So using feedback will give any advantage then simple comparator as used by me earliers??
These are very different circuits with different parts in them. The circuit You showed before uses
Comparator which will change from low to high (or vice versa) when 1.65V threshold is passed. The circuit in SoR page (the one with an Op-Amp) uses, well... an
Op-Amp and
NOT the
Comparator (yes, they look the same, but are different things). So, the second circuit is used to amplify voltage coming from phototransistor and resistor voltage divider. Both circuits will work if colour difference of line to be followed and the ground around it is well defined (say, white line, black ground around it and there are no greys in between). Your circuit is OK and it would perform the same way as a circuit I posted before (only You don't use comparator making circuit more simple to implement, cheaper as well and taking less space), however them two circuits are not immune to noise (changing lighting conditions, slightly varying colours of line and ground around it). To get that immunity, you have to implement Schmitt Trigger to Your comparator based circuit, this will give You well defined transitions between high and low which are immune to signal noise and inaccuracies (to some extent).
