[Carlos] sent us his project that uses an Arduino as a pH meter. In order to sense the acidity or alkalinity of a solution, a glass electrode is connected to the ADC of the Arduino through a fairly complicated calibration, amplification, and filtering circuit. Admittedly, it may not be cheaper or as accurate as some commercial models, but it is an open project and can be interfaced with a computer via USB.

Google has opened up a new Android Developer Challenge for submissions. About $2,000,000 in prize money is available, with $250,000 going to the best overall app. Submissions are due by August 31, leaving about a week to get apps in for judging. Time is short, but the prizes are big. Hopefully we’ll see some exciting things come from the contestants now that the community has grown since the previous ADC in 2008.

[via Phandroid]

Here’s another nerdy present that was built for Valentine’s Day. [João Silva] created a temperature sensing Munny. A Munny is a vinyl toy made to be customized. Other than these Munny speakers, we haven’t seen them in many electronics projects. The LM35CZ temperature sensor has an analog output that connects to the ADC on the ATtiny15L. The microcontroller changes the RGB LED’s color based on the temperature: blue for cold, green for comfortable, and red for hot. It only flashes every three minutes to conserve the power in the coin cells. His one-off circuit board also includes an ISP header for programming. The Munny’s head looks like it does a great job diffusing the light.

Bug Labs makes hardware modules that can be combined to create your own custom gadgets. They’ve just released what we consider the most useful module: BUGvonHippel. Unlike the previous single purpose modules, the BUGvoHippel is a universal interface. The bus features USB, power/ground, DAC/ADC, I2C, GPIO, SPI, serial, and more. BUG applications are written in Java using a custom IDE.

The $79 module is named after MIT professor Eric von Hippel, who wrote Democratizing Innovation. You can find an interview with him below.

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