Single tuned voltage amplifier

OBJECTIVE: To plot the frequency response of a single tuned voltage amplifier.

APPARATUS :

  1. Transistor BC107 - 1 No.
  2. Resistors 33kohms -1No, 56kohms -1No, 100kohms -1No, 560ohms -1No.
  3. Capacitors 0.1µf -1No, 1µf- 2 Nos.
  4. Inductor 100 mH -1No.
  5. CRO(Dual Channel) (0-20 MHz)
  6. Function generator ( 1Hz to 1 MHz)
  7. Regulated power supply (0-30V)
  8. Breadboard
  9. 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 vi=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 VS frequency.

5. Calculate the bandwidth from the graph.

OBSERVATIONS:

Tabular form:

frequencyGain=(Vo/Vi)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

fo=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:

  1. What do you mean by tuned amplifiers?
  2. What are advantages and disadvantages of tuned amplifiers?
  3. What are the applications of tuned amplifiers?
  4. Define resonant frequency?
  5. Define Quality factor
  • Created
    Sep 19, 2019
  • Updated
    Mar 05, 2020
  • Views
    2,477