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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    CAPACTIANCE OF CONDENSER BY

    CHARGING AND DISCHARGING

    AIM: To determine the time constant of the resistance capacitance series circuit by

    charging and discharging characteristics. From the results find the capacitance of a

    capacitor.

    APPARATUS: High resistance (R), Electrolytic capacitor (C), accumulator charge

    and discharge key, tap key, digital stop watch and DMM, bread board and

    connecting wires.

    INTRODUCTORY INFORMATION: Capacitor in series with resister may be used

    in electronic or electronic circuit to control the time required for a current or

    voltage to reach a specified value. Operation of this circuit is circuit given below.

    R and C are connected in series when we just start charging capacitor, charge on

    capacitor is such that potential difference across capacitor Vc is zero but charging

    current is maximum as charge starts collecting on C, Vc starts increasing but both

    charging current and the potential difference across resistor VRstarts decreasing at

    progressively decreasing rate C:

    ( E = VR + Vc ), Vc is given by Vc = E ( 1 e- t/RC

    )where RC = T = Time constant

    of the circuit Vc = Voltage across C at time.

    NATURE OF GRAPH:

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    CIRCUIT DIAGRAM: -

    E-transistor power supply (5V)

    C = Electronic Capacitor of Capacitance

    R = 320 K

    DMMDigital millimeter.

    C & DCharge and discharge key

    T - Tap key

    OBSERVATIONS: -

    1. Resistance used R = 320 k.

    3. theoraticaltical values of time constant T = RC sec

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Table: 1 Table: 2

    Charging curve Discharging curve

    Sl.

    no

    Charging

    time t

    Sec

    Voltage

    across

    capacitor

    V. Volt

    Obs

    No.

    Discharging time

    t

    sec

    Time Voltage across C

    Vc Volt

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    11

    12

    13

    14

    15

    16

    17

    18

    19

    20

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    When discharging key is pressed battery is cut of capacitor is short circuited

    through R. Hence it starts discharging Voltage value decreases exponentially.

    Progressively decreasing value of the Voltage Vc is given by Vc = E(et/Rc

    )

    Where the product RC is called time constant and t is the time at which voltage

    across C is Vc

    The time required to rise the voltage across the capacitor to 63. 2 % of the

    maximum applied Voltage is called the time constant of Rc circuit

    :: Time constant = T = Rc

    It is also the time during which the Voltage across the capacitor falls to 37 % of its

    initial maximum value.

    Equation Vc = E( et/ RC

    )

    Represents the

    decreasing curve.

    PROCEDURE: For Table I

    Set up the circuit as shown in the figure set the range selection. Switch on

    DMM charge the capacitor for s by pressing C and D lay to the position and

    simultaneously start the stop watch. After 5 release the C & D key and record Vc

    on DMM and time t. Discharge the capacitor fully by closing the tap key T for few

    seconds. Now carry out the procedure for time t = 10, 20, 25, ___ until capacitor

    voltage reaches the emf of battery

    CALCULATION:

    Time constant for charging curve = T1

    Time constant for discharging curve = T2

    Time constant =( T1+T2)/2=

    Capacitance of condenser C = T/R=

    (Note: for each value of t the capacitor should be discharged before charging).

    Tabulate the observations and then plot the charging curve from the charging curve

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    determine the time constant the time value corresponding Vc = 0.632 V max is the

    time constant T.

    For Table II:

    First charge the capacitor to the battery voltage by pressing C & D key to

    position 1 and holding in this position for about 2 to 3 minutes. Then immediately

    press C and D key to the position 2 and simultaneously start the stopwatch. Allow

    the capacitor to discharge for 5 After 5 second release the key and record Vc and

    time. Again charge the capacitor back to its E value and repeat the procedure as

    described already for time interval mentioned in the chart. Record the observations

    and plot-discharging curve. From this curve determine the time constant. Time for

    which curve Vc = 0.37 Vmax is the time constant.

