Mini Library For Kids Gets Blinky Lights And Solar Upgrade

June 28, 2020 by Donald Papp 1 Comment

Reading is big in Québec, and [pepelepoisson]’s young children have access to a free mini library nook that had seen better days and was in dire need of maintenance and refurbishing. In the process of repairing and repainting the little outdoor book nook, he took the opportunity to install a few experimental upgrades (link in French, English translation here.)

The mini library pods are called Croque-Livres, part of a program of free little book nooks for children across Québec (the name is a bit tricky to translate into English, but think of it as “snack shack, but for books” because books are things to be happily devoured.)

After sanding and repairs and a few coats of new paint, the Croque-Livres was enhanced with a strip of WS2812B LEDs, rechargeable battery with solar panel, magnet and reed switch as door sensor, and a 3.3 V Arduino to drive it all. [pepelepoisson]’s GitHub repository for the project contains the code and CAD files for the 3D printed pieces.

The WS2812B LED strip technically requires 5 V, but as [pepelepoisson] found in his earlier project Stecchino, the LED strip works fine when driven directly from a 3.7 V lithium-polymer cell. It’s not until around 3 V that it starts to get unreliable, so a single 3.7 V cell powers everything nicely.

When the door is opened, the LED strip lights up with a brief animation, then displays the battery voltage as a bar graph. After that, the number of times the door as been opened is shown on the LED strip in binary. It’s highly visual, interactive, and there’s even a small cheat sheet explaining how binary works for anyone interested in translating the light pattern into a number. How well does it all hold up? So far so good, but it’s an experiment that doesn’t interfere at all with the operation of the little box, so it’s all good fun.

Get The Party Started With A Mesh WiFi Light Show

June 26, 2020 by Sven Gregori 1 Comment

Wildly blinking LEDs may not be the ideal lighting for the average office environment, but they’ll surely spice up any party. And since a party without music is just a meeting, having both synced up is a great way to set the mood. Sure, you could simply roll out your standard LED strip instead, but that gets a bit boring, and also a bit tricky if you want to light up several places the same way. [Gerrit] might have built the perfect solution though, with his (mu)sic (R)eactive (Li)ghts, or muRLi, which are a set of individual lights that synchronize a programmable pattern over WiFi.

The system consists of muRLi itself as the base station that defines and sends the light pattern through WebSockets, and several muRLi Nodes that house a set of WS2812B LEDs to receive and display it. Both are built around a Wemos D1 Mini configured to set up a WiFi mesh network, and depending what’s in reach, the nodes connect either to the base station or other nodes, giving the system definitely enough reach for any location size. The music is picked up by a MAX4466-amplified microphone inside the base station — adding some more flexibility to positioning the system — and analyzed for volume and audio spectrum, which is also shown on an OLED.

The best part however is how the light patterns are programmed. Instead of hard-coding it into the firmware, [Gerrit] went for a modular approach with little ROM cartridges to plug into the muRLi base station. The cartridge itself contains just an I2C EEPROM, storing JavaScript code that is interpreted by the firmware using mJS. The scripts have access to the analyzed audio data and amount of LEDs within the network, and can dynamically generate the patterns as needed that way. Everything is neatly housed in 3D-printed enclosures, with all the design and source files available on the project’s GitHub page — but see for yourself in the video after the break.

If you don’t care about the wireless part but enjoy light synced up with music, have a look at a plain MIDI solution for that. As for [Gerrit], we’re definitely looking forward to seeing his next endeavor one day, since we also enjoyed his last one.

Continue reading “Get The Party Started With A Mesh WiFi Light Show” →

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.

Continue reading “Fiber Optic Ceiling Pumps To The Beat” →

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.

Continue reading “Hacking A Cheap Disco Light For UV Effects” →

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.