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P RACTICAL M ANUAL

NATIONAL D IPLOMA

ELECTRICAL / ELECTRONICSDEPARTMENT

The Federal Polytechnic, IlaroOgun State

Nigeria.

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TABLE OF CONTENTS

ELECTRICAL ENGINEERING SCIENCE/EEC112.........................................................3Measurement of Resistance.............................................................................................4Ohms Law (1) ................................................................................................................6Ohms Law (2) ................................................................................................................8Kirchhoffs 1st Law (Voltage Divider Rule).................................................................10Resistors in series...........................................................................................................12Kirchhoffs 2nd law (Current Law)...............................................................................13Resistivity of Materials .................................................................................................15Demonstration of Sinusoidal Signal .............................................................................16

ELECTRONICS 1.............................................................................................................17COURSE CODE/EEC 124................................................................................................17

Physical Identification Of A PN-Junction Diode And Test Of Its Functionality..........18Determination Of Transistor (Npn) Characteristic Curve.............................................20Operation Of Zener Diode As Voltage Regulator.........................................................22Output Characteristics Of A Common Source Fet........................................................24

Measurement and instrumentation I/EEC 128...................................................................26Measurement of Resistance using Ohmmeter................................................................26Determination of Errors in Measurement......................................................................28Ohms Law (1)...............................................................................................................29Ohms Law (2) ..............................................................................................................31

ELECTRONICS II/EEC 234.............................................................................................34Performance Of A Common Emitter Amplifier............................................................34Determination Of Gain/ Frequency Curve.....................................................................36Application Of Negative Feedback To Amplifiers........................................................38

Operation Of Lc Oscillators...........................................................................................40Rectification...................................................................................................................42

MEASUREMENT AND INSTRUMENTATION II/EEC 235.........................................45Measurement of voltage, current and frequency using digital instrument.....................45Measurement of power using single-phase wattmeter...................................................47

TELECOMMUNICATIONS/EEC 244.............................................................................50Demonstration Of Amplitude Modulation And Demodulation ....................................50Determination Of Frequency Modulation......................................................................52

ELECTRICAL MACHINES/EEC 236..............................................................................55Efficiency Of Transformers...........................................................................................55Transformer Voltage Regulation...................................................................................56

Transformer Load Test..................................................................................................58Determination Of No-Load Current Componets...........................................................60Open Circuit And Short Circuit Test On A Transformer..............................................62

Department Of Electrical Engineering, The Federal Polytechnic, Ilaro Ogun State. 2

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COURSE TITLE/CODE:

ELECTRICAL ENGINEERINGSCIENCE/EEC112


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Experiment 1Title:Measurement of ResistanceObjective: At the end of the experiment the student should be able to:Identify ResistorsMeasure Resistance using an Ohmmeter andDetermine resistance values using colour codes

Background Theory: Resistor is a component, which determines the currentmagnitude in an electric circuit according to Ohms law, depending on the resistor valueand the voltage passed through it. The most commonly used resistors come in cylindrical

packages with 4 colour rings. Three are close to each other while the last one is slightlyfar away. The three close rings indicates the value of the resistor and the fourth itstolerance.

Apparatus: TPS 3321, Power supply, Multimeter, Banana wires and resistors-1M, 91K, 10K, 5.1, 1K, 100Diagram

Procedure:1. Do not connect the TPS 3321 to the Power Supply2. Identify five resistors on the TPS Trainer panel.3. Having identified the five resistors, R1, R2, R3, R4 and R5 on the TPS3321, write

out the colour of R1 determine the value using colour code method.4. Write down the value in the table provided.5. Repeat the same for the remaining resistors.

6. Turn the Multimeter selector to Ohms range, choose the 20K region. Insert thered probe to the voltage and resistance socket and the black probe to the commonsocket.

7. Connect the Multimeter probe to the two ends of the resistor R1.8. Take the reading in the meter and if necessary adjust the range to have a readable

value judging from your answer when colour code was used.9. Record the reading in the space provided and10. Repeat then same for the rest of the resistors.


