Hackaday Links: November 24, 2019

It barely seems like it, but it’s been a week since the 2019 Hackaday Superconference wrapped up in sunny Pasadena. It was an amazing weekend, filled with fun, food, camaraderie, and hacks galore. For all who were there, it’ll likely take quite some time before spinning down to Earth again from the post-con high. For those who couldn’t make it, or for those who did but couldn’t squeeze in time for all those talks with everything else going on, luckily we’ve got a ton of content for you to review. Start on the Hackaday YouTube channel, where we’ve got videos already posted from most of the main stage talks. Can’t-miss talks include Chris Gammell’s RF deep-dive, Kelly Heaton’s natural electronic art, and Mohit Bhoite’s circuit sculpture overview. You’ll also want to watch The State of the Hackaday address by Editor-in-Chief Mike Szczys. More talks will be added as they’re edited, so watch that space for developments.

One of the talks we missed – and video of which appears not to be posted yet – was Adam Zeloof’s talk on thermodynamic design for your circuits. While we wait for that, here’s an interesting part that might prove useful for your next high-power design. It’s a Thermal Jumper Chip, which is essentially a ceramic SMD component that can conduct heat but not electricity. It’s intended to be used where a TO-220 case needs to be electrically isolated but thermally connected to a heatsink. Manufacturer TT Electronics has a whole line of the chips in various sizes and specs, plus a lot of other cool components like percussive igniters.

We got an interesting tip this week about a new development in the world of 3D-printing. A group from Harvard demonstrated a multinozzle extruder that can print multimaterial objects in a single pass. The work is written up in a Nature article entitled “Voxelated soft matter via multimaterial multinozzle 3D printing”, which is unfortunately paywalled, but the abstract and supplementary videos are really interesting. This appears not to be a standard hot plastic extrusion process; rather, the extruder uses elastomeric inks that cure after they’re extruded. They manage some clever tricks, including a millipede-like, vacuum-powered soft robot extruded in one pass from both soft and rigid silicone elastomers. It’s genuinely interesting stuff, and watching the multimaterial extruder head switch materials at up to 50 times per second is mesmerizing.

People really seemed to get worked up over the transit of Mercury across the face of the Sun last week, and for good reason – astronomical alignments such as these which can be seen from Earth are rare indeed, and worth taking time to see. Not everyone was in the right place at the right time with the right gear to view the transit directly, though, which is why we were glad that Justin over at The Thought Emporium did a video on leveraging online assets for space-based observations. We’ve featured a ton of hacks using SDRs and the like to intercept data from weather satellites, and while those hacks are fun and you should totally try them, Justin points out that most of these streams are readily available for free over the Internet. Clouds, lightning, forest fires and Earth changes, and yes, even the state of the Sun can all be monitored from the web.

Speaking of changes, do you know what has changed in Unix over the last 50 years? For that matter, did you know that Unix turned 50 recently? Sean Haas did after reading this article in Advent of Computing, which he shared on the tipline. The article compares a modern Debian distro to documentation from 1971 that pre-dates Unix version 1; we assume the “Dennis_v1” folder in the doc’s URL refers to none other than Dennis Ritchie himself. It turns out that Unix is remarkably well-conserved over 50 years, at least in the userspace. File system navigation and shell commands are much the same, while programming was much different. C didn’t yet exist – Dennis was busy – but there were assemblers and linkers, plus a FORTRAN compiler and an interpreter for BASIC. It’s comforting to know that if you drop into a wormhole and end up sitting in front of a PDP-11 with Three Dog Night singing “Joy to the World” on the radio in the background, you’ll at least be able to look like you belong there.

And finally, it’s nearly Sparklecon time again. Sparklecon VII will be held on January 25 and 26, 2020, at the 23b Shop hackspace in Fullerton, California. We’ve covered previous Sparkelcons and we’ve even sponsored the meetup in the past, and it looks like a blast. The organizers have put out a Call for Proposals for talks and workshops, so if you’re in the mood for some mischief, get your application going. And be quick about it – the CFP closes on December 8.

