Hackaday Links: December 13, 2020

December 13, 2020 by Dan Maloney 16 Comments

Our Sun is getting a bit frisky these days, and has rewarded us with perhaps the best screensaver image ever taken. The incredibly detailed photo of a sunspot was actually taken back in January by the Daniel K. Inouye Solar Telescope, a 4-meter instrument with adaptive optics that can image the sun from the near-infrared to visible wavelengths and resolve surface details down to 20 km. The photo, with a distinct “Eye of Sauron” look, shows the massive convection cells surrounding the dark sunspot; an accompanying animation shows the movement of plasmas along the tortured lines of magnetic flux that cause the sunspot to form. It’s fascinating to watch, and even more interesting to mull over the technology that went into capturing it.

With the dustup surrounding the youtube-dl DCMA takedown by GitHub fresh on the open-source community’s minds, GitHub Universe 2020 had an interesting discussion about maintaining open-source software projects that’s worth watching. They focused on the challenges that youtube-dl maintainers face in keeping the tool working, and the impact their effort has on the people and groups that rely on them. To underscore that point, they featured a researcher with Human Rights Watch who depends on youtube-dl in her work, and made it quite clear that keeping up with all the API changes that constantly break open source tools like youtube-dl make the role of the maintainers that much more critical.

Speaking of GitHub, here’s a frightening and fascinating new tool: Depix, the password de-pixelizer. Developer Sipke Mellema noticed that his company often used pixelization to obscure passwords in documentation, and wondered if he could undo the process. He wrote up an article describing the pixelization process using a linear box filter and his method for attacking it, which involves generating a De Bruijn sequence in the same font, text size, and colors as the original document and feeding a screenshot of that and the pixellated password into the tool. We suspect it’ll only work for a subset of obfuscated passwords, but it’s still pretty clever.

‘Tis the season for Advent calendars, and the folks at QEMU have posted theirs. Open each of 24 doors on the calendar and you’re rewarded with a downloadable QEMU disk image that implements something fun. Minesweeper, a ray tracer that fits into a boot loader, and of course Conway’s Game of Life. The GW-BASIC image on Day 3 caught our eye — brings back some memories.

For anyone who has ever watched a Pixar film and wondered how all that animation actually works, here’s a great lesson in making art with math. The video is by Inigo Quilez and goes through the basics of rendering images using raymarching SDFs, or signed distance functions. In the beginning, it seemed like it was going to be a little bit like drawing an owl, but his descriptions of the math involved and how each element of the animation is just another formula is fascinating. What’s more, there’s a real-time rendering tool where you can inspect the code and edit it. Alas, my changes only made things worse, but it was still fun and instructive to play with. Check out the video after the break!

Continue reading “Hackaday Links: December 13, 2020” →

A 3D – To – 2D Converter To Make Plots From STLs.

December 13, 2020 by Jenny List 13 Comments

We’ve become used to finding models on websites such as Thingiverse and downloading them to print. After all, whose hackerspace doesn’t have a pile of novelty prints? How about printing them on paper? For the plotter enthusiast that can be particularly annoying. Never fear, [Trammell Hudson] is here with an online 3D to 2D converter just for plotters. [Trammell’s] creation makes a vector image suitable for a plotter while eliminating spurious behind-the-scenes lines.

Plotter drawings are the pen-and-paper equivalent of a vector CRT display, in which the graphics are printed as continuous strokes. Rendering a 3D model as a wireframe for a plotter requires the removal of any pen strokes that comes from the 3D space behind the surface in view. Loading various models into the web page seemed to do a pretty good job of this, though the ubiquitous Benchy 3d printer test model lived up to its billing as a torture test in taking several minutes to render.

As anyone who has followed the #PlotterTwitter social media hashtag will know, there is a considerable community of pen plotter enthusiasts who are pushing the boundaries of what their machines can do. [Trammell] has posted his plotter producing some of the work created with this tool, and we can see that it’s likely to work better with lower-poly models.

We’ve featured a lot of plotters over the years as they seem to be a popular project. If you’d like one then they can be made from the most available parts, including those scavenged from scrap DVD drives, or printers.

