APK LIST ANDROID APP FREE DOWNLOAD

It’s hurricane season in the northern hemisphere right now, and plenty of news and weather organizations remain dedicated to alerting people if a storm is about to impact their area. There’s no shortage of ways to receive this information, either. We all have our favorite weather app or forecasting site, and there are emergency alerts to cell phones, TV, and radio stations as well. If none of that suits you, though, you can also roll out your own weather alert readerboard . [Damaged Dolphin] built a weather alert readerboard using a Raspberry Pi and a 64×128 LED matrix. The Raspberry Pi runs Raspbian and uses a HAT from Adafruit, and once connected to the internet pulls down weather information for a specific area using custom python code. From there it can display any emergency weather alerts instantly on the readerboard screen including alerts for hurricanes. It does rely on data from the National Weather Service though, so if that is not available in your area some modifications wi

[Jean-Francois Debroux] spent 35 years designing analog ASICs. He’s started a book and while it isn’t finished — indeed he says it may never be — the 180 pages he posted on LinkedIn are a pretty good read. The 46 sections are well organized, although some are placeholders. There are sections on design flow and the technical aspects of design. Examples range from a square root circuit to a sigma-delta modulator, although some of them are not complete yet. There are also sections on math, physics, common electronics, materials, and tools. The text is decidedly practical. For example, there’s a succinct summary of what a MOSFET channel width and length do to parameters such as capacitance, noise, and saturated resistance. If you prefer a PDF copy, here’s a tip. When viewing the document, click on the full-screen button. Then at the top, you’ll see a download button. The link there looks as though it isn’t a static link, so you’ll need to visit the post yourself to do the download. I

To get the perfect mix for your paint, you need a good shake that is as random as possible. [Mark Rhodes] wanted to automate the process of mixing paint, so he built a 3D printed shaker to thoroughly shake small paint bottles. Using only a single motor, it shakes the bottle along three axes of rotation and one axis of translation. A cylindrical container is attached to a U-shaped bracket on each end, which in turn is attached to a rotating shaft. Only one of these shafts are powered, the other is effectively an idler. When turned on, it rotates the cylinder partially around the pitch and yaw axis, 360 degrees around the roll axis, and reciprocates it back and forth. The design appears to be based on an industrial mixer known as a “ Turbula “. Another interesting feature is how it holds the paint bottle in the cylinder. Several bands are stretched along the inside of the cylinder, and by rotating one of the rings at the end, it creates an hourglass-shaped web that can tightly hold the

Those little pocket TVs were quite the cool gadget back in the ’80s and ’90s, but today they’re pretty much useless at least for their intended purpose of watching analog television. (If someone is out there making tiny digital-to-analog converter boxes for these things, please let us know.) Now that analog pocket TVs are obsolete, they’re finally affordable enough for hacking into a useful tool like an inspection camera . [technichenews] found a nice Casio TV and a suitable analog pinhole camera that also does IR. Since the camera has RCA plugs and the TV’s video input is some long-gone proprietary 3.5mm cable, [technichenews] made a new video-only cable by soldering the yellow RCA wires up to the cable from an old pair of headphones. Power for the camera comes from a universal wall wart set to 12V. Our favorite part of this project is the way that [technichenews] leveraged what is arguably the most useless part of the TV — the antenna — into the star. Their plan is to use the camer

[Erik Knutsson] is stuck inside with a bunch of robot parts, and we know what lies down that path. His Open Personal Assistant Robotic Platform aims to help out around the house with things like filling pet food bowls, but for now, he is taking one step at a time and working out the bugs before adding new features. Wise. The build started with a narrow base, an underpowered RasPi, and a quiet speaker, but those were upgraded in turn. Right now, it is a personal assistant on wheels. Alexa was the first contender, but Mycroft is in the spotlight because it has more versatility. At first, the mobility was a humble web server with a D-pad, but now it leverages a distance sensor and vision, and can even follow you with a voice command. The screen up top gives it a personable look, but it is slated to become a display for everything you’d want to see on your robot assistant, like weather, recipes, or a video chat that can walk around with you. [Erik] would like to make something that assi

