this report still not done yet and got many errors

1. ELECTRICAL ENGINERING
LABORATORY 1
EEE230
EXPERIMENT 5
DIODE APPLICATION
1

2. CONTENTS
Title Page
Introduction/theory PART A:3-4
PART B:9-10
Result PART A:5-6
PART B:11-13
Discussion/Question PART A:7-8
PART B:14
Conclusion 15
References 16
2

3. PART A ; Rectifier circuit using diode
Introduction
In this experiment, we have learned about the applications of diode. First, we were
revising the basic of equipments handling. Secondly. we were knew that one of the
main component used in the making of rectifier circuits are diodes and there are
three types of rectifier circuits Thirdly, we have been introduced to the function of
a capacitor in a rectifier circuit. Lastly, we also have learned about how to build a
simple diode clipping and diode clamping circuits
Theory
Usually we have three main type of rectifier it is a half-wave rectifier circuit,
center tap full-wave rectifier circuit and full-wave bridge rectifier circuit.
Firstly about half-wave rectifier circuit, when diode was connect to source
AC voltage supply, itwill be alternatelyforward-biased, and then reverse-biased,
during each cycle of the AC sine-wave. When a singlediode is used in a rectifier
circuit, current will flow through the circuit only during one-half of the input
voltage cycle like in figure below. For this reason, this rectifier circuit is called a
half-wave rectifier. The output of a half-wave rectifier circuit is pulsating DC.
Second is about center tap full-wave rectifier circuit is uses two diodes
connected to the secondary of a center tapped transformer. The AC on each side of
3

4. the center-tap is ½ of the total secondary voltage. Only one diode will be biased on
at a time the prose to be center tap full-wave rectifier is like below.
Last is about full-wave bridge rectifier circuit, The Bridge is shown in the
figure below. The circuit has four diodes connected to form a bridge. The ac input
voltage is applied to the diagonally opposite ends of the bridge. The load
resistance is connected between the other two ends of the bridge.
4

5. RESULT PART A
Experiment 5.1
Without capacitor With capacitor
Experiment 5.2
Without capacitor With capacitor
5

6. Experiment 5.3
Without capacitor with capacitor
Input
Output
dc output voltage Ripple voltage
(without capacitor) (with capacitor)
Half-wave rectifier 6.60V 0.80V
Center tap full-wave rectifier 5.56V 0.38V
Full-wave bridge rectifier 5.52V o.43V
6

7. DISCUSSION
Based on the experiment above, on the first positive half cycle the diode conducts charging the
capacitor left. This is on the right end, the right end of the capacitor with respect to the ground. It
is also has an AC peak sine wave coupled across it from source to node. The sum of the two is
a peak sine riding on a negative DC level. The diode only conducts on successive positive
excursions of source V if the peak exceeds the charge on the capacitor. This only happens if the
charge on the capacitor drained off due to a load. The charge on the capacitor is equal to
positive peak of V. The AC riding on the negative end, right end, is shifted down. The positive
peak of the wave form is clamped to 0V because the diode conducts on the positive peak.
In the negative cycle of the input AC signal, the diode is forward biased and conducts,
charging the capacitor to the peak positive value. During the positive cycle, the diode is reverse
biased and thus does not conduct. The output voltage is therefore equal to the voltage stored in
the capacitor plus the input voltage gain.
In the positive cycle of the input AC signal, the diode is forward biased and conducts,
charging the capacitor to the peak voltage value. During the negative cycle, the diode is reverse
biased and thus does not conduct. The output voltage is therefore equal to the voltage stored in
the capacitor plus the input voltage gain, so Vout = negative.
A positive biased voltage clamp is identical to an equivalent but with output voltage
offset by the bias amount. A negative biased voltage clamp but with the output voltage offset in
the negative direction by the bias amount.
Based on the experiment above, on the first positive half cycle the diode conducts
charging the capacitor left. This is on the right end, the right end of the capacitor with respect to
the ground. It is also has an AC peak sine wave coupled across it from source to node. The sum
of the two is a peak sine riding on a negative DC level. The diode only conducts on successive
positive excursions of source V if the peak exceeds the charge on the capacitor. This only
happens if the charge on the capacitor drained off due to a load. The charge on the capacitor is
7

8. equal to positive peak of V. The AC riding on the negative end, right end, is shifted down. The
positive peak of the wave form is clamped to 0V because the diode conducts on the positive
peak.
In the negative cycle of the input AC signal, the diode is forward biased and conducts,
charging the capacitor to the peak positive value. During the positive cycle, the diode is reverse
biased and thus does not conduct. The output voltage is therefore equal to the voltage stored in
the capacitor plus the input voltage gain.
In the positive cycle of the input AC signal, the diode is forward biased and conducts,
charging the capacitor to the peak voltage value. During the negative cycle, the diode is reverse
biased and thus does not conduct. The output voltage is therefore equal to the voltage stored in
the capacitor plus the input voltage gain, so Vout = negative.
A positive biased voltage clamp is identical to an equivalent but with output voltage
offset by the bias amount. A negative biased voltage clamp but with the output voltage offset in
the negative direction by the bias amount.
8

