I will use a TCRT1000 it is a optical sensor that gives measurement data in the range of 4 mm's
• Peak operating distance: 1 mm
No it is not. It is simply a reflective optical sensor designed to give a digital signal to measure if an object is in front of it.
If i put a diode on last op amp's end to achieve "if it goes under 750 do nothing just wait" can i achieve what i want?
The design of the circuit in the video you linked is very poor, and not worth trying to reproduce. The video producer made it clear that he had great difficulty getting it to work correctly, and that this was just a "one off" experiment.
e measuremnt sensor gives me 750 on this zero position
750 what? Things have units, what is the units of which you want 750 of them?Using the map function you can have any range of numbers mapped to another arbitrary range of numbers. There is no need for the sensor to give you a specific number.
what are the shortcomings of the circuit?
It doesn't work.
The TCRT1000 using with arduino giving number 0 to 1023 depending onjects reflectanse as you told.