LEGO Rolling ball clock

Philo writes “When Bob Kojima announced his rolling ball clock on Lugnet a few months ago, I knew I had to build one someday… I bought a stock of balls on Bricklink, and here is the result. The main modification was the use of a RCX to obtain good long time stability – I finally obtained less than 1 minute drift over 24 hours.” Thanks Bf5man! – Link.