experiment 3 for b.electronic
TRANSCRIPT
UNIVERSITI PENDIDIKAN SULTAN IDRIS
SFE 3013
BASIC ELECTRONICS
LABORATORY REPORT 3
EXPERIMENTS FOR DIODE CHARACTERISTICS
SITI NOR AMIRA BINTI MOHMAD NOOR
D20091035073
NUR HAFIZAH BINTI ABDU HADI
D20091035072
PENDIDIKAN SAINS
SEMESTER 1 (2011/2012)
LECTURER:
DR SYED ABDUL MALIK SYED MOHAMAD
Experiment 3: Experiments for Diode Characteristics.
Objective:-
1) To understanding the characteristics of each type of diode.
2) To recognize the specification of each type of diode.
3) To learn how to test the characteristics of each type of diode by using various instruments
4) How to Judge the accepted and defective diode.
Apparatus:-
1) KL 21001 linear circuit
2) Experiment module KL 23001
3) Experiment instrument: oscilloscope and digital multimeter
4) Tool: Basic hand tools
5) Materials: as indicated in the KL 23001
Procedure:-
Part A- Experiment for silicon diode
Plotting the V-I characteristics curve of silicon diode (1) using oscilloscope.
1) Fix the module KL 23001 linear circuit lab then located the block marked 23001-
block a.
2) Insert the short circuit jumper clip referring figure 3.1 b
3) The 2.0Vpp, 1Khz sine wave to IN terminal
4) Using channel 2 for Y component to test point TP1 and TP2 then used channel 2 for
X component of oscilloscope to test points TP3 and TP2. TP1 used for vertical input
and TP3 used for horizontal input.
5) Change the display method ad oscilloscope to display the wave at screen.
6) Record the graph at oscilloscope.
Plotting the V-I characteristics curve of silicon diode (2) using digital multimeter.
1) Fix the module KL 23001 linear circuit lab then located the block marked 23001- block a.
2) Insert the short circuit jumper clip referring figure 3.2. the voltmeter and ammeter was
connected.
3) Connect the 12VDC to the .IN. terminal, then adjust VR2 (10 kΩ) to apply
4) voltage to 2 terminals of the diode as shown in Table (1) from 0.1V to 0.7V and
5) view the corresponding I f (forward current). Use VR2 to continuously adjust V f
6) to view how I f will change then record in Table (1).
7) 4 Insert the short-circuit jumper clip by referring to Figure 3.2 and short-circuit clip
8) arrangement diagram in Figure 3.3 (b) (reverse connection). Connect the
9) Voltmeter and Ammeter.
10) 5 Connect 12VDC to the .IN. terminals then adjust VR2 (10 kΩ) to apply reverse
11) voltage to 2 terminals of the diode as shown in Table (2) from 0V to 5V, and view
12) the corresponding I R. Then record in Table (2)
13) 6 Plot the values of Table (1) (2) on the coordinate paper (Fig 2)
Plotting the V-I characteristics curve of germanium diode (3) using digital multimeter.
1. First, fix the module KL-23001 in the KL-21001 Linear Circuit Lab, then locate
the block marked 23001- block a.
2. Insert the short-circuit clip jumper by referring to Figure 3.4 and the short-circuit
clip jumper arrangement diagram in Figure 3.5 (a) (forward connection). Connect
the Voltmeter and Ammeter.
3. Connect the 12VDC to the .IN. terminal, then adjust VR2 (10 kΩ) to applyvoltage to 2
terminals of the diode as shown in Table (3) from 0.1V to 0.7V and view the
corresponding I f (forward current). Then record in Table (3).
4. Insert the short-circuit jumper clip by referring to Figure 3.4 and short-circuit clip
jumper arrangement diagram in Figure 3.5 (b) (reverse connection). Connect
theVoltmeter and Ammeter.
5. Connect 12VDC to the .IN. terminals then adjust VR2 (10 kΩ) to apply reverse
voltage to 2 terminals of the diode as shown in Table (4) from 0V to 5V, and view the
corresponding I R (without breakdown). Then record in Table (4)
6. Plot the values of Table (3) (4) on the coordinate paper (Fig 3).
Plotting the V-I characteristics curve of germanium diode (4) using oscilloscope
1. First, fix the module KL-23001 in the KL-21001 Linear Circuit Lab, then locate the
block marked 23001- block a.
2. Insert the short-circuit jumper clip by referring to Figure 3.6 and the short-circuit
jumper clip arrangement diagram in Figure 3.7.
3. Connect the 2.0 Vp-p, 1 kHz sine wave to the .IN. terminal. Use Channel 2, CH2(Y)
of the Oscilloscope to test points TP1 and TP2. Used Channel 1, CH1(X) of
Oscilloscope to test points TP3 and TP2. TP1 will be used as the vertical input and
TP3 will be used as the horizontal input while TP2 is the common ground point.
4. Change the display method of the Oscilloscope by adjusting .TIME/DIV. knob to, X-
Y. at the .Horizontal. menu (rotate anti-clockwise). View and record the curve on the
Oscilloscope in Fig (4).
5. Adjust VR2 (10 kΩ), then view the change of the curve.
Result and analysis:-
Graph V-I for silicone diode.
This graph show that the voltage is increase when the current is apply. It doesn’t current
leaked. Form theory it has current leaked but we cannot measured it, the value is very small
and our instrument cannot read it. This graph show the voltage vs current is forward biase. If
the diode is reverse biase the current not flow.
