Build Your Own Interactive Chalkboard On The Cheap

You could spend thousands of dollars on a smart board. Or you could make your own for $40.

String2string
String2string team member Caleb Zulawski demonstrates the smart board he and his compatriots built for under $40.String2string

Technology that translates your writing and doodles into computer-generated imagery has been around for a while, but it generally requires special material to write on as well as a smart writing implement, and it doesn't run cheap. But if you happen to have a chalkboard, some pulleys, and a few ultrasonic sensors lying around, you can make one yourself.

A team of three students--David Katz, Harrison Zhao and Caleb Zulawski--has undertaken just such a project for a hacking competition this past weekend at Cooper Union in New York.

The team connected a chalk-holder to two strings. Each string is connected to a pulley and a weight. As the chalk moves, it pulls on the strings, causing the pulley weights--each of which is encased in a PVC tube on one side of the board--to go up and down. Using ultrasonic sensors at the bottom of each of the tubes, the String2string software can figure out how far away the weights are, and thus calculate--using some fancy geometry--the position of the chalk relative to the board. It can then duplicate that same movement on a digital canvas, recreating any writing or drawing done on the board. In theory, the team says, the technique will work with boards of any size, and would presumably translate easily to large pads of paper or whiteboards.

Those drawings are stored and can be downloaded digitally as images--if they're only composed of text, the team says that the images can be easily processed with optical character recognition to turn it into editable text.

Most impressively, the materials used to create the project only run about $40, the bulk of which went to an Arduino microcontroller that does the actual heavy lifting; the team has even made their software available for free for those who want to duplicate their endeavor. Comparatively, interactive whiteboards often cost several hundreds or thousands of dollars, although they do bring additional capabilities like collaboration and sharing. But if all you're looking for is turning analogue writing into digital, seems like it can be done much, much cheaper.