9. PART B:Diode clipping and clamping circuit.
Theory
Diode characteristics
From the figure above we can see the diode has a terminal not like the
transistor. The negative (-ve) terminal is know as cathode and for positive (+ve)
terminal is know as anode.
Diode in electrical is a component just allow electricity flow in one direction from
anode to cathode. The diode can become conductor went the diode are place in
forward bias and also become insulator if place in reverse bias.
Like the figure (a) the diode become a conductor because went diode in forward
bias the resistance in diode become lower and in figure (b) the diode became
higher resistance because of that the current cannot through it.
9

10. Diode clipping circuit
A clipping circuit consists of linear elements like resistors and non-linear elements
like junction diodes or transistors, but it does not contain energy-storage elements
like capacitors. This clipping function is to cut the upper or the lower portion of
signal this figure below is example the circuit for diode clipping circuit.
Diode clamping circuit
The clamping circuit is difference with the clipping circuit, because the clamping
circuit are build is to clamp to a required DC level, basically the circuit of
clamping is the load was parallel with diode like in figure below.
10

11. RESULT PART B
PART 1
Waveform Result for Figure 5.7
Waveform Result for Figure 5.8
11

12. Waveform Result for Figure 5.9
Waveform Result for Figure 5.1
12

13. PART 2
13

14. DISCUSSION
Part 1 Clipping Circuit : Principles of operation
The schematic of a clamper reveals that it is a relatively simple device. The two
components creating the clamping effect are a capacitor, followed by a diode in
parallel with the load. The clamper circuit relies on a change in the capacitor’s time
constant; this is the result of the diode changing current path with the changing input
voltage. The magnitude of R and C are chosen so that is large enough to ensure
that the voltage across the capacitor does not discharge significantly during the diode's
"Non conducting" interval. During the first negative phase of the AC input voltage,
the capacitor in the positive clamper charges rapidly. As Vin becomes positive, the
capacitor serves as a voltage double; since it has stored the equivalent of Vin during
the negative cycle, it provides nearly that voltage during the positive cycle; this
essentially doubles the voltage seen by the load. As Vinbecomes negative, the
capacitor acts as a battery of the same voltage of Vin. The voltage source and the
capacitor counteract each other, resulting in a net voltage of zero as seen by the load
Part 2 Clamping circuit : Basic operation
The schematic of a clamper reveals that it is a relatively simple device. The two
components creating the clamping effect are a capacitor, followed by a diode in
parallel with the load. The clamper circuit relies on a change in the capacitor’s time
constant; this is the result of the diode changing current path with the changing
input voltage. The magnitude of R and C are chosen so that is large enough to
ensure that the voltage across the capacitor does not discharge significantly during
the diode's "Non conducting" interval. During the first negative phase of the AC input
voltage, the capacitor in the positive clamper charges rapidly. As Vin becomes
positive, the capacitor serves as a voltage double; since it has stored the equivalent
of Vin during the negative cycle, it provides nearly that voltage during the positive
cycle; this essentially doubles the voltage seen by the load. As Vinbecomes negative,
the capacitor acts as a battery of the same voltage of Vin. The voltage source and the
capacitor counteract each other, resulting in a net voltage of zero as seen by the
load.
14

15. CONCLUSION
part A
From that experiment we can conclude the diode can change the AC input to the
DC output. Because the diode just allows current flow to it just in one direction
only. How we know in this experiment we find many type of rectifier such as half-
wave rectifier circuit like in figure 5.1, center tap full-wave rectifier circuit like in
figure 5.2 and full-wave bride rectifier like in figure 5.3, every circuit are given the
different type of output voltage supply and different type of output wave form and
this experiment we also get how to use oscilloscope and multimeterbetter. This
experiment we also know with is the best rectifier. And the best rectifier is full-
wave rectifier.
Part B
From both experiment we can conclude the diode can become insulator when in
reverse biased and also can be a conductor when in forward biased because that’s
time the resistance become low and can make the current easily flow trough diode.
In this experiment also we know the how to differentiate the clipping circuit and
clamping circuit just look at the circuit for example the clipping circuit the load is
in series with the diode and the clamping circuit is the load is parallel with the
diode. This experiment we know the clipping and clamping circuit are function to
cut the signals peak.
15

16. REFERENCE
Internet
http://sleepycity.net/troublemakers/diodehttp:
http://www.electronickitsbychaneyelectronics.com
http://penang.i-learn.uitm.edu.my
http://www.scribd.com/
http://nuclearpowertraining.tpub.com/
http://metroamp.com/wiki/
http://www.allaboutcircuits.com
Books
Laboratory manual
Fundamentals of electric circuit
16