Kritik sah

If you have trouble staying focused and getting work done, the Pomodoro Technique of working in 25-minute intervals with 5-minute breaks is pretty hard to beat. The only problem is that it requires a lot of input from the user, and all that timer-setting can get in the way of actually getting down to business. The absolute worst is when you find yourself working hard, but see that forgot to set the damn timer (ask us how we know). In essence, the tomato itself can only do so much — you have to actually use it and honor the timer, put in the work, and believe in the system. But what if you didn’t have to do as much? With [Erfan Sn]’s design, all you have to do is plug it in to a USB port and the countdown starts automatically. Not only does this Pomodoro timer force you to get with the program, it also makes you take breaks from the screen by putting the computer into sleep mode when the 25 minutes (or whatever time you set in the software) are up. This thing even keeps track of your

Many of us have marveled at art installations that feature marbles quietly and ceaselessly tracing out beautiful patterns in sand. [DIY Machines] is here to show us that it’s entirely possible to build one yourself at home! The basic mechanism is simple enough. The table uses a Cartesian motion platform to move a magnet underneath a table. On top of the table, a metal sphere attached to the magnet moves through craft sand to draw attractive patterns. An Arduino and Raspberry Pi work together to command the stepper motors to create various patterns in the sand. Low-cost pine is used to build most of the table, with oak used for the attractive bare wooden top. RGB LEDs surround the sand surface in order to light the scene, with options for mad disco lighting or simple white light for a subtler look. Other nice touches include sitting the craft sand atop a layer of faux leather, so the ball moving through the sand doesn’t make annoying crunching sounds as the ball moves. It’s a great

Global supply chain issues are beginning to hit closer to home for the hacker community, as Raspberry Pi has announced their first-ever price increase on their flagship Pi 4 . The move essentially undoes the price drop on the 2GB version of the Pi 4 that was announced in February, and sets the price back up from $35 to $45. Also rolled back is the discontinuation of the 1GB version, which will now be available at the $35 price point. The announcements come from Eben Upton himself, who insists the price increase is only temporary. We applaud his optimism, but take it with a grain of salt since he also said that 2021 production across the board will stay at the seven million-unit level, which is what they produced in 2020. That seems to speak to deeper issues within the supply chain, but more immediately, it’s likely that the supply of Pi products will be pinched enough that you’ll end up paying above sticker price just to get the boards you need. Hope everyone is stocked up. On the to

[Kevin Norman] got himself a smart body scale with the intention of logging data for his own analysis, but discovered that extracting data from the device was anything but easy . It turns out that the only way to access data from his scale is by viewing it in a mobile app. Screen-scraping is a time-honored method of pulling data from uncooperative systems, so [Kevin] committed to regularly taking a full-height screenshot from the app and using optical character recognition (OCR) to get the numbers, but making that work was a surprisingly long process full of dead ends. First of all, while OCR can be reliable, it needs the right conditions. One thing that ended up being a big problem was the way the app appends units (kg, %) after the numbers. Not only are they tucked in very close, but they’re about half the height of the numbers themselves. It turns out that mixing and matching character height, in addition to snugging them up against one another, is something tailor-made to give OC

[Geyes30]’s Raspberry Pi project does one thing: it finds arbitrary text in the camera’s view and reads it out loud . Does it do so flawlessly? Not really. Was it at least effortless to put together? Also no, but it does wonderfully illustrate the process of gluing together different bits of functionality to make something new. Also, [geyes30]’s kids find it fascinating, and that’s a win all on its own. The device is made from a Raspberry Pi and camera and works by sending a still image from the camera to an optical character recognition (OCR) program, which converts any visible text in the image to its ASCII representation. The recognized text is then piped to the espeak engine and spoken aloud. Getting all the tools to play nicely took a bit of work, but [geyes30] documented everything so well that even a novice should be able to get the project up and running in an afternoon. Sometimes a function like text-to-speech is an end result in and of itself. This was also true of anothe

[Zach Armstrong] presents for your viewing pleasure a simple guide to building a solid-state Tesla coil . The design is based around a self-resonant setup using the UCC2742x gate driver IC, which is used in a transformer-coupled full-wave configuration for delivering maximum power from the line input. The self-resonant bit is implemented by using a small antenna nearby the coil to pick up the EM field, and by suitably clamping and squaring it up, it is fed back into the gate driver to close the feedback loop. Such a setup within reason allows the circuit to oscillate with a wide range of Tesla coil designs, and track any small changes, minimizing the need for fiddly manual tuning that is the usual path you follow building these things. Since the primary is driven with IGBTs , bigger is better. If the coil is too small, the resonant frequency would surpass the recommended 400 kHz, which could damage the IGBTs since they can’t switch much faster with the relatively large currents need