A Pair Of Steppers Are Put To Work In This Automatic Instrument Pickup Winder

December 13, 2020 by Dan Maloney 7 Comments

For something that’s basically a coil of wire around some magnetic pole pieces, an electric guitar pickup is a complicated bit of tech. So much about the tone of the instrument is dictated by how the pickup is wound that controlling the winding process is something best accomplished with a machine. This automatic pickup winder isn’t exactly a high-end machine, but it’s enough for the job at hand, and has some interesting possibilities for refinements.

First off, as [The Mixed Signal] points out, his pickups aren’t intended for use on a guitar. As we’ve seen before, the musical projects he has tackled are somewhat offbeat, and this single-pole pickup is destined for another unusual instrument. That’s not to say a guitar pickup couldn’t be wound on this machine, of course, as could inductors, solenoids, or Tesla coils. The running gear is built around two NEMA-17 stepper motors, one for the coil spindle and one for the winding carriage. The carriage runs on a short Acme lead screw and linear bearings, moving back and forth to wind the coil more or less evenly. An Arduino topped with a CNC shield runs the show, allowing for walk-away coil winding.

We do notice that the coil wire seems to bunch up at the ends of the coil form. We wonder if that could be cured by speeding up the carriage motor as it nears the end of the spool to spread the wire spacing out a bit. The nice thing about builds like these is the ease with which changes can be made — at the end of the day, it’s just code.

Continue reading “A Pair Of Steppers Are Put To Work In This Automatic Instrument Pickup Winder” →

RC Starship Perfects Its Skydiving Routine

December 13, 2020 by Tom Nardi 12 Comments

There’s a good chance you already saw SpaceX’s towering Starship prototype make its impressive twelve kilometer test flight. While the attempt ended with a spectacular fireball, it was still a phenomenal success as it demonstrated a number of concepts that to this point had never been attempted in the real world. Most importantly, the “Belly Flop” maneuver which sees the 50 meter (160 foot) long rocket transition from vertical flight to a horizontal semi-glide using electrically actuated flight surfaces.

Finding himself inspired by this futuristic spacecraft, [Nicholas Rehm] has designed his own radio controlled Starship that’s capable of all the same aerobatic tricks as the real-thing. It swaps the rocket engines for a pair of electric brushless motors, but otherwise, it’s a fairly accurate recreation of SpaceX’s current test program vehicle. As you can see in the video after the break, it’s even able to stick the landing. Well, sometimes anyway.

Just like the real Starship, vectored thrust is used to both stabilize the vehicle during vertical ascent and help transition it into and out of horizontal flight. Of course, there are no rocket nozzles to slew around, so [Nicholas] is using servo-controlled vanes in the bottom of the rocket to divert the airflow from the motors. Servos are also used to control the external control surfaces, which provide stability and a bit of control authority as the vehicle is falling.

As an interesting aside, Internet sleuths looking through pictures of the Starship’s wreckage have noted that SpaceX appears to be actuating the flaps with gearboxes driven by Tesla motors. The vehicle is reportedly using Tesla battery packs as well. So while moving the control surfaces on model aircraft with battery-powered servos might historically have been a compromise to minimize internal complexity, here it’s actually quite close to the real thing.

Unfortunately, the RC Starship made a hard landing of its own on a recent test flight, so [Nicholas] currently has to rebuild the craft before he can continue with further development. We’re confident he’ll get it back in the air, though it will be interesting to see whether or not he’s flying before SpaceX fires off their next prototype.

Continue reading “RC Starship Perfects Its Skydiving Routine” →

Creality WiFi Takes On Octoprint

December 13, 2020 by Al Williams 78 Comments

A very common hack to a 3D printer is to connect a Raspberry Pi to your printer and then load Octoprint or a similar program and send your files to the printer via the network. [Teaching Tech] noticed that Creality now has an inexpensive WiFi interface that promises to replace Octoprint and decided to give it a quick review.

