Hackaday Prize Entry: 10 Watt Individually Addressable RGB LEDs

Individually addressable RGB LEDs like Neopixels, WS2812s, and  WS2811s are the defacto standard for making blinkey glowey projects. To build a very bright display, you need a lot of them, relegating very bright RGB displays to those of us who can afford the hardware and figure out how to drive that many LEDs. For his Hackaday Prize entry, [AJ Reynolds] is cranking these tiny RGB LEDs up a notch by building an individually addressable 10 Watt RGB floodlight.

Instead of building an RGB LED floodlight from scratch, [AJ] is leveraging the most mediocre of what China has to offer. He found 10 Watt RGBs for a dollar a piece and a few floodlight cases that cost about $5 a piece. By dispensing with the white LED in the floodlight case and replacing it with a 10 Watt RGB LED and some custom circuitry, [AJ] can build a powerful RGB floodlight with a BOM cost of under $15.

While there are big RGB floodlights out there, controlling them either means a custom proprietary protocol or messing around with DMX. A floodlight that speaks the same language as a WS2811 leverages an enormous amount of work from the world of Arduino and a lot of projects from around the Internet, making this a great entry for really bright blinkies and an excellent entry for The Hackaday Prize.

The 2015 Hackaday Prize is sponsored by:

Alarm Notifies the Office When the Coffee is Ready

[Stian] thought it would be nice if his coworkers could be electronically notified when the latest batch of coffee is ready. He ended up building an inexpensive coffee alarm system to do exactly that. When the coffee is done, the brewer can press a giant button to notify the rest of the office that it’s time for a cuppa joe.

[Stian’s] first project requirement was to activate the system using a big physical button. He chose a button from Sparkfun, although he ended up modifying it to better suit his needs. The original button came with a single LED built-in. This wasn’t enough for [Stian], so he added two more LEDs. All three LEDs are driven by a ULN2003A NPN transistor array. Now he can flash them in sequence to make a simple animation.

This momentary push button supplies power to a ESP8266 microcontroller using a soft latch power switch. When the momentary switch is pressed, it supplies power to the latch. The latch then powers up the main circuit and continues supplying power even when the push button is released. The reason for this power trickery is to conserve power from the 18650 li-on battery.

The core functionality of the alarm uses a combination of physical hardware and two cloud-based services. The ESP8266 was chosen because it includes a built-in WiFi chip and it only costs five dollars. The microcontroller is configured to connect to the WiFi network with the push of a button. The device also monitors the giant alarm button.

When the button is pressed, it sends an HTTP request to a custom clojure app running on a cloud service called Heroku. The clojure app then stores brewing information in a database and sends a notification to the Slack cloud service. Slack is a sort of project management app that allows multiple users to work on projects and communicate easier over the internet. [Stian] has tapped into it in order to send the actual text notification to his coworkers to let them know that the coffee is ready. Be sure to watch the demo video below. Continue reading “Alarm Notifies the Office When the Coffee is Ready”

Lighting The Great Indoors With A Solar Security Light

Look at any list of things to do to make your house less attractive to the criminal element and you’ll likely find “add motion sensing lights” among the pro tips. But what if you don’t want to light up the night? What if you want to use a motion sensor to provide a little light for navigating inside a dark garage? And what if the fixture you’ve chosen is a solar fixture that won’t quite cooperate? If you’re like [r1ckatkinson], you do a teardown and hack the fixture to do your bidding.

[r1ckatkinson]’s fixture was an inexpensive Maplin solar unit with PIR motion sensing, with the solar panel able to be mounted remotely. This was perfect for the application, since the panel could go outside to power the unit, with the lamp and PIR sensor inside. Unfortunately, the solar cell is also the photosensor that tells the unit not to turn on during the day. Armed with scratch pad and pencil, [r1ckatkinson] traced the circuit and located the offending part – a pull-down resistor. A simple resistor-ectomy later and he’s got a solar-powered light working just the way he likes it.

A simple hack, but effective. Seeing off-the-shelf gear modified is always a treat. Of course there’s something to be said for the more home-brew approach to security lighting, too.

Trick Google Used Hides Secret Messages on LCD Screens

[Travis] didn’t get picked to go to Google I/O this year, but he did have some I/O inspired fun after the fact. His friends who did go told him about specially modified LCD screens Google had scattered around the event. The screens showed normal show information when viewed with the naked eye. When viewed through a special transparent badge included with the I/O swag though, a URL for Google’s scavenger hunt would magically appear. [Travis] was intrigued by the effect, and became hell-bent on reproducing it himself.

