ECA LAB

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• LIST OF EXPERIMENTS

A) DESIGN AND SIMULATION IN SIMULATION LAB USING
MULTISIM:

1.TWO STAGE RC COUPLED AMPLIFIER.
2. COMMON SOURCE AMPLIFIER.
3. TWO STAGE RC COUPLED AMPLIFIER.
4. RC PHASE SHIFT OSCILLATOR USING TRANSISTORS.
5. CLASS A POWER AMPLIFIER.
6. CLASS B COMPLEMENTARY SYMMETRY AMPLIFIER.
7. CURRENT SHUNT FEEDBACK AMPLIFIER.

B) TESTING IN THE HARDWARE LABORATORY:

8. SINGLE TUNED VOLTAGE AMPLIFIER.
9. HARTLEY & COLPITT’S OSCILLATORS.
10. CLASS A POWER AMPLIFIER.
11. COMMON EMITTER AMPLIFIER.
12. COMMON SOURCE AMPLIFIER.
13. TWO STAGE RC COUPLED AMPLIFIER.

              

HARDWARE LAB

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• EXPERIMENT NO- 1

                   TWO STAGE RC COUPLED AMPLIFIER
  
  
  
  
  AIM:
  
  
  1.      To study & plot the frequency response of a RC coupled amplifier with a pair of shunted emitter capacitors of 10μF and 100μF.
  2.      To calculate maximum gain.
  3.      To calculate bandwidth.
  4.      To verify A_V< A_V1. A_V2
  
  
  COMPONENTS & EQUIPMENT REQUIRED:
  
  

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1.	Trainer Board containing (a)    DC Supply voltage. (b)   NPN Transistor. (c)    Resistors. d) Capacitors.	12 V BC 107 47 KΩ 2.2 KΩ 1 KΩ 10 KΩ  10mF  100mF.	1 2 2 2 5 2 6 2
  2.	Cathode  Ray Oscilloscope.	(0-20)MHz	1
  3.	Function Generator.	0.1 Hz-10 MHz	1
  4	BNC Connector		2
  5	Connecting Wires	5A	10

  
  
      
  THEORY:
  
  
          When the voltage gain provided by a single stage stage is not sufficient, we have to go for more than one stage in the amplifier. In the circuit diagram, two stages are shown connected through a link. When the link is open, the voltage gain of first stage is high. However, when the link is closed the gain is reduced. This is because of the input impedance of the second stage will be in parallel with the load resistance of the first stage. Therefore the input impedance is reduced. Hence overall gain is decreased.  The fall in amplifier gain at low frequencies is due to the effect of coupling and bypass capacitor.
  
  

  

  
  
  At medium and high frequencies, the factor ‘f’ makes X_c is very small, so that all by coupling and bypass capacitors behaves as short circuit. There are also stray capacitance ‘C_s’, which are capacitances between connecting wires and ground. All these capacitances values are very small so that at low and medium frequencies, there impedances are very high. As the frequency increases the reactance of the stray capacitance fall. When these reactance becomes small enough they begin to shunt away some of the input and output currents are thus reduces the current gain. Even if no external stray capacitance is present, the device internal capacitances through the semiconductor material limit the circuit frequency response.
  A cut-off frequency is the frequency at which the transistor gain falls to 0.707 of its maximum gain.
  The range of frequencies over which the gain of an amplifier is equal to or greater than 70.7% of its maximum gain is known as maximum gain.
  
  
  PROCEDURE:
  
  
  1.     Connect the circuit as shown in figure for 10 μF.
  2.     Adjust input signal amplitude in the function generator and observe an amplified voltage at the output without distortion.
  3.     By keeping input signal voltage, say at 50 mV, vary the input signal frequency from 0-1 MHz as shown in tabular column and note the corresponding output voltage.
  4.     Repeat the same procedure for C=100μF.
  
  
  PRECAUTIONS: -
             
        1.  No loose contacts at the junctions.
        2.  Check the connections before giving the power supply
        3.  Observations should be taken carefully.
  
  
  RESULT:
  
  

  1.     Frequency Response of RC coupled (2 stage) amplifier for 10μF and 100 μF is plotted.

  2.      For C=10 μF, Gain=

  
  
          Bandwidth =f_H – f_L =
  
  

  3.     For C=100μF, Gain=

  
  
          Bandwidth =f_H – f_L =
  
  
   4. A_V< A_V1. A_V2 is verified.
  
  
  VIVA QUESTIONS:
  
  
  1. What are the advantages and disadvantages of multi-stage amplifiers?
  2. Why gain falls at HF and LF?
  3. Why the gain remains constant at MF?
  4. Explain the function of emitter bypass capacitor, Ce?
  5. How the band width will effect as more number of stages are cascaded?
  6. Define frequency response?
  7. Give the formula for effective lower cut-off frequency, when N-number of stages are cascaded.
  8. Explain the effect of coupling capacitors and inter-electrode capacitances on overall gain.
  9. By how many times effective upper cut-off frequency will be reduced, if three identical stages
  are cascaded?
  10. Mention the applications of two-stage RC-coupled amplifiers.
  
  
  CIRCUIT DIAGRAM:
  

  
  
  
  
  
  EXPECTED GRAPH:
  

  

  
  
  
  
  
  
  
  
  
  
  
  
  
  
     TABULAR FORM:
                C=10μF V_in = 50 mV
  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K
  15	300K
  16	500K
  17	700K
  18	900K
  19	1M

  
  
  
  
       TABULAR FORM:
          C=100μF V_in = 50 mV
  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K
  15	300K
  16	500K
  17	700K
  18	900K
  19	1M

     C=100 μF:

  Frequency (in Hz)	V01	V02	Av1	Av2	Av= Av1x Av2 Theoretical value	Av (Practical value)
  10K
  20K

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  EXPERIMENT NO    2

  VOLTAGE SERIES AND CURRENT SHUNT FEEDBACK AMPLIFIER

  
  

      AIM:

  
  

       To study  the frequency response of a

  
  

   1. Current shunt feedback amplifier

           a) Without a shunt Capacitor.

        b) With a shunt Capacitor.

