Persistence of vision wheel

[rsocor01]

You can easily use IR to generate your index pulse; Mount the continuously lit IR LED on the chassis, and an IR detector on the spinning platform. Align them such that they see each other once every revolution.

Or mount both on the chasis in such a way that the spinning LEDs will block the path between them once every revolution and you are set.

[ardhuru]

No, that wont work. The information that the beam has been detected/broken is needed on the rotating assembly. Getting that information on the fixed chassis will serve no purpose.

Anand