A Raspberry Pi 4 Video Streaming Backpack

Were you aware that there’s a market for backpack-housed live streaming video systems, and that they can cost as much as $1600? Apparently these things are popular with social media moguls who want to stream themselves living their fabulous lives to people sitting at home watching on YouTube or Twitch. But believing that even slack jawed yokels like us should have access to the same technology, [Speedify Labs] has been working on less expensive DIY alternative based on the Raspberry Pi 4.

Now you’ll note we didn’t use the term “cheap” to describe this build. As detailed here, it’s still going to cost you around $600. You could always swap out the Sony AS-300 camera and Elgato Cam Link capture device with cheaper versions, but the goal of this project was to deliver high quality HD video that’s comparable to what the professional rigs are capable of, so those kinds of concessions were avoided.

Whatever video source your audience and budget are comfortable with, it eventually gets fed into the Raspberry Pi 4 which uses an ffmpeg one-liner to encode the video and ultimately push it out as 720p at 24 FPS, which [Speedify Labs] says seems to be about as good as the Pi can do. The operator is able to start and stop the stream at will using a Circuit Playground Express and a Python script.

Of course, the trick to all of this is getting the video stream uploaded over potentially flaky mobile networks. But as you might have guessed, that’s where [Speedify Labs] gets to flex their eponymous product: a VPN with software channel bonding that allows you to combine multiple Internet connections for higher bandwidth and reliability. With their software, the Pi is able to stream the video through two mobile phones connected to it over USB. As demonstrated in the video below, the setup was able to maintain the stream even as they walked in and out of buildings.

Our very own [Lewin Day] wrote about his experiments with streaming video over 4G on the Raspberry Pi which might be of interest to anyone looking to take their show on the road. Though if you want to get serious it would be worth taking a look at the impressive mobile streaming rig that [Jenny List] saw at the BornHack 2019 hacker camp in Denmark.

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A Farewell To YouTube Sub Counters Set To Break With API Change

Of all the things you never would have guessed you’d need just ten years ago, a YouTube subscriber counter would probably rank highly. You would have guessed that the little hits of dopamine accompanying each tick upward of a number would be so addictive?

As it turns out, lots of people wanted to keep a running total of their online fans, and a bewilderingly varied ecosystem of subscriber counters has cropped up. All of them rely on the API that YouTube exposes for such purposes, which as [Brian Lough] points out is about to change and break every subscription counter ever made. In the YouTube sub counter space, [Brian] is both an enabler – he built an Arduino wrapper to fetch YT sub counts easily – and a serial builder of displays for other YouTubers. The video below shows a collection of his work, many based on RGB LED matrix display, like the one used in his Tetris-themed sub counter. They’re all well-built, nice to look at, and sadly, destined for obsolescence sometime in August when the API changes.

The details of the API changes were made public in April, and for the subs count it amounts to rounding the count and displaying large counts as, for instance, 510k as opposed to 510,023. We’re confident that [Brian] and other display builders will be able to salvage some of their counters with code changes, but others will probably require hardware changes. Thanks, YouTube.

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Measure Your YouTube Importance

How do you hack your motivation? Do you put red marker Xs on a paper calendar every day you exercise? Do you use an egg timer to sprint through dozens of emails? Do you lock all the doors and shut off your data to write some bulletproof code? If you are [Hulk], you build a YouTube Desktop Notifier showing his YouTube subscribers and views. This is his ticket to getting off the couch to make a video about just such a device. There is something poetic about building a mechanism to monitor its own success making a feedback loop of sorts. The Hackaday.io page follows the video, so anyone who wants to build their own doesn’t have to scribble notes while pausing the video which is also posted below the break.

The hardware list is logical, starting with a NodeMCU module programmed through the Arduino IDE. Addressable 7-segment displays show the statistics in red, but you can sub in your preferred color with the back-lighting LEDs. It should be possible to share the CLK pins on the displays if you are important enough to need more digits. [Hulk] already outlined a list of improvements including switching to addressable backlights and adding daily and monthly tracking.