   2. Voltage series feedback amplifier.

                                a) With a Resistor.

                         

      COMPONENTS & EQUIPMENT REQUIRED:

  
  

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1.	Trainer Board containing (a)    DC Supply voltage. (b)   NPN Transistor. (c)    Resistors. d) Capacitors.	12 V BC 107 47 KΩ 2.2 KΩ 1 KΩ 10 KΩ  100 KΩ 0.1mF  22 mF.	1 2 2 2 1 1 1 1 1 1
  2.	Cathode Ray Oscilloscope.	(0-20)MHz	1
  3.	Function Generator.	0.1 Hz-10 MHz	1
  4	BNC Connector		2
  5	Connecting Wires	5A	5

  PROCEDURE:

  
  

  1.      Current series (Without a shunt Capacitor).

       a) Connect the circuit diagram as shown fig.

       b) Adjust input signal amplitude in the function generator and observe an  

            amplified voltage at the output without distortion.

    c) By keeping input signal voltage, say at 50 mV, vary the I/P signal 

            frequency from 50Hz to 1 MHz in step as shown in tabular column and 

             note the corresponding O/P voltage.

  2.      For Voltage series feedback amplifier (with & without resistance, R_f ), repeat the above procedure.

  
  

  PRECAUTIONS:

             

          1.   No loose contacts at the junctions.

          2.   Check the connections before giving the power supply

          3.   Observations should be taken carefully.

  RESULT:

  
  

  Hence the frequency response for voltage series and current shunt amplifiers are studied and plotted

  
  

                          a). Voltage series.

                           Bandwidth =f_H – f_L =

  
  

                          b). Current series (with & without Capacitor)

                          Bandwidth =f_H – f_L =

                            

  
  

  VIVA QUESTIONS:

  
  

  1. What is feedback and what are feedback amplifiers?

  2. What is meant by positive and negative feedback?

  3. What are the advantages and disadvantages of negative feedback?

  4. Differentiate between voltage and current feedback in amplifiers?

  5. Define sensitivity & define De-sensitivity?

  6. Give the topology of current amplifier with current shunt feedback?

  
  

  TABULAR COLUMN  1:              Vin = 50 mV

  
  

              Current Shunt:         

                       

  	With Feedback Without Capacitor		Without Feedback With Capacitor
  Frequency (in Hz)	Output Voltage (Vo)	Gain (in dB) = 20log10(Vo/Vi)	Output Voltage (Vo)	Gain (in dB) = 20log10(Vo/Vi)
  20
  40
  80
  100
  500
  1000
  2000
  5000
  10K
  50K
  100K
  200K
  400K
  600K
  800K
  1000K

  
  

  
  

  TABULAR COLUMN  2:        Vin = 50 mV

  
  

  Voltage Series:

  
  

  Frequency (in Hz)	Output Voltage (Vo)	Gain (in dB) = 20log10(Vo/Vi)
  20
  40
  80
  100
  500
  1000
  2000
  5000
  10K
  50K
  100K
  200K
  400K
  600K
  800K
  1000K

  
  

  CIRCUIT DIAGRAM:

  

  
  

  

  
  

  

  
  
  

  EXPECTED GRAPH:

  

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  EXPERIMENT NO-3

  
  

  RC PHASE SHIFT OSCILLATOR

   AIM:To find practical frequency of RC phase shift oscillator and to compare it with theoretical frequency for R=10KW and C = 0.01mF, 0.0022mF & 0.0033mF  

   respectively

  
  

  COMPONENTS AND EQUIPMENTS REQUIRED:

  
  

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1	RC phase shift oscillator trainer board containing a) DC supply voltage b) Capacitor c) Resistor d) NPN Transistor	12V 1000mF 0.047mF 0.01mF 0.0022mF 0.0033mF 1KW 10KW 47KW 100KW BC 107	1 1 1 3 3 3 1 2 1 1 1
  2	CRO	(0-20) MHz	1
  3.	BNC Connector		1
  3	Connecting wires	5A	6

  PROCEDURE:1.. Connect the circuit as shown in figure.

  2. Connect the 0.0022 mF capacitors in the circuit and observe the waveform.

  3. Time period of the waveform is to be noted and frequency should be calculated by the formula f = 1/T.

  4. Now fix the capacitance to 0.033 mF and 0.01mF and calculate the frequency and tabulate as shown.

  5. Find theoretical frequency from the formula f = 1/2PRCÖ6 and compare theoretical and practical frequencies.

  PRECAUTIONS: -1. No loose contacts at the junctions.

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  RESULT: -

  1.      For C = 0.0022mF & R=10KW

                          Theoretical frequency=

                          Practical frequency=

  2.      For C = 0.0033mF & R=10KW

                          Theoretical frequency=

                           Practical frequency=

  3.      For C = 0.01mF & R=10KW

                         Theoretical frequency=

             Practical frequency=

  VIVA QUESTIONS:

  
  

  1. What are the conditions of oscillations?

  2. Give the formula for frequency of oscillations?

  3. What is the total phase shift produced by RC ladder network?

  4. What are the types of oscillators?

  5. What is the gain of RC phase shift oscillator?

  CIRCUIT DIAGRAM:

  

  

  
  

  
  

  EXPECTED WAVEFORM:

  

  
  

  
  

  TABULAR COLUMN:

  
  

  S.No	C (mF)	R (W)	Theoretical Frequency (KHz)	Practical Frequency  (KHz)	Vo (p-p) (Volts)
  1	0.0022	10K
  2	0.0033	10K
  3	0.01	10K

  @@@@@@@@@@@@@@@@@@@@@@@@@@@

  
  

  EXPERIMENT NO-4

  (A)   HARTLEY OSCILLATOR

  
  

  AIM:

  
  

           To find practical frequency of a Hartley oscillator and to compare it with theoretical frequency for L = 10mH and C = 0.01mF, 0.033mF and 0.047mF.

