Electronics - Basic Op-Amp Circuits - Discussion

Zener diode does not control the voltage it only provides a "reference" voltage. The one that controls how much current will be fed to the load is the Transistor. It uses the Zener diode as a voltage reference but the Zener diode is not the one controlling the flow of current it merely provides "REFERENCE" hence it can also be referred to as a "REFERENCE ELEMENT" not CONTROL ELEMENT they are entirely different from each other. Distinguish the difference.

In the basic shunt regulator, the control element is a transistor (Q1) in parallel with the load.

Not only transistor, Zener diode can also be used as control element in shunt regulator.

Correct Option is (A).

Zener diode always be used as a Voltage reference and Regulating device so answer will be (A).

@Brajendra.

Of Course Zener diode always be used as a Voltage reference in a basic shunt voltage regulator.

Zener diode used as control element ? Not.

So Answer([B].False) is correct.

Zener diode's voltage remain same so it is sometime used a voltage regulator and some time a reference. So the statement can't be false totally.

In transistor shunt regulator, transistor is a control element.

While in zener shunt regulator, zener is a control element.

Zener diode is only used as a reference, not a control element. Distinguish the difference.

In question only mentioned control element.

Zener diode control the voltage.

In shunt regulator, zener diode act as reference volage source means it is control element only.
So, A is correct answer.