Hello guys, I want to know what is purpose of the transistor T3(BC547B) in this circuit. I understand it provides base current to the series pass transistor T5(2N3055). Also i want to know
1. what is the function of transistor T4(BC557B) and T2(BC547B) and T1(BC547B)??
2. Here D1 (1w,15V) is a zener diode?
3.What is BZ1(24V) in this schematic?