We’ve had something of an anniversary of late, and it’s one that will no doubt elicit a variety of reactions from our community. It’s now 25 years ago that Windows 95 was launched, the operating system that gave the majority of 1990s PC users their first taste of a desktop-based GUI and a 32-bit operating system. To the strains of the Rolling Stones’ Start me up , Microsoft execs including Bill Gates himself jubilantly danced on stage at the launch of what was probably to become the company’s defining product, perhaps oblivious to the line “ You make a grown man cry ” which maybe unwittingly strayed close to the user experience when faced with some of the software’s shortcomings. Its security may seem laughable by the standards of today and the uneasy marriage of 16-bit DOS underpinning a 32-bit Windows operating system was clunky even in its heyday, but perhaps now is the best time to evaluate it unclouded by technical prejudice. What can we see of Windows 95 in the operating syste

E-waste is a gigantic problem, and it can seem impossible as a lone individual to make any kind of dent in it. But [akshar1101] is trying to do their part by looking past the defective aspects of broken, discarded electronics to draw out the possibilities of what’s left. This friendly night light is made from the PCBs of four broken Nokia 5110 LCD modules . The screens were all toast, but the nice white LEDs that used to light them from the sides work just fine. [akshar1101] cleverly tied all the LED and GND lines together with single right-angle header pins. To power the LEDs, they wired up a JST receptacle to one of the PCBs and connected a 3.7 V lithium battery pack that sits underneath. [akshar1101] diffused the piercing white lights into a soft glow with two pieces of acrylic. We love to see electronic components get saved from landfills, especially when they can be turned into something useful and beautiful. Something about the traces on these boards makes them visually interes

A heat wave spreading across a large portion of the west coast of the United States is not surprising for this time of year, but the frequency and severity of these heat waves have been getting worse in recent years as the side effects from climate change become more obvious. In response to this, the grid operators in California have instituted limited rolling blackouts as electricity demand ramps up. This isn’t California’s first run-in with elective blackouts, either. The electrical grid in California is particularly prone to issues like this, both from engineering issues and from other less obvious problems as well. Infrastructure: An Old Problem The physical problems with the electric grid are straightforward and covered often as part of the background noise of almost-forgotten issues with aging infrastructure systems as a whole. In a majority of North America, the electrical grid as well as roads, bridges, water and wastewater systems, airports, and virtually any other piece

Conductive filament isn’t an ideal electrical conductor, but it’s a 3D-printable one and that’s what makes [Hercemer]’s 3D-printed flashlight using conductive filament work. Every part of the flashlight is printed except for the 9 volt battery and LEDs. Electrically speaking, the flashlight is a small number of LEDs connected in parallel to the terminals of the battery, and turning it on or off is done by twisting or loosening a cap to make or break the connection. The main part of the build is a 3D-printed conductive cylinder surrounded by a printed conductive ring with an insulator between them. This disk- or pad-shaped assembly forms not only the electrical connection between the LEDs and battery terminals, but also physically holds the LEDs. To attach them, [Hercemer] simply melts them right in. He uses a soldering iron to heat up the leads, and presses them into the 3D-printed conductive block while hot. The 9 V battery’s terminals contact the bottom when the end cap is twisted

Kotlin is a relatively new programming language; a derivative of Java with lots of little handy functional bits such as coroutines . [Foalyy] is porting an app to Android and learning Kotlin at the same time, and after wrapping their mind around coroutines, has written up a concise five-part tutorial on them . Coroutines in Kotlin are a way to simplify writing asynchronous code, which is code that doesn’t necessarily execute in the order it is written. Coroutines are like light-weight threads that can be launched and managed easily, making it simpler to bridge together blocking and non-blocking code. (However, coroutines are not threads. They are more akin to suspending functions that play very well together.) [Foalyy] found that the official Kotlin documentation on coroutines went into great detail on how coroutines function, but wanted a more bottom-up approach to understanding how they work and can be used. Luckily for anyone who thinks the same way, [Foalyy] wrote it all up and

