Transistor Shunt Voltage Regulator

A shunt voltage regulator provides legislation by shunting present away from force to modify the manufacturing voltage. Figure shows the circuit of shunt voltage regulator. The voltage drop across show resistance is dependent upon the existing provided to your load RL. The production voltage is equal to the sum of Zener voltage (VZ) and transistor base-emitter voltage (VBE) i.e., Vout = VZ + VBE If force opposition decreases, the current through base of transistor decreases. Being truly a outcome that is total less collector up-to-date is shunted. Consequently, the strain becomes that are present, hence maintaining the voltage that is controlled the stress. Reverse occurs if the load opposition enhance.

Drawbacks. A shunt voltage regulator has the following drawbacks :

In order that Q3 is ON, voltage across R4 must be about 0.7 V. This means that load current then is IL =0.7V/ 1 Ω = 700 mA. Therefore, if load current is less than 700 mA, Q3 is off. If load current is more than 700 mA, Q3 will be turned on.

1) A large portion of the total current through RS flows through transistor rather than to the load.

2) There is considerable power loss in RS.

3) There are problems of overvoltage protection in this circuit.