Single tuned voltage amplifier
OBJECTIVE: To plot the frequency response of a single tuned voltage amplifier.
APPARATUS :
 Transistor BC107  1 No.
 Resistors 33kohms 1No, 56kohms 1No, 100kohms 1No, 560ohms 1No.
 Capacitors 0.1µf 1No, 1µf 2 Nos.
 Inductor 100 mH 1No.
 CRO(Dual Channel) (020 MHz)
 Function generator ( 1Hz to 1 MHz)
 Regulated power supply (030V)
 Breadboard
 Connecting wires.
THEORY:
The signal to be amplified and it is applied between the terminals base and emitter. The tank circuit (i.e L & R) is located at collector terminal and it may be varied in such a way that the resonant frequency becomes equal to the frequency of the input signal. At resonant the tuned circuit offers high impedance and thus given input signal is amplified and thus appears with large value across it and other frequencies will be rejected. The response of the tuned amplifiers falls sharply below and above the resonant frequency. So the tuned circuit selects the desired frequency and rejects all other frequencies.
CIRCUIT DIAGRAM:
PROCEDURE:
1. Connections are to be made as per the circuit diagram on bread board properly.
2. Set input signal v_{i}=50mV using the Signal Generator.
3. Keep the input voltage constant and vary the frequency from 10 Hz to 100kHz in steps as shown in the tabular column and note the output voltage.
4. Plot the graph of voltage gain in dB V_{S} frequency.
5. Calculate the bandwidth from the graph.
OBSERVATIONS:
Tabular form:
frequency  Gain=(V_{o}/V_{i})  Gain in dB= 20log(gain) 
10Hz  
100Hz  
500Hz  
1kHz  
1.2khz  
1.22kHz  
1.24kHz  
1.26kHz  
1.28kHz  
1.30kHz  
1.32kHz  
1.34kHz  
1.36kHz  
1.38kHz  
1.40kHz  
1.42kHz  
1.44kHz  
1.46kHz  
1.5kHz  
2kHz  
10kHz  
100kHz 
(the values for the above designed circuit will be obtained from 1.2 or 1.30KHz to 1.40KHz . before or after this values the output will not be seen .)
Frequency response:
THEORITICAL CALCULATIONS:
L=100mH , C=0.1µF
f_{o}=1/2pv (LC)
RESULT:
Thus the frequency response of single tuned voltage amplifier has been studied and its bandwidth has been calculated.
LEARNING OUTCOMES:
Students are able to Design and analyze single tuned amplifier.
VIVA QUESTIONS:
 What do you mean by tuned amplifiers?
 What are advantages and disadvantages of tuned amplifiers?
 What are the applications of tuned amplifiers?
 Define resonant frequency?
 Define Quality factor

UpdatedMar 05, 2020

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