    PROCEDURE:

    RESULT:

    Time constant of the resistance capacitance series circuit=

    Capacitance of condenser =

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    RESONANCE IN LCR CIRCUIT

    AIM ; Set up series and parallel resonance Circuit with the resonance frequency fo

    = 2250.5 H Study the response of circuit as a function of frequency. Determine the

    band width, resonant frequency & quality factor of the circuit take R = 50 , L =

    50 mH and C = 0.1 F

    APPARATUS : - Inductor, Capacitor, resistance box, Plug key, frequency

    generator, multimeter.

    FORMULA:-(i) fo = resonant frequency =

    Here L= 50mH = 50 * 103Hz

    C= 0.1 F = 0.1* 10-6F

    R = 50

    (ii) Band Width = f = f2f1

    f2Upper half power frequency

    f1Lower half power frequency

    (iii) Quality factor

    Here fo = Resonant frequency determined by experimental method

    f = band width

    THEORY: - The property of cancellation of reactance when inductive and

    capacitive reactance in series or the cancellation of susceptance when inductor and

    capacitor are in parallel is called as resonance.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    CIRCUIT DIAGRAM FOR SERIES LCR CIRCUIT:

    AFGAudio frequency generator

    LInductor = 50 mH

    CCapacitor = 0.1 F

    RResistor = 50

    NATURE OF GRAPH:

    From graph ,

    Foresonant frequencyI max = mA

    There are two types of resonance Circuits

    1) LCR series resonance

    2) LCR Parallel resonance

    1) LCR Series resonance when LCR are in series the effective impedance is a

    function of frequency

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Zeff = effective impedance

    Zeff = R + J (wL 1/Wc)

    At certain frequency fo, the effective impedance drops to minimum &

    current in the circuit is of maximum value the frequency at which effective

    impedance drops to minimum or current in the circuit maximum is called resonant

    frequency. The variation of the current in the circuit with respect to frequency of

    current applied voltage is shown in the graph the line drawn parallel to frequency

    axis, from a point corresponding to current value 0.707. I max on the current

    frequency graph intersects is called lower half & second intersect is called upper

    half frequency.

    2) LCR Parallel resonance : - When LCR are connected in Parallel the effective

    impedance zeff raises current in the circuit drops to minimum. Nature of variationof impedance of the circuit with the frequency as shown in the graph. The frequency

    at which Zeff raises to maximum value & current drops to minimum value is called

    resonant frequency fo.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    TABULAR COLUMN: -

    SL. no Frequency f in (Hz) Current I in (mA)1

    2

    34

    5

    6

    7

    8

    9

    10

    11

    12

    13

    14

    15

    16

    17

    18

    19

    20

    21

    22

    23

    2425

    In this case fo = At resonance frequency the effective impedance of

    circuit. Zeff = Zmax =

    In case of parallel resonance circuit the band width is defined as the difference

    between the frequencies corresponding to two points on either side of resonant

    frequency, where value of the impedance drops to 0.707 times the maximum value

    of impedance.

    Band width - f = f2f1

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Quality factor

    fo =

    CIRCUIT DIAGRAM; - LCR PARALLEL RESONANT CIRCUIT

    AFG - Audio frequency generator

    LInductor50 mH

    CCapacitor0.1 F

    RResistor50

    KPlug Key

    NATURE OF GRAPH: -

    OBSERVATION: -

    1) Vin =

    2) Zmax =

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    CALCULATION: -

    1) Band width, f = f2f1=

    2)Quality Factor,

    TABUALR COLUMN: -

    SL. No Frequency f (Hz) Current I (mA) Impedance Z = VinI

    From graph : for parallel

    Zmax =

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    INVERTING AND NON INVERTING AMPLIFIER

    AIM: -

    1) Set up an Op- amp IC 741 as inverting amplifier having an absolute value of

    gain equal to 10 compare the observed voltage to the theoretical values of the

    output for various input voltages sketch the input & output wave forms for

    any one of output.

    2) Set up an Op amp IC741 as non inverting amplifier having an absolute

    value of gain equal to 11 compare the measured output voltages with the

    theoretical value of output for various input values. Sketch the input &

    output voltages wave forms for any one of inputs.

    APPARATUS:- Op amp IC 741, Resistors, audio frequency generator,breadboard, CRO, Connecting wires, DCPower Supply.

