SCHOOL OF ELECTRICAL ENGINEERING
Laboratory Manual
Basic Electrical & Electronics Engineering - BEEE102P
Name
: Ajay Tiwari
Reg. No : 23BCT0075
Slot
: L13 + L14
SCHOOL OF ELECTRICAL ENGINEERING
Course Name
: Basic Electrical and Electronics Engineering Practical
Course Code
: BEEE102P
Register Number : 23BCT0075
Hardware Experiments
Sl.No
Name of the Experiment
4
Design of regulated power supply using Zener diode
5
Characteristics of PN junction diode
Ex. No.: 24
Design of regulated power supply using Zener diode
Aim:
To verify the performance of Zener diode
Apparatus/Tool required
S. No.
Name of the apparatus
1
Zener diode
Range /
Type
-
2
RPS
0 – 30 V
1 No.
3
Voltmeter
0 – 30 V
2 No.
4
Resistor
330 Ω
1 No.
5
Resistor
1 kΩ
1 No.
6
Breadboard
-
1 No.
7
Wires
-
Few
Quantity
1 No.
Theory
Zener diodes are generally used in the reverse bias mode. This voltage across the diode (Zener
Voltage, Vz) remains nearly constant even with large changes in current through the diode
caused by variations in the supply voltage or load. This ability to control itself can be used to
great effect to regulate or stabilize a voltage source against supply or load variations. The Zener
diode maintains a constant output voltage until the diode current falls below the minimum Iz
value in the reverse breakdown region, which means the supply voltage, V
S, must be much
greater than Vz for a successful breakdown operation. When no load resistance, R L, is connected
to the circuit, no load current (I L = 0), is drawn and all the circuit current passes through the
Zener diode which dissipates its maximum power. So, a suitable current limiting resistor, (R S) is
always used in series to limit the Zener current to less than its maximum rating under this "noload" condition.
As shown in the circuit diagram, a more stable reference voltage can be produced by connecting
a simple Zener regulator circuit across the output of the rectifier. The breakdown condition of
the Zener can be confirmed by calculating the Thevenin voltage, V TH, facing the diode is given
as:
This is the voltage that exists when the Zener is disconnected from the circuit. Thus, V THhas to
be greater than the Zener voltage to facilitate breakdown. Now, under this breakdown condition,
irrespective of the load resistance value, the current through the current limiting resistor, I S, is
given by
The output voltage across the load resistor, V L, is ideally equal to the Zener voltage andthe load
current, IL, can be calculated using Ohm’s law:
Thus the Zener current, IZ, is
Now that you have constructed a basic power supply, its quality depends on its load and line
regulation characteristics as defined below.
Load Regulation: It indicates how much the load voltage varies when the load current changes.
Quantitatively, it is defined as:
where V NL = load voltage with no load current (IL = 0) and V FL = load voltage with full load
current. The smaller the regulation, the better is the power supply.
Line Regulation: It indicates how much the load voltage varies when the input line voltage
changes. Quantitatively, it is defined as:
where VHL = load voltage with high input line voltage, and V LL = load voltage with low input line
voltage. As with load regulation, the smaller the regulation, the better is the power supply.
Circuit Diagram
330
0-15V
0-15V
V
1k
Zener Diode
Table (i) Line Regulation: Load Resistor = 1000 Ω
Sl.No
InputDC Voltage (Vi)
in Volts
Output DC Voltage (VL)
in Volts
1
2 volts
1.75 V
2
4 volts
3.75 V
3
6 volts
5V
4
8 volts
5V
5
10 volts
5V
6
12 volts
5V
7
14 volts
5.1 V
8
16 volts
5.1 V
9
18 volts
5.1 V
10
20 volts
5.1 V
Table (ii) Load Regulation: Input d.c. voltage = 10 V
Sl.No
Load Resistance in
ohms
Output DC Voltage (V L)
in Volts
1
1k Ω.
4.75V
2
5.6k Ω.
5.1 V
3
10k Ω.
5.1 V
Photograph of the practical circuit done in the lab
Procedure:
Line Regulation:
1. Connect the circuit as shown in the diagram
2. Keep the load resistance constant at a particular value
3. Vary the input voltage and note down the variation in the output voltage
Load Regulation:
1. Connect the circuit as shown in the diagram
2. Keep the input voltage constant at a particular value
3. Vary the load resistance and note down the variation in the output voltage
Result:
the voltage across the zener will remain steady at its breakdown voltage Vz for all the value
of zener current as long asd the current remain in the breakdown region.Hence a regulated
DC output voltage Vo=Vz is obtained across Rl
Ex. No.: 5
Characteristics of PN junction diode
Aim:
To plot two cost-ampere characterstics of PN junction diode
Apparatus/Tool required
S. No:
Component
name
Specification / Range
Quantity
1.
PN diode
1N4001
1
2.
Resistor
1KΩ
1
3.
D.C Voltmeter
0-1V , 0-15V
1
4.
D.C Ammeter
0-50mA , 0-200uA
1
0 – 3 Volts
1
------
1
Variable DC
5.
6.
supply
Bread Board
Theory:
When PN diode is forward baised ,the applied voltage or applied potential difference due to
hole and electron or applied potential difference due to hole and electron to move towards the
junction .Eventually potential barrier disappear and diode start conducting.
When reverse baised , the hole and electron mpves towards the battery, increasing the width of
potential barrier. Therefore no current passes, but in practical a very small current ( uA ) flow
and the current is known as reverse leakage current . When leakage voltage is applied due to the
free electron and current flow and breakdown happen and this is called breakdown voltage.
Circuit diagram:
fig:- forward bias
T
A
M
P
LC
V
O
A
(
C
D
P
C
PV
W
NEP
A
C
P2
fig:- Reverse bias
P-N Diode diagram
P-N Diode symbol
Tabular column;forward characteristics
Reverse characteristics
S,No
Vf(volt)
If(mA)
S.No
VR(Volt)
IR(UA)
1
0.1
0
1
0.5
40
2
0.2
0
2
1.0
70
3
0.3
0.5
3
1.5
100
4
0.4
0.5
4
2.0
130
5
0.5
1
5
2.5
160
6
0.6
7
6
3.0
180
7
0.62
10
7
3.5
210
8
0.64
12
8
4.0
240
9
0.66
15
9
4.5
270
10
0.68
18
10
5.0
300
11
0.7
22
11
5.5
330
12
0.72
26
12
6.0
360
13
0.74
32
13
6.5
390
Model Calculation:
Forward resistance :-
Vf/
If = 0.5-0.4/( 1-0.5 )*10^-6 = 0.02 *10^3= 20 Ω
Reverse resistance :-
VR/
IR = 1.5-1/( 100-70)*10^-6 = 16.67KΩ or 16670Ω
Photograph of the practical circuit done in the lab
Precautions:
The power supply should be off before connecting circuit
The regulated power supply should be set to minimum position while giving power supply
Result :
. Forward Resistance = 20 Ω
. Reverse Resistance = 16670Ω
. Cut in Voltage = 0.7V
32