ELECTRICAL ENGINEERING DEPARTMENT,
University of Engineering & Technology Lahore
(New Campus)
Electronic Devices & Circuits Lab Report (EE- 216L)
Submitted to:
Ms. Iqra Farhat
Submitted by:
M. Abdullah (2022-EE-265)
(Experiment No.8)
Characteristics of Zener Diode as Voltage Regulation
Objective: The objective of the experiment is to investigate the
characteristics of a Zener diode in voltage regulation. This includes
studying its behavior under varying load conditions and analyzing its
ability to maintain a stable output voltage despite fluctuations in
input voltage and load resistance. The experiment aims to
understand the Zener diode's voltage regulation capabilities and to
determine its practical applications in electronic circuits for voltage
stabilization purposes.
Theory: Zener diodes are semiconductor devices designed to operate
in the reversebiased breakdown region of their voltage-current
characteristic curve. Unlike regular diodes, which are typically used
for forward conduction, Zener diodes are employed in reverse
breakdown mode where they exhibit a stable voltage across their
terminals, known as the Zener voltage (Vz). This unique property
makes Zener diodes suitable for voltage regulation applications.
Zener diodes
When a Zener diode is reverse-biased and the applied voltage exceeds
its Zener voltage, it enters into the breakdown region. In this region,
the Zener diode conducts current relatively freely while maintaining a
nearly constant voltage across its terminals, regardless of changes in
applied voltage (within a specified range) or variations in load
resistance. This phenomenon occurs due to the avalanche or Zener
breakdown mechanism, depending on the construction of the diode.
Circuit Diagram
Materials and Equipment:
DC power supply
Digital Multimeter
Zener Diode (6.2V)
Resistor (1K ohm)
Procedure:
1. Apply a DC voltage to the input of the circuit according to the
circuit diagram.
2. Measure the input and output voltages and current using
Digital Multimeter.
3. Note and observe the behavior of the circuit.
Experimental setup:
Lab setup;
Figure (A) recording & observing the behavior of a Zener Diode as Voltage
Regulation circuit in Lab.
Proteus simulations:
Figure (B) Input Voltage = 6.65V, Circuit Current = Iz = 0.5mA & Voltage
across Diode = 6.15
Figure (C) Input Voltage = 12.1V, Circuit Current = Iz = 5.88mA & Voltage
across Diode = 6.22
Figure (D) Input Voltage = 36V, Circuit Current = Iz = 29.7mA & Voltage
across Diode = 6.27
Observations & Calculations
Input Voltage = 6.6V – 34.2V
Resistor = 1Kohm
Zener Diode = 6.2V
Iz (mA) Vz (Volts) Vin (Volts)
0.5 6.18 6.6
1 6.19 7.19
2 6.20 8.1
3 6.20 9.1
4 6.22 10.2
6 6.22 12.1
8 6.22 14.2
10 6.27 16.1
15 6.28 21.0
20 6.32 25.7
30 6.32 34.2
Discussion: The experiment investigating the characteristics of a
Zener diode in voltage regulation has provided valuable insights into
its functionality and practical applications. Through the analysis of
the Zener diode's behavior under varying load conditions and input
voltages, several important conclusions can be drawn.
The experiment illustrated the practical significance of Zener diodes
in voltage regulation circuits. These devices find wide-ranging
applications in electronic systems requiring precise voltage
stabilization, such as voltage regulators, power supplies, and voltage
references.
Conclusion: the experiment elucidated the fundamental
characteristics of Zener diodes in voltage regulation and
demonstrated their crucial role in maintaining stable output voltages
in electronic circuits. Understanding these characteristics is essential
for designing reliable and efficient voltage regulation circuits for
various electronic applications.