    THEORY: - The operational amplifier is most commonly termed as Op amp. Due

    to its use in performing mathematical operations, it has been given the name

    operational amplifier. Because of their low cost, small size, flexibility Op amp are

    in the field of process control, communications, computers, power and signal

    sources delays & measuring systems.

    In linear applications output voltage of the amplifier varies linearly wire the

    input voltages off their exists a phase difference of 180obetween input and part of

    output which is feedback. The feedback maker the gain of the circuit stable, noise

    distortion is less, higher band width and improved output & input impedance values

    study of such an inverting amplifier gain properly to the purpose of experiment in

    case of non inverting amplifier (gain) there is no phase difference between input &

    output quantities.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    CIRCUIT DIAGRAM: -

    Inverting amplifier.

    NonInverting amplifier

    AFGaudio frequency generator

    R1Resistor = 10 K

    R210 K

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    IC 741Opamplifier.

    Inverting amplifier:

    Amplifier which provides a phase difference of 180obetween input & output

    is called inverting amplifier.

    Closed loop gain of gain of the inverting amplifier

    = Vo/ Vin

    where

    Vooutput voltage

    Vininput voltage

    The 3 terminals of Op-amp is at potential Vin. Hence the potential of 2

    terminal of Op-amp is also equal to Vin

    :. VA = VB = Vin

    VA = Potential of terminal 2 of Op-amp

    VB = Potential of terminal 3 of Op-amp

    For outside I = Vo -VA

    R2

    I = Vo-Vin

    R2

    At inverting terminal 2 of Op-amp

    I = VA-O = Vin (: VA= Vin)

    R1 R1

    Entire current passes through R2

    VOVin = Vin

    R2 R1

    VO = Vin + Vin = Vin(R1+ R2)

    R2 R2 R1 R1R2

    VO = R2 (R1+ R2) = (R1+ R2)

    Vin R1 R2 R1

    :. VO/Vin = gain of amplifier

    = 1+R2/R1

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    NATURE OF GRAPH OF INVERTING AMPLIFIER

    NONINVERTING AMPLIFIER

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Here +ve sign of gain indicates that the input & output are in phase in case of

    noninverting amplifier gain will be always greater than 1.

    The terminal 3 of Op-amp is ground therefore from concept of virtual

    ground; the terminal 2 is also at ground potential.

    OBSERVATIONS & TABULAR COLUMNS

    Inverting amplifier

    R1= . R2=

    Gain on amplifier = - R2/R1 =

    Frequency =

    Input voltage Vin(volt) Output voltage Voin

    volt

    Calculated output voltage Vo

    = - Vin R2/R1

    Non Inverting amplifier

    R1= R2= gain = 1+(R2/R1) =2

    Input voltage Vin(volt) Output voltage Vovolt Calculated output voltage

    Vo = -Vin ( 1+R2/R1)

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    I = Vin - VA

    R

    Vininput voltage

    VApotential of terminal 2 of Op-amp ground potential = 0

    :. I = Vin/R

    on output side

    R = VAVO O VoOutput voltage

    R VApotential at terminals

    R = VO/R

    Entire current flowing through R1, passes through

    R2 :. Vin = VO

    R1 R2

    VO/Vin = -R2/R1gain of amplifier hereVe sign denotes that input & output are

    out of phase.

    Here gain can be greater, less than or equal to 1, depending on values of R1&

    R2

    Noninverting amplifier where in input & output are in phase is called non-

    inverting amplifier gain VO/Vin.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    INDENTIFICATION AND MEASUREMENT OF

    R ,L AND C IN A BLACK BOX

    AIM: - To identify the terminals of R, L and C to determine the values of R, L and

    C in the black box.

    APPARATUS: - Black box containing R, L and C, Audio Frequency Generator

    (AFG) AC voltmeter, bread board connecting wires, resistance box, DC and AC

    source etc.

