Voltage Regulator Using Zener Diode Circuit

Zener diode regulator is a basic electronic circuit which is very useful for those interested in hobby circuits. This circuit is used for obtaining a regulated voltage at the output which can be used for biasing other circuit elements. Now how to use zener diode as voltage regulator? When zener is in reverse breakdown region, the zener voltage remains almost constant irrespective of the current through it.
This regulated voltage output gives the circuit, its name ‘Voltage Regulator’. This property of diode is also employed in clipper circuits.

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The major benefit of using zener diode as a voltage regulator is that it helps us to avoid the bulky&costly DC source to a great extend. Now lets see how to make a ZENER VOLTAGE REGULATOR. The circuit only contains a zener diode and passive electronic element- resistor . Active source is provided for power supply to the circuit. Zener voltage regulator is also known as Zener voltage limiter due to its voltage regulation property irrespective of the current through the zener diode.

Zener as voltage regulator Circuit Diagram

Components Required

1. Resistors (100Ω)
2. Potentiometer (1KΩ)
3. Zener diode

Working of Zener Voltage regulator

• A zener diode functions as an ordinary diode when it is forward biased. It is a specially designed device for operating in the reverse bias condition.

• The 100Ω resistance is used to limit the current through zener diode beyond its maximum limit. 

• When the input voltage increases, IL remains the same (load current), is (current through the series resistor) and Iz (zener current) increases. 

• If input voltage decreases, IL remains the same. Iz &Is decreases. If Iz falls lower than minimum zener current required to keep the Zener in breakdown region, the regulation will stop and voltage at output will decrease.

Pinout of Zener diode

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