OLED hack saves juice on Nexus One

Want to really stretch the battery life on your phone? If you have an OLED display [Jeff Sharkey] may have the answer. He did some testing with his Nexus One to see if color alterations can save on current. Darker colors draw less amperage and he found that the red pixels are the most efficient. He did a little work with SurfaceFlinger, which handles the display on Android devices to make this easy, but what will you get by going red? He measured that using only the red pixels dropped the current use down to 35% of what the full color display was pulling. This reminds us of those efforts to save energy by running a black background with Google. Whether you use it or not his post is an interesting read.

Tomato irrigation

No hack will be more readily accepted by the significant other more than an automated vegetable watering system. [Jouni’s] homemade rig keeps those tomatoes happy with just the right amount of moisture. A bucket serves as the reservoir, a submersible pump gets the water to the soil through a bit of plastic hose. An Arduino monitors the soil sensor, watering and tweeting about it when things dry out too much. Don’t miss the soil moisture sensor post if you need some tips on how to get that end of things working. The rest is pretty straightforward.

Coded safety for diy laser

Finally we see a hack that is focuses on safety when it comes to high-power laser hacks. A safety switch has been added to the butt of the flashlight body which houses the laser diode. When the safety is flipped on an LED blinks to prompt the user for a security code. If you enter the correct code on a momentary push switch, electrical access to the laser is enabled. There are also a couple of nice features such as continuous on and auto shutoff.

This would be hard to implement if you’re working on a watertight package but we like the fact that an unsuspecting house guest won’t go blind if searching for a flashlight during a storm. One last thing, the code entry system is PIC based which reminds us of [Alan Parekh’s] one-button system.

Great interactive LED puzzle

The GLIP project takes the delight of blinking LEDs and combines it with the ingenuity of modular communications. This takes the Puzzlemation concept a few steps further. In that project the modules were programmed through a base station and could be removed and used as a puzzle from there. The GLIP project uses a master block that you can see tethered in the photo. But the blocks communicate with each other via an infrared protocol. This way they can be continuously updated as they are place next to each other. Each module includes an STM32F105 ARM Cortex-M3 processor, quite a punch for the little blocks. Take a look at what they can do after the break.

Continue reading “Great interactive LED puzzle”

Three pendulum harmonograph

Just the other day we were thinking “You know what we need more of around here? Harmonographs!” And our requests were answered when [Paul] sent in his three pendulum harmonograph. For those unaware, it’s a mechanical device that draws Lissajous curves or “really cool circles” to quote some of our staff.

[Paul] includes all the plans necessary to make your own harmonograph and begin drawing today. If you can’t wait, there’s a video of the three pendulum harmonograph etching a masterpiece after the jump. Continue reading “Three pendulum harmonograph”

Store update: Remember this?

The Hack a Day store has a couple new items.  It was brought to our attention that we once held a T-shirt contest, and people really wanted access to that design. Well, now you can get it. The design on the shirt will be roughly 13″x10″ and located at the hem under the right arm. Please note that this is not identical to the previously made ones that you may have noticed at CES.  The design is also available as a large sticker.

We would love to see our stuff in the wild, so please upload your pictures to Flickr and put them in the Hack a Day pool.