You might wonder why you’d want this system when Octoprint exists? Mainly, the value proposition is the price. You can buy the Creality box for about $20. A Raspberry Pi with a similar case would be at least twice that price. In addition, the box integrates with a Thingiverse-like library and does cloud slicing, which is attractive when you have a very small computer connected to your printer.

However, [Teaching Tech] found some issues. The box was pretty picky about connecting to printers and there were many other problems. The 3D model library wasn’t very comprehensive, although that could change if the thing got very popular. Worse, the slicer didn’t really produce stellar results.

We have to admit, an attractive network interface for $20 would be of interest. But it is hard to see how this would be a better value than Octoprint unless you were very short on cash and had no Raspberry Pi surplus laying around. You still need an SD card and a power supply, so those extras are a wash.

On the other hand, if Creality fixes the problems and expands the 3D model library, we’d buy one. But it remains to be seen if either of those things will happen, much less both of them. We do wish [Teaching Tech] had opened the thing up for us. Maybe next time.

Continue reading “Creality WiFi Takes On Octoprint” →

Can You Use An Easy-Bake Oven For Reflow Soldering?

December 13, 2020 by Kristina Panos 12 Comments

The answer is yes, yes you can. As long as you have one made after about 2011, at least. In the video after the break, [Blitz City DIY] takes us briefly through the history of the venerable Easy-Bake Oven and into the future by reflow soldering a handful of small blinky boards with it.

You’re right, these things once used special light bulbs to cook pint-sized foods, but now they are legit ovens with heating elements that reach 350°F and a little above. The only trouble is that there’s no temperature controller, so you have to use low-temperature solder paste and an oven thermometer to know when to pull the little tray out. Other than that, it looked like smooth sailing.

If you’re only doing a board every once in a while, $40 for a reflow oven isn’t too shabby. And yeah, as with all ovens, once you’ve reflowed a board in it, don’t use it for food.

If you’d rather build an oven, high-powered light bulbs will still do the trick.

Continue reading “Can You Use An Easy-Bake Oven For Reflow Soldering?” →

IRC Over LoRa, For When Things Really Go South

December 12, 2020 by Tom Nardi 74 Comments

As a society, we’ve become accustomed to always-on high-speed data connections, whether we’re at home on the computer or out and about with a mobile device. But what happens if a natural disaster knocks out the local infrastructure? Sure some people will be able to fire up their radio if they need to reach out and touch someone, but even among hackers, hams are a minority. What we really need is a backup Internet.

The team behind the CellSol project hopes to show that building a volunteer-operated distributed communications network is not only within the capabilities of the hacker community but probably much easier and cheaper to do than you might think. Each node in the network, known as a Pylon in CellSol parlance, can shuttle data between the LoRa backbone and WiFi-enabled devices like smartphones and computers. Once the network is up and running, users don’t need any special hardware or software to use it.

Now to be clear, nobody is talking about surfing the web here. When a user connects to one of the ESP32 Pylons, they’ll be able to access a simplistic chat system through their browser. If the Pylon has an active Internet connection the chat can be bridged to an IRC channel. Without Internet connectivity, the pylon will simply give users on the CellSol network a means to communicate among each other. To keep things simple there’s no user names, private messages, or encryption. This is bare-bones, end-of-the-world style communication.

Want to join the CellSol revolution? All you really need is an ESP32, a LoRa radio, and the open-source firmware. If you get something like the Heltec LoRa 32 development board, you don’t even need to solder anything together. Just flash the board and go. Once you have a few Pylons going, you can also put together a cheap repeater node using a LoRa equipped Arduino. Both devices are small and energy efficient enough that they could easily be battery or solar powered. As you can see in the video after the break, the team even envisions a future where they could be dropped off in public areas via drone.

This isn’t the first time we’ve seen the ESP32 used to establish an off-grid LoRa communications network, and like those previous attempts, it’s usefulness will largely depend on how many people you can convince to set up their own nodes and repeaters. But if you’ve got some open minded friends who live relatively close by, this could be a great way to have a little chat.

Continue reading “IRC Over LoRa, For When Things Really Go South” →