aster94:
i found the potentiometer useful if i move the ir emitter, but when i will have a final board you are right i will put a fixed resistor 10k or a little bit less@GoForSmoke maybe i didn't understood your question. but a few post ago you made this nice calculation:
4000rpm = 66 2/3 rps = 15 millis/rev = 41 2/3 micros per degree
I wasn't sure if it was for this thread. That was days ago.