Actually, right now I need a voltage amplifier to amplify 5V of the Arduino pin to exactly 15V (or atleast 12V if 15 not possible).
No "amplifier" will give you a voltage outside the supply rails. If you need to create 12v from 5v, you need to either use a boost converter (cheap DC DC converters come from ebay), or start with 12v (this could be used to get 5v via either buck converter or linear regulator)If you're switching power to something, use a Mosfet not an amplifier
Can anyone share some good tutorial on LM324 as I have been working on it and it seems quite good and cheap. So share some good links please especially if there's some Proteus simulations available for LM324.