# ZENER DIODE VOLTAGE REGULATOR

AIM

To design and set up a voltage regulator using Zener diode

COMPONENTS AND EQUIPMENTS

1. Bridge rectifier circuit

2. Zener diode (6.2 volt)

3. Resistors

4. Capacitors

5. Voltmeter

6. Ammeter

7. Rheostat

CIRCUIT DIAGRAM

DESIGN

To get a 5.6 V as output, select SZ 5.6 as Zener diode .Take load current as 5 mA.

= 5.6/5 mA

= 1.1 K (use 1.2 K)

R1 is used to limit the current .Take 1 K resistor as R1.

THEORY

Zener diode is a P-N junction diode specially designed to operate in the reverse biased mode. It is acting as normal diode while forward biasing. It has a particular voltage known as break down voltage, at which the diode break downs while reverse biased. In the case of normal diodes the diode damages at the break down voltage. But Zener diode is specially designed to operate in the reverse breakdown region.

The basic principle of Zener diode is the Zener breakdown. When a diode is heavily doped, it’s depletion region will be narrow. When a high reverse voltage is applied across the junction, there will be very strong electric field at the junction. And the electron hole pair generation takes place. Thus heavy current flows. This is known as Zener break down.

So a Zener diode, in a forward biased condition acts as a normal diode. In reverse biased mode, after the break down of junction current through diode increases sharply. But the voltage across it remains constant. This principle is used in voltage regulator using Zener diodes.

PROCEDURE

1. Check the components using multimeter

2. Wire up and test a bridge rectifier circuit.

3. Wire up the regulator circuit

4. Apply the output of rectifier to the regulator

5. Now keep the input voltage constant and vary the rheostat at output. Note down the voltmeter and ammeter readings

6. Now take the voltmeter and ammeter readings by varying the input voltage

6. Plot the graphs for line and load regulation and find the values by taking the slopes of the graphs.

OBSERVATIONS

 Vin(volts) Vout(volts)
 Vo(volts) IL(mA)

GRAPH

1. LINE REGULATION

Line regulation=Change in output\Change in input

RESULT

A Zener voltage regulator was designed .Graphs were plotted. Line regulation and load regulation was calculated.

Line regulation=……………..

SAMPLE VIVA QUESTIONS

1. What is the basic principle of Zener diode?

Zener breakdown

2. What is Zener break down?

When a diode is heavily doped, it’s depletion region will be narrow. When a high reverse voltage is applied across the junction, there will be very strong electric field at the junction. And the electron hole pair generation takes place. Thus heavy current flows. This is known as Zener break down.

3. What is the break down voltage of Zener diode?

It is the reverse voltage at which break down of PN junction occurs

##### We recommend:
• C S hiremath
July 6, 2015

load regulation=(Vnl-VFl)/ Vfl or =(VNl-VFl)/VNl ?
What are typical values ?

• C S hiremath
July 6, 2015

Which is correct & typical values of load regulation

• William Marshall
January 9, 2013

I wish to build a Zener diode voltage regulator so as to charge a 6 volt wet-cell battery from a 12 vdc charging system on a small tractor. Any help you can provide to me would be greatly appreciated.

• August 8, 2012

please make the diagrams visible to us

• Shivani
July 15, 2011

Same request again! Diagrams need to be made visible!!

• kiru
May 10, 2011

please make the diagrams visible to us

• sarbjit singh
August 29, 2010

hello sir…
i m an electrical engineer, but i didnt have any practicle knowledge, But now i think your website will help me to improve my self. Thank you s

• Santosh Kittur
August 5, 2009

hello sir…
i m an electrical engineer, but i didnt have any practicle knowledge, But now i think your website will help me to improve my self. Thank you sir..

In above ZENER DIODE VOLTAGE REGULATOR details i didnt get some data, like circuit, line regulation, load regulation… So can you help me…

• Peter Ellmers
April 25, 2009

Hi
I found your post re voltage regulation. We have a need to control voltage for audio input to a car audio amplifier.
With the amp switched to low power input in works well with MP3 input voltage (2-3 volts)
But with high power head units (9 volts – can deliver 50 watts per channel), the amp can handle this if the high input switch is activated.
We do not want to activate this but leave switch in low power setting – but use a voltage regulator so input voltage is always low and same for all.
Ie. We can use MP3 or head unit power amp without switching and adjusting gain control.
Hope I make sense and would really appreciate any comments.
Best Regards
Peter