I have understood that you can create a linear regulator using a high-current BJT power transistor in the emitter follower configuration and one operational amplifier (and a voltage reference, which can be a voltage source or some kind of Zener diode or similar).
How does such a circuit work?
What is the minimum supported voltage drop of such a circuit? Is it worse or better than dedicated linear regulator ICs?
Are there any reasons to use such a circuit in the modern days where adjustable-voltage linear regulator ICs are widely available at a very cheap price?