A New Spin On 360 Degree Displays

July 21, 2021 by Michael Shaub 20 Comments

Back in 2018, [Salah] created a prototype display that seems to defy logic using little more than a Pringles can and a fast motor. While not volumetric, this hack does show the same 2D image from any vantage point in 360 degrees around it.

How can cardboard create this effect? Somewhat like a zoetrope uses slits to create a shutter effect, this display uses a thin slit to limit the view of the image within to one narrow vertical slice at a time. When moving fast enough, Persistence of Vision kicks in to assemble these slices into a complete image. What we think is so cool about this hack is that the effect is the same from any angle and by multiple viewers simultaneously.

The project page and video demonstration after the break are light on details, though the idea is so simple as to not require additional explanation. We assume the bright LED seen in the video below was added to overcome the relatively dim appearance of the image when viewed through the narrow slit and isn’t strictly required.

Continue reading “A New Spin On 360 Degree Displays” →

Clever PCB Brings Micro USB To The Arduino Uno

July 21, 2021 by Tom Nardi 38 Comments

Even with more and more devices making the leap to USB-C, the Arduino Uno still proudly sports a comparatively ancient Type-B port. It wouldn’t be a stretch to say that many Hackaday readers only keep one of these cables around because they’ve still got an Uno or two they need to plug in occasionally.

Looking to at least move things in the right direction, [sjm4306] recently set out to create a simple board that would let him mount a micro USB connector in place of the Uno’s original Type-B. Naturally there are no components on the PCB, it simply adapts the original through-hole footprint to the tight grouping of surface mount pads necessary to mount a female micro USB port.

The design is straightforward, but as [sjm4306] explains in the video below, there’s actually more going on here than you might think. Looking to avoid the premium he’d pay to have the board house do castellated holes, he cheated the system a bit by having the board outline go right through the center of the standard pads.

Under a microscope, you can see the downside of this approach. Some of the holes got pretty tore up as the bit routed out the edges of the board, with a few of them so bad [sjm4306] mentions there might not be enough of the pad left to actually use. But while they may not be terribly attractive, most of them were serviceable. To be safe, he says anyone looking to use his trick with their own designs should order more boards than they think they’ll actually need.

Of course you could go all the way and retrofit the Uno with a USB-C port, as we’ve seen done with devices in the past. But the latest-and-greatest USB interface can be a bit fiddly, especially with DIY gadgets, so we can’t blame him for going with the more reliable approach.

Continue reading “Clever PCB Brings Micro USB To The Arduino Uno” →

ZeroBug: From Simulation To Smooth Walking

July 21, 2021 by Danie Conradie 9 Comments

Thanks to 3D printing and cheap hobby servos, building you’re own small walking robot is not particularly difficult, but getting them to walk smoothly can be an entirely different story. Knowing this from experience, [Max.K] tackled the software side first by creating a virtual simulation of his ZeroBug hexapod, before building it.

Learning from his previous experience building a quadruped, ZeroBug started life in Processing as a simple stick figure, which gradually increased in complexity as [Max.K] figured out how to make it walk properly. He first developed the required movement sequence for the tip of each leg, and then added joints and calculated the actuator movements using reverse kinematics. Using the results of the simulations, he designed the mechanics and pulled it back into the simulation for final validation.

Each leg uses three micro servos which are controlled by an STM32F103 on a custom PCB, which handles all the motion calculations. It receives commands over UART from a python script running on a Raspberry Pi Zero. This allows for user control over a web interface using WiFi, or from a gamepad using a Bluetooth connection. [Max.K] also added a pincer to the front to allow it to interact with its environment. Video after the break.

The final product moves a lot smoother than most other servo-driven hexapods we’ve seen, and the entire project is well documented. The electronics and software are available on GitHub and the mechanics on Thingiverse.