Graph V-I for germanium diode.
From this graph, the voltage increase when the current is increase. Then, this graph showed it
has leaked current. From theory, the value of leaked current for germanium is higher than
silicon that why, we can measure the value of leaked current by using digital multimeter. This
forward biase graph. The theorically if diode reverse biase the current not flow. But this graph
show that it has current. This current called saturated current or leaked current.
Data for Silicone diode by using digital multimeter
TABLE 1
Forward (V) 0.1 0.2 0.3 0.4 0.5 0.6
Forward (mA)
0.1 X 10-3 0.3 X 10-3 0.002 0.02 0.17 1.08
Reverse (V) 1.0 2.0 3.0 4.0 5.0 6.0
Reverse (µA) 0 0 0 0 0 0
Data for Germanium diode by using digital multimeter.
TABLE 2
Forward (V) 0.1 0.2 0.3 0.4 0.5
Forward (mA)
0.2 0.3 0.8 1.6 2.6
Reverse (V) -1.0 -2.0 -3.0 -4.0 -5.0
Reverse (µA) -2.3 -3.3 -4.4 -5.5 -7.0
Discussion:-
Rectifier diodes are electronic devices that are used to control the current flow direction in an
electrical circuit. Two commonly used materials for diodes are germanium and silicon. While
both germanium diodes and silicon diodes perform similar functions, there are certain
differences between the two that must be taken into consideration before installing one or the
other into an electronic circuit. In our experiment we used these types of diodes.
Characteristics of silicon diode
The construction of a silicon diode starts with purified silicon. Each side of the diode
is implanted with impurities (boron on the anode side, arsenic or phosphorus on the
cathode side), and the joint where the impurities meet is called the "p-n junction".
Silicon diodes have a forward-bias voltage of 0.7 Volts. Once the voltage differential
between the anode and the cathode reaches 0.7 Volts, the diode will begin to conduct
electrical current across its p-n junction. When the voltage differential drops to less
than 0.7 Volts, the p-n junction will stop conducting electrical current, and the diode
will cease to function as an electrical pathway. Because silicon is relatively easy and
inexpensive to obtain and process, silicon diodes are more prevalent than germanium
diodes.
a. Silicon diodes are excellent general-purpose diodes and can be used in nearly all
electrical circuits where a diode is required.
b. Silicon diodes are more durable than germanium diodes and are much easier to
obtain. While germanium diodes are appropriate for precision circuits, unless there
is a specific requirement for a germanium diode, it is typically preferable to use
silicon diodes when fabricating a circuit.
c. Silicon diodes have a greater ease of processing, lower cost, greater power
handling, less leakage and more stable temperature characteristics than germanium
diodes.
d. Silicon diode is suitable for all high voltage application.
e. It has much smaller leakaged current, only a few nano-Amperes compared to
germanium diode that have 1000 times more leaky than silicon diode.
Characteristics of germanium diode.
Germanium diodes are manufactured in a manner similar to silicon diodes.
Germanium diodes also utilize a p-n junction and are implanted with the same
impurities that silicon diodes are implanted with. Germanium diodes, however, have a
forward-bias voltage of 0.3 Volts. Germanium is a rare material that is typically found
with copper, lead or silver deposits. Because of its rarity, germanium is more
expensive to work with, thus making germanium diodes more difficult to find (and
sometimes more expensive) than silicon diodes.
a. Germanium diodes are best used in low-power electrical circuits (low voltage
application). The lower forward-bias voltage results in smaller power losses and
allows the circuit to be more efficient electrically.
b. Germanium diodes are also appropriate for precision circuits, where voltage
fluctuations must be kept to a minimum.
c. However, germanium diodes are damaged more easily than silicon diodes.
d. Germanium diode’s lower forward drop (0.2V to 0.3V versus 0 .7V to 1.0V) make
them better at small signal detection and rectification.
e. Temperature stability of germanium diode is poor because Germanium is more
sensitive to temperature and sometimes it can be a problem or can be useful.
Specification of silicon and germanium diode
Parameter Germanium SiliconDepletion layer 0.15V 0.6VForward current A few milli-amperes Tens of amperes
Reverse leakage current A few micro-amperes A few nano-amperes
Max. reverse voltage volts Hundreds of volts
Temperature stability poor Good
Junction capacitance Very low (point contact) Comparatively high
From table above it show that the silicon is good stability that why the value that we
get in table 1 the reverse biase has 0 V. That means silicon is good diode. While
germanium has value for reverse biase so it has leaked current. Silicon diode is most
suitable for electronics .
Conclusion:-
From this experiment we can conclude that, we understand about the characteristics of
silicone and germanium diode. They have specification, then from it we also can recognize
which one is silicone or germanium. Besides that, we learn how to test the characteristics of
diodes by using various instrument then we know the germanium has leaked current. And
silicone doesn’t leaked current. So we can judge here, the silicone is more accepted diode
while the germanium is defective diode. Our experiment is verify.
References:-
1) Laboratory manual2) http://www.learnabout-electronics.org/diodes_03.php3) http://www.ehow.com/list_6823105_characteristics-silicon-germanium-diodes.html4) http://wiki.answers.com/Q/
Why_would_you_use_silicon_diodes_instead_of_germanium_diodes