  
  

  COMPONENTS AND EQUIPMENTS REQUIRED:

          

      

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1	Hartley Oscillator trainer board containing a) DC supply voltage b) Inductors c) Capacitor           d) Resistor e) NPN Transistor	12V 5mH 0.22mF 0.01mF 0.033mF 0.047mF 1KW 10KW 47KW BC 107	1 2 2 1 1 1 1 1 1 1
  2	Cathode Ray Oscilloscope	(0-20) MHz	1
  3.	BNC Connector		1
  4	Connecting wires	5A	4

                   

  
  

  PROCEDURE:

  1.      Connect the circuit as shown in figure.

  2.      Connect 0.01mF capacitor in the circuit and observe the waveform.

  3.      Time period of the waveform is to be noted and frequency is to be calculated by the formula f = 1/T .

  4.      Now fix the capacitance to 0.033 mF and 0.047mF and calculate the frequency and tabulate the readings as shown.

  5.      Find the theoretical frequency from the formula

  

        Where L_T = L₁ + L₂  = 5 mH + 5mH = 10 mH and compare theoretical                             

        and practical values.

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  
  

  RESULT:

      

  1. For C = 0.01mF, & L_T = 10 mH;

                 Theoretical frequency =

                 Practical frequency =

       

  2.      For C = 0.033mF, & L_T = 10 mH;

                 Theoretical frequency =

                             Practical frequency =

  
  

  3.       For C = 0.047mF, & L_Ts = 10 mH;

                   Theoretical frequency =

                               Practical frequency = 

  
  CIRCUIT DIAGRAM:

  

  
  

  EXPECTED WAVEFORM:

  
  

  

  
  

  TABULATIONS:

  
  

  S.No	LT(mH)	C (mF)	Theoretical frequency (KHz)	Practical frequency (KHz)	Vo (peak to peak)
  1	10	0.01
  2	10	0.033
  3	10	0.047

  @@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT NO-4

  (B)  COLPITTS OSCILLATOR

  
  

  AIM:

  
  

           To find practical frequency of Colpitt’s oscillator and to compare it with theoretical 

           Frequency for L= 5mH and C= 0.001mF, 0.0022mF, 0.0033mF respectively.

  COMPONENTS & EQIUPMENT REQUIRED: -

  
  

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1	Colpitts Oscillator trainer board containing a) DC supply voltage b) Inductors c) Capacitor           d) Resistor          e) NPN Transistor	12V 5mH 0.01mF 0.1mF 100 mF 1KW 1.5KW 10KW 47KW BC 107	1 1 1 1 1 1 1 1 1 1
  2	Cathode Ray Oscilloscope	(0-20) MHz	1
  3.	BNC Connector		1
  4	Connecting wires	5A	4

  
  

  PROCEDURE:-1. Connect the circuit as shown in the figure

  2. Connect C₂= 0.001mFin the circuit and observe the waveform.

  3. Time period of the waveform is to be noted and frequency should be calculated    

      by the formula f=1/T

  4. Now, fix the capacitance to 0.002 mF and then to 0.003 mF and calculate the   

       frequency and tabulate the reading as shown.

  6.      Find theoretical frequency from the formula

  
  

  

  Where

  

  
  

   and compare theoretical and practical values.

  
  

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  RESULT:

  
  

  Frequency of oscillations of Colpitts oscillator is measured practically and  compared with theoretical values .

  1. For C=0.0022mF  & L= 5mH                                                    

                          Theoretical frequency =

   Practical frequency =

  
  

  2. For C=0.0033mF  & L= 5mH                                                   

   Theoretical frequency =

                          Practical frequency =

  
  

  3. For C=0.001mF  & L= 5mH   

                          Theoretical frequency =

   Practical frequency  =                                               

  
  

  VIVA QUESTIONS:

  
  

  1. What are the applications of LC oscillations?

  2. What type of feedback is used in oscillators?

  3. What is the expression for the frequency of oscillations of Colpitt’s and Hartley oscillator?

  4. Whether an oscillator is dc to ac converter. Explain?

  5. What is the loop gain of an oscillator?

  6. What is the difference between amplifier and oscillator? 

  7. What is the condition for sustained oscillations?

  8. How many inductors and capacitors are used in Hartley Oscillator?

  9. How the oscillations are produced in Hartley oscillator?

  10. What is the difference between damped oscillations undamped oscillations?

  11. How does Colpitt’s differ from Hartley?

  
  CIRCUIT DIAGRAM: -

  
  

  
  

  

  
  

  
  

  COLPITTS OSCILLATOR

  
  

  EXPECTED WAVEFORM:

  

  
  

  
  

  TABULAR COLUMN:

  
  

  S.NO	L(mH)	C1 (mF)	C2 (mF)	CT (mF)	Theoretical Frequency (KHz)	Practical Frequency (KHz)	Vo(V) Peak to peak
  1	5	0.01	0.001
  2	5	0.01	0.0022
  3	5	0.01	0.0033

  
  

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT NO- 5

  
  

