Toddler-Friendly MP3 Player Navigates With Light

June 18, 2020 by Tom Nardi 15 Comments

When designing this custom MP3 player for his grandson, [Luc Brun] ran into a unique problem. He wanted the boy to be able to operate the player on his own, but being only 2½ years old, the user interface would have to be exceedingly straightforward. Too many buttons would just be a distraction, and a display with text would be meaningless at his age.

In the end, [Luc] came up with a very interesting way of navigating through directories full of MP3 files using a few push buttons and a ring of WS2812 LEDs. The color of the LEDs indicate which directory or category is currently being selected: spoken nursery rhymes are red, music is orange, nature sounds are yellow, and so on. The number of LEDs lit indicate which file is selected, so in other words, three orange LEDs will indicate the third music track.

At his grandson’s age, we imagine at least a little bit of him navigating through this system is just luck. But as he gets older, he’ll start to form more solid connections between what he’s hearing and the color and number of the LEDs. So not only is this interface a way to help him operate the device himself, but it may serve as a valuable learning tool in these formative years.

On the other hand, if your goal is just to distract a youngster for as long as possible, an overwhelming number of LEDs, buttons, and switches might be exactly what you want.

Metasurface Design Methods Can Make LED Light Act More Like Lasers

June 18, 2020 by Maya Posch 33 Comments

Light-emitting diodes (LEDs) are not exactly new technology, but their use over time has evolved from rather dim replacements of incandescent signal lights in control panels to today’s home lighting. Although LEDs have the reputation of being power-efficient, there is still a lot of efficiency to be gained.

UC Santa Barbara researchers [Jonathan Schuller] and his team found that a large number of the photons that are generated never make it out of the LED. This means that the power that was used to generate these photons was essentially wasted. Ideally one would be able to have every single photon successfully make it out of the LED to contribute to the task of illuminating things.

In their paper titled ‘Unidirectional luminescence from InGaN/GaN quantum-well metasurfaces‘ (pre-publication Arxiv version) they describe the problem of photon emission in LEDs. Photons are normally radiated in all directions, causing a ‘spray’ of photons that can be guided somewhat by the LED’s packaging and other parameters. The challenge was thus to start at the beginning, having the LED emit as many photons in one direction as possible.

Their solution was the use of a metasurface-based design, consisting out of gallium nitride (GaN) nanorods on a sapphire substrate. These were embedded with indium gallium nitride (InGaN) quantum wells which emit the actual photons. According to one of the researchers, the idea is based on subwavelength antenna arrays already used with coherent light sources like lasers.

With experiments showing the simulated improvements, it seems that this research may lead to even brighter, more efficient LEDs before long if these findings translate to mass production.

(Thanks, Qes)

Fiber Optic Ceiling Pumps To The Beat

June 17, 2020 by Moritz v. Sivers 3 Comments

For years [Centas] dream was to take the stars to his home and build a fiber optic ceiling. Even though there are many fiber optic star ceiling kits commercially available, we are glad he decided to go full DIY on this project as the result is simply astonishing.

[Centas] chose to make a model of a section of the sky as it is visible from his home and generated a map of 1,200 stars with the planetarium software Celestia. The most time-consuming part of making a star ceiling is always poking lots of holes for the fibers. In [Cenas] case this turned out to be especially cumbersome as he decided to install the fibers after hanging the ceiling panel so he came up with a method to catch the fiber with a fishing pole after pushing it through from the bottom. The finished ceiling looks really great though with its rounded edges that contain RGB LED strips for side illumination. [Cenas] also painted the ceiling after installing the fibers so they are not visible when they are not lit but there is still enough light shining through the paint.

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Hacking A Cheap Disco Light For UV Effects

June 15, 2020 by Lewin Day 21 Comments

Back in the early days of disco, filament bulbs were all the rage. Whether tungsten, halogen, or other obscure types, party lighting involved lots of watts and lots of heat. These days, the efficiency of LEDs makes everything a lot cheaper, lighter, and lower power. [Big Clive] decided to dive into a cheap moonflower-type disco light from China, replacing the insides along the way.

The final effect particularly shines when used on fluorescent materials.

The light originally consisted of an 8×8 grid of LEDs, driven by shift registers for a simple chase effect. Surprisingly, the power supply and other hardware inside seemed to at least make an attempt to meet UK regulations. However, [Big Clive] had other plans, whipping up a replacement PCB packing 64 UV LEDs. The video is informative, showing how with a few simple passive components, it’s easy to drive these LEDs from mains without excessive circuitry required to step down to more usual DC voltages.

