Color Sensing With An RGB LED And Photoresistor

December 8, 2011 by Mike Szczys 11 Comments

[Fjord Carver] brings together an RGB LED and CdS Photoresistor to make a color sensor. Those Cadmium Sulfide lights sensors usually have a very wide swing of resistance when exposed to varying levels of light sensitivity. That makes for great resolution when reading them using the ADC of a microcontroller. The LED comes into play by shining known wavelengths of light on the surface being measured. Three separate readings are taken with each of the LED’s different colors, then used to extrapolate the RGB value of the test material. We saw the very same method used a couple of years back. This time around it’s an Arduino doing the measuring instead of a PIC.

So why isn’t that sensor shown in this picture? It’s because we appreciate the application which [Fjord] is using for this sensor. He built a lamp that shines the same color as the surface on which it is placed.

RGB Upgrade For Ikea Single Color Fiber Optic Lamp

November 10, 2011 by Mike Szczys 23 Comments

Five bucks will buy you a STRÅLA lamp from Ikea. It’s a battery operated hanging lamp that pipes the light out through multiple branches of fiber optic bundles. But you’ll only get white out of this, which is pretty boring. [Boris] decided to swap out the stock LED for an RGB unit and drive it with an Arduino.

The lamp nucleus is just a couple of pieces of plastic which can be popped apart to reveal the shard of PCB hosting one LED. The body of that diode is flat on the top, and [Boris] filed down his replacement to match the form factor. There are only two conductors in the wire that runs between that PCB and the battery pack, so he replaced them with four conductors (R,G,B, and GND). His prototype uses the Arduino’s PWM capabilities to control the colors, but [Boris] recommends transitioning to a simple chip like a PIC 12F675 or one of the smaller ATtiny microcontrollers after you’ve got the bugs worked out.

See how this turned out in the clip after the break.

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Camping Light Retrofitted As A Solar Recharging Station

November 4, 2011 by Mike Szczys 8 Comments

With grand plans of tenting out for several days at a music festival [Josh] needed a way recharge his portable devices. In the past he’s lugged around a 12V battery with him, but this year he wanted to make things easier. He ended retrofitting a camping light to do the job with the help of the summer sun.

The first step of the project was to source some rechargeable batteries. He toyed with the idea of Li-Ion cells but ended up going with NiMH because the charging is more forgiving and he got them at a great price. Because of the lower operating voltage (1.2V versus Alkaline’s 1.5V) he needed to squeeze two more into the lamp housing. Here you can see that he just managed to get them to fit in the wire-run area down the middle of the case.

Next comes the recharging circuit. He based his design around an ATmega44, using a voltage divider and the ADC to detect when the batteries are topped off. During the day this is connected to an external solar panel and it’s ready to charge his phone when he gets back at night.

Sustainability Hacks: Thin Client Server

October 2, 2011 by Brian Benchoff 44 Comments

It’s not environmentally friendly, but most of us run a small home server 24 hours a day. A small server is a useful tool to have that unfortunately wastes a lot of energy. [kekszumquadrat]’s thin client home server is actually a passable LAMP box that doesn’t draw a ton of power.

[kekszumquadrat] started looking at the SheevaPlug when beginning his quest but was a little concerned about the power supply failing. Looking for alternatives, he ran across a lot of cheap thin clients on eBay. The price was right and everything runs Linux, so a few days later he had an HP t5710 thin client on his doorstep.

This little computer came a copy of an embedded version of XP on a flash drive connected to the IDE port. Ditching that “operating system”, [kekszumquadrat] connected a USB hard drive and installed Arch Linux. After a few updates and package installations, he had a useful machine connected to the Internet.

Compared to the 7 Watts the SheevaPlug draws, the 15 W thin client is an energy hog. Compared to our improvised servers, [kekszumquadrat] is doing a remarkable job. Recycling old hardware never hurt anyone, either.

Anthropomorphizing An Ikea Lamp (like Pixar But In Real Life)

September 8, 2011 by Mike Szczys 16 Comments

ArduinoArts is animating an inexpensive Ikea lamp as a contest entry. Seeed Studio’s Toy Hacking Contest calls for the competitors to work their magic using the Grove Toy Kit, which is an extensible sensor connection system for the Arduino. Most of the items in the kit were used to add interactivity to the lamp. Check out the video after the break to see the motion that two servos provide. The lamp can move its shade back and forth as if shaking its head, and the whole arm assembly can rotate in relation to the base. The sensors detect when you’ve repositioned the lamp head and the device will yell at you if it doesn’t appreciate its new pose. It also reacts to noise and motion, switching on the LED that replaces the original bulb in both cases, and asking: “Are you Sarah Connor” when motion is detected. These basic modifications really make for some fun animatronic behavior.

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Super Mario Coin Block Lamp Is A Nintendo Fanboy’s Dream Come True

June 25, 2011 by Mike Nathan 9 Comments

super_mario_coin_block_lamp

[Laurence] was racking his brain coming up with potential birthday gifts for his friend when the idea of a Super Mario Bros. coin block lamp popped into his head. The block is constructed from drain pipe, a few pieces of plywood, some perspex, and a whole lot of awesome.

He wanted the lamp to make sounds when it was turned on and off, so he put together an audio circuit based on [LadyAda’s] WaveShield. His design is similar, though he swapped out the DIP packages for SOIC versions, adding a DAC, Op amp, and an audio buffer to fit his needs.

Once he had his electronics in order, he started construction of the lamp, painting the drain pipe green and mounting it under his light’s base. He built a large perspex box to serve as the coin block itself, printing the familiar graphics on tracing paper which he then glued into place. An arcade button adorns the top of the box, making for a very appropriate and fun light switch.

Be sure to check out the video below to see the lamp in action. We’re just a bit jealous of [Laurence’s] friend, and we sure wouldn’t mind having one of these in our office to sit alongside this mechanical coin block we featured a while back.

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Dimming Control For An Ikea Solar Desk Lamp

May 16, 2011 by Mike Szczys 15 Comments

[Frank] decided to augment his desk lamp’s features by adding dimming controls (translated). Since the light source is a triad of LEDs the best method of dimming their intensity is to use Pulse Width Modulation. That’s the method that he went with, and luckily the SUNNAN lamp from Ikea which he’s using as the donor for the project has just enough room to squeeze in the parts necessary for this hack.

You need two main bits to use PWM with a lamp like this; a microcontroller (or possibly a timer chip like the 555) and a transistor to protect that chip from the current necessary to run the LEDs at full brightness. [Frank] went with an ATtiny13 and a 2N2222 transistor, both quite common and very inexpensive (you can even pull the microcontroller from a light bulb if you know where to look). Two buttons were added to the top of the lamp base which allow for up and down controls. There’s even an SOS function which is triggered by pressing both buttons at the same time. [Frank’s] happy to show off the completed project in the clip after the break.

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