Detect fast movement using photodiode

[Acetronics2]

Word on the street is: Use a PIC with Schmitt trigger inputs for better results. Better results due to Schmitt triggers hysteresis's gives input port a snap action, dampens analog effect.

Yesss Joe ...

Much better, as comparators directly can generate the interrupt ...

Over that I'd try to use a compensation stage to correct for ambiant light ... look at the attached scheme ... left side of Transistor T2.

Alain