As we stare dejectedly at our screens and consider what might have been during the 2020 summer that didn’t quite happen, here’s a little something to look forward to in a future where the COVID-19 pandemic will with any luck be much less of a threat. We have have had precious little in the way of events in 2020, but the call for participation has been announced for one of the largest planned for 2021 . MCH2021 will be big European summer camp of next year, and is scheduled for the 6th to the 10th of August at Scoutinglandgoed Zeewolde in the Netherlands province of Flevoland. It will be the latest in a long line of such events going back to 1989, and with such a track record we know it’s going to be a good one. We know that among our community are many people who’ll be interested in going to MCH, and that each and every one of you will have some fascinating insights that others would love to hear about. The challenge of the MCH orga is to bestow upon you the courage to stand up in fro

When [marzsman]’s eight-year-old daughter thought up a game they could play together involving rainbows, he was all ears. She is a certified rainbow expert, after all. They had a few R&D sessions and came up with a rainbow sorting speed trial game that looks fun to play and fairly easy to build . Press that blue button on the side, and the RGB LEDs along the top are put in randomized order. The object of this game is simple — just sort the rainbow before the other player by pressing each LED’s corresponding arcade button. Whoever sorts faster is rewarded with a rainbow animation behind their set of way-cool clear buttons. Inside the laser-cut box is an Espruino, which is a handy little microcontroller that speaks JavaScript. All of the arcade buttons are wired up as a key matrix. The astute among you have noticed there is six of everything, and that’s because indigo light is too hard to distinguish from blue. Check out the intense gameplay after the break. If [marzsman]’s daught

Tech history is rife with examples of bizarre product demos, but we’ve got to think that Elon Musk’s Neuralink demo this week will have to rank up there with the weirdest of them. Elon’s job here was to sell the proposition that having a quarter-sized plug removed from your skull by a surgical robot and having it plunge 1,024 tiny wires into your gray matter will be totally normal and something that all the cool kids will be doing someday. We watched the 14-minute supercut of the demo , which went on for considerably longer than that due to the realities of pig wrangling, and we remain unsold on the technology. Elon selling it as “a Fitbit in your skull, with tiny wires” probably didn’t help, nor did the somewhat terrifying appearance of the surgical robot needed to do the job. On the other hand, Gertrude the Bionic Pig seemed none the worse for her implant, which was reportedly wired to her snout and sending data wirelessly. The demonstration of reading joint positions directly from

They say that imitation is the sincerest form of flattery. If we were going to imitate one of master circuit sculptor Mohite Bhoite’s creations, we’d probably pick the little blinky solar satellite as a jumping off point just like [richardsappia] did. It’s cute, it’s functional, and it involves solar power and supercapacitors. What more could you want? SATtiny is a pummer , which is BEAM robotics speak for a bot that soaks up the sun all day and blinks (or ‘pumms’, we suppose) for as long as it can throughout the night on the juice it collected. This one uses four mini solar panels to charge up a 4 F supercapacitor. At the controls is an ATtiny25V, which checks every eight seconds to see if the supercapacitor is charging or not as long as there is enough light. Once night has fallen, the two red LEDs will pumm like a pair of chums until the power runs out. Check out the brief demo after the break. Would you rather have something more nightstand-friendly? Here’s a mini night light sc

Retailers have instituted enhanced cleaning procedures in response to the COVID-19 pandemic, with an aim to keep frequently touched surfaces as clean as possible. Certainly one of the most commonly handled objects in the entire store is the payment terminal by the register, and the PIN pad specifically. Which is why [Josh Starnes] is working on a UV sterilizer that mounts onto a standard credit card terminal . It’s a simple enough idea, but as is often the case, figuring out how to properly execute it is where things get tricky. [Josh] has already moved through several design iterations for his 3D printed enclosure in an attempt to make something that’s unobtrusive enough to be practical. The goal is to make something that the user won’t mistake for some kind of skimming device, which can certainly be tricky . The skeptics in the audience will be happy to hear that [Josh] isn’t bothering with an LED UV source, either. We’ve all seen the pitfalls of trying to sanitize using UV LEDs ,