Continue reading “ZeroBug: From Simulation To Smooth Walking” →

Retrotechtacular: Nuvistor, Vacuum’s Last Gasp

July 21, 2021 by Jenny List 51 Comments

In 2021 all our electronics are solid state, in that they exclusively use semiconductor devices as their active components. Some of us may experiment with vacuum tubes, but only for curiosity or aesthetic purposes. Semiconductors have overtaken vacuum devices in all but the rarest of niche applications due to their easier design requirements, greater reliability, lower cost, and increased performance.

It was not always this way though, and there was a period at the start of the semiconductor era when transistors and vacuum tubes existed together side-by-side and competed directly. Vacuum tube manufacturers continued to create new devices into the 1970s, and in doing so they pushed the boundaries of their art in unprecedented directions. [David W Knight] has a page dedicated to the Nuvistor, something his calls the “final evolution of the thermionic valve”. His comparison photo seen above shows a Nuvistor on the left — a miniature vacuum tube you’ve likely never seen before.

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Precise Sundial Tells Time To The Minute

July 21, 2021 by Bryan Cockfield 16 Comments

We’re always a fan of an interesting or unique clock build around here, which often use intricate pieces of technology to keep time such as weights and gears, crystal oscillators, or even a global network of satellites in the case of GPS. While these are all interesting methods of timekeeping, the original method of tracking the sun is often forgotten. With this clock, the sun is the main method of keeping track of time, but unlike traditional sundials it has a number of advancements that let it keep surprisingly accurate time. (Google Translate from German)

While most sundials can only show hours, this one from [leon andré], a retired physicist, has a method for displaying minutes as well. It uses pinholes instead of shadows to keep track of the position of the sun, with the pinhole casting a bright spot of sunlight onto a diagram below. The diagram keeps track of the minutes, and consists of curved lines which help account for the sun’s changing path throughout a typical year. The dial keeps track of local solar time, as any sundial would, but by rotating it along its vertical axis it can be calibrated for the timezone that it’s in regardless of its position.

As far as clock builds go, one that is completely passive like this semi-digital sundial is fairly unique, especially for its accuracy. And, when set to local solar time, it will be the most reliable method of keeping time long-term than possibly any other clock we’ve seen before, as long as it’s not too cloudy outside. On the other hand, it is possible to augment a sundial with some modern technology as well.

Thanks to [Adrian] for the tip!

What Exactly Is A Gaussian Blur?

July 21, 2021 by Lewin Day 29 Comments

Blurring is a commonly used visual effect when digitally editing photos and videos. One of the most common blurs used in these fields is the Gaussian blur. You may have used this tool thousands of times without ever giving it greater thought. After all, it does a nice job and does indeed make things blurrier.

Of course, we often like to dig deeper here at Hackaday, so here’s our crash course on what’s going on when you run a Gaussian blur operation. Continue reading “What Exactly Is A Gaussian Blur?” →

It’s Linux – But On An ESP32

July 21, 2021 by Jenny List 44 Comments

GNU/Linux is an open-source marvel that has over the past three decades given us an almost infinitely versatile and powerful UNIX-like operating system. But even it has its limitations, particularly at the lower end of the hardware scale where less fully-featured processors often lack the prerequisites such as a memory management unit. Thus [JuiceRV]’s feat of booting a Linux kernel on an ESP32 microcontroller seems impossible, what’s happening?

The ESP’s dual 32-bit Xtensa cores are no slouch in the processing power department, but without that MMU it’s not an obvious Linux candidate platform. The solution to this problem comes in the form of an emulated RISC-V virtual machine which provides just enough grunt for a Linux 5.0.0 kernel to boot.

By any measure this represents an impressive piece of work, but will this new-found ability to run Linux on a microcontroller take the world by storm? Of course not, unless your tastes run to the very slowest of computing experiences. It is however the essence of the hack, and for that we salute it.

It’s not the first time Linux has run on a microcontroller, in the past someone hooked up a 30 pin SIMM and an SD card to an 8-bit Atmel chip and did it in a similar way with an ARM emulator.

Via CNX Software.

Header image: Ubahnverleih, CC0.