Hackaday Prize Entry: Cheap Visible Light Communication

September 3, 2016 by Gerrit Coetzee 24 Comments

[Jovan] is very excited about the possibilities presented by Visible Light Communication, or VLC. It’s exciting and new. His opening paragraphs is filled with so many networking acronyms that VLC could be used for, our browser search history now looks like we’re trying to learn english without any vowels.

In lots of ways he has good reason to be excited. We all know that IR can communicate quite a bit, but when you’re clever about frequency and color and throw in some polarizers with a mix of clever algorithms for good measure you can get some very high bandwidth communication with anything in line of site. You can do it for low power, and best of all, there are no pesky regulations to stand in your way.

He wants to build a system that could be used for a PAN (Personal Area Network). To do this he’ll have to figure out a way to build the system inexpensively and using less than a watt of power. The project page is full of interesting experiments and quite a few thesis on the subject of LEDs.

For example, he’s done work on how LEDs respond to polarization. He’s tested how fast an LED can actually turn on and off while still being able to detect the change. He’s also done a lot of work characterizing the kind of light that an LED emits. We don’t know if he’ll succeed yet, but we like the interesting work he’s doing to get there.

Altitude Controlled LED Jacket Changes Color As You Climb

September 3, 2016 by Jenny List 6 Comments

When your climbing gym throws a “glow in the dark” party, how can you stand out? For [Martijn], the answer was obvious. He made a jacket adorned with 32 WS2812 addressable LEDs whose color is addressable depending on the altitude to which he has climbed.

The build is centered on an Arduino Pro Mini with a barometric sensor and an NRF24L01 for radio communications. A pair of pockets contain AA batteries for power, and he’s all set to climb. A base station Arduino with the same set-up transmits an up-to-the-minute reading for ground level temperature, which is compared to the local reading from the barometric sensor and used to calculate a new color for the LEDs. A Kalman filter deals with noise on the pressure reading to assure a stable result. Arduino sketches for both ends are provided on the project’s Hackaday.io page.

The LEDs are mounted on the jacket’s stretch fabric with an excess of wire behind the scenes to cater for the stretch. You can see the resulting garment in the short YouTube video below the break.
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10,000 Lumen Sunrise Lamp Curses The Darkness

September 2, 2016 by Richard Baguley 26 Comments

Some of us need a bit of help to get up in the mornings. This can come in the form of a sunrise lamp, which simulates the light of the sunrise to fool our poor sleep-deprived brains into waking up in the depths of winter. [Lincoln Johnson] found the ones he tried were not bright enough to wake him, so he decided to build his own: a 10,000-lumen monster that can wake him up from across the room.

It uses a lot of LEDS: 5 meters of 5630 LED strip, which pulls a circuit bending 72 watts when running at full blast. This monstrosity is powered by an Arduino Pro, which is programmed to slowly increase the brightness over a period of 30 minutes, thus simulating the sunrise. It uses PWM control to fade the LEDs, and also includes a dot matrix display to show the time. Honestly, if you are able to sleep through this thing blasting your eyes, you are probably dead.

NES Light Gun Fires Awesome Laser Effect

August 31, 2016 by Gerrit Coetzee 26 Comments

[Seb Lee-Delisle]’s NES lightgun gave us pause as the effect is so cool we couldn’t quite figure out how he was doing it at first. When he pulls the trigger there erupts the beam of light Sci Fi has trained us to expect, then it explodes in a precision sunburst of laserlight at the other end as smoke gently trails from the end of the barrel. This is a masterpiece of hardware and trickery.

seb-lee-delisle-nes-zapper-trick-thumb — Demo video posted by @seb_ly

The gun itself is a gutted Nintendo accessory. It looks like gun’s added bits consist of two LED strips, a laser module (cleverly centered with two round heatsinks), a vape module from an e-cigarette, a tiny blower, and a Teensy. When he pulls the trigger a cascade happens: green light runs down the side using the LEDs and the vape module forms a cloud of smoke in a burst pushed by the motor. Finally the laser fires as the LEDs finish their travel, creating the illusion.

More impressively, a camera, computer, and 4W Laser are waiting and watching. When they see the gun fire they estimate its position and angle. Then they draw a laser sunburst on the wall where the laser hits. Very cool! [Seb] is well known for doing incredible things with high-powered lasers. He gave a fantastic talk on his work during the Hackaday Belgrade conference in April. Check that out after the break.

