Supercap Lights Your Way In Times Of Need

February 10, 2012 by Mike Szczys 46 Comments

You won’t find [Antoine] stumbling around in the dark. He just finished working on this LED flashlight which draws power from a super-capacitor (translated). He realized that lighting a high-efficiency LED takes so little power that there are many benefits in play when deciding to move away from batteries. When compared to a super capacitor, batteries have a shorter life span, are heavier, and take up more space.

The biggest drawback of a super capacitor in this situation is the low voltage operation. The output will start at 2.7V and drop as the current is discharged. [Antoine] used one of our favorite simple circuits to overcome this issue, the Joule Thief. That circuit is commonly seen paired with an LED in order to boost input voltage to a usable level. That’s precisely what’s going on here.

The final hack in his circuit is the addition of that red LED which you can see in the middle of the board. This takes the place of a Zener diode and drops the charging voltage to a safe level. That indicator light will not come on until the cap is fully topped off. This way it tells you when the device is done charging.

Color Sensor Gives The RGB Values Of Anything

February 7, 2012 by Brian Benchoff 28 Comments

[Rick Osgood] wanted to build a color sensor that could be held up to any object to get RGB color values. He originally started with a photoresistor and a few LEDs, but couldn’t get that to work reliably. [Rick] finally completed his color sensor after finding a digital luminosity sensor on Adafruit, ending up with a pretty accurate piece of hardware to judge the color of something.

The idea behind the color sensor is to light up red, green, and blue LEDs and see how much light is reflected back from the object with a luminosity sensor. [Rick] chose an Arduino to do all the heavy lifting for the light sensor and activating the LEDs.

After a few tests [Rick] got his color sensor working, but it’s not up to par with what he had expected. This isn’t really a problem: the LEDs probably don’t have the same brightness and the luminosity sensor doesn’t respond evenly across the entire rainbow. Those things can always be fixed in software, though. It’s a nice project that could serve as part of a prototype for this color picker pen.

Building LED Walls On The Cheap

February 6, 2012 by Brian Benchoff 7 Comments

Around this time last year, [KopfKopfKopfAffe] was enlisted as a set designer and was told to build some sort of light effects for electronic music parties. The budget for the project wasn’t much at 200 Euros, but he did manage to build decent 5×5 RGB LED matrix that is fully controllable by a computer.

[KopfKopfKopfAffe] didn’t have the time or money to wait for manufactured PCBs, so a bunch of perfboard was placed in a CNC mill with a pen to act as a plotter. All the lines that needed soldered were drawn on by the mill, a feat that probably saved hours of looking at the design before committing solder to iron.

A total of five boards were constructed, each one capable of controlling five RGB LEDs. Each board can be dasiy-chained with an RS-232 serial connection for further expansion. The only thing that’s needed to control the matrix is 17 bits that includes an address and RGB color data for each LED. The system only cost about 10 Euros per node, but we think that could be significantly reduced by leaving out the Molex and DB-9 connectors. [Kopf] project turned out very nice, check it out after the break.

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Using Routers As Displays

February 4, 2012 by Brian Benchoff 18 Comments

Have you ever seen an LED display made out of routers? [Sean] took eight Netgear routers and made an 8×4 display out of them. Because that wasn’t cool enough, a very small version of Conway’s Game of Life was added to the build.

Each router is running a copy of OpenWrt, a Linux distro meant for limited hardware. Instead of an 802.11 protocol, each router runs the B.A.T.M.A.N. advanced mesh protocol. This protocol allows each router to communicate with all the other routers.

Instead of each router receiving data from a master, the routers calculate each step in the Game of Life independently. Once the routers communicate their initial states, each router is responsible for displaying its four LEDs for each new generation. In the video after the break, you can see [Sean]’s routers calculating random Game of Life boards. Sadly, we didn’t notice a GoL oscillator being randomly generated, but with a 4×8 play field even a Glider wouldn’t last very long.

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Lamp Upgrade Makes You A Hot-head

January 30, 2012 by Mike Szczys 15 Comments

[Cameron] decided to give his twenty-year-old headlamp a makeover. He uses it when he’s out for a run and wanted to have more light to see where he’s going, as well as a red tail light on the back. The stock design uses an incandescent bulb on the front of the head band, and a battery pack on the back. He managed to convert the device to output 700 lumens without major changes to the form factor of the unit.

The first change he decided on is to use a Cree XLamp which provides the 700 lumens of light by drawing about 9.5 Watts of power. Obviously the original battery pack isn’t going to do well under that kind of load, so he also sourced a 5000 mAh Lithium battery. A bit of circuit design and PCB layout gives him two driver chips for the four-element LED module, a charging circuit for the battery, and an ATtiny13 to drive the head lamp and flash the red LED tail light. See the blinky goodness in the video after the break.

That’s a lot of light, but we wonder if he experiences a warm forehead from the heat sink used to keep that LED package cool? Continue reading “Lamp Upgrade Makes You A Hot-head” →

Paint Your Pictures, No PC Needed

January 30, 2012 by Kevin Dady 14 Comments

LEDs and and cameras always make a fun mixture, and its not all that hard to have quite a bit of fun as well. The Light Painting Stick is similar to other long exposure camera tricks like LightScythe and gets about the same reults. The difference is the Light Painting Stick is self contained meaning you don’t have to drag nearly as much stuff along with you to have fun.

Hardware used is HL1606 controlled RGB led strip commonly found at Adafruit, the brains are a Leaf Labs Maple micro controller board with an SD card and some human interfaces attached, and is powered by a 6 volt lantern battery.

Images are 64*infinity 24 bit BMP files which means there is not much fuss preparing your graphics other than doing a simple rotate. You can select which image is displayed by using a 2 way switch and the LEDs on the stick. Select your images, dial in your speed with the potentiometer, and you’re ready to hit the fire button for some photo fun.

Followup: Troll Physics Solved

January 27, 2012 by Brian Benchoff 48 Comments

A month ago, we saw a marvelous demonstration of troll physics from YouTube user [Fredzislaw100]. In his video, we saw a circuit of three switches and three LEDs wired in series and but not acting like the should. A lot of the comments for this post elicited reasonable explanations like modifying the battery or pure camera wizardry via After Effects. Thankfully, [Alan] stepped in and showed us how it was done. The solution uses two AC power sources with diodes in two of the switches and LEDs and inductors in the third pair. [Alan]’s build was rather large compared to the original video, so we were wondering how this circuit could be made invisible.

[Fredzislaw100] just posted a video on how he did it. Like [Alan]’s build, it uses two AC power sources, diodes, and inductors. In contrast to every single guess about where the circuit is hidden, the majority of the build is inside the battery connector. [Fredzislaw] did some amazing work hiding a 74LV132 quad NAND Schmitt trigger inside the battery connector. The diodes were easily hidden on LEDs 1 and 3 with some red nail polish, but we’re amazed by the inductor built into the LED seen in the title pic.

So there you go. With a ton of electronics know-how and an extremely steady hand (and a microscope), you too can build your own troll circuit. Check out the video after the break.

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