Linux Fu: The Kitchen Sync

January 10, 2019 by 12 Comments

One of the great things about Linux and similar operating systems is they are configurable. If you don’t like something, there’s a great chance you can change it easily with a few entries in a file somewhere. For example, take bash — a very popular shell by any measure. If you want a different style of command line editing, there’s an option. You want the tab key to match files regardless of case? Another option. Usually, these are set in one of your so-called profile files like .bashrc in your home directory.

As long as you are sitting in front of your single computer working, this is great. You customize your .bashrc and other files to your heart’s content and then you work in an environment that acts the way you want it to. The problem is when you have a lot of computers. Maybe you have a web server, a desktop, a firewall machine, and a few dozen Raspberry Pi computers. How do you keep all the configurations the same? Then once they are the same, how do you keep them up to date?

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Is Baking A Raspberry Pi The Recipe For Magic Smoke?

January 10, 2019 by 35 Comments

No, Hackaday hasn’t become a baking blog. We’re just here to give you a bit of advice: if [MickMake] ever offers you one of his fresh-baked Pis, proceed with caution. While we have no doubt that there will be some interesting smells wafting out of his kitchen, these aren’t the tasty pies you’re looking for. There’s no delicious home-baked treat when that timer dings, just a handful of Raspberry Pis that have had an exceptionally hard day.

To properly explain the odd sight of some Raspberry Pis laid out on a cookie sheet, we need to take a step back. [MickMake] originally set out to see how everyone’s favorite Linux SBC would handle the harsh Australian heat, and thought that setting them up on his car’s dashboard would be a suitable torture test. But as luck would have it, a storm rolled in while he was making the video which brought temperatures down to a “cool” 30 C (86 F); basically jacket weather at the bottom of the world. So naturally, he decided to put them in his oven instead.

Placed on an insulating sheet and with a thermocouple between them to get an accurate idea of the temperature they were experiencing, an original Pi, a Pi 2, and a pair of Pi 3s were sent on the ride of their lives. In addition to monitoring them over the network, he also added a “heartbeat” LED to each Pi so he’d be able to tell at a glance if any of them had given up the ghost. As if these poor little Pis didn’t have it bad enough already, [MickMake] decided to take things a step farther and run sysbench on them while they took their trip through Hades.

The Pis are actually rated for temperatures up to 85C, and all the participants of the experiment hit that point without any issues. At 87.3 C (~190 F) the original Pi dropped off the network, but its LED was seen bravely blinking on. At 105.7 C (~222 F) it finally breathed its last, followed by the pair of Pi 3s tapping out at 112 C (233 F). The Pi 2 fought on, but it fell right at the 119 C (246 F) mark.

But what about when they cooled off? Somewhat surprisingly, [MickMake] successfully powered all four back up and was unable to find any damage to the Pis, either physically or operationally. Even the SD cards survived, and the Pis popped right back onto the network and were ready for another round of Silicon Chef. Not bad considering they were subjected to temperatures three times higher than the official limit.

Testing electronics in your home oven might seem a bit suspect, and admittedly we’d probably turn down a slice of the next few frozen pizza’s [MickMake] runs through it, but it’s not really so far removed from how proper reliability testing is performed.

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Transistor Tester Becomes Car Display

January 10, 2019 by 11 Comments

These days, the electronics hobbyist is lucky to have access to a wide range of ready-made modules that enable sensors, screens, and microcontrollers to all be linked up with ease. However, this manner of working generally ends up with a project that becomes more of a PCB salad than a finished product. Oftentimes, it’s possible to find something off the shelf that’s close to your requirements, and repurpose it to work. That’s exactly what [Aaron] did.

[Aaron] wanted to install a display in his classic Jeep to display the time and some basic parameters. A screen and a microcontroller were called for, and a cheap open-source transistor tester had exactly that already. Consisting of an ATmega-328P linked up to an 128 x 64 graphic LCD module, it had most of what [Aaron] needed from the get go.

To repurpose the device, [Aaron] started by swapping the 8 MHz crystal for a 16 MHz one to make it more easily programmable through the Arduino IDE. Then, a custom firmware was written, which communicates with a DS3232 real time clock, temperature and pressure sensors, and also monitors battery voltage. It’s all neatly installed in the vehicle behind a 3D printed faceplate, and the graphic LCD is clear and easy to read – if you speak German.

[Aaron] has helpfully outlined the various online resources that helped with the hack, including the transistor tester schematic. Our very own [Adam Fabio] reviewed these units in 2015.

If you’ve cleverly reused some existing hardware yourself, be sure to let us know on the tip line. Video after the break.

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Adaptive Spoon Helps Those With Parkinson’s

January 9, 2019 by 6 Comments

There are a lot of side effects of living with medical conditions, and not all of them are obvious. For Parkinson’s disease, one of the conditions is a constant hand tremor. This can obviously lead to frustration with anything that involves fine motor skills, but also includes eating, which can be even more troublesome than other day-to-day tasks. There are some products available that help with the tremors, but at such a high price [Rupin] decided to build a tremor-compensating utensil with off the shelf components instead.