    THEORY: - Black box is a box that contains Resister; Inductor and Capacitor with

    one end of the each connected to one common terminal of black box and other ends

    to each are connected to different terminals of the black box. Therefore given black

    box has four terminals A, B, C, and D

    CIRCUIT DIAGRAM:

    Observation: -

    Tr. No Measure Resistance across Resistance

    1 AB

    2 AC

    3 AD

    4 BC

    5 BD

    6 CD

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    INFERENCE: -

    1. _____________ Terminal is common for R =

    2. _____________ Terminal is one end of the capacitor

    3. Resistance across ________&_______ terminals is maximum

    4 R and L are in series between terminal ___________and ____________

    5. The terminal __ is node for components R, L and C

    6. Capacitor is present between _______and _______terminals.

    7. Resitance is present between _______and

    _______terminals

    8. Inductor is present between _______and _______terminals

    CIRCUIT DIAGRAM II: -

    To determine terminals of L and R, and also to determine values of C L and

    R.

    AFGAudio frequency generatorR - Resistance box (0-1000)

    V1 - dc voltmeter (0-10V)

    V2 - dc voltmeter (0-5V) BB Black box with terminals A, B, C & D

    OBSERVAITON: -

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    1. Resistance RL in resistance box R =

    2. Frequency of alternating voltage input =

    3. Nodal terminal is ___B

    4. Probe is connected to ________terminal of black box

    Given : B is a nodal terminal.

    Payable RL Voltmeter reading Iac = V1-V2

    /R

    A

    Z = V2/Iac Mean Z

    Bet m

    V1Volt

    Bet N

    V2Volt

    V1-V2

    Volt

    A

    AB

    B

    BC

    C

    BD

    CALUCATION: -

    C = = __________F

    L= =______________mH

    INFERENCE: -

    1. Nodal terminal is __

    2. R and L are in series between __ and__ terminals

    3. Resistance across BD determined by II multimeter ___

    4. Resistance across XD determined by part II =______

    : Resistance across BD determined by multimeter Resistance across XD

    determined by Part II

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    : Resistance is present in between __ & __ terminals .

    5. Capacitor is present between __ and __ terminals

    : Inductor must be between __ & __ terminals

    : R, L and C Connections in black box are of type.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    ZENER DIODE AS A VOLTAGE REGULATOR

    Aim:

    To determine Zener diode as a voltage regulator to provide a constant voltage from

    a source whose voltage may vary over sufficient range.

    Apparatus:

    Zener Diode, battery,resistor,resistance box,voltmeter,plug key, connecting wires.

    THEORY:

    Zener Diode of Zener Voltage Vz is reverse connected across the load RL across

    which constant output is derived. The series resistance R absorbs the output voltage

    across fluctuations so as to maintain constant voltage across the load. When an

    input DC source is applied to the Zener diode, the output voltage will be the same as

    the input voltage. When the input voltage exceeds the breakdown voltage of the

    Zener diode, the output voltage remains constant even when the input voltage isincreased. Hence Zener diode acts as a voltage regulator.

    CIRCUIT DIAGRAM:

    Ba - Battery (0 V to 20 V) R - Resistor (220 )

    RL - Resistance Box V - Voltmeter

    K - Plug Key

    NATURE OF GRAPH:

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    TABULAR COLUMN:

    LOAD REGULATION

    INPUT VOLTAGE Vin=

    Resistance RL (ohm) Voltage across Zener Diode VZ (volts)

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    LINE REGULATION

    Load RL=

    Input voltage Vin(volts) Voltage across Zener Diode VZ (volts)

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Procedure:

    1. Connections are made as shown in the circuit diagram.

    2. Supply an input voltage of 10 V.

    3. Unplug 100 resistance from the resistance box. Note down the corresponding

    voltmeter reading.

    4. Continue the procedure for 200 , 300 , 10 K and note down thecorresponding voltmeter reading.

    5. Unplug 10 K of resistance from the resistance box

    6. Supply an input voltage of 1 V and note down the corresponding voltmeter

    reading.

    7. Continue the procedure for 2 V, 3 V,.15 V and note down the correspondingvoltmeter reading.

    8. Plot the graph of RL v/s Vz and Vin v/s Vz.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    ENERGY GAP OF A SEMICONDUCTOR

    THERMISTOR

    AIM: Determine the resistance of the thermistor at various temperatures. Plot the

    characteristic graph log 10 R (1/T) and hence determine the energy gap of the

    given thermistor.

