How The Turntable Paradox Works

December 14, 2022 by Zoe Skyforest 35 Comments

Leave most objects on top of a turntable, and set it spinning, and they’ll fly off in short order. Do the same with a ball, though, and it somehow manages to roll around on top for quite some time without falling off. [Steve Mould] set about unpacking this “Turntable Paradox” in a recent YouTube video.

In the basic case, the fact that the ball rolls is what keeps it on the turntable. As the turntable spins, the ball spins in the opposite direction, as per Newton’s first law of motion. As long as the ball is allowed to roll up to the same speed as the turntable, it will pretty much stay in place in the absence of any other perturbing forces. In the event the ball is nudged along the turntable, though, it quickly ends up in a more complicated circular motion, orbiting in a ratio to the speed of the turntable itself. [Steve] explains the mechanisms at play, and dives into the mathematics behind what’s going on.

Sometimes, demonstrations like these can seem like mere curiosities. However, understanding physical effects like these has been key to the development of all kinds of complicated and fantastical machinery. Video after the break.

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Nanoaetherphone Is A Special MIDI Controller

December 14, 2022 by Zoe Skyforest 11 Comments

MIDI controllers can be simple straightforward keyboards, or wild magical devices that seem to snatch notes from the very aether itself. As you might expect from the name, the Nanoaetherphone II is one of the latter.

The device is inspired by the Theremin, and was built to celebrate its 100th anniversary. The Nanoaetherphone II is all about using sensors to capture data from wireless hand-wavey interactions, and turn it into MIDI messages. To this end, it has an LDR sensor for detecting light levels, which determines volume levels. This is actuated by the user’s thumb, blocking the sensor or allowing ambient light to reach it. At the front of the handheld unit, there is also an ultrasonic range sensor. Depending on how close the sensor is to the user’s hand or other object determines the exact note sent by the device. As a MIDI controller, it is intended to be hooked up to an external synthesizer to actually generate sound.

The overall concept isn’t too complicated, and the design makes it easy to pickup and play. We imagine it could even be foolproofed by programming it only to play notes from a given scale or mode, allowing for easy soloing without too many of those ill-tempered blue notes. Jazz enthusiasts might prefer it to just spit out any and all notes, of course.

We love a good MIDI controller around these parts, and we’ve seen everything from knitted models to those made out of old phones. Video after the break.

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Self-Assembling Virus Model Is 3D Printed

December 14, 2022 by Zoe Skyforest 11 Comments

Sometimes a visual or tactile learning aid can make all the difference to elucidating a concept to an audience. In the case viruses and their methods of self-assembly, [AtomicVirology] made a 3D printed device to demonstrate how they work.

The result of this work is a printed dodecahedron, assembled from multiple components. Each face of the dodecahedron consists of a 5-sided pentagon, and is a separate piece. Each face contains magnets which allow the various faces to stick together. Amazingly, when a bunch of these faces are all thrown into a container and jumbled together, they eventually assemble themselves into complete dodecahedrons.

While it’s no virus, and the parts can’t replicate themselves en masse, the demonstration is instructive. Viruses themselves self-assemble in a similar fashion, thanks to sub-units that interact with each other in the tumultuous environment of a host cell.

We love a good teaching tool around these parts. 3D printing has the benefit of allowing teachers to create their own such devices with just a few hours spent in some CAD software.

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HUD-Like Clock Is A Transparent Time Display

December 14, 2022 by Zoe Skyforest 13 Comments

While we have all types of displays these days, there’s something special about those that appear to float in the air. This HUD clock from [Kiwi Bushwalker] is one such example.

The build relies on four 8×8 LED matrixes to display the four digits that make up the time, run by the MAX7219 driver chip. However, the LEDs aren’t viewed directly — that would be too simple. Instead, the matrixes shoot their light up at an angle towards a tilted piece of clear acrylic. This creates a “heads-up display” look where the numbers appear to float in the air. The clock gets accurate time from an NTP time server over WiFi, thanks to the ESP32 microcontroller that runs the show.