Plenty of people don’t bother to read the  current newspaper, let alone editions that were published over 100 years ago. But there’s a wealth of important historical information buried in these dusty old publications, assuming you can find a way to reliably digitize and index it all. You might think the solution is as simple as running images of the paper through optical character recognition (OCR) software, but as [John Scancella] explains, the problem is a bit more complicated than that . Stretching the text vertically highlights the columns. Ultimately, the issue largely comes down to formatting. The OCR software reasonably assumes all the text is in orderly horizontal lines, because in the vast majority of cases, it would be. That’s how you’re reading these words now. But as anyone who’s seen an old time newspaper knows, that’s not how things were necessarily written back then. Pages consisted of multiple narrow columns of stories separated by vertical lines; if the OCR tries

The joys of overengineering a simple gift. [Joren] wanted to create a dress for his daughter’s fourth birthday that would react with lights in sequence for a song from Frozen . The dress and an LED strip, along with a digital microphone and a battery were easy to procure. But how to make it all work? An ESP32 did the trick. While the project’s name–Olaf–sounds like it was from Frozen, according to the GitHub page it actually means Overly Lightweight Acoustic Fingerprinting. Right. However, as the name implies, it can learn to identify any sound you want. One interesting twist. The code is in C, so running it through Emscripten allows the code to run in your browser and you can watch it work alongside a YouTube video of the movie. You can see in the image above that the fingerprint screen gets red dots until it matches the audio and then the dots turn green, indicating a match. Even if you don’t want a magic Frozen dress, the code on GitHub could be a good starting point for develo

Humans continuously communicate with our bodies, and face masks cover one of the most expressive parts. For some, this is a muffler on strangers, but devastating for people who rely on lip-reading. Several masks exist that have a clear window for precisely this purpose, but they’re specialty and high-demand. [Erin St Blaine] over at Adafruit shows how she makes windowed masks with stuff you may already have in your house. Even if your sewing machine is locked up the local maker-space, you are in luck, because you don’t need a single stitch. For the thread-inclined, it is easy to tweak the recipe. The part of the mask that touches your face is terry cloth, but any breathable cotton towel should work. There is a PDF in the instructions where you can print templates in four sizes. You will also find a cutout for the plastic window salvaged from your cold soft drink cup. A water bottle should work too. Flexible glue holds the fabric together, but to attach the ear-loops, we fall back on

The half-track is a vehicle design that has gradually fallen out of favour in the decades since World War II. Combining the benefits of easy driving and handling of wheeled vehicles with the strong mud and snow performance of a tracked vehicle, they served a niche before largely being phased out with the rise of the armoured personnel carrier. [JackCarter] wished to build his own, so whipped up a lasercut RC version of the SdKfz 251 22. The work is impressive, with [JackCarter] creating the design in Solidworks from photos and illustrations of the vehicle. The moving parts are lasercut, including the tracks themselves, assembled from many tiny lasercut MDF parts. The benefit of using lasercutting to make the model is that it was easy for [Jack Carter] to create simple jigs to ease the process of putting the tracks together. A NodeMCU with a motor shield controls the gear motors used to drive the tracks, and drives a servo for steering. Control is via a smartphone, thanks to the Blynk

Most hobby-grade software defined radio setups don’t transmit. Of the few that do, most of them put out anemic levels around one milliwatt or so. If you want to do something outside of the lab, you’ll need an amplifier and that’s what [Tech Minds] shows how to do in a recent video . (Embedded below.) The video covers LimeSDR, HackRF, and the Pluto SDR, although the amplifiers should work with any transmitter. The SPF5189Z module is quite cheap and covers 50 MHz to 4 GHz, amplifying everything you throw at it. The downside is that it will amplify everything you throw at it, even parts of the signal you don’t want, such as spurs and harmonics. There are other modules, depending on your needs. The CN0417 covers a very narrow range from 2.4 GHz to 2.5 GHz. (If you can call 100 MHz bandwidth “narrow”.) The RF2126 will cover from 400 Mhz to 2.7 GHz. None of these are powerhouses. The maximum 20 dB gain will only give you a watt or so out with the minimal drive from most SDR transmitters.

