Experiment No. 6 bsc.4th semester
Object
To study the effect of negative feedback on the response
of on audio frequency amplifier
Apparatus
Resistance , value , condenser , circuit connection.
Observation table
|
S . No |
Input frequency Hz |
Output voltage (Vo) with feedback |
Output voltage (Vo) without feedback |
Gain is dB with feedback |
Gain in dB without feedback |
|
1. |
10 |
0.4 |
0.6 |
26 |
29.54 |
|
2. |
20 |
0.6 |
0.8 |
29.54 |
32.04 |
|
3. |
50 |
0.8 |
1.2 |
32.04 |
35.56 |
|
4. |
100 |
1.2 |
2.0 |
35.56 |
40.00 |
|
5. |
200 |
2 |
3.6 |
40.00 |
45.10 |
|
6. |
500 |
3.2 |
5.6 |
44.00 |
48.94 |
|
7. |
1000 |
3.6 |
6.8 |
45.10 |
50.62 |
|
8. |
2000 |
4 |
7.2 |
46.02 |
51.12 |
|
9. |
5000 |
4 |
7.2 |
46.02 |
51.12 |
|
10. |
10000 |
4 |
7.2 |
46.02 |
51.12 |
|
11. |
20000 |
4 |
7.2 |
46.02 |
51.18 |
|
12. |
50000 |
4 |
6.4 |
46.02 |
50.10 |
|
13 |
1300000 |
3.6 |
5.2 |
46.10 |
48.10 |
Calculation
1.
Voltage gain
= Vo/Vc
1.
With feedback =
Vo/Vi = 0.4/20x10⁻ᶾ
= 20
2.
Without feedback
= Vo/Vi = 0.6/20x10⁻ᶾ
= 30
2.
Band width – FH – FL
1. with feedback – FH –FL
= 190x10ᶾ - 370
= 189.69 KHz
2. without feedback – FH –
FL
= 110x10ᶾx420
109.58 KHz
|
14 |
200,000 |
2.8 |
3.2 |
42.92 |
44.08 |
|
15 |
500000 |
1.6 |
1.6 |
38.06 |
38.06 |
|
16 |
1000000 |
0.8 |
0.8 |
32.04 |
32.04 |
Result
1.
Band width with
feedback = 189.63 KH3
2.
Band width without
feedback = 109.58 KHz
Precautions
1.
Output of
oscillator should be checked every frequency used to keep it constant 1 volt.
2.
Resistance R₁ and R₂
should be high enough to impose little damping on the output of such value that
BA is large compared with unity.
Note.
(Please note: if a particular experiment is not visible, please search for it using the search box—for example, Experiment No. 6. (To study the effect of negative feedback on response of an audio frequency amplifier.)
कृपया ध्यान दीजिये अगला एक्सपेरिमेंट न दिख रहा हो वो आप सर्च बॉक्स में सर्च कर लीजिये . जैसे , एक्साप्रिमेंट नंबर. 6 या फिर (To study the effect of negative feedback on response of an audio frequency amplifier.)
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