Sometimes you need something to be utterly, totally, irredeemably black. Not just a little bit black, not just really really really dark blue, but as black as it is possible to get. It might be to trap light in a camera or a telescope, for artistic purposes, or even to make your warplane a more difficult target for enemy missiles. Either way, we’re here to help, not to judge. So what are your options?
Well, first of all, there’s the much-lauded Vantablack. The name itself is a clue as to its origin – Vertically Aligned Nano Tube Arrays. It works by coating an object with a forest of carbon nanotubes in a complicated vacuum deposition process. When light hits the surface, some of it is absorbed by the nanotubes, and any that is reflected tends to be absorbed by neighbouring nanotubes rather than escaping the surface coating of the object.
Twitter is kind of a crazy place. World leaders doing verbal battle, hashtags that rise and fall along with the social climate, and a never ending barrage of cat pictures all make for a tumultuous stream of consciousness that runs 24/7. What exactly we’re supposed to do with this information is still up to debate, as Twitter has yet to turn it into a profitable service after over a decade of operation. Still, it’s a grand experiment that offers a rare glimpse into the human hive-mind for anyone brave enough to dive in.
One such explorer is a security researcher who goes by the handle [x0rz]. He’s recently unveiled an experimental new piece of software that grabs Tweets and uses them as a “noise” to mix in with the Linux urandom entropy pool. The end result is a relatively unpredictable and difficult to influence source of random data. While he cautions his software is merely a proof of concept and not meant for high security applications, it’s certainly an interesting approach to introducing humanity-derived chaos into the normally orderly world of your computer’s operating system.
Noise sampling before and after being merged with urandom
This hack is made possible by the fact that Twitter offers a “sample” function in their API, which effectively throws a randomized collection of Tweets at anyone who requests it. There are some caveats here, such as the fact that if multiple clients request a sample at the same time they will both receive the same Tweets. It’s also worth mentioning that some characters are unusually likely to make an appearance due to the nature of Twitter (emoticons, octothorps pound signs, etc), but generally speaking it’s not a terrible way to get some chaotic data on demand.
On its own, [x0rz] found this data to be a good but not great source of entropy. After pulling a 500KB sample, he found it had an entropy of 6.5519 bits per byte (random would be 8). While the Tweets weren’t great on their own, combining the data with the kernel’s entropy pool at /dev/urandom provided something that looked a lot less predictable.
The greatest weakness of using Twitter as a source of entropy is, of course, the nature of Twitter itself. A sufficiently popular hashtag on the rise might be just enough to sink your entropy. It’s even possible (though admittedly unlikely) that enough Twitter spam bots could ruin the sample. But if you’re at the point where you think hinging your entropy pool on a digital fire hose of memes and cat pictures is sufficient, you’re probably not securing any national secrets anyway.
(Editor’s note: The way the Linux entropy pool mixes it together, additional sources can only help, assuming they can’t see the current state of your entropy pool, which Twitter cats most certainly can’t. See article below. Also, this is hilarious.)
We get a lot of awesome projects sent our way via the tip line. Well, mainly it seems like we get spam, but the emails that aren’t trying to sell us something are invariably awesome. Even so, it’s not often we get a tip that contains the magic phrase “determine Mach number” in its list of features. So to say we were interested in the Asgard Air Data Computer (ADC) is something of an understatement.
Now we’ll admit right up front: we aren’t 100% sure who the target audience for the Asgard is, but it certainly looks impressive. Team member [Erik] wrote into tip line with information about this very impressive project, which is able to perform a number of measurements on incoming air, such as true speed, viscosity, and temperature. The team says it has applications ranging from HVAC to measuring the performance of bicycles. We don’t know who’s going so fast on their bike that they need to measure air speed, but of course the hacker community never ceases to amaze us.
Even if you don’t have a jet fighter that could benefit from a high performance ADC such as Asgard, you have to be impressed by the incredible work the team has done not only designing and building it, but documenting it. From the impeccably designed 3D printed case to the stacked PCB internals, every aspect of Asgard screams professional hardware.
