Wattcher, twittering Kill A Watt plans posted


You probably saw [Phillip Torrone] and [Limor Fried]’s twittering Kill A Watt earlier this week. It was an entry in the Core77/Greener Gadgets Design Competition. We saw a little bit about how it was assembled, but now they’ve posted a full guide to assembling the hardware. Each Kill A Watt gets an XBee radio that transmits back to a receiver that logs the power usage. The difficult part when putting this design together was the XBee required 50mA when transmitting. This is well above the Kill A Watt’s internal power supply. They remedied this by adding a 10,000uF supercap to act as a rechargeable battery. The daily twittering is just a side-effect of the project. The Kill A Watts transmit every 2 seconds, so you’ll get a very accurate report of your power usage. This is a great project for renters who can’t permanently modify their power infrastructure. Each Kill A Watt can support quite a few appliances since they’re rated for 15A, ~1800W.

Tiny projector teardown


The team from Tech-On has taken the time to teardown two interesting microprojectors. The first model they tackled was the Optoma PK101. It’s based around a digital micromirror device (DMD) like those used in DLP. Separate high intensity red, green, and blue LEDs provide the light source. A fly-eye style lens reduces variations between images. They noted that both the LEDs and processors were tied directly to the chassis to dissipate heat.

The next projector was the 3M Co MPro110. It uses Liquid Crystal on Silicon (LCoS) technology. The light source is a single bright white LED. The projector seems to have more provisions for getting rid of heat than the previous one. The most interesting part was the resin polarizing beam splitter. It not only reflected specific polarizations, but also adjust the aspect ratio.

[via Make]

Arduino buyers guide and the Seeeduino


Make has assembled a buyers guide for the many different types of Arduino devices. The Arduino is an open hardware platform designed to make prototyping easily accessible. The design allows for other people to modify, expand, and improve on the base, and many people have started producing their own versions. The guide features a lot of the hardware we’ve covered in the past like the LilyPad, Arduino Pro, Sanguino, Duemilanove, Ethernet Shield, and Freeduino.

Out of the pack, the Seeeduino (pictured above) definitely caught our eye. It’s a low profile SMD design much like the Arduino Pro. They’ve taken advantage of the space saved by the SMD ATmega168 by adding more useful headers. In addition to the ICSP, you get the pins in UART order and an I2C header. Vcc is switch selectable for 3.3 or 5volts. The reset switch has been moved to the edge plus two additional ADC pins. Our favorite feature is the new spacing on the digital pins. Arduino digital pin headers have an inexplicable 160mil gap between the banks. The Seeeduino has the standard row for shield compatibility, but has an additional row spaced at standard 100mil spacing for use with protoboard. At $23.99, it’s competitively priced too.

SketchUp adds dynamic components

Google just announced the release of SketchUp 7. SketchUp is a 3D modeling program with a fairly robust free version. They’ve added quite a few features and the one that caught our eye in particular was dynamic components. Dynamic components have behavior specific to the object. The example in the video above shows a staircase changing the number of steps as its height is increased instead of distorting the overall staircase shape. The new version also allows for interaction, so model properties change based on user actions.

Google has always encouraged sharing of objects created in SketchUp. Thingiverse launched today with a similar emphasis. The site is built to encourage the exchange of plans for physical objects. It supports many different file types from plain images, AutoCAD dxfs to Eagle schematics. Many of the designs already posted are made to be cut out by a laser cutter or built by a 3D printer.

[via Make]

Dean Kamen’s Stirling engine car


[Dean Kamen]’s company, the people behind the Segway, have created a hybrid car that uses a Stirling engine instead of a standard internal combustion engine. Stirling engines are closed cycle, meaning heat is applied to the outside of the cylinder walls. They are generally more efficient than standard car engines, but haven’t been used much outside of industrial applications. We suspect that the drivetrain arrangement is similar to the Chevy Volt where the engine is used to charge batteries which are in turn driving an electric motor. This is different from modern hybrids that can have either electric motor or gas engine driving the wheels. The article is unfortunately full of classic [Kamen] hyperbole and minimal detail. He calls the Stirling engine “an insurance policy” for the electric car since it can recharge the battery. That’s right, folks. If you run out of juice, you can put gas in the car. I doubt many Prius owners will fall out of their chair over that. Being a Stirling engine, we’d be more impressed if you could charge the thing by rubbing warm toast on it.

[via Make]