Many of us are vaguely familiar with the levels of hell described in Dante’s epic poem from the 14th century, even if we’ve never visited ourselves. It’s natural to wonder in which circle of hell one might end up, but that’s a question that [scubabear’s] arcade build seeks to answer. The artwork is vibrant and enticing. The stand-up cabinet was built for The Magic Castle, Hollywood’s exclusive private club for the magic set. The design is loosely inspired by old-fashioned love testers, the sort of which you might have seen in that Simpsons episode. The club has traditionally issued members with unique RFID tags in keychains, which can be used to trigger special objects in the facility. In this case, when a member scans their keychain and places their hand on a handprint, the machine starts up. The hand is detected by an Adafruit touch sensor board, and the machine begins determining the fate of the member while playing a short musical interlude. Once calculated by the Raspberry

Science is built on reproducibility; if someone else can replicate your results, chances are pretty good that you’re looking at the truth. And there’s no statute of limitations on reproducibility; even experiments from 70 years ago are fair game for a fresh look. A great example is this recent reboot of the 1952 Miller-Urey “primordial soup” experiment which ended up with some fascinating results. At the heart of the Miller-Urey experiment was a classic chicken-and-the-egg paradox: complex organic molecules like amino acids and nucleic acids are the necessary building blocks of life, but how did they arise on Earth before there was life? To answer that, Stanley Miller, who in 1952 was a graduate student of Harold Urey,  devised an experiment to see if complex molecules could be formed from simpler substances under conditions assumed to have been present early in the planet’s life. Miller assembled a complicated glass apparatus, filled it with water vapor and gasses such as ammonia,

There are a huge number of available keyboards out in the world these days, catering to all of the plainest and the most advanced desires. However, if you want something that’s  just right,  sometimes it pays to build your own. [Zach] did just that. One of the key features of [Zach]’s build is that it diverges away from the Cherry MX switch form factor. The design uses low-profile switches instead, which help with keeping the keyboard low enough to avoid it causing wrist problems. The keyboard also uses IO expanders to hook up all the key switches, helping to reduce the incidence of ghost keys. The board can also be split in half, allowing it to be repurposed as a smaller macropad when desired. It’s all wrapped up in a cool 3D printed case, and there are even three OLED displays on the right-hand side. They’re soldered to the PCB on special cutouts that allow the displays to flex and trigger tactile switches, acting as giant pressable buttons. [Zach] does a great job explaining all

As a kid, you might remember taking a whole fistful of markers or crayons, gently lining them all up for maximum contact, mashing them into the paper, and marveling at the colorful multitude of lines. It seemed like an easy way to write many times more things with less effort. While not quite the same idea but in a similar vein, [Aaron Francis] shared an experience of creating handwriting robots to write thousands of letters . Why did [Aaron] need to write thousands of letters? Direct mailing, of course! If you were sending someone a letter, if it looked handwritten they’re much more likely to open it. What better way to make it look handwritten than to use a pen rather than a printer? They started off with Axidraw, a simple plotter made by EMSL. Old laptops controlled a few plotters and they started to make progress. As with most things, scale became tricky. Adding more plotters just means more paper to replace and machines to restart. An automated system of replacing paper is fiend

Human respiration takes in oxygen and in turn, we exhale carbon dioxide. Thus, an uptick of carbon dioxide levels around us can indicate we’re in the presence of other humans, and also, perhaps, the pathogens they carry. To explore this phenomenon, [C Scott Ananian] developed a mod for the Watchy open-source smartwatch, which lets it detect carbon dioxide. The idea behind the build is simple. If you’re around increased CO2 levels, it may be because you’re surrounded by people, and thus more likely to be exposed to COVID-19. To detect CO2, the watch relies on a Sensiron SCD40 or SCD41 sensor. This is read by the Watchy’s ESP32 microcontroller, and results are graphed on the watch’s e-Paper display. The Watchy is also given a nice new aluminum case to fit the additional hardware. It’s cool having a graph on your wrist of the ambient concentration of CO2, and at the very least, it could make a good talking point next time you’re at a particularly boring party. You’ll also be more than

In the world of the cockpit simulator hobby, no detail is too small to obsess over. Getting the look and feel of each and every cockpit control just right is important, and often means shelling out for cockpit-accurate parts. But not always, as these DIY magnetically captured toggle switches show. Chances are good you’ve seen [The Warthog Project]’s fantastically detailed A-10 Thunderbolt II cockpit simulator before; we’ve featured it recently , and videos from the ongoing build pop up regularly in our feeds. The sim addresses the tiniest of details, including the use of special toggle switches that lock into place automatically using electromagnets. They’re commercially available, but only for those with very deep pockets — depending on the supplier, up to several thousand dollars per unit! The homebrew substitute is mercifully cheap and easy to build, though — a momentary DPST toggle switch is partially gutted, with a length of nail substituted for one of its poles. The nail stic

