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 opamp IC. Prefix can change depending on the manufacturer, like UA741 and LM741 is same Op Amp IC.