well I have photodiodes and LDRs just for testing i used LDRs but i'm sure photodiodes are maybe faster ..maybe not don't know ..and I'm guessing the lm393 is faster than the lm358 dual op amp ..should I connect both negative inputs together and just use one POT to adjust sensitivity ? the lm393 will only sink so it will
have to trigger on negative edge if i use the comparator