The main source of inspiration for this project was the Liftware Steady, but at around $200 this can be out of reach for a lot of people. The core of this assistive spoon has a bill of material that most of us will have lying around already, in order to keep costs down. It’s built around an Arduino and an MPU6050 inertial measurement unit with two generic servo motors. It did take some 3D printing and a lot of math to get the utensil to behave properly, but the code is available on the project site for anyone who wants to take a look.

This project tackles a problem that we see all the time: a cost-effective, open-source solution to a medical issue where the only alternatives are much more expensive. Usually this comes up around prosthetics, but can also help out by making biological compounds like insulin directly for less than a medical company can provide it.

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MIT Scratch 3.0 Opens New Doors For Users And Builders Alike

January 9, 2019 by 26 Comments

We typically feature projects from people sharing what they’ve learned while building something for themselves. But our community has a healthy contingent who deploy their skills for the benefit of future generations, developing a child’s natural curiosity for play into interest in understanding the technical world they will grow up in. This field is where MIT’s release of Scratch 3.0 can open up interesting possibilities.

Scratch is a block-based programming language designed for elementary school children, letting them learn fundamental concepts while experimenting in an environment filled with visual and audible feedback. In an effort to make Scratch more widely available, version 2.0 in 2013 moved to the web. But it was built using interactive web technology of the time: Adobe Flash. As Flash has fallen out of favor and scheduled to be phased out in 2020, Scratch 3.0 used React to make the shift to HTML5.

The most immediate benefit is that Scratch can now be used on tablets, which all have modern browsers but very few of which have Flash. Another common educational hardware platform is the Raspberry Pi, which supported Scratch 2 via a convoluted software stack that was far from ideal. Now any hardware with a modern browser can run Scratch, no Flash binaries or custom wrappers are required. The Raspberry Pi foundation certainly seemed excited about this change.

But a more exciting and longer term benefit is Scratch extensions, a mechanism for Scratch programs to communicate with external hardware and online resources. This has evolved in parallel with Scratch 2.0 under the experimental ScratchX umbrella and version 3.0 brings it into core. The launch featured a few official extensions (for connecting to micro:bit, LEGO Mindstroms EV3, etc.) with the promise that custom third-party extensions will soon be possible. This will significantly streamline building a Scratch interface for kid-friendly programmable hardware. Something we’ve seen done for a drone, for exploring SDR, and even for a dollhouse. We’ll be keeping an eye out for the official release of Scratch 3.0 custom extension API, but anyone not afraid of working with fluid pre-release code are certainly welcome to dive in right now.

Smartphone App Uses AR To Visualize The RF Spectrum

January 9, 2019 by 21 Comments

Have you ever wished you could see in the RF part of the radio spectrum? While such a skill would probably make it hard to get a good night’s rest, it would at least allow you to instantly see dead spots in your WiFi coverage. Not a bad tradeoff.

Unwilling to go full [Geordi La Forge] to be able to visualize RF, [Ken Kawamoto] built the next best thing – an augmented-reality RF signal strength app for his smartphone. Built to aid in the repositioning of his router in the post-holiday cleanup, the app uses the Android ARCore framework to figure out where in the house the phone is and overlays a color-coded sphere representing sensor data onto the current camera image. The spheres persist in 3D space, leaving a trail of virtual breadcrumbs that map out the sensor data as you warwalk the house. The app also lets you map Bluetooth and LTE coverage, but RF isn’t its only input: if your phone is properly equipped, magnetic fields and barometric pressure can also be AR mapped. We found the Bluetooth demo in the video below particularly interesting; it’s amazing how much the signal is attenuated by a double layer of aluminum foil. [Ken] even came up with an Arduino with a gas sensor that talks to the phone and maps the atmosphere around the kitchen stove.

The app is called AR Sensor and is available on the Play Store, but you’ll need at least Android 8.0 to play. If your phone is behind the times like ours, you might have to settle for mapping your RF world the hard way.

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Glasses Frames Crafted Out Of Wood

January 9, 2019 by 10 Comments

Most glasses and sunglasses on the market make use of metal or plastic frames. It’s relatively easy to create all manner of interesting frame geometries, tolerances can be easily controlled for fitting optical elements, and they’re robust materials that can withstand daily use. Wood falls short on all of these measures, but that doesn’t mean you can’t use it to make a beautiful pair of glasses.

ZYLO is a company making wooden eyewear, and this video from [Paide] shows the build process in detail. Modern tools are used to make things as efficient as possible. Parts are lasercut and engraved to form the main part of the frames as well as the temples (the arms that sit over the ears to hold them on your face). A special jig is used to impart a curve on the laminated wood parts before further assembly is undertaken. Metal pre-fabricated hinges and screws are used to bolt everything together like most other modern sunglasses, but there’s significant hand finishing involved, including delicate inlays and highlighting logo features.

In contrast, Manuel Arroyave works very differently in the creation of his Cedoro glasses. Sheets are first laminated together, before the shape is roughed out by a special horizontal axis milling setup. Even small details like the hinges are delicately hand-crafted out of wood and fitted with tiny wooden dowels.

It goes to show that there’s always more than one way to get a job done. We’re tempted to break out the laser cutter and get started on some custom shades ourselves. Perhaps though, you’re too tired to put your sunglasses on by yourself? Nevermind, there’s a solution for that, too. Video after the break.

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