An operational amplifier (Op-Amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. Chose from Ventor catalog for lowest price in India and widest verity. LM358, LM741, LM324, LF353, OP07, MC1458 are some popular op-amp IC. Prefix can change depending on the manufacturer, like UA741 and LM741 is same IC.