Strobe lights serve as a good techometer for rotary equipments. recently i have been working on the same. But as u depicted that the trigger signal is being generated by the rotating shaft, would not be the case of measuring the rotary speed of the engine. I belive you are going to do somethign else. If u explain what do you want the strobe light to do, it would be helpful for understanding your requirement. I could give you the design which i made and tested, but it does have a triggering circuitry and does not directly couple to the rotating shaft.
- Ali Sajjad