NPN series voltage regulator is a linear voltage regulator circuit composed of three diodes and a triode. Among them, two diodes are series voltage regulator tubes, and the other diode is protection tube; A triode is an amplifier tube used to amplify the input voltage. The advantage of this voltage regulator is that the output voltage is stable, but the disadvantage is low efficiency, large volume and high cost.
With the npn type diode self-voltage drop, serialized power supply, this power supply is generally low voltage because a diode is only 0.7v, and the current is not large.