NAME – Saurav Gupta

Roll no – 19ME3FP14

EXPERIMENT – 3
HALF WAVE & FULL WAVE RECTIFIER
AIM :
1.Explain rectification.

2. To study the characteristics of half and full wave rectification for positive and negative cycles.

APPARATUS

BACKGROUND KNOWLEDGE
• Rectifier:
A Rectifier is a circuit that converts alternating current (AC) current into direct
current (DC). It is an essential part of power supply. The unique property of a
diode, permitting the current to flow in one direction, is utilised in rectifiers. It
takes current that flows alternately Sl. No. Name Of The Equipment Qty. 1
Resistor 1 2 Voltmeter 1 3 Ammeter 1 4 Oscilloscope 1 5 Transformer - 6
Connecting Wires - 7 Diodes - 2 in both directions, and modifies it so that the
output current flows only in one direction.
• Half-wave Rectifier:
Electronic devices can convert AC power into DC power with high efficiency.
During the positive half cycle, the diode is forward biased and it conducts and
hence a current flow through the load resistor. During the negative half cycle,
the diode is reverse biased and it is equivalent to an open circuit, hence the
current through the load resistance is zero. Thus, the diode conducts only for
one half cycle and results in half wave rectification.
• Full-wave Rectifier:
We know, the half-wave rectifier is very simple and does work but it isn't very
efficient. It only uses half of the incoming ac cycle, and wastes all of the energy
available in the other half. For greater efficiency, we would like to be able to
utilize both halves of the incoming ac. A full-wave rectifier converts the whole
of the input waveform to that of a constant polarity (positive or negative) at its
output. We can use two separate half-wave rectifiers on alternate half-cycles,
to provide full-wave rectification.
• Full Wave Rectifier – Center Tapped Transformer:
During the positive half cycle of the transformer secondary voltage, diode D1 is
forward biased and D2 is reverse biased. So a current flows through the diode
D1, load resistor RL and upper half of the transformer winding. During the
negative half cycle, diode D2 becomes forward biased and D1 becomes reverse
biased. The current then flows through the diode D2, load resistor RL and
lower half of the transformer winding. This rectifier configuration, like the half-
wave rectifier, calls for one of the transformer's secondary leads to be
grounded. In this case, however, it is the center connection, generally known
as the center tap on the secondary winding.
• Bridge Rectifier:
Another type of circuit that produces the same output waveform as the full
wave rectifier circuit above, is that of the Full Wave Bridge Rectifier. This type
of single phase rectifier uses four individual rectifying diodes connected in a
closed loop “bridge” configuration to produce the required output.
GRAPHS AND OBSERVATION TABLE OF HALF-WAVE AND FULL-
WAVE RECTIFIER :
Circuit diagram of half-wave & full-wave rectifier :
RESULT & CALCULATIONS:
The Half and Full Wave Rectifier circuit design output waveforms have been
studied and the required parameters have been calculated. Ripple factor is
defined as the ratio of effective value of AC component to the average DC
value.
SUMMARY OF ALL THE CALCULATIONS (DONE BELOW) :
FOR HALF WAVE RECTIFIER :
FOR FULL WAVE RECTIFIER :
DISCUSSION :
 In this part of the laboratory, the operations of half and
full-wave rectifier were observed with the help of
oscilloscope.
 A rectifier is an electrical component that converts
alternating current (AC) to direct current (DC).
 A rectifier is analogous to a one-way valve that allows an
electrical current to flow in only one direction.
 The process of converting AC current to DC current is
known as rectification.
 As we are aware that all electrical appliances use a DC
power supply to function.
 Bridge rectifiers are widely used for large appliances,
where they are capable of converting high AC voltage to
low DC voltage.
 V-I CHARACTERSTISTICS OF DIODE
OBJECTIVE :
1.Explain the function of a P-N junction diode
2.Explain forward and reverse biased characteristics of a Silicon diode
3.Explain forward and reverse biased characteristics of a Germanium diode

Aim of the experiment:

1.VI Characteristics of a Diode
2. To understand half-wave rectifier

Tools used:
● AC Sine Source
● Ammeter
● Voltmeter
● Rheostat
● Free Wire
● Diode
● Capacitor
● DC Source
● Zener Diode

THEORY:

The diode is a device formed from the junction of a p-type and n-

type semi-conductor material. At the junction there is a small
potential difference due to intermixing of holes and electrons.
This creates the depletion zone. During forward bias, the p side
isconnected to the positive terminal of the battery and the n side to
the negative terminal.This allows the Electrons from the battery to
push the electrons on the n-side towards the junction thereby
reducing the depletion layer. The same occurs on the other side.
During reverse bias, the p side is connected to the negative
terminal of the battery and the n side to the positive terminal. The
negative terminal pulls the holes towards the terminal,which leaves
behind charged ions thereby increasing the depletion region. The
sameoccurs on the other side.During forward bias the diode starts
conducting current after the cut-in voltage.
Cut-involtage for Si = 0.6 eV and for Ge = 0.3 eV During reverse
bias the diode resists the flow ofcurrent until the breakdown
voltage is reached, after which it acts like an open switch.

Baising Conditions :
i. Zero Bias –No external voltage is applied across the P-N
junction.
ii. Reverse Bias –The voltage potential is connected -ve to
the P-typeand +ve to the N-type material across the
diode. Width of thedepletion layer increases and also
voltage barrier.
iii. Forward bias -The voltage potential is connected +ve to
the P-typeand -ve to the N-type material across the
diode. Width of thedepletion layer decreases and also
voltage barrier.
OBSERVATION TABLE , GRAPHS
AND CIRCUIT DIAGRAM :

FORWARD BIASED SILICON DIODE

For other value of VF
REVERSE BIAS SILICON DIODE :
FOR OTHER VALUE OF VR
FORWARD BIASED GERMANIUM DIODE :
REVERSE BIASED GERMANIUM DIODE :
SUMMARY/RESULT :
Thus from the graphs we can conclude that a diode conducts the
electricity in only forward biased situation ,The order of the current
is in mA in case of forward biased situation where as in reverse
biased situation , the order of the current is that of micro ampere.
Cut-involtage for Si = 0.6 eV and for Ge = 0.3 eV
respectively.During reverse bias the diode resists the flow of
current until the breakdown voltage is reached, after which it
acts like an open switch.

DISCUSSION :
• When a junction diode is Forward Biased the thickness of
thedepletion region reduces and the diode acts like a short
circuitallowing full circuit current to flow.

• When a junction diode is Reverse Biased the thickness of

thedepletion region increases and the diode acts like an open
circuitblocking any current flow, (only a very small leakage
current willflow).

• Due to forward bias condition ,the voltage barrier is

reduced,therefore allows a large amount of current to flow
through it like ashort circuit after a specific voltage is reached
called knee voltage.For silicon (0.6V), Ge(0.3V).

• Due to reverse bias condition, voltage barrier is increased

that leadsto have a very low amount of current flow in micro
Amp ideallytreated insulator. After applied voltage increased
uptobreakdown(Vapplied increases to such a such that it
overcomesdiode’s voltage barrier) leads to convert it as
conductor Frominsulator. Large amount of current starts to 12
pass through havingvoltage approxmetly constant .as shown in
graph.