Data collected from Asgard can be stored on the internal micro SD if the device is to be used in stand-alone mode, or you can connect to it over USB or Bluetooth thanks to the HC-05 module. The team has even put together some scripts to merge the Asgard’s generated air data with GPS position information.
We’re not sure which is more fun – putting together a little RC truck with parts laying around on your workbench, or driving it around through a Linux terminal. We’ll take the easy road and say they’re both equally fun. [technodict] had some spare time on his hands and decided to build such a truck.
He started off with a great little chassis that can act as the base for many projects. Powering the four motors is a cheap little dual H bridge motor driver and a couple rechargeable batteries. But the neatest part of this build is that it’s controlled using a little bit of python and driven directly from a terminal, made possible by the Raspberry Pi Zero of course.
With Raspberry Pi Zero now having built in WiFi and Bluetooth – we should see a lot more projects popping up with one at its heart. Be sure to visit [technodict’s] blog for full source and details. And let us know how you could use that little chassis for your next mobile project!
Gardening is a rewarding endeavour, and easily automated for the maker with a green thumb. With simplicity at its focus, Hackaday.io user [MEGA DAS] has whipped up a automated planter to provide the things plants crave: water, air, and light.
[MEGA DAS] is using a TE215 moisture sensor to keep an eye on how thirsty the plant may be, a DHT11 temperature and humidity sensor to check the airflow around the plant, and a BH1750FVI light sensor for its obvious purpose. To deliver on these needs, a 12V DC water pump and a small reservoir will keep things right as rain, a pair of 12V DC fans mimic a gentle breeze, and a row of white LEDs supplement natural light when required.
The custom board is an Arduino Nano platform, with an ESP01 to enable WiFi capacity and a Bluetooth module to monitor the plant’s status while at home or away. Voltage regulators, MOSFETs, resistors, capacitors, fuses — can’t be too careful — screw header connectors, and a few other assorted parts round out the circuit. The planter is made of laser cut pieces with plenty of space to mount the various components and hide away the rest. You can check out [MEGA DAS]’ tutorial video after the break!
[rudolph] was at a loss on what to get his niece for Christmas. It turns out she’s a huge fan of Stranger Things, so the answer was obvious: make her an alphabet wall she can control!
Downsizing the scale to fit inside a document frame, [rudolph] calls their gift rudLights, and a key parameter of this build was to make it able to display any phrases sent from their niece’s Amazon Fire tablet instead of constantly displaying hard-coded phrases. To do so, it has a HC-05 Bluetooth module to forward the commands to the NeoPixel LEDs running on a 5V DC power supply.
[rudolph] enlisted the help of their son to draw up the alphabet display — printed straight onto thematically decorative wallpaper — and cut out holes in the light bulbs for the LEDs. Next up was cut some fibre board as a firm backing to mount the electronics inside the frame and drill holes for the NeoPixels. It was a small odyssey to cut and solder all the wires to the LEDs, but once done, [rudolph] divided their rudLight alphabet into three rows and added capacitors to receive power directly.
Mounting a motor on a PCB is nothing new, right? But how about making the PCB itself part of the motor? That’s what [Carl Bugeja] has done with his brushless DC motor in a PCB project, and we think it’s pretty cool.
Details on [Carl]’s Hackaday.io page are a bit sparse at this point, but we’ve been in contact with him and he filled us in a little. The PCB contains the stator of the BLDC and acts as a mechanical support for the rotor’s bearing. There are six spiral coils etched into the PCB, each with about 40 turns. The coils are distributed around the axis; connected in a wye configuration, they drive a 3D-printed rotor that has four magnets pressed into it. You can see a brief test in the video below; it seems to suffer from a little axial wobble due to the single bearing, but that could be handled with a hat board supporting an upper bearing.
We see a lot of potential in this design. [Carl] mentions that the lack of cores in the coil limit it to low-torque applications, but it seems feasible to bore out the center of the coils and press-fit a ferrite slug. Adding SMD Hall sensors to the board for feedback would be feasible, too — in fact, an entire ESC and motor on one PCB could be possible as well. [Carl] has promised to keep the project page updated, and we’re looking forward to more on this one.
