Silly Idea: Clockless Watch

Using a metal brush, a low pass filter, and a schmit trigger as digital clock source for the calculation circuit, you could make a horribly inefficient electronic watch that used the position of the sun (by a low res ccd or even photodiodes) and a compass to calculate the time. Can’t use a crystal or rc, because that would be cheating! Might as well just have it keep the time!