So what does he have planned for this laser zapper? Laser Duck Hunt anyone? He has a show in a month called Hacked On Classics where this build will be featured as part of the Brighton Digital Festival.

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Charliplexed 7-Segment Display Takes Advantage Of PCB Manufacturers

August 23, 2016 by Elliot Williams 32 Comments

Cutting out precise shapes requires a steady hand, a laser cutter, or a CNC mill, right? Nope! All you need is PCB design software and a fabrication facility that’ll do the milling for you. That’s the secret sauce in [bobricius]’s very pleasing seven-segment display design.

His Hackaday.io entry doesn’t have much detail beyond the pictures and the board files, but we’re not sure we need that many either. The lowest board in the three-board stack has Charlieplexed LEDs broken out to six control pins. Next up is a custom-routed spacer board — custom routed by the PCB house, that is. And the top board in the stack is another PCB, this one left clear of copper where the light shines out.

We want to see this thing lit up! We’ve played around with using PCB epoxy material as a LED diffuser before ourselves, and it can look really good. The spacers should help even out the illumination within segments, while preventing bleed across them. Next step? A matrix of WS2812s with custom-routed spacers and diffusers. How awesome would that be?

RGB LEDs: How To Master Gamma And Hue For Perfect Brightness

August 23, 2016 by Elliot Williams 26 Comments

You would think that there’s nothing to know about RGB LEDs: just buy a (strip of) WS2812s with integrated 24-bit RGB drivers and start shuffling in your data. If you just want to make some shinies, and you don’t care about any sort of accurate color reproduction or consistent brightness, you’re all set.

But if you want to display video, encode data in colors, or just make some pretty art, you might want to think a little bit harder about those RGB values that you’re pushing down the wires. Any LED responds (almost) linearly to pulse-width modulation (PWM), putting out twice as much light when it’s on for twice as long, but the human eye is dramatically nonlinear. You might already know this from the one-LED case, but are you doing it right when you combine red, green, and blue?

It turns out that even getting a color-fade “right” is very tricky. Surprisingly, there’s been new science done on color perception in the last twenty years, even though both eyes and colors have been around approximately forever. In this shorty, I’ll work through just enough to get things 95% right: making yellows, magentas, and cyans about as bright as reds, greens, and blues. In the end, I’ll provide pointers to getting the last 5% right if you really want to geek out. If you’re ready to take your RGB blinkies to the next level, read on!

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MagicShifter 3000: An Over-Engineered POV Stick With A 15-Year Journey

August 22, 2016 by Moritz Walter 64 Comments

3 hackers, 16 LEDs, 15 years of development, one goal: A persistence of vision display stick that fits into your pocket. That’s the magicShifter 3000. When waved, the little, 10 cm (4 inches) long handheld device draws stable images in midair using the persistence of vision effect. Now, the project has reached another milestone: production.

The design has evolved since it started with a green LED bargraph around 2002. The current version features 16 APA102 (aka DotStar) RGB LEDs, an ESP-12E WiFi module, an NXP accelerometer/magnetometer, the mandatory Silabs USB interface, as well as a LiPo battery and charger with an impressive portion of power management. An Arduino-friendly firmware implements image stabilization as well as a React-based web interface for uploading and drawing images.

After experimenting with Seeedstudio for their previous prototypes, the team manufactured 500 units in Bulgaria. Their project took them on a roundtrip through hardware manufacturing. From ironing out minuscule flaws for a rock-solid design, over building test rigs and writing test procedures, to yield management. All magicShifter enclosures are — traditionally — 3D printed, so [Overflo] and [Martin] are working in shifts to start the 500 prints, which take about 50 minutes each to complete. The printers are still buzzing, but assembled units can be obtained in their shop.

Over all the years, the magicShifter has earned fame and funding as the over-engineered open hardware pocket POV stick. If you’re living in Europe, chances are that you either already saw one of the numerous prototype units or ran into [Phillip Tiefenbacher] aka [wizard23] on a random hacker event to be given a brief demo of the magicShifter. The project always documented the status quo of hardware hacking: Every year, it got a bit smaller, better, and reflected what parts happened to be en vogue.

The firmware and 3D-printable enclosure are still open source and the schematics for the latest design can be found on GitHub. Although, you will search in vain for layout or Gerber files. The risk of manufacturing large batches and then being put out of business by cheap clones put its mark on the project, letting the magicShifter reflect the current, globalized status of hardware hacking once more. Nevertheless, we’re glad the bedrock of POV projects still persists. Check out the catchy explanatory video below.

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