    THEORY: Thermistor is temperature sensitive resistor. Its thermal resistance is

    related to the body temperature. Thermistor is made up of Germanium, Nickel, and

    Manganese. These thermistors are available in different shapes and size. They are in

    the form of beads, rods and discs. The compound employed will determine whether

    the device has +ve orve temperature coefficient. Thermistors of resistance ranging

    from 1200 at 800 k are available.

    The energy required to transfer an electron from valence bond to conduction

    band is called energy gap. The conductivity J of a semiconductor is given by = ze( -Eg/

    2kt) * e((e + n)

    where I > Z is total number of carriers per unit value of

    semiconductor in conduction band and value band

    ii) Eg: Energy gap

    iii) K: Boltzmanns constant = 8. 62*10-5 eV/ k

    iv) e: Electronic charge

    v) e = Mobility of electrons

    vi) T = Temperature in Kelvin

    vii) n = mobility of holes

    viii) = Conductively = 1/s

    ix) S = Specific resistance

    OBSERVATIONS:

    Room temperature =

    Applied Voltage V =

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Tabular Column:

    Obs No Temp t

    in C0

    Abs temp

    T = t + 273k

    Current I

    in mA

    Resistance

    R = V/ I

    Log R

    1/ T (sec-1

    )

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    11

    12

    13

    Nature of graph:

    CALCULATION:

    Energy gap:- m * 4.606 * 8.62 * 10-5

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    SEMICONDUCTOR DIODE

    AIM: Obtain current against voltage characteristic for semiconductor diode under

    forward bias and condition from the characteristic curves determine important

    parameters related to diode.

    APPARATUS: Battery, milliammeter, Voltmeter, diode, rheostat, plug key.

    THEORY: Forward bias:

    When a positive terminal of a dc source is connected to the P side and

    negative terminal to the n-side of the PNjunction diode it is said to be forwardbiased. Forward bias Voltage opposes the potential barriers at the depletion layer.

    As forward bias voltage is (VF) increases from 0 to the battery potential value

    initially there will not be flow of forward current later forward current slowly

    increases. When forward voltage is more than barrier potential effect of barrier

    potential becomes too less. In this region as the forward potential increases forward

    current also increases therefore whenever diode is forward, resistance of diode is

    small.

    CIRCUIT DIAGRAM: (Forward bias)

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    DDiode, BaBattery, RhRheostat, MAMilliammeter (0-25 mA),

    V-voltmeter, KPlug key, AAnode, KCathode

    NATURE OF GRAPH: -

    PROCEDURE: Forward bias

    1)

    Connections are made as shown in the circuit diagram.

    2) Note down the readings of the Vfwith corresponding If until it reaches

    to its maximum.

    3) Plot the graph of Vfversus If.

    4) Find the slope of the graph and calculate if by using the formula,

    Where, RFis the forward resistance.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    DSemiconductor VacacVoltmeter

    KPlug key Vdcdc - Voltmeter

    CCapacitor = 0.1mf Aammeter

    OBSERVATION: -

    When the plug key is open, then

    Imax=

    Vdc =

    Vac =

    Ripple factor =

    TABULAR COLUMN: -

    SL.NO Iz (mA) Vdc (V) Vac (V)

    ripple factor

    ripple factor =

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    % voltageregulation =

    OBSERVATION : - (Forward bias)

    TABULAR COLUMN: -

    Obs No Voltmeter reading

    Vf Volt

    Milliammeter

    Reading If(mA)

    PROCEDURE:

    1) Connections are done as shown in the circuit diagram.

    2) Keep the plug key (k) open, switch on the Ac mains note down Vdc and Vac.

    3) The plug key is closed and the reading of I, Vac and Vdc are noted down for

    corresponding readings.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    4) With the increase of Rheostat it is varied for different readings of I, Vac are

    noted.

    5) After completion of taking the readings calculate the ripple factor using formula.

    6) Calculate the percentage of regulator using the formula.

    Where, VNLis the Voltmeter reading when no current is passed through it.

    CALCULATIONS: -

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    RC PHASE SHIFT OSCILLATOR

    AIM: - Set up the RC Phase Shift oscillator using transistor and determine the

    frequency of alternating voltage developed by Oscillator.

