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PEEE II Practical Session 2
Discovering Voltage Regulators
________________________________________________________________________
1. OBJECTIVE:
To study the behaviour of a voltage regulator.
To understand the meaning of Line Regulation and Load Regulation.
2. EQUIPMENT NEEDED
PC with Internet Connection
Power Supply
Digital Multimeter
IC 7805, IC 7905
Resistors: 100W) x 2; 1k x 2
Capacitors: 10F 25V x 2
3. PROCEDURES
.1 IC 7805
3.1.1 Connect up the circuit as shown in Figure 2.1. Be careful how you connect the capacitors as they have polarities. Please ask your lecturer if in doubt.
3.1.2 Vary the Vin with values between 8V and 15V. Measure the value of Vout for each value of Vin and record them in Table 2.1 below.
Vin
Vout
8V
4.93
9V
4.93
10V
4.93
11V
4.93
12V
4.93
13V
4.93
14V
4.93
15V
4.93
Table 2.1
3.1.3 What can you conclude about the effect of Vin on Vout?
The input doesn’t affect the output
3.1.4 Now, fix Vin at 10V and vary the load resistance RL with values shown in Table 2.2 below. Measure the output voltage Vout.
RL
Vout
50
4.91
100
4.925
200
4.92
500
4.92
1k
4.92
2k
4.92 Table 2.2
3.1.5 What can you conclude about the effect of RL on Vout?
It doesn’t affect the voltage 3.1.6 THINK: The output of a power supply after rectification and filtering is almost DC but has a small ripple riding on it. How can the IC 7805 be useful in obtaining a “perfect” DC output?
3.1.7 Log on to the internet and/or refer to your textbook and answer the following questions:
a.a) Find out what the IC 7805 is called
5V Regulator
_____________________________________________________________
a.b) If a constant DC voltage of 12V is required (instead of 5V) which IC can we use in place of IC 7805? What if -12V is required instead?
_____7912____________________________________________________
a.c) The ability for the
Discovering Voltage Regulators
________________________________________________________________________
1. OBJECTIVE:
To study the behaviour of a voltage regulator.
To understand the meaning of Line Regulation and Load Regulation.
2. EQUIPMENT NEEDED
PC with Internet Connection
Power Supply
Digital Multimeter
IC 7805, IC 7905
Resistors: 100W) x 2; 1k x 2
Capacitors: 10F 25V x 2
3. PROCEDURES
.1 IC 7805
3.1.1 Connect up the circuit as shown in Figure 2.1. Be careful how you connect the capacitors as they have polarities. Please ask your lecturer if in doubt.
3.1.2 Vary the Vin with values between 8V and 15V. Measure the value of Vout for each value of Vin and record them in Table 2.1 below.
Vin
Vout
8V
4.93
9V
4.93
10V
4.93
11V
4.93
12V
4.93
13V
4.93
14V
4.93
15V
4.93
Table 2.1
3.1.3 What can you conclude about the effect of Vin on Vout?
The input doesn’t affect the output
3.1.4 Now, fix Vin at 10V and vary the load resistance RL with values shown in Table 2.2 below. Measure the output voltage Vout.
RL
Vout
50
4.91
100
4.925
200
4.92
500
4.92
1k
4.92
2k
4.92 Table 2.2
3.1.5 What can you conclude about the effect of RL on Vout?
It doesn’t affect the voltage 3.1.6 THINK: The output of a power supply after rectification and filtering is almost DC but has a small ripple riding on it. How can the IC 7805 be useful in obtaining a “perfect” DC output?
3.1.7 Log on to the internet and/or refer to your textbook and answer the following questions:
a.a) Find out what the IC 7805 is called
5V Regulator
_____________________________________________________________
a.b) If a constant DC voltage of 12V is required (instead of 5V) which IC can we use in place of IC 7805? What if -12V is required instead?
_____7912____________________________________________________
a.c) The ability for the