Up-adjustable regulated power supply circuit

The output voltage of the three-terminal fixed voltage regulator is fixed, but according to its circuit characteristics, it can form a continuously adjustable
power supply with an output voltage. The principle is to float the three-terminal voltage regulator and add a booster voltage. The circuit is shown in Figure 14-53.
    The output voltage of the circuit can be calculated according to the following formula:
    Usc=(UA+Ube) 1+Lu)
where UA-the fixed output voltage value of the three-terminal regulator, v;
Ub. ——Transistor emitter junction voltage drop, about 0. 7V.
It can be seen that as long as the Rz resistance value is changed (that is, the potentiometer is adjusted), the output voltage can be changed.