[dual-lcd-3Travis] figured out the transparent badge was actually a polarizing filter. Every standard LCD has two of them, usually bonded to the glass of the LCD itself. If you remove the filters from a LCD, you’ll get a prime view of the backlight – unless you’re wearing polarizing glasses of course. Google’s monitors didn’t have that effect though. They showed a full color display, with a second full color hidden display only visible through the polarizer. [Travis] is intelligent and experienced, so it only took a bit of three-dimensional thinking for him to figure out Google’s trick. There are actually two LCDs used in the display. The first is a standard LCD with backlight. The trick is to strip the polarizing film off a second LCD and place it in front of the first. The second LCD will be invisible to anyone – without the polarizer.

[Travis] quickly set about replicating the display using several obsolete VGA LCDs. He quickly found that the hard part was peeling the polarizing plastic from the thin glass LCD sandwich. Several LCDs gave up their lives in the effort, but in the end [Travis] was successful. He made everything fit in one case by using a thin LED backlight in a case designed for a monitor with a Cold Cathode Fluorescent Lamp (CCFL).  The result looks exactly like a standard LCD – that is, until viewed through a polarizing filter. Click past the break to see the hidden message LCD in action!

Continue reading “Trick Google Used Hides Secret Messages on LCD Screens”

Upgrading an Old Camera with a New Light Meter

[Marc] has an old Voigtländer Vito CLR film camera. The camera originally came with an analog light meter built-in. The meter consisted of a type of solar panel hooked up to a coil and a needle. As more light reached the solar panel, the coil became energized more and more, which moved the needle farther and farther. It was a simple way of doing things, but it has a down side. The photo panels stop working over time. That’s why [Marc] decided to build a custom light meter using newer technology.

[Marc] had to work within the confines of the tiny space inside of the camera. He chose to use a LM3914 bar display driver IC as the primary component. This chip can sense an input voltage against a reference voltage and then display the result by illuminating a single LED from a row of ten LEDs.

[Marc] used a photo cell from an old calculator to detect the ambient light. This acts as a current source, but he needed a voltage source. He designed a transimpedence amplifier into his circuit to convert the current into a voltage. The circuit is powered with two 3V coil cell batteries, regulated to 5V. The 5V acts as his reference voltage for the display driver. With that in mind, [Marc] had to amplify this signal further.

It didn’t end there, though. [Marc] discovered that when sampling natural light, the system worked as intended. When he sampled light from incandescent light bulbs, he did not get the expected output. This turned out to be caused by the fact that incandescent lights flicker at a rate of 50/60 Hz. His sensor was picking this up and the sinusoidal output was causing problems in his circuit. He remedied this by adding two filtering capacitors.

The whole circuit fits on a tiny PCB that slides right into position where the original light meter used to be. It’s impressive how perfectly it fits considering everything that is happening in this circuit.

[Thanks Mojay]

Solar-Cell Laser Communication System

Forget the soup cans connected by a piece of string. There’s now a way to communicate wirelessly that doesn’t rely on a physical connection… or radio. It’s a communications platform that uses lasers to send data, and it’s done in a way that virtually anyone could build.

This method for sending information isn’t exactly new, but this project is one of the best we’ve seen that makes it doable for the average tinkerer. A standard microphone and audio amplifier are used to send the signals to the transmitter, which is just a typical garden-variety laser that anyone could find for a few dollars. A few LEDs prevent the laser from receiving too much power, and a solar cell at the receiving end decodes the message and outputs it through another amplifier and a speaker.

Of course you will need line-of-sight to get this communications system up and running, but as long as you have that taken care of the sky’s the limit. You can find incredibly powerful lasers lying around if you want to try to increase the communication distance, and there are surprisingly few restrictions on purchasing others that are 1W or higher. You could easily increase the range, but be careful not to set your receiving station (or any animals, plants, buildings, etc) on fire!

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Color Light Painting With A 3D Printer

Light painting, or taking a few RGB LEDs, a camera with a long exposure, and turning the world into Tron, has been around for a while. We haven’t seen many people using their household CNC machines for the same effect. [ekaggrat] is the exception. He’s already used a 3D printer to do some light painting, and now he’s doing it in color.

This build is an extension of an earlier project we saw that used a white LED to draw pictures within the build volume of a delta printer. Just like the last time, [ekaggrat] wired LEDs up to a RAMPS board and toggled pins with the M42 command. This build merely triples the complexity of the wiring; the RGB LED is wired to pins 4,5, and 6 of the controller board, and the shutter release button of his camera is wired up to pin 11 with an optoisolator.

The ability to blink out Gcode is one thing, getting his two-year-old daughter to stand still for 3D scanning is another thing entirely. With the data in hand, [ekaggrat] was able to run this model through a script that would generate a light painting of his daughter. You can grab the script for that on GitHub, or check out the video below.

Continue reading “Color Light Painting With A 3D Printer”