More than once, we’ve looked at a cool board like the TTGO T-Display and thought, “What can we build with this?” If you are [Volos Projects], the answer is a tiny Internet radio . He’s done a lot of other projects with the board including some games and a weather station. You can see the project in the video below. Of course, the core Internet streaming code would be useful with any ESP32, but the display makes for a good-looking unit. The code is available on GitHub . With judicious use of network and audio libraries, the player only takes a few hundred lines of code. Pretty impressive considering it even shows a visualization on the tiny display screen. What we’d really like to see is a nice case, power supply, and speaker option to make a tiny and portable unit. With a 3D printer, it is easy to make very professional-looking projects, as we often see. On the other hand, it does look better than the breadboard version you can see towards the end of the video. It is, though, a nea

I’d love to tell you that I’m never wrong, but I’ve been wrong a lot. Remember the Arduino? When it was brand new, I thought it was some silly collection of libraries and a drop-down menu for people who are too lazy to just type out their own #include statements. Needless to say, it launched about a million hacks and brought microcontroller programming into the mainstream. Oops. Similarly, about fifteen years ago, I saw an educational project out of MIT’s Media Lab. It consisted of a bunch of blocks that had LCD screens on them and would interact with each other when put together. The real hook, though, was that each block had an accelerometer inside, so you could “pour water” out of one block into another, for instance. At that time, accelerometers were expensive, even in quantities. Even one of these cubes must have cost $100 at the time, much less a whole set. Accelerometers were so expensive that I wouldn’t have thought about incorporating one into a project, much less a dozen,

If you’ve ever seen a painting in which the eyes follow you around the room, you might have found that a bit uneasy. [CuriousInventor] has taken that concept further with a skeleton that literally holds a gaze on anyone in its field of view.  The heart of the system is a Raspberry Pi Zero, fitted with a Pi Camera. Running OpenCV, code is set up to track humans and turn the skeleton’s head to face any that are detected. This is achieved via a servo in the skeleton’s neck. A servo bonnet is used to drive the servos without unnecessarily straining the Raspberry Pi. The skeleton itself doesn’t look modified in any way, though most of the electronics are mounted inside a pretty obvious plastic box. We’d love to see a version 2 with all the hardware housed neatly inside the skull. It’s a fun hack that makes for an enjoyable Halloween decoration. OpenCV can do other useful things, too, however, like spotting weeds . Video after the break. from Blog – Hackaday https://ift.tt/3pNosbz

Many a hacker is a fan of the cheapest calipers on the market. Manufactured in China and priced low enough that they’re virtually disposable, they get a lot of jobs done in the world where clinical accuracy isn’t required. However, their batteries often die when left in a drawer for a long time. [Ben] was sick of that, and got to hacking. The result was a quick-and-dirty mod that allows the calipers to be powered by a AAA battery. The average AAA cell has 5-10 times the capacity of the typical LR44 coin cells used in these devices. [Ben] whipped this up with an eye to making it work rather than making it nice, so there are some shortcuts taken. The battery housing was 3D-printed on the lowest-quality settings that were viable, and it’s held to the calipers with hot glue. Similarly, bare wire ends were used instead of proper contacts, taking advantage of the battery being crammed in to make a good connection. It’s a hack that will likely save [Ben] much frustration, as he’ll now rar

A student once asked his lab instructor why his amplifier was oscillating. After looking at it and noting the wild construction, the instructor remarked, “A better question would be why shouldn’t it oscillate?” The truth of it is, our circuits generate noise and especially if they are oscillating anyway. Distortion and nonlinearities generate harmonics and other component imperfections also contribute. [FesZ Electronics] has a great video series about noise in switching power supplies and the latest talks about the hot loop . If you want to improve the noise performance of your next design, these videos are well worth watching. You can see the hot loop video below. We really liked the homebrew noise probes. In addition to real-world probing. The video also observes circuit operation under simulation. Even if you don’t care about noise performance, there’s a lot of good information about basic switching power supply design here. You can see the difference in a PCB that has a small h

