[Al Skierkiewicz]

I am more of the make it simple school. Digikey sells a variety of opto sensors that are meant to read a reflected light beam. They contain an LED and a phototransistor. A simple wiring job with a 5 volt-9 volt supply and two resistors should be able to sense the hour hand. Choose an opto sensor that will fit behind the face, drill a hole behind the face at the appropriate spot for sensing the position of the hour hand. The addition of some reflective tape on the back of the hand should be enough to trigger the sensor, then it is a simple matter to mount the sensor so that it just begins to read the position when the hand moves to the correct spot. A variable resistor in the photo transistor circuit will allow you to adjust the sensitivity so it only senses the hand and not ambient light. Use the switched output to trigger whatever device you want. (Sonalert, another LED, etc.)