Big fizzing electrical arcs are fun, and handled properly, not too dangerous either. The Jacob’s Ladder is one such piece of arc-generating equipment, one that featured heavily in vintage sci-fi films. It remains a charming demonstration of high-voltage electrical principles, and you can easily build your own mini version at home . The build starts with a basic high-voltage step-up kit that turns 4V DC into 15 kV at the output. At this voltage level, it’s possible to generate an arc in air. To create the Jacob’s ladder, the kit is wired up to a pair of closely-spaced electrodes that slowly get farther apart as they go up vertically. When an arc jumps from one electrode to the other, it ionises the air, and the voltage sags due to the current flow. The flowing current heats up the air, which begins to rise, taking the current path with it, causing the familiar climbing arc we all know and love. As the distance between the electrodes increases towards the top, the arc can eventually no

Millions of people all over the world don’t have access to clean drinking water, and it’s largely because of pollution by corporations and individuals. Solving this problem requires an affordable, scalable way to quickly judge water quality, package the data, and present it to an authority that can crack down on the polluters before the evidence dissipates. Ideally, the solution would be open source and easy to replicate. The more citizen scientists, the better. [Andrei Florian]’s WaterAid flows directly from this line of thinking. Dip this small handheld device below the surface, and it quickly takes a bunch of water quality and atmospheric readings, averages them, and sends the data to a web dashboard using an Arduino MKR GSM . WaterAid judges quality by testing the pH and the turbidity of the water, which gauges the amount of impurities. Commercial turbidity sensors work by measuring the amount of light scattered by the solids present in a liquid, so [Andrei] made a DIY version wi

Microwaves used to be simple to use. Set the dial for the desired time, and hit start. Then, everything went digital and the average microwave now takes between four and six button presses in precise order just to start heating. Music players have gone down a similar path, and those that grew up in the era of vinyl records can find modern digital media simply too hard to work with. To solve this problem, [ananords] whipped up Juuke, a music player focused on ease of use . The Juuke has a simplistic interface intended to be as easy to use as possible. Songs are selected using printed cards with embedded RFID tags – placing them on the Juuke triggers playback. Volume is controlled with a simple knob, and the only two buttons are for play/pause and shuffle mode. Underneath, an Arduino Uno runs the show, hooked up to a RC522 RFID interface board. Music is handled by the DFPlayer mini, which loads tracks off a microSD card. The DFPlayer can be hooked up to a speaker directly, but there’s

This week our own [Donald Papp] wrote a thought-provoking piece on buying and selling 3D-printer models . His basic point: if you don’t know what you’re getting until you’ve purchased it, and there’s no refund policy, how can you tell if your money is being well spent? It’s a serious problem for these nascent markets , because when customers aren’t satisfied they won’t come back. It got me thinking about my own experience, albeit with all of the free 3D models out there. They are a supremely mixed bag, and even though you’re not paying for the model, you’re paying in printing time, filament, and effort. It pays to be choosy, and all of [Donald]’s suggestions hold in the “free” market as well. Failenium Falcon. Image by Johannes Only download models that have been printed at least once , have decent documentation about things like layer height, filament type, and support, and to the best of your abilities, be critical about the ability to fabricate the part at all. Fused-deposition

Your entry for the 2020 Hackaday Prize needs to be in by Monday morning, August 31st! This is the deadline for initial entries, if you’re one of the one hundred lucky projects that advance to the finals you’ll still have another month to polish up your project. Why not make this weekend your own personal hackathon? Entries focus on four challenges outlined by our non-profit partners this year. From improving modular dome housing and developing manufacturing techniques in disaster zones, to designing interfaces for people with physical challenges and protecting natural ocean landscapes, there’s plenty of room to be creative here. In addition to the $50,000 grand prize there are still nine other top prizes up for grabs. You can do this. Tell your story, show a proof of concept, and document it to convince the judges your project is viable. It’ll be tight, but hackers work best when deadlines are looming. We can’t wait to see what you come up with between now and Monday! The Hacka

