When designing the XO computer, One Laptop Per Child designed the sound card to be able to measure DC voltages. Now why would the talented team behind the "$100 laptop" go to the trouble of hacking an audio jack microphone into a data port? Maybe they had the same revelation as Martin Visser did:
A colleague of mine who has quite a few OLPCs, mainly for testing the wireless stuff out, told of the absolutely clever analog input port the OLPC has. Not content with a regular AC microphone input, it can be configured in two other modes.Taking this idea a step further in his comment on Building One Laptop Per Socialized Child, Nick explains how children could use cheap sensors to learn about electricity:
One is a straight DC input that can measure between 0 and 3VDC. I immediately thought of kids in Africa being able to hack electronics together from old radios and the like and using the OLPC as a simple oscilloscope or voltmeter.
The other analog input puts 2.5V and allows you to measure across this. This means a simple potentiometer can be read. Great for all sorts of science experiments, but also a good way of providing another interface to control the Tamtam musical instruments.
One of the many possible IPL activities would focus on electricity. The student would be guided to build his own battery (using fruits for examples). Then, by questioning, he would be guided to understand how to connect more of them to obtain more voltage or current. The student would both simulate it with e-toys, and measure it physically with the sound card.To capitalize on these learning opportunities, One Laptop Per Child developers like Jaya Kumar, are creating dedicated voltmeter to oscilloscope activities, transforming the Children's Machine into a full science learning laboratory. Just check out Walter Bender's update on their progress:
Arjun Sarwal reports that the Measure Activity now features a frequency-domain representation in addition to a time-domain representation. Journal integration is complete. He also built a $1 temperature-sensing peripheral and a $1.50 intrusion alarm system; both have been tested using the measure activity.But don't just take Arjun's or my word for how cool an oscilloscoped XO laptop could be. Check out the measure activity movie:See, with their simple sound card hack, the OLPC developers will allow children to fulfill Walter Bender dreams of children using XO technology to not just play Dance Dance Revolution but to build their own Dance Dance Revolution machines, learning learning in the process.
"The great thing about the XOs is that they are inherently networked, so by simply connecting a sensor to each XO, and using a combination of such sensors and the cameras, a highly powerful, flexible and robust sensor network for surveillance can be built."