Transistor series regulator circui

Removed from the output voltage UB2 as part of the sampling voltage is applied to the base of transistor T2. Zener diode Dz its stable voltage Uz as the reference voltage applied to the emitter of T2. R3 is a regulator of the current limiting resistor. Transistor T2 composition is relatively amplification circuit, it is sampled voltage Uz UB2 is compared with a reference voltage and amplified air circuit breaker the base potential of the transistor T1.  the input voltage Ui applied to the transistor T1 in series with the load RL circuit, therefore, change the T1-collector voltage drop across RL UCE1 can adjust the voltage Uo. That is, the voltage regulator Electric transformer Uo can be adjusted through the transistor T1, so T1 is called the regulator. Due to the adjustment element is a transistor tube, and in the circuit in series with the load, so called tandem-type transistor regulator circuit. Resistor R4 and the base bias resistors T1, T2 is the collector load resistance.
When the grid voltage is reduced or the load electri cenergy meter is reduced leaving the output terminal voltage decreased when its sampling voltage UB2 is reduced accordingly, T2 base potential drop. T2 emitter potential but both the stability of the regulator Uz remain constant so UBE2 emitter voltage decreases, resulting in the decrease of the collector current T2 Uc2 collector potential rises. Since amplification T2 T1 collector and the base of the regulator connected together, so the T1 base potential rises, causing the collector current increases the pressure drop UCE1 reduced. Because T1 and RL series, so the output voltage Uo basically unchanged.