mention scope creep because that’s what [Jan Derogee] blames for this slider’s protracted development time, as well as its final form. The design is a bit unconventional in that it not only dollies the camera left and right but also works in pan and tilt axes, and it does this without putting any motors on the carriage. Instead, the motors, which are located near the end of the slider rails, transmit power to the carriage via loops of 217timing belt. It’s a little like the CoreXY mechanism; rotating the motors in the same direction and speed slides the carriage, while moving them in opposite directions pans the camera. A Sparkfun Pro Micro in the controller coordinates the motors for smooth multi-axis motion, and the three steppers — there’s a separate motor for the tilt axis — sound really cool all working at the same time. Check out the video below for the full story.

We’ve seen a few fun projects from [Jan] before. Check out his linear clock, the persistence of phosphorescence display, or his touchpad for retrocomputers.

source https://hackaday.com/2020/12/18/a-camera-slider-with-a-twist/

Harkening back to a not-so-distant past where duels settled arguments, [Joris Wegner] put a twist on the idea of quarrels with a gun that damages your online persona rather than your physical one. The controversy of social media is nothing new, but most people today have a large percentage of their lives online. A gun that can destroy your social media by deleting your account feels far more potent than most would like to admit.

At the heart of this build, each gun contains a battery-powered ESP8266 that connects to another ESP8266 in the gun case, which in turn is connected to a computer. When a trigger is pulled, the computer deletes the Facebook account with the credentials stored on the gun. It offers a new look at the importance of one’s social media presence. While the concept of being attacked on social media is nothing new, the idea of digitally dying on social media is perhaps something new. This particular project was put on hold when [Joris] realized that Facebook accounts can be reactivated after 30 days, which renders the gesture less potent.

Playful and interesting twists on the idea of a gun are nothing new here on Hackaday. We’ve seen also [Joris’] work before with a MIDI-controlled video distortion box.

source https://hackaday.com/2020/12/18/a-bullet-for-the-digital-you/

It’s a luxury to be able to access a modern machine shop, complete with its array of lathes, mills, and presses. These tools are expensive though, and take up a lot of space, so if you want to be able to machine hard or thick metals without an incredible amount of overhead you’ll need a different solution. Luckily you can bypass the machines in some situations and use electricity to do the machining directly.

This project makes use of a process known as electrochemical machining and works on the principle that electricity passed through an electrolyte solution will erode the metal that it comes in contact with. With a well-designed setup, this can be used to precisely machine metal in various ways. For [bob]’s use this was pretty straightforward, since he needed to enlarge an existing hole in a piece of plate steel, so he forced electrolyte through this hole while applying around half an amp of current in order to make this precise “cut” in the metal, avoiding the use of an expensive drill press.

There are some downsides to the use of this process as [bob] notes in his build, namely that any piece of the working material that comes in contact with the electrolyte will be eroded to some extent. This can be mitigated with good design but can easily become impractical. It’s still a good way to avoid the expense of some expensive machining equipment, though, and similar processes can be used for other types of machine work as well.

source https://hackaday.com/2020/12/18/machining-without-machines/