Monitoring online values without a computer monitor is satisfying on a level because it shows what motivates us, whether that is Bitcoin or the weather.

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Electromechanical YouTube Sub Counter Trades Clicks For Clacks

Acquiring a new YouTube subscriber is a blessed event that deserves far more fanfare than a phone notification. But maybe blinkenlights don’t really do it for you anymore, or you simply prefer to be soothed sonically rather than visually. Well, what could be more satisfying than the crisp clack of an electromechanical 7-segment display? Six of them, of course. These things look great, they sound great, and once they’re set, they don’t need power to stay that way.

These displays switch between black and white by reversing current flow through their electromagnets, so [Zack] turned to the H-bridge in order to use them with DC. One H-bridge for each segment of six displays adds up fast, though. To get around this, [Zack] tied one pole of each electromagnet together for a common signal input, and used the other pole to control each segment individually. Then, he was able to tie all the A segments together, all the B segments, and so on, and only needs 13 H-bridges to do it all.

There was just one thing [Zack] didn’t count on. Once he got the board soldered up and running, the displays started acting funny. The low impedance of the coils was causing them to influence each other over the common path, so he added diode arrays to keep them in line.

[Zack]’s using an ESP32 to get the 411 through the Google API, and four octal serial switches to drive the displays. Even more satisfying than all those clacks is the displays’ operational economy baked into [Zack]’s code—as they count up, any segments common to the first digit and the next digit remain on. Increment your way past the break to check out the build video.

Not focused on numbers, but still want to celebrate each new sub? Try a dancing robot or a Tetris twist.

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UPnP, Vulnerability As A Feature That Just Won’t Die

UPnP — in a perfect world it would have been the answer to many connectivity headaches as we add more devices to our home networks. But in practice it the cause of a lot of headaches when it comes to keeping those networks secure.

It’s likely that many Hackaday readers provide some form of technical support to relatives or friends. We’ll help sort out Mom’s desktop and email gripes, and we’ll set up her new router and lock it down as best we can to minimise the chance of the bad guys causing her problems. Probably one of the first things we’ll have all done is something that’s old news in our community; to ensure that a notorious vulnerability exposed to the outside world is plugged, we disable UPnP on whatever cable modem or ADSL router her provider supplied.

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The Magic Flute Of Rat Mind Control Aims To Mix Magic And Science

Well this is unusual. Behold the Magic Flute of Rat Mind Control, and as a project it is all about altering the response to the instrument, rather than being about hacking the musical instrument itself. It’s [Kurt White]’s entry to the Musical Instrument Challenge portion of The Hackaday Prize, and it’s as intriguing as it is different.

The Raspberry-Pi controlled, IoT Skinner box for rats, named Nicodemus.

[Kurt] has created a portable, internet-connected, automated food dispenser with a live streaming video feed and the ability to play recorded sounds. That device (named Nicodemus) is used as a Skinner Box to train rats — anywhere rats may be found — using operant conditioning to make them expect food when they hear a few bars of Black Sabbath’s Iron Man played on a small recorder (which is a type of flute.)

In short, the flute would allow one to summon hordes of rats as if by magic, because they have been trained by Nicodemus to associate Iron Man with food.

Many of the system’s elements are informed by the results of research into sound preference in rats, as well as their ability to discriminate between different melodies, so long as the right frequencies are present. The summoning part is all about science, but what about how to protect oneself from the hordes of hungry rodents who arrive with sharp teeth and high expectations of being fed? According to [Kurt], that’s where the magic comes in. He seems very certain that a ritual to convert a wooden recorder into a magic flute is all the protection one would need.

Embedded below is something I’m comfortable calling the strangest use case video we’ve ever seen. Well, we think it’s a dramatized use case. Perhaps it’s more correctly a mood piece or motivational assist. Outsider Art? You decide.

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