It’s a straightforward clock build in many ways, but we particularly like the use of the heads-up display technique. It’s almost surprising we don’t see these projects more often, for things like car dashboard displays or targeting womp rats in a T-16 landspeeder. If you’ve been whipping up your own HUD projects, don’t hesitate to notify the tipsline!

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Open World 3D Game Runs On The RP2040 Microcontroller

December 13, 2022 by Zoe Skyforest 15 Comments

The Raspberry Pi RP2040 is versatile and cheap, but it’s by no means known as the most powerful microcontroller on the world. Regardless, it is capable of great things, as demonstrated by [Bernhard Strobl], who built a 3D open world game engine that runs on that very platform.

The graphics are simple, but with a compelling low-poly style.

The game engine itself is built to run on the Pimoroni PicoSystem, which is essentially a handheld gaming platform built around the RP2040 chip. The engine takes advantage of the multi-core nature of the RP2040, using the second core as a dedicated rasterizer to keep frames pumping out.

The basic game [Bernhard] built in the engine features 50 NPC characters and 50 further zombies, all running at the same time. Specs are impressive, with the engine’s included game simulating a “world” of 120 x 120 meters in size. As a maximum limit, the engine can handle a 2.56 x 2.56 km world, thanks to the use of 8-bit integers for directional data. However, limited storage space would make it difficult to achieve such a large world in practice.

We don’t get to see much of the gameplay in the YouTube video, but the quality of the graphics is impressive for such a cheap microcontroller. It seems within the bounds of possibility that an actual open-world game could be practical on the PicoSystem if only enough storage were available. Video after the break.

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VHS-Decode Project Could Help Archival Efforts

December 13, 2022 by Zoe Skyforest 47 Comments

Archiving data from old storage media can be a highly complex process. It can be as simple as putting a disk in an old drive and reading out the contents. These days, though, the state of the art is more complex, with advanced techniques helping to recover the most data possible. The VHS-Decode project is an effort to improve the archiving of old analog video tapes.

The project is a fork of the LaserDisc-focused ld-decode, started by [Chad Page] back in 2013, which readers may recall was used for the Domesday Duplicator — a device aimed to recover data from the BBC’s ancient Domesday LaserDiscs. VHS-Decode is designed to capture the raw RF signals straight out of a tape head, which are the most direct representation of the signals on the physical media. From there, these signals can be processed in various ways to best recover the original audio and video tracks. It’s much the same technique as is used by floppy disk recovery tools like the FluxEngine.

Despite the VHS name, the code currently works with several tape formats. VHS, S-VHS and U-Matic are supported in PAL and NTSC formats, while Betamax, Video8 and High8 tape capture remains a work in progress. Using the code requires a video tape player with test points or traces that make signals from the head accessible. Capturing those signals is achieved via a Domesday Duplicator hardware device, or alternatively a Conexant CX2388x analog-to-digital converter, often found in many old PCI TV tuner cards. Various techniques can then be used to turn the captured signals into watchable video files.

We love a good archival project, and VHS-Decode is clearly a useful tool when it comes to salvaging old video tapes. Continue reading “VHS-Decode Project Could Help Archival Efforts” →

Building A Lamp To Help With Seasonal Depression

December 13, 2022 by Zoe Skyforest 13 Comments

The sun plays a big biological role in our lives, regulating our circadian rhythms and doing a whole bunch more as well. Some people find the reduced sunlight of the winter months to have negative emotional effects, and rely on artificial lighting to counteract this. [Samasrinivas] built a lamp of their own design for this very purpose.

The lamp is constructed around an abstract sculptural form made in air-dry clay. Light is provided via a string of Neopixel RGBW LEDs. Run by an Adafruit Feather Huzzah, they’re programmed to trigger with the sunrise to provide a bright light in the morning on grey days when the outside world isn’t quite delivering the same. The Adafruit queries an online weather API to get the right sunrise time every day without requiring user intervention. The lamp can also be programmed to provide warm light during later hours.

We’ve featured a few circadian lighting projects before, including one that goes for a whole-of-house effect with smart bulbs. For some, they’re a valuable way to help boost mood and maintain consistent sleep cycles.