This document presents a project on designing a series voltage regulator. A group of four students - Raj Saha, Parthib Roy, Rahul Kumar, and Aishwarya Maitra - completed the project under the guidance of their teacher, Mrs. Anindita Sinha. The project involved building a circuit using a Zener diode and transistor to regulate an input voltage of 12.5V to an output of around 5.18V. The document discusses the applications, circuit diagram, materials used, working principle, calculations, conclusions, and references for the project.

1. MINI PROJECT PRESENTATION
ON
Designing a series voltage
regulator
Submitted by:
Names: Raj Saha, Parthib Roy, Rahul Kumar, Aishwarya Maitra
ROLL NOs: -
11900320005,11900320010,11900320015,11900320020
Under the guidance of
Mrs. Anindita Sinha

2. ACKNOWLEDGEMENT
We would like to express our sincere
thanks to Mrs. Anindita Sinha (project
guide), for her valuable guidance and
support in completing our project.
We would also like to express our gratitude
towards Mrs. Arpita Roy Sarkar, Mrs.
Priyanka Nandy (Project teacher) for giving
us this great opportunity to do a project on
Series Voltage Regulator(6V). Without their
support and suggestions, this project would
not have been completed.

3. CONTENT
S
• Introduction
• Some application of Voltage Regulator
• Circuit Diagram
• Materials Required
• Model
• Working Principle of Voltage
Regulator
• Calculation
• Input / Output Graph
• Conclusion
• References

4. INTRODUCTION
A voltage regulator is a voltage stabilizer that is designed to automatically
stabilize a constant voltage level. A voltage regulator circuit is also used to
change or stabilize the voltage level according to the necessity of the
circuit. Thus, a voltage regulator is used for two reasons:-
1. To regulate or vary the output voltage of the circuit.
2. To keep the output voltage constant at the desired value in-spite of
variations in the supply voltage or in the load current.
Series Regulators use a power transistor connected in series between the
unregulated DC input and the load. The output voltage is controlled by
the continuous voltage drop taking place across the series pass transistor.

5. SOME APPLICATIONS OF VOLTAGE
REGULATORS
• Use in all power supplies to electronic gadgets to regulate voltage and save the device
from damage
• Used with the alternator of internal combustion engines to regulate the alternator
output.
• Used for electronics circuits to supply a precise amount of voltage

6. CURCUIT
DIAGRAM

7. MATERIALS REQUIRED
• R1=0.55 k Ω = 560 Ω (Approx)
• R2=0.14 k Ω = 120 Ω (Approx)
• R3=0.7 k Ω = 680 Ω (Approx)
• R4=4.30 k Ω = 4.7 k Ω (Approx)
• DC Power supply
• Q1 = SL100
• Q2 = BC107
• Multimeter
• Breadboard

8. OUR
MODEL

9. WORKING PRINCIPLE
A voltage regulator is a circuit that creates and maintains a fixed output voltage, irrespective of changes to the input voltage or load
conditions.
Voltage regulators (VRs) keep the voltages from a power supply within a range that is compatible with the other electrical
components. While voltage regulators are most commonly used for DC/DC power conversion, some can perform AC/AC or AC/DC power
conversion as well.
Zener Controlled Transistor Series Voltage Regulator
Such a circuit is also named an emitter follower voltage regulator. It is called so because the transistor used is connected in an emitter
follower configuration.
The circuit consists of an N-P-N transistor and a Zener diode, the collector and emitter terminals of the transistor are in series with
the load. Thus this regulator has the name series in it. The transistor used is a series pass transistor.
Zener Controlled Transistor Series Voltage Regulator
The output of the rectifier that is filtered is then given to the input terminals and regulated output voltage Vload is obtained across
the load resistor Rload. The reference voltage is provided by the Zener diode and the transistor acts as a variable resistor, whose
resistance varies with the operating conditions of base current, Ibase.

10. CALCULATIO
N
V0 = 6v Iz = 40mA
Vz = 0.75v0 = 0.75*6 V = 4.5V
IR2 = 10mA (For minimum current)
IE1(max) = IL+ID2
= 40+10 = 50mA
Specified for Q1:
Vin = 9V
hFE1(min) = 50 (CL 100)
IB1 = IE1(max)/ hFE1 = 50/50
= 1mA
IC2 = 5mA
VB1= VBE1 + V0 = 0.6 + 6 = 6.6
R1 = (Vin-VB1)/(Ic2+IB1)
= (12-6.6)/6
= 0.9 k Ω
(Voltage at the base of Q1 is VB1 =
Vo+ VBE1 = 0.7)
R2 = (Vo-Vz)/IRZ = 0.15 k Ω
Assuming,
I4 = 1mA
R4 = (Vz+VBE2)/I4 = 5.1 k Ω
VR4 = R4I =( 5.1*103)*10-3 = 5.1V
R3 = (Vo-VR4)/I4 = 0.9 k Ω

11. CONCLUSIO
N
The Zener diode, with its accurate and specific reverse breakdown voltage,
allows for a simple, inexpensive voltage regulator. Combined with the right
resistor, fine control over both the voltage and the supply current can be
attained.
However, the low power ratings of standard Zener diodes and resistors make
this solution impractical for high power devices.
We have used potentiometer(5 k Ω) in place of R3 and R4 for getting our
desired output. In circuit for Vin=12.5 volt we have got Vout=5.18 volt which in
approximately near our desired output.

12. REFERENCES
We referred to these following books and websites while making our project:
https://www.electronics-notes.com/articles/analogue_circuits/power-
supply-electronics/linear-psu-series-regulator-circuit.php
"Write Your Topic Or Idea"
Electronic Devices And Curcuits – David. A. Bell
"Write Your Topic Or Idea"