  CLASS A POWER AMPLIFIER

  
  

              AIM:

  
  

  1.      To study and plot the frequency response of a Class A Power Amplifier.

  2.      To calculate efficiency of Class A Power Amplifier.

  
  

  
  

    COMPONENTS & EQUIPMENT REQUIRED:

  
  

  S.No	Apparatus	Range/ Rating	Quantity (in No.s)
  1.	Trainer Board containing (a)    DC Supply voltage. (b)   NPN Transistor. (c)    Resistors. d) Capacitor. e) Inductor.	12 V BC 107 560Ω 100KΩ 470Ω 22 mF. 50mH	1 1 1 1 1 1 1
  2.	D.C Milliammeter	0-100mA	1
  3.	Cathode Ray Oscilloscope.	(0-20)MHz	1
  4.	Function Generator.	0.1 Hz-10 MHz	1
  5.	BNC Connector		2
  6.	Connecting Wires	5A	5

  
  

          THEORY:

  
  

                             In CLASS A amplifier, the transistor is biased such that the output current flows, ie. Transistor is ON for the full cycle (360⁰) of the input a.c. signal. In CLASS A Power amplifier there is no distortion when compared with other amplifiers. The maximum value of theoretical efficiency is 25% for a series fed and 50% for a transformer coupled power amplifier.

  
  

           Conversion Efficiency:

                            It is the measure of the ability of an active device in converting the d.c. Power of the supply into the a.c. power delivered to the load. Conversion efficiency is also referred to as theoretical efficiency and collector circuit efficiency (for transistor amplifier) and is denoted by η. By definition, the percentage efficiency is

  
  

                                      η. = Signal power delivered to the load  x 100 %

                                             d.c. power supplied to output circuit

                           

  PROCEDURE:

  
  

  1.      Connect the circuit as shown in figure.

  
  

  2.      Adjust input signal amplitude in the function generator and observe an amplified voltage at the output without distortion.

  
  

  3.      By keeping input signal voltage, say at 50 mV, vary the input signal frequency from 0-1 MHz as shown in tabular column and note the corresponding output voltage.

  
  

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  
  

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  
  

  RESULT:

  
  

  1. Frequency Response of CLASS-A Power amplifier is plotted.
  2. Efficiency of CLASS A Power amplifier is found to be___________
  3. Bandwidth f_H – f_L = ____________

  VIVA QUESTIONS:

  
  

  1. Differentiate between voltage amplifier and power amplifier

  2. Why power amplifiers are considered as large signal amplifier?

  3. When does maximum power dissipation happen in this circuit ?.

  4. What is the maximum theoretical efficiency?

  5. Sketch wave form of output current with respective input signal.

  6. What are the different types of class-A power amplifiers available?

  7. What is the theoretical efficiency of the transformer coupled class-A power amplifier?

  8. What is difference in AC, DC load line?.

  9. How do you locate the Q-point ?

  10. What are the applications of class-A power amplifier?

  CIRCUIT DIAGRAM:

  
  

  

  
  
  

           

  
  

  EXPECTED GRAPH:

  
  

  

  Bandwidth=f_H – f_L

  TABULAR FORM:

  V_in = 50 mV

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K

  
  

  
  

  CALCULATIONS:

  
  

  When signal is removed, V_i=0

  
  

  Zero signal current, I_c = 

  
  

  
  

  Input Power,      P_in=V_cc x I_c

  
  

  
  

  Output Power,

                                  =

  

  
  

  
  

  Efficiency, η =

  

                          =

  
  

                        =

  
  

                    =

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  
  

  EXPERIMENT NO- 6  

    

  SINGLE TUNED VOLTAGE AMPLIFIER

  
  

            AIM:

  
  

  1.   To study & plot the frequency response of a Single Tuned voltage amplifier

  1.      To find the resonant frequency.

  2.      To calculate gain and bandwidth.

  
  

   COMPONENTS & EQUIPMENT REQUIRED:

  
  

  S.No	Apparatus	Range/ Rating	Quantity (in No.s)
  1.	Trainer Board containing (a)    DC Supply voltage. (b)   NPN Transistor. (c)    Resistors. d) Capacitor. e) Inductor.	12 V BC 107 47 KΩ 150Ω 1 KΩ 10 KΩ  10mF  22 mF. 0.022 mF. 0.033mF. 1mH	1 1 1 1 1 2 2 1 1 1 1
  2.	Cathode Ray Oscilloscope.	(0-20)MHz	1
  3.	Function Generator.	0.1 Hz-10 MHz	1
  4.	BNC Connector		2
  5.	Connecting Wires	5A	5

  
  

    THEORY:

             

             A Tuned Amplifier uses a parallel tuned circuit a parallel tuned circuit has high input impedance at its frequency of resonance, and the impedance falls off sharping as the frequency departs from the frequency of resonance. Hence the gain Vs frequency curve of a tuned amplifier is very similar to the impedance Vs frequency curve of a tuned amplifier are therefore, used for amplification of a narrow band of frequencies.

  
  

             A resonant circuit generally uses either a variable inductor or variable capacitor for adjusting the resonant frequency at the center of the band of frequencies to be amplified. Over this narrow band of frequency, the gain of the tuned amplifier remains more or less constant.

             An important example is the radio frequency (R.F) amplifier, which amplifies either a single radio frequency signal or a narrow band or frequencies center about the resonant frequency. The tuned circuit formed by L & C resonates at the frequency of operation.

  
  

  

  
  

            PROCEDURE:

  
  

  1.      Connect the circuit as shown in figure.

  2.      Connect the 0.022μF capacitor

  3.      Adjust input signal amplitude in the function generator and observe an amplified voltage at the output without distortion.