    FORMULA: - Frequency of alternating voltage developed by oscillator

    Hz

    Where, Rc= Collector resistance

    R= Resistance in phase shift network

    C= Capacitance of capacitor in phase shift oscillator.

    THEORY: - In RC Phase Shift oscillator, three RC Sections are used to provide 180

    degree phase shift and the remaining 180 degree phase shift is provided by the transistor.

    Therefore there is a total 360 degree phase shift.

    CIRCUIT DIAGRAM:

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    TABULAR COLUMN: -

    Theoretical value of frequency Measured value of frequency

    r

    o

    Capacitance

    C(F)

    Resistance

    R(k)

    Frequency(F) Length

    of onewave

    A(div)

    Time base

    B(s/div)

    Time

    periodT=A*B

    sec

    Frequency

    F=1/T Hz

    WAVEFORM:-

    PROCEDURE:-

    1] Connections are made as shown in the circuit diagram.

    2] Adjust the potentiometer to obtain a stable wave form on CRO. 3] Find the time

    period T.4] Then calculate the frequency f= 1/ T Hz.

    5] Compare this value with the theoretical value, repeat the experiment for different

    values of R.

    CONCLUSION: -

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    COLPITTS OSCILLATOR

    AIM: - Set up Colpitts Oscillator using transistor determine the frequency of oscillating

    for various set of capacitors C1 & C2.

    APPARATUS: - BC547, NPN Transistor, resistor, capacitors, power supply.

    FORMULA: - Frequency of Oscillator

    Where, L=inductance=38.95 H= 38.95 x 10-6

    H

    C=capacitance= .. microfarads

    THEORY: - The tank circuit provides 180-degree phase shift and the amplifier provides

    180 degree. Thus, there is a total phase shift of 360-degree. Hence the feedback is +ve.

    The frequency of oscillation is,

    CIRCUIT DIAGRAM:

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    TABULAR COLUMN:

    Sl no Theoretical value of frequency Measured value of frequency

    Capacitor

    C1(F)

    C=(C1*C2)/

    (C1+C2)

    In F

    F=1/2L MHz

    Length

    one wav

    (div)

    Time ba

    B (ms/di

    Time peri

    AB

    Sec-1

    Frequency

    F=1/T

    Hz

    PROCEDURE: -

    1] Connections are made as shown in the circuit diagram2] Adjust the CRO controls to obtain the wave form on CRO

    3] Measure the time period T and find the frequency, f= 1 / T H 4] Measure & compare

    this value with expected value

    5] Repeat the experiment for different value of C

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    FULL-WAVE BRIDGE RECTIFIER

    AIM:Set up a Full-Wave Bridge Rectifier with a capacitor filter and study its

    performance.

    APPARATUS:Transformer, Diode, Capacitor, Resistance Box, Rheostat, DC

    Milliammeter, DC Voltmeter, AC Voltmeter, Plug key.

    FORMULA:

    Ripple Factor =

    % Voltage Regulation =

    Ripple Factor in absence of filter = r = 0.482

    Efficiency of Rectifier = 81.2 %

    THEORY:

    Rectifier is a device that converts alternating current into unidirectional direct

    current. A full-wave rectifier rectifies both the positive and negative half-cycles of

    the input ac signal. A bridge rectifier utilizes 4 diodes connected as in the circuit

    diagram to accomplish full wave rectification.

    Operation of the circuit is like thisDuring positive half cycle of input sine wave,point A is positive w.r.t. point B. Diodes D1 and D2 are forward biased where as

    diodes D3 and D4 are reverse biased.. Hence only diodes D1 & D3 conduct during

    the positive half cycle while diodes D3 & D4 do not conduct current. If the filtering

    condenser C is not in the circuit then always current through (both during +ve & -ve half cycles of input current flows through input resistance) R & Rh (in circuit)will flow in the same direction. But current flowing through load in the absence of

    the filter is unidirectional and pulsating one, point D of the diode acts as the Anode

    and point C acts as Cathode. Output of the rectifier being pulsating, contains DC

    component as well as AC component. This type of output is not useful for driving

    sophisticated electronic circuits. In fact, these circuits require steady DC output.

