Xose Pérez — a resident of the small town of Sant Pol, north of Barcelona, Spain — rather than buying a normal watch, built the Solr digital wrist watch, a sort of a digital wrist-mounted sundial. The user reads this device by aligning the sun’s shadow from a nylon screw with a white line on the watch’s PCB face. When this is aligned correctly, direction is sensed by a magnetometer, which is then used to calculate the time, shown on a tiny numeric indicator below the dial.
Solr is somewhat inaccurate due to the variation in the sun’s transit through the sky, as well as any user error; yet, he justifies the watch design as a possible excuse for being late, or simply as a way to embarrass your kids! However the watch is justified, it’s a unique project that reads time in a very fascinating way. If better accuracy was needed, the month and day could be added in to compensate for the sun’s variation throughout the year.
Interestingly, according to Pérez’s write-up, there is a legend in the town of Sant Pol that says that people there restored an old sun dial that had been tarnished by the sun and rain, placing it under a roof in order to keep it pristine. This, of course, prevented the sundial from working correctly, and those from neighboring towns would mockingly say to them “Sant pol quin’hora és?” or “Sant Pol, what time is it?” This irony isn’t lost on Pérez, who points out that this could be classified as a useless project, especially since the the tiny numeric display is difficult to read in the sun!