Eyeballs are often watching us, but they’re usually embedded in the skull of another human or animal. When they’re staring at you by themselves, they can be altogether more creepy. This Halloween project from [allpartscombined] aims to elicit that exact spooky vibe . The project relies on a Kinect V2 to do body tracking. It feeds data to a Unity app that figures out how to aim the eyeball at any humans detected in the scene. The app sends angle data to an Arduino over serial, with the microcontroller generating the necessary signals to command servos which move the eyeball. With tilt and pan servos fitted and the precision tracking from the Kinect data, the eye can be aimed at people  in two dimensions. It’s significantly spookier than simply panning the eye back and forth. The build was actually created by modifying an earlier project to create an airsoft turret, something we’ve seen a few times around these parts . Fundamentally, the tracking part is the same, just in this case,

Student and hacker [prusteen] recently fell in love with the Pomodoro method of time management. That’s where you concentrate on your task for 25 minutes, then take a five-minute break, and repeat this four times with a longer break at the end. Initially, [prusteen] was keeping track on their phone, but hated having to change the timer value between Pomodoros and break times. In order to keep the flow mode engaged, [prusteen] came up with this darling little study buddy that does it all with the push of a button. By default, this tomato shows the current time, which we think is a handy and often-overlooked feature of Pomodoro timer builds. Press that momentary switch on the front, and it starts counting upward to 25 minutes. Then it beeps in stereo through a pair of buzzers when the time is up, and automatically starts a five-minute break timer. Press it again and the display goes back to clock mode, although judging by the code , doing this will cancel the timer. Inside the juicy

Sometimes you don’t know what you want until you see it, and that goes for keyboard designs as much as it does the dessert cart. The Railroad is [DiplomacyPunIn10Did]’s first keyboard design, believe it or not . And, well, we like what we see. Good thing it’s open-source, eh? While we personally don’t normally go for straight-up ortholinear keyboards, this one looks split enough to be comfortable. We love that there is both an ISO Enter and a regular-sized Return, although we might put another Enter on the left side if it were our keyboard. That’s the beauty of this whole open-source keyboard thing, though. I could assign any number of those animal-capped keys to Enter. Another plus is that The Railroad uses semi-normal keycap sets, with none of this 1.25u nonsense of certain split keyboards. All the files and the BOM are available on GitHub under a Creative Commons license . This represents JLCPCB’s max length, by the way. [DiplomacyPunIn10Did] wanted to add a num pad, but it would

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Hackaday editors Elliot Williams and Mike Szczys flap their gums about all the great hacks of the week. Something as simple as a wheel can be totally revolutionary, as we saw with a white cane mod for the visually impaired which adds an omniwheel that knows where it’s going. We enjoyed the collection of great hacks from all over the community that went into a multi-two-liter water rocket build. You’ll hear Elliot and Mike’s great debate about the origin of comments in computer code. And we spend plenty of time joking around about the worlds longest airplane flight (it was in a tiny Cessna and lasted over two months!) Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments! Direct download (55 MB) Where to Follow Hackaday Podcast Places to follow Hackaday podcasts: Google Podcasts iTunes Spotify Stitcher RSS Episode 142 Show Notes: What’s that Sound? That sound was the Swish Rhapsody numbe

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When we think of using a press to form metal we think of large stamps with custom made metal dies under unimaginable hydraulic pressure. It’s unlikely we’d e think of anything 3D printed. And in a commercial environment we’d be right. But your average garage hacker is far more likely to have access to a bench vise and a 3D printer. It’s in this context that [The Shipping Container Garage] has spent considerable time, effort, and money perfecting a process for pressing copper parts with 3D printed dies , which you can watch below the break. In the quest to make a custom intake manifold for his project car, [The Shipping Container Garage] first made 3D printed jigs for cutting out a manifold flange that bolts to the cylinder head. It’s a process he calls Analog CNC, as all the cutting is done by hand. Buoyed by his success, he proceeded with the next step: making manifold runners. His metal of choice was copper. While softer than many metals such as steel, he found it too hard. In the

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In a brilliant write-up, [Stephen Tong] brings us his “ Use-After-Free for Dummies “. It’s a surprising tale of a vulnerability that really shouldn’t exist, and a walkthrough of how to complete a capture the flag challenge. The vulnerable binary is running on a Raspberry Pi, which turns out to be very important. It’s a multithreaded application that uses lock-free data sharing, through pair of integers readable by multiple threads. Those ints are declared using the volatile keyword, which is a useful way to tell a compiler not to optimize too heavily, as this value may get changed by another thread. On an x86 machine, this approach works flawlessly, as all the out-of-order execution features are guaranteed to be globally transparent. Put another way, even if thread one can speed up execution by modifying shared memory ahead of time, the CPU will keep the shared memory changes in the proper order. When that shared memory is controlling concurrent access, it’s really important that or