Digital Smart Boards have been used in schools for years now, but a lot of classrooms simply can't afford the luxury. 3 students have designed a clever way of converting an existing blackboard, into a smart board. Harrison, David and Caleb designed and created this at the HackCooper NY Hackathon.

2 pieces of string are connected via pulleys to a chalk holder, each having a weight on the end. The weights slide inside a tubes either side of the blackboard. At the bottom of each tube is an ultrasonic sensor, measuring precisely the position of the weight in the tube. With a little bit of calibration, the system can work out the X/Y location of the chalk.

The chalk communicates with the computer via radio remotes and the Arduino sends the received data to a Python program over serial. The Python program has to filter and smooth the data to create recreate the strokes.  The whole class can see the board in real time via their smart devices, as the project uses a Node.js server to share the data. Using a server also allows the data to be saved, so even after erasing, the data can still be viewed and downloaded.

The team managed to create this awesome project in only 24 hours, using various cheap bits of gear. $40 got them some PCV pipe, weights, pulleys, the Arduino and the sensors. You can read more on the Hackerleague website, and all the source is on GitHub.