    A circuit that converts pulsating output from rectifier into a steady DC level is

    known as Filter, because it filters off or smoothens the output.

    The filter used here is a Shunt Capacitor Filter. Here, capacitor of suitable value C1

    is connected across the rectifier and is parallel to the load resistance R & Rh. Thistype of filter is Capacitor Input Filter. It often allows impedance path for DC

    portion of the output. The filtering action is shown in the output wave form. By

    looking at it, one can see that even after filtering action, small amount of AC

    remains unfiltered in the output. The remaining AC in DC component of the output

    is called Ripple (unfiltered AC remains in outut). and is written a r = 1 / 4 .

    This indicates that ripple factor depends on C and load resistance.

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    CIRCUIT DIAGRAM:

    OBSERVATION:

    Sl. No.Load

    Resistance

    Vdc

    (Volt)

    Vac

    (Volt)

    Iac

    (mA)

    Ripple

    Factor

    Vac / Vdc

    % Voltage

    Regulation

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    PROCEDURE:

    1) Connections are done as shown in the circuit diagram.

    2) Keep the plug key (k) open, switch on the Ac mains note down Vdc and Vac.

    3) The plug key is closed and the reading of I, Vac and Vdc are noted down for

    corresponding readings.

    4) With the increase of Rheostat it is varied for different readings of I, Vac are

    noted.

    5) After completion of taking the readings calculate the ripple factor using formula.

    6) Calculate the percentage of regulator using the formula.

    Where, VNLis the Voltmeter reading when no current is passed through it.

    CALCULATIONS:

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    ZENER DIODE CHARACTERISTICS

    AIM: - Set up electronic circuit to study the reverse current characteristics of

    zenerdiode of power 0.5w and breakdown voltage 6.2v and hence determine.

    1. Knee current I

    2. Incremental zener resistance Rz

    3. Range of Iz over which Vz remains constant

    APPARATUS: - Transistor, power supply, Rheostat, current limiting resistor,

    Zener diode, digital multimeter, to measure Vz, digital multimeter Iz.

    THEORY: - Zener diode is reverse biased, heavily doped P.N diode that is operated

    in the breakdown region, where current is limited by both external resistance and

    power rating of the diode.

    Zener diode at breakdown voltage VB breakdown due to zener effect and

    avalanche effect usually at breakdown voltage one of the above two effects will

    predominate depending upon breakdown potential difference.

    In case of zener effect, breaking of the bond i.e covalent bond by strong

    electric field occurs. Avalanche effect occurs due to at higher voltage, when

    thermally generated electrons acquire enough to produce more carriers by collision.

    Maximum current required to sustain breakdown is called knee current Ik

    The maximum current which zener diode can withstand without getting overheated

    or burnt is represented by I max. If the current is more than this maximum value,

    zener diode will burn out due to overheating.

    To reduce overheating, a limiting resistance Rs is connected in series with

    zener diode.

    Value of Rs is calculated as follows:

    P = Power of zener diode = Vz Iz

    :. Iz = P

    Vz

    Where, Vz = break down voltage of diode

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    Iz = Current

    I max = Selected maximum current allowed to pass through zener diode = 50% of

    Iz

    Then Rs = VinVz

    Imax

    Where, Vin = applied voltage.

    Reverse current character of zener diode is as shown in the nature of graph.

    Diode passes some resistance called zener dynamic resistance Rz. Ideal

    zener diode characteristic is not truly vertical, however the zener dynamic R is

    very small. This means for considerable increase in Iz the value of Iz remains almost

    same. Vz value of diode remain constant over range IkI amx

    CIRCUIT DIAGRAM:

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    EXPERIMENT NO: DATE:

    Department of BCA and B.Sc(CS) ,KSCD.

    NATURE OF GRAPH:

    OBSERVATIONS:-

    1. Voltage selected in TPS = Vin =

    2. Zener diode break down voltage =

    3. I amx

    4.

    Limiting resistance =

    5. Actual value of Rs, selected =

    TABULAR COLUMN:

    SI. NO. IZin

    mA

    VZ

    (VOLTS)

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    EXPERIMENT NO: DATE:

    CACULATIONS:

    AB=

    BC=

    RZ=

    Range of current = IK to Imax

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