  4.      By keeping input signal voltage, say at 50 mV, vary the input signal frequency from 0-1 MHz as shown in tabular column and note the corresponding output voltage.

  5.      Repeat the same procedure for  0.033μF capacitor.

  6.      Plot the graph: gain (Vs) frequency.

  7.      Calculate the F_t and Fp

  
  

  
  

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  
  

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  
  

     

  RESULT:

  
  

  1.      Frequency response of RF Tuned voltage amplifier is plotted.

  2.      For 0.022μF, gain = ________dB

  Bandwidth= _________

  3.    For 0.033μF, gain = ________dB

  Bandwidth= _________

  
  

  
  

  VIVA QUESTIONS:

  
  

  1. What is the purpose of tuned amplifier?

  2. What is Quality factor?

  3. Why should we prefer parallel resonant circuit in tuned amplifier.

  4. What type of tuning we need to increase gain and bandwidth.?

  5. What are the limitations of single tuned amplifier?

  6. What is meant by Stagger tuning?

  7. What is the conduction angle of an tuned amplifier if it is operated in class B mode?

  8. What are the applications of tuned amplifier

  9. What are the different types of  tuned circuits ?

  10. State relation between resonant frequency and bandwidth of a Tuned amplifier.

  11. Differentiate between Narrow band and Wideband tuned amplifiers ?

  12. Calculate bandwidth of a Tuned amplifier whose resonant frequency is 15KHz and Q-factor is 100.

  13. Specify the applications of Tuned amplifiers.

  
  CIRCUIT DIAGRAM:

  

     EXPECTED GRAPH:

  
  

  

  
  

  
  

  
  

  TABULAR COLUMN -1:

  
  

  V_in = 50 mV

  C= 0.022μF

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K

  
  

  
  

  TABULAR COLUMN-2:

  
  

  V_in = 50 mV

  C= 0.033μF

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K

  
  
  
  @@@@@@@@@@@@@@@@@@@@@@@@@@@@
  

  SIMULATION LAB

  EXPERIMENT NO: 1

  CE AMPLIFIER

  AIM:     

  
  

  
  

  To plot the frequency response of CE amplifier and calculate gain bandwidth.

  
  

  SOFTWARE REQUIRED:    MultiSim Software

  
  

  COMPONENTS & EQUIPMENTS REQUIRED: -

  
  

  
  

  S.No	Apparatus	Range/ Rating	Quantity (in No.s)
  1.	CE Amplifier trainer Board with DC power supply        DC power supply        NPN transistor  Carbon film resistor     (e)Carbon film resistor    (f) Capacitor.	BC 107 100KW, 1/2W    2.2KW, 1/2W 0.1µF	1 1 1 1 1 2
  2.	Cathode Ray Oscilloscope.	(0-20)MHz	1
  3.	Function Generator.	0.1 Hz-10 MHz	1
  4.	BNC Connector		2
  5.	Connecting Wires	5A	5

  
  

  
  

  
  

  PROCEDURE: -

  
  

   1. Connect the circuit diagram as shown in figure.

   2. Adjust input signal amplitude in the function generator and observe an  amplified voltage at the output without distortion.

   3. By keeping input signal voltages at 50mV, vary the input signal frequency from 0  to 1MHz in steps as             shown in tabular column and note the corresponding output  voltages.

  
  

  PRECAUTIONS: -

  
  

  1.   Oscilloscope probes negative terminal should be at equipotential points (i.e.ground voltage= 0), because both terminals are internally shorted in dual trace oscilloscope.

  2.   Ensure that output voltage is exactly an amplified version of input voltage  without any distortion (adjust input voltage amplitude to that extent)

  3.   No loose connections at the junctions.

  
  

  RESULT: -

  
  

  Frequency response of CE amplifier is plotted.

  Gain, A_V = ________dB.

  Bandwidth= f_H­-_-f_L =________Hz.

  
  

  VIVA QUESTIONS

  1. What are the advantages and disadvantages of single-stage amplifiers?

  2. Why gain falls at HF and LF?

  3. Why the gain remains constant at MF?

  4. Explain the function of emitter bypass capacitor, Ce?

  5. How the band width will effect as more number of stages are cascaded?

  6. Define frequency response?

  7. What is the phase difference between input and output waveforms of a CE amplifier?

  8. What is early effect?

  
  

  
  

  TABULAR COLUMN:

  
  

  Input voltage: V_i = 50mV

  
  

  Frequency (in Hz)	Output (Vo) (Peak to Peak)	Gain AV=V0/Vi	Gain (in dB) = 20 log 10 VO/ Vi
  20
  600
  1K
  2K
  4K
  8K
  10K
  20K
  30K
  40K
  50K
  60K
  80K
  100K
  250K
  500K
  750K
  1000K

  
  

  CIRCUIT DIAGRAM:

  
  

  

  CE AMPLIFIER

  
  

  

  EXPECTED GRAPH:

  
  

                                                              Bandwidth = f_H-f_L

  
  

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT NO: 2

  
  

  COMMON SOURCE AMPLIFIER

  
  

  AIM: -

  
  

  a) To Plot the frequency response of a common source amplifier.

  b) Calculate gain.

  c) Calculate bandwidth.

  
  

  SOFTWARE REQUIRED:  Multi Sim Software

  
  

  COMPONENTS & EQUIPMENTS REQUIRED: -

  
  

  S.No	Device	Range/Rating	Quantity (in No.s)
  1.	FET amplifier Trainer Board with (a) DC supply voltage (b) FET (c) Capacitors (d) Resistors	12V BFW 11 0.1mF 47mF 1.5KW 4.7 KW 1MW	1 1 2 1 1 1 1
  2.	Signal generator	0.1Hz-1MHz	1
  3.	CRO	0Hz-20MHz	1
  4.	Connecting wires	5A	4

  
  

  
  

  PROCEDURE: -

  
  

  1.Connect the circuit diagram as shown in figure.

