LED Hacks

1821 Articles

Monitor GitHub Activity With An RGB LED Matrix

October 16, 2013 by 2 Comments

tim-display

Ever wonder who is forking your code? [Jack] did, so he built a real time GitHub activity display for his company’s repositories. The display is based a Wyolum The Intelligent Matrix (TiM) board. The TiM is an 8 x 16 matrix of the ubiquitous WS2811/Smart Pixel/NeoPixel RGB LEDs with built-in controller. We’re seeing more and more of these serial LEDs as they drop in price. Solder jumpers allow the TiM to be used as 8 parallel rows of LEDs (for higher refresh rates), or connected into one long serial chain.

[Jack] wasn’t worried about speed, so he configured his board into a single serial string of LEDs. An Arduino drives the entire matrix with a single pin. Rather than reinvent the wheel, [Jack] used Adafruit’s NeoMatrix library to drive his display. Since the TiM uses the same LEDs as the Adafruit NeoPixel Matrix, the library will work. Chalk up another victory for open source hardware and software!

An Electric Imp retrieves Github data via WiFi and passes it on to the Arduino. This is a good use of a microcontroller such as the AVR on the Arduino. [Jack’s] display has a scrolling username. Every step in the scroll animation requires all the pixel data be clocked out to the TiM board. The Arduino can handle this while the IMP takes care of higher level duties.

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Hack A Solar Garden Light Into A Flashlight

October 12, 2013 by 4 Comments

solargardenflashlight

While browsing through his local dollar store, [Taylor] came across a suspicious looking rock that, upon closer inspection, turned out to be a solar garden light. He scooped it up, took it home and cracked it open, modding it to function as a handheld solar flashlight.

Inside was a pathetically small 40mAh rechargeable battery, which he upgraded to a more standard rechargeable AA. The garden rock came pre-built with its own boost converter to kick up the voltage for the LED, but it was fairly dim. We’re guessing [Taylor] didn’t bother reverse engineering the converter and instead simply did some trial and error, but he managed to increase the LED’s brightness by slapping on a different value inductor.

As fun as it may be to have a rock for a flashlight, [Taylor] decided to cobble together a custom case out of a spare USB charger, making a battery holder and adding a pushbutton. The result is a handy solar flashlight that takes around five hours to charge. Check out some other custom lights: a lithium-powered PVC flashlight or one with a snazzier aluminum body and interchangeable heads.

Light Up Earrings

October 11, 2013 by 14 Comments

light up earrings

Unfortunately [ch00f’s] been too busy to write for Hack a Day lately, but he has finished off an awesome little project — Christmas LED earrings!

As with all his projects, there is a brilliant write up that covers everything — even for the stuff that didn’t work. But what we really have to admire about this project in particular is the scale at which he was working. The tiny battery squished in between the two boards? A mere 19mAh. Which is actually enough to power the earrings for a few hours, but is only the size and thickness of a few microSD cards!

The second thing that really popped out at us was the boards themselves, there’s just no room for a programming header! To work around this [ch00f] actually made the PCBs in 3 segments, programmed it, and then cut off the programming header section! If that’s not enough ingenuity, how about this – He also included hall effect sensors on-board to turn them off while charging! Not to mention an intricate wood box to charge them in…

Stick around after the break to see the great demo video, it even has some classy music from the 1930’s which really sets the mood.

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LED Blinds Turn Windows Into Displays

October 10, 2013 by 20 Comments

[Dinofizz] is almost done with his vertical LED blinds. The build makes use of 768 diffused white LEDs (10mm size), at a resolution of 48×16, and it only requires one 16-channel LED driver (a MBI5026), which makes use of 3x 4-to-16 demultiplexers. Did we mention it has 16 shades of grayscale too?

At the heart of the many piles of painstakingly soldered wires is an ATmega644A microcontroller which takes care of interpreting the data for the display. He didn’t write the firmware himself though, that credit goes to [Jay Clegg] who does some pretty cool work with Evil Mad Science’s Peggy 2.0 LED driver.