Turning on a lightbulb has never been easier. You can do it from your mobile. Voice activation through home assistants is robust. Wall switches even play nicely with the above methods. It was only a matter of time before someone decided to make it fun, if you consider a Rubik’s cube enjoyable. [Alastair Aitchison] at Playful Technology demonstrated that it is possible to trigger a relay when you match all the colors . Video also after the break. The cube does little to obfuscate game data, so in this scope, it sends unencrypted transmissions. An ESP32 with [Alastair]’s Arduino code, can track each movement, and recognize a solved state. In the video, he solves the puzzle, and an actuator releases a balloon. He talks about some other cool things this could do, like home automation or a puzzle room, which is in his wheelhouse judging by the rest of his YouTube channel. We would love to see different actions perform remote tasks. Twisting the top could set a timer for 1-2-3-4-5 minutes,

As popular as the venerable Yaesu FT-817 transceiver might be with amateur radio operators, it’s not without its flaws, particularly in the user interface department. [Andy (G7UHN)] is painfully familiar with these flaws, so he designed this auxiliary display and control panel for the FT-817 to make operating it a little easier. There are a ton of ways to enjoy ham radio, but one of the more popular ways is to bust out of the shack and operate in the great outdoors. From the seashore to mountain peaks, hams love giving their rigs some fresh air and sunshine. The battery-powered, multimode, all-band FT-817 is great for these jaunts, but to fit as much radio into a small package as they did, Yaesu engineers had to compromise on the controls. Rather than bristling with buttons, many of the most-used features of the radio are buried within menus that require multiple clicks and twists to access. [Andy]’s solution is a PCB bearing an Arduino Nano, an LCD screen, and a whole bunch of actu

Cats are nature’s born hunters. Whether its rodents, insects, or lasers, they’ll pounce and attack with ruthless efficiency. Built to challenge a cat, or perhaps merely to tease it, Sourino is a robotic mouse built with common off-the-shelf parts . A test subject appears unamused. So named for the combination of Souris (French for “mouse”) and Arduino, the project is driven by an Arduino Nano. Hooked up to three sets of ultrasonic transducers, this gives the robot mouse much improved obstacle avoidance abilities compared to using just a single transducer front-and-centre. The ‘bot can navigate basic mazes or household floors with ease. A pair of geared motors are used for drive, using simple skid-steering to turn corners. It’s all packed in a 3D printed enclosure, which mounts the various components and exposes the ultrasonic sensors. There’s even an IR remote enabling mode selection or full manual control. While the ‘bot lacks the speed and agility of common house mice, it’s neve

[Ottverse] has an interesting series in progress to demystify video compression. The latest installment promises to explain discrete cosine transforms as though you were five years old. We’ll be honest. At five, we probably didn’t know how to interpret this sentence: …the Discrete Cosine Transform takes a set of N correlated (similar) data-points and returns N de-correlated (dis-similar) data-points (coefficients) in such a way that the energy is compacted in only a few of the coefficients M where M << N. Still, the explanation is pretty clear and we really liked the analogy with the spheres and the stars in a constellation. The example Matlab code is probably also lost on a five-year-old, but we liked it. Anyone, we think, can understand the practical result where removing too much data — high compression — resulted in a poor quality image, but the image quality was pretty good even when 75% of the data vanishes. So while you might not want to show this to your five-yea

Most of us can say that we have taken an obsolete hard drive out of a computer and felt it was a waste to toss it in the e-waste pile. Some of us have children’s drawings hung on the fridge with actuator magnets, or maybe a vast spreadsheet suspended on a steel filing cabinet. Let us not forget that there is also a high-speed, low-noise motor in there. On some models it is separate from the PCB, so grab an Electronic Speed Controller (ESC), your microcontroller of choice, and make yourself a salvaged HDD centrifuge like [Cave Man] has. His build uses the tray as a chassis, but he modeled and printed a new face in the same style as the original. On top, he has an OLED screen for displaying the requested speed, measured speed, and runtime. Next to the display is a four-button pad with a customized legend for setting parameters. The video after the break shows the machine running through its paces. This version accommodates the tiny capillary tubes, microhematocrit tubes, for processing