  2.Adjust input signal amplitude in the function generator and observe an amplified voltage at the output without 3.distortion.

  4.By keeping input signal voltage, say at 50mV, vary the input signal frequency from 0 to 1MHz in steps as shown in tabular column and note the corresponding output voltages.

  PRECAUTIONS:

      Oscilloscopes probes negative terminal should be at equipotential points(i.e. ground voltage is zero) because both terminals are internally shorted in dual trace oscilloscope.

  RESULT: -

  
  

  Hence,  the frequency response of FET (CS) amplifier is plotted.

  Gain = _______dB (maximum).

  3.   Bandwidth= f_H-_-f_L = _________Hz.

  VIVA QUESTIONS:

  1. What is the difference between FET and BJT?

  2. FET is unipolar or bipolar?

  3. Draw the symbol of FET?

  4. What are the applications of FET?

  5. FET is voltage controlled or current controlled?

  TABULAR COLUMN:Input = 50mV

  Frequency (in Hz)	Output Voltage (Vo)	Gain Av=Vo/Vi	Gain (in dB) = 20log10(Vo/Vi)
  20
  40
  80
  100
  500
  1000
  5000
  10K
  50K
  100K
  200K
  400K
  600K
  800K

  
  

  
  

  
  CIRCUIT DIAGRAM:

  
  

  

  
  

  COMMON SOURCE AMPLIFIER

  
  

  EXPECTED GRAPH:

  

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT NO- 3

  
  

  TWO STAGE RC COUPLED AMPLIFIER

  AIM:

  
  

  1.To plot the frequency response of a RC coupled amplifier with a pair of shunted emitter   capacitors of 10 μF and 100μF.

  2. To calculate gain.

  3. To calculate bandwidth.

  
  

  SOFTWARE REQUIRED:  MultiSim Software

  
  

  COMPONENTS & EQUIPMENT REQUIRED:

  
  

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1.	Trainer Board containing a) DC Supply voltage. b) NPN Transistor. c) Resistors. d) Capacitors.	12 V BC 107 47 KΩ 2.2 KΩ 1 KΩ 10 KΩ  100mF  10mF.	1 2 2 2 5 2 6
  2.	Cathode Ray Oscilloscope.	(0-20)MHz	1
  3.	Function Generator.	0.1 Hz-10 MHz	1
  4	BNC Connector		2
  5	Connecting Wires	5A	10

  
  

      THEORY:

  
  

          When the voltage gain provided by a single stage stage is not sufficient, we have to go for more than one stage in the amplifier. In the circuit diagram, two stages are shown connected through a link. When the link is open, the voltage gain of first stage is high. However, when the link is closed the gain is reduced. This is because of the input impedance of the second stage will be in parallel with the load resistance of the first stage. Therefore the input impedance is reduced. Hence overall gain is decreased.  The fall in amplifier gain at low frequencies is due to the effect of coupling and bypass capacitor.

  

  
  

  At medium and high frequencies, the factor ‘f’ makes X_c is very small, so that all by coupling and bypass capacitors behaves as short circuit. There are also stray capacitance ‘C_s’, which are capacitances between connecting wires and ground. All these capacitances values are very small so that at low and medium frequencies, there impedances are very high. As the frequency increases the reactance of the stray capacitance fall. When these reactance becomes small enough they begin to shunt away some of the input and output currents are thus reduces the current gain. Even if no external stray capacitance is present, the device internal capacitances through the semiconductor material limit the circuit frequency response.

  A cut-off frequency is the frequency at which the transistor gain falls to 0.707 of its maximum gain.

  The range of frequencies over which the gain of an amplifier is equal to or greater than 70.7% of its maximum gain is known as maximum gain

  PROCEDURE:

  
  

  1. Connect the circuit as shown in figure for 10 μF.

  2. Adjust input signal amplitude in the function generator and observe an amplified voltage at the output without distortion.

  3. By keeping input signal voltage, say at 50 mV, vary the input signal frequency from 0-1 MHz as shown in tabular column and note the corresponding output voltage.

  4. Repeat the same procedure for C=100μF.

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  
  

  RESULT: -

  
  

  Hence, the  frequency Response of RC coupled (2 stage) amplifier for 10μF and 100 μF is plotted.

   1. For C=10 μF,

   Gain=

    Bandwidth =f_H – f_L =

  
  

   2.    For C=100μF

   Gain=

  
    Bandwidth =f_H – f_L = CIRCUIT DIAGRAM:

  

  
  

  TWO STAGE RC COUPLED AMPLIFIER

  
  

  
  

  EXPECTED GRAPH: 

  

  
  

  TABULAR FORM:

  C=10μF V_in = 50 mV

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K
  15	300K
  16	500K
  17	700K
  18	900K
  19	1M

  
  

  
  

  
  

  TABULAR FORM:

  
  

  C=100μF V_in = 50 mV

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K
  15	300K
  16	500K
  17	700K
  18	900K
  19	1M

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT  - 4

  
  

  CLASS B POWER AMPLIFIER

  (COMPLEMENTARY SYMMETRY)

  
  

  
  

  AIM:

  
  

  To study the frequency response of CLASS B Complementary Symmetry amplifier and to calculate its          

    efficiency.