The final result is a neat UV grid light that would look excellent through some fog on the dance floor. We’ve seen [Big Clive]’s teardowns before, too – like this nefarious CAN bus interceptor found in a Mercedes. Video after the break.

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Office Status Light Turns “Do Not Disturb” To “Busy”

June 13, 2020 by Jenny List 16 Comments

Open-plan offices with too many desks crammed into them are the scourge of many a tech start-up, and at [Danny Salzman]’s employer, distractions reached an all-time high. His boss instigated a free/busy indicator using coloured cards, but he felt he could do one better and came up with an IoT status light to do the job.

At its heart is a machinery status light of the tri-colour “traffic light” variety, driven by a set of relays under the command of a Particle Photon STM32 ARM Cortex M3 based microcontroller board. The plan to write a super-clever API and integration with Slack or Google Calendar never came together, instead it’s operated by a set of bash shell aliases.

Unfortunately for [Danny] though, it didn’t work as intended. Instead of his colleagues staying away as he had hoped, they flocked to his desk to ask about the new feature, making it not entirely useful as a “Do Not Disturb” light. Still, we like it, and it’s given us ideas about those machinery status lights.

He says he may dig it out for his home during the COVID-19 lockdown. Perhaps he could take some inspiration from this home WiFi status dongle.

A Levitating Lamp Without Magnets

June 10, 2020 by Moritz v. Sivers 9 Comments

If you think of levitating objects you probably think about magnets but this is not what [Aaron Hung] used to build his levitating LED lamp. To be fair, his lamp is not really levitating but merely generates the illusion through the principles of tensegrity. We have featured a number of tensegrity structures over the last months but this is maybe the first time somebody has used it to build a daily-use item.

In his instructable [Aaron Hung] points out that according to Earnshaw’s theorem magnetic levitation using static magnetic fields like those of permanent magnets is actually impossible. If you are interested, the Wikipedia article also explains why floating superconductors and the Levitron toy do not contradict this theorem. (TL;DR: they’re dynamic.)

Coming back to [Aaron Hung]’s tensegrity lamp, the construction is rather simple and only requires an Arduino Nano, a Neopixel ring, a 9 V battery some wood or cardboard, and fishing line. The tensegrity part of the lamp consists of two similar pieces of laser-cut wood which are held together by fishing line so that the top part seems to float in mid-air. Normally, tensegrity structures are very fragile so [Aaron Hung] added some extra lines for stability which allowed him to hang the lamp from the top section without collapsing the whole structure. After coding some animations for the Neopixel ring and adding a paper lampshade the project was finished.

We would like to see more tensegrity versions of classic DIY projects and it was fun to see that similar objects were already built from Lego.

[Video after the break].

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UV Phone Sanitizer Shows The Power Of Modern DIY

June 8, 2020 by Tom Nardi 94 Comments

Editor’s Update: According to the schematic for this project, SST-10-UV-A130-F405-00 (PDF) LEDs are used which produce 405nm UV-A light. The manufacturer, Luminus, does not recommend that part for disinfection or sterilization. Luminus sells UV-C LEDs for that purpose, generating 275-285nm. After publication the part number used was changed to and American Opto L933-UV265-2-20 which is a UV-C LED producing 265-278nm.

The global COVID-19 pandemic has had a serious impact on the hacking and making scene, though it hasn’t been all bad. Sure, shipping on average is taking a lot longer than we’d like when ordering parts, but otherwise being stuck at home has given many people far more time to work on their projects than they would have had otherwise. In some cases, it’s also been a reminder of just how far we’ve come in terms of what the dedicated individual is capable of producing within the confines of their own home.

As a perfect example, take a look at this UV sanitizer box built by [Md Raz]. Looking for a way to quickly and easily kill germs on smartphones and other small devices, he used the considerable capabilities afforded to the modern hacker to produce a professional-looking device in far less time than it would have if he had to outsource things like PCB manufacturing or injection molding.

Inside the 3D printed enclosure is an array of SMD UV-C LEDs that, according to the manufacturer’s specs, will destroy viruses and bacteria in 5 minutes. To make sure the LEDs are given enough time to do their job, [Md] is using an ATtiny85 to control the countdown and a seven segment display to let the user know how much longer they have to wait. All the electronics are held on PCBs produced with a BotFactory SV2 desktop PCB printer, but for those of us with somewhat more limited budgets, a mill or even a modified laser engraver could be used to produce similar boards.