What we really have to admire is the amount of effort he put into this project. He used custom PCBs to daisy chain the blinds together, 300 feet of 16-way ribbon cable, and approximately 4000 individual solder joints! You’d think there would have been an easier way!

Making use of his high rise windows, he now has the ability to broadcast messages for the world to see. After the break check out the video of them in action!

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Extremely Precise Positional Tracking

October 10, 2013 by 19 Comments

lumi

A few folks over at Carnegie Mellon have come up with a very simple way to do high-speed motion tracking (PDF) with little more than a flashlight. It’s called Lumitrack, and while it looks like a Wiimote on the surface, it is in reality much more accurate and precise.

The system works by projecting structured light onto two linear optical sensors. The pattern of the light is an m-sequence – basically a barcode where every subset of the m-sequence is unique. By shining this light onto a linear sensor, Lumitrack can calculate where the light is coming from, and thus the position of whatever is holding the light.

Even though the entire system consists of only an ARM microcontroller (in the form of a Maple Mini board), two linear optical sensors, and a flashlight with an m-sequence gel, it’s very accurate and very, very fast. The team is able to read the position at over 1000 frames/second, nearly the limit of what can be done with the Maple’s serial connection.

Already there are some interesting applications for this system – game controllers, including swords, flight yokes, and toy cars, and also more artistic endeavors such as a virtual can of spray paint. It’s an interesting piece of tech, and with the right parts, something any of us can build at home.

You can see the Lumitrack demo video below.

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LED-Guided Piano Instruction

October 8, 2013 by 29 Comments

LEDpianoGuide

[Kay Choe] can’t play the piano. Rather, he couldn’t, until he converted his keyboard to include LED-guided instruction. [Kay] is a microbial engineering graduate student, and the last thing a grad student can afford is private music lessons. With $70 in components and a cell phone, however, he may have found a temporary alternative.

The build works like a slimmed-down, real-world Guitar Hero, lighting up each note in turn. We’ve seen a project like this before, with the LEDs mounted above the keys. [Kay]’s design, however, is much easier to interpret. He embedded the LEDs directly into the keys, including ones above each black key to indicate the sharps/flats. An Android app takes a MIDI file of your choice and parses the data, sending the resulting bits into an IOIO board via USB OTG. A collection of shift registers then drives the LEDs.

For a complete novice, [Kay] seems to benefit from these lights. We are unsure whether the LEDs give any indication of which note to anticipate, however, as it seems he is pressing the keys after each one lights up. Take a look at his video demonstration below and help us speculate as to what the red lights signify. If you’re an electronics savant who wants to make music without practicing a day in your life, we recommend that you check out [Vladimir’s] Robot Guitar.

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Halloween Doorknocker Decoration Hack

October 8, 2013 by 8 Comments

halloweenDoorHack

If you’re new to hacking, Halloween is a great excuse to get started, and [Chuck] has put together an inexpensive animated Halloween decoration that you can show off on your front door. After scoring a $5 plastic Halloween doorknocker from Wal-Mart, [Chuck] gathered together a small pile of components and then set about breathing some life (death?) into its scary but motionless face.

Though he opted to use a Digispark, you should be able to use any Arduino that is small enough to stuff inside the plastic head. [Chuck] cut some holes in the eyeballs and glued in two RGB LEDs, then cobbled together a quick-and-dirty mount in the mouth area to hold a small servo. The lights and the servo are wired to the Digispark, which turns the lights on and instructs the servo to slam the ring against the door. It’s is battery powered and currently has only two settings: on or off. This should be good enough to scare the kids for this year, but [Chuck] has plans to add a much-needed motion sensor and sound via a Bluetooth connection. 

As simple as this build is, it could be just the thing to get you in the holiday spirit, or to introduce the young hacker in your home to the world of electronics and coding. Check out the short video of the doorknocker after the break, then swing by [Chuck’s] website for detailed build instructions and his Github for the source code. If you’re having trouble finding this doorknocker at Wal-Mart, [Chuck] recommends a similar one on Amazon. Don’t stop now! Make some Flickering Pumpkins too, or if you want a challenge, hack together your very own Pepper’s Ghost illusion.

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