  SOFTWARE REQUIRED:  MultiSim Software

  APPARATUS REQUIRED: 

             

             

  S.No	Device	Range/ Rating	Qty (in No.)
  1	CLASS B Power amplifier Trainer Kit		1
  2	Signal Generator	(0Hz-1 MHz)	1
  3	Cathode Ray Oscilloscope	(0 Hz –20 MHz)	1
  4	D.C Milliammeter	(0-50) mA	1
  5	Decade Resistance Box	(1-100) KΩ	1
  6	BNC Connector		2
  7	Connecting Wires	5A	6

  
  

  THEORY:

  
  

     In a CLASS B amplifier the transistor is biased almost at cut off, so that it remains forward biased only for one half cycle of the input signal. Hence its conduction angle is only 180⁰. It has the following two advantages over CLASS A power amplifier. Possible to obtain greater power output Efficiency is higher. Negligible power loss (as no output current flows) at no input signal. And also it eliminates the disadvantages of Push-Pull configuration like bulky and expensive output transformer. The maximum theoretical efficiency of a CLASS B power amplifier is 78.5 %.

  
  

  
  

  PROCEDURE:

  
  

  1. Switch ON the CLASS B amplifier trainer.

  
  

  2. Connect Milliammeter to (A) terminals and DRB to the R_L terminals and fix R_L=50Ω.

  
  

  3. Apply the input voltage from the signal generator to the V_s terminals.

  
  

  4. Connect channel 1 of CRO to the V_s terminals and channel 2 across the load.

  
  

  5. By varying the input voltage, observe the maximum distortion less output waveform.  

      And note down the voltage reading.

  
  

  6. Calculate the efficiency.

  
  

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  
  

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  
  

  RESULT:  

  
  

  Thus efficiency of CLASS B (Complementary symmetry) amplifier is  calculated and frequency response is studied.

  VIVA QUESTIONS:

  
  

  1. Differentiate between voltage amplifier and power amplifier?

  2. Explain impedance matching provided by transformer?

  3. Under what condition power dissipation is maximum for transistor in this circuit?

  4. What is the maximum theoretical efficiency?

  5. Sketch current waveform in each transistor with respective input signal?

  6. How do you test matched transistors required for this circuit with DMM?.

  7. What is the theoretical efficiency of the complementary stage amplifier.

  8. How do you measure DC and AC out put of this amplifier?

  9. Is this amplifier working in class A or B. ?

  10. How can you reduce cross over distortion?

  

           CIRCUIT DIAGRAM:

  
  

  CLASS B POWER AMPLIFIER (COMPLEMENTARY SYMMETRY)

  
  

  OBSERVATIONS:

  
  

  V_s=2v

  
  

  FREQUENCY	Vo (volts)	Idc (mA)	Efficiency
  10 KHz

  
  

  CALCULATIONS:

  

  
  

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT NO-5

  
  

  RC PHASE SHIFT OSCILLATOR

  AIM:

  
  

  To find practical frequency of RC phase shift oscillator and to compare it with  theoretical frequency for R=10KW and C = 0.01mF, 0.0022mF & 0.0033mF  

   Respectively

  
  

   SOFTWARE REQUIRED:  MultiSim Software

  
  

  COMPONENTS AND EQUIPMENTS REQUIRED:

  
  

  S.No	Device	Range/ Rating	Quantity (in No.s)
  1	RC phase shift oscillator trainer board containing a) DC supply voltage b) Capacitor c) Resistor d) NPN Transistor	12V----------- 1000mF------- 0.047mF------ 0.01mF-------- 0.0022mF------ 0.0033mF---- 1KW----------- 10KW--------- 47KW---------- 100KW--------- BC 107--------	1 1 1 3 3 3 1 4 1 1 1
  2	CRO	(0-20) MHz	1
  3.	BNC Connector		1
  3	Connecting wires	5A	6

  
  

  
  

  PROCEDURE:

  
  

  1. Connect the circuit as shown in figure.

  2. Connect the 0.0022 mF capacitors in the circuit and observe the waveform.

  3. Time period of the waveform is to be noted and frequency should be calculated by the formula f = 1/T.

  4. Now fix the capacitance to 0.033 mF and 0.01mF and calculate the frequency and tabulate as shown.

  5. Find theoretical frequency from the formula f = 1/2PRCÖ6 and compare theoretical and practical frequencies.

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  
  

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  RESULT: -

  
  

  For C = 0.0022mF & R=10KW

                          Theoretical frequency=

                          Practical frequency=

  
  

  
  

  For C = 0.0033mF & R=10KW

                          Theoretical frequency=

                           Practical frequency=

  
  

  
  

  For C = 0.01mF & R=10KW

                         Theoretical frequency=

             Practical frequency=

  VIVA QUESTIONS:

  
  

  1. What are the conditions of oscillations?

  2. Give the formula for frequency of oscillations?

  3. What is the total phase shift produced by RC ladder network?

  4. What are the types of oscillators?

  5. What is the gain of RC phase shift oscillator?

  
  CIRCUIT DIAGRAM:

  

  
  

  RC PHASE SHIFT OSCILLATOR

  EXPECTED WAVEFORM:

  
  

  
  

  

  
  

  TABULAR COLUMN:

  
  

  S.No	C (mF)	R (W)	Theoretical Frequency (KHz)	Practical Frequency  (KHz)	Vo (p-p) (Volts)
  1	0.0022	10K
  2	0.0033	10K
  3	0.01	10K

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  EXPERIMENT NO- 6

  
  

  SINGLE TUNED VOLTAGE AMPLIFIER

  
  

  AIM:

  
  

  1. To study & plot the frequency response of a Single Tuned voltage amplifier

  2. To find the resonant frequency.

  3. To calculate gain and bandwidth.

  
  

  SOFTWARE REQUIRED:  MultiSim Software

  
  

  COMPONENTS & EQUIPMENT REQUIRED:

  
  

  S.No	Apparatus	Range/ Rating	Quantity (in No.s)
  1.	Trainer Board containing DC Supply voltage. NPN Transistor. Resistors. d) Capacitor. e) Inductor.	12 V BC 107 47 KΩ 150Ω 1 KΩ 10 KΩ 10mF 22 mF. 0.022 mF. 0.033mF. 1mH	1 1 1 1 1 2 2 1 1 1 1
  2.	Cathode Ray Oscilloscope.	(0-20)MHz	1
  3.	Function Generator.	0.1 Hz-10 MHz	1
  4.	BNC Connector		2
  5.	Connecting Wires	5A	5

  
  

  THEORY:

            

             A Tuned Amplifier uses a parallel tuned circuit a parallel tuned circuit has high input impedance at its frequency of resonance, and the impedance falls off sharping as the frequency departs from the frequency of resonance. Hence the gain Vs frequency curve of a tuned amplifier is very similar to the impedance Vs frequency curve of a tuned amplifier are therefore, used for amplification of a narrow band of frequencies.

  
  

             A resonant circuit generally uses either a variable inductor or variable capacitor for adjusting the resonant frequency at the center of the band of frequencies to be amplified. Over this narrow band of frequency, the gain of the tuned amplifier remains more or less constant.

  

             An important example is the radio frequency (R.F) amplifier, which amplifies either a single radio frequency signal or a narrow band or frequencies center about the resonant frequency. The tuned circuit formed by L & C resonates at the frequency of operation.

  
  

  
  

           

  
  

  PROCEDURE:

  
  

  
  
  

  1. Connect the circuit as shown in figure.

  2. Connect the 0.022μF capacitor

  3. Adjust input signal amplitude in the function generator and observe an amplified voltage at the output without distortion.

  4. By keeping input signal voltage, say at 50 mV, vary the input signal frequency from 0-1 MHz as shown in tabular column and note the corresponding output voltage.

  5. Repeat the same procedure for  0.033μF capacitor.

  6 Plot the graph: gain (Vs) frequency.

  1.      Calculate the F_t and Fp

  
  

  PRECAUTIONS: -

             

  1. No loose contacts at the junctions.

  
  

  2. Check the connections before giving the power supply

  3. Observations should be taken carefully.

  
  

  RESULT:

  
  

  Frequency response of RF Tuned voltage amplifier is plotted.

  For 0.022μF, gain = ________dB

  Bandwidth= _________

  3.    For 0.033μF, gain = ________dB

  Bandwidth= _________

  
  

  
  CIRCUIT DIAGRAM:

  

  
  

  SINGLE TUNED VOLTAGE AMPLIFIER

  
  

    

  EXPECTED GRAPH:

  

  
  

  TABULAR FORM-1:

  
  

  V_in = 50 mV

  C= 0.022μF

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K

  TABULAR FORM-2:

  
  

  V_in = 50 mV

  C= 0.033μF

  
  

  S.No	Frequency (in Hz)	Vo (in volts)	Gain A =  Vo/ Vi	Gain(dB) Av =    20 log(Vo/ Vi )
  1	100
  2	200
  3	400
  4	800
  5	1K
  6	2K
  7	4K
  8	8K
  9	10K
  10	20K
  11	40K
  12	80K
  13	100K
  14	200K

  
  
  BELOW ARE VIVA QUESTIONS 

1. What is the type of capacitor used in RC coupled amplifier for a) coupling two

phases b) by pass emitter

Ans. Generally electrolytic capacitors are used

2. What is signal source used for experiment of an RC coupled amplifier and how

much maximum voltage it could give

Ans. A function generator with 1 MHz highest frequency 0-30 V P – P output

is used in sine wave mode

3. What is the pin configuration on bread board used in the lab

Ans. In the bread boards there are two rows of horizontally shorted pin bank

on top and bottom, there are vertically shorted rows of pins in two halfs up

and down from the center of the bread board.

4. For Class – A amplifier How do you bring operating point of amplifier at center

of supply voltage

Ans. By adjusting the value of resistor used from base to supply.

If Vc < Vcc/2 base resistor is increased and if Vc > Vcc/2 it is decreased

5. What are the transistors used in complementary push pull experiment give type

number

Ans. A matched pair of NPN (CL100 or SL100) and PNP (CK100 or SK100)

used. Matching can be done by testing above in diode position of DMM for

same drop and HFE sockets of NPN, PNP for β.

6. How do you determine AC power output in class A amplifier i.e., do you measure

current or voltage and how?

Ans. P-P voltage is measured using CRO since AC current cannot be

measured.

7. How much current do you pass through reference zener in series regulated power

supply experiment

Ans. Iz min approximately equal to 5 mA is used.

8. In shunt regulator how is the value of resistor between base and emitter of shunt

transistor determined

Ans. VBE = 0.7 V, Resistor between BE = 0.7 / Iz min. practically 100 is

used

9. How do you determine Q of oil used in tuned amplifier experiment

Ans. Q = ωL /Rs where ω is Resonant frequency; R is series resistance of coil

10. What is the transistor used in shunt regulator and what is its Case style

Ans. NPN transistor SL100 is used the case style is TO2

11. Name one NPN and PNP transistors we have used in ECA lab

Ans. BC 107 NPN, CK 100 PNP

12. What ammeter do you need to measure DC power to class – C amplifier (DMM,

Analog coil meter or Analog moving iron meter)

Ans. Analog coil meter

13. What is the input resistance of oscilloscope you have used

Ans. 1 M , ± 1 %

14. What is the lamp used on all instruments to show presence of mains

Ans. In all modern equipment LED(Light emitting diode) is used in various

colors