Gold = 5%

Brown = 1

Black = 0Red = 2

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RESULTS:

No Resistor Symbol

Firstcolour

Secondcolour

Thirdcolour

Fourthcolour

1st

digit2nd

digit3rd

digit%toler

ance

NorminalValue

MeasuredValue

1 R12 R23 R34 R45 R56 R6

EXERCISES:What conclusions can you draw from the two readings? (i.e. Colour Code and Meter Values)


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Experiment 2

Title:

Ohms Law (1)Objective: At the end of the experiment, the student should be able to determinethe relationship that exists between Current and Voltage across a resistor.Background Theory: The current that flows through a resistor in a d.c. circuit is directly

proportional to the potential difference between the two ends of the resistor, provided all physical conditions are constant. i.e. V/I =R

Apparatus: TPS 3321, Two multimeters and banana wires.

Diagram:

Fig 2.1 Simple d.c. circuit for verification of Ohms law

Procedure:1. Connect the TPS 3321 to power supply2. Switch On the power supply3. Turn the power supply control knob until you obtain 0V4. Connect the red probe of the meter to positive terminal of the power supply5. Connect the black probe of the meter to a terminal of the resistor R56. Connect the second terminal of the resistor to ground.

7. Measure and record the current in the circuit through the ammeter.8. Repeat the procedure (4) (8) for Vs = 2-10V with steps of 2.


+

-R V

I

I

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Result/Analysis: Tabulate the readings as shown below;

R5() Vs(V) I(A)0246810

Exercises:Plot the graph of Voltage against CurrentFrom the experiment, draw your conclusions.


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Experiment 3

Title:

Ohms Law (2)Objective: At the end of the experiment, the student should be able to determinethe relationship that exists between Current and Resistance.Background Theory: The current that flows through a resistor in a d.c. circuit is Inversely

proportional to the resistance of the resistor for a constant voltage. i.e. I1/R.


Diagram:


Procedure:1. Connect the TPS 3321 to power supply2. Switch On the power supply3. Turn the power supply control knob until you obtain 5V4. Connect the red probe of the meter to positive terminal of the power supply5. Connect the black probe of the meter to a terminal of the resistor R5 (1K )6. Connect the second terminal of the 1K resistor to ground.7. Measure and record the current in the circuit through the ammeter and record as

shown below.8. Repeat the procedure (5) (7) for resistors 1M, 91K, 10K, 1K, 100.


+

-1K 5V

A

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Result/Analysis: Tabulate your readings as shown below;

R Vs(V) Resistance I(mA)1 52 53 54 55 56 5

Exercises:Plot the graph of Current against ResistanceFrom the experiment, draw your conclusions.


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Experiment 4

Title:

Kirchhoffs 1st

Law (Voltage Divider Rule)Objective: At the end of the experiment, the student should be able to the principleof Voltage Divider Rule from the connection of resistors in a circuit.

Background Theory: This connection is very common in electronics circuits,a case where some resistors are connected in series. This brings about a voltage divider since the 1 st Kirchhoffs law states that the algebraic sum of voltages in a circuit is zero.The equation holds that

i.e.

Apparatus: TPS 3321, Two multimeters and banana wires, Resistors 1K &100

Diagram:


Procedure:1. Connect the TPS 3321 to power supply2. Connect the circuit as shown in fig 4.2, connecting the free sockets of R5 and R6

using banana wires.3. Connect the +12v socket to the first socket of R5 and then the other socket of R6

to the negative of the power supply (the GRD)4. Allow the Supervisor to crosscheck the connections then Switch On the power

supply5. Turn the multimeter to voltage mode and use the 20Volts range. Connect the

meter probes to the socket of R6. Write out the voltage VR6


+-

V

R

1R

2

I

Rn

+

-12V

1K

100

I

R 5

R 6

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6. Measure and record VR5 as well and record.

RESULTS:VR6 =VR5 =

Measure the Source Voltage VsCheck if Vs = VR5 + VR6

9. = = =?

Exercise: What does the formula in step 9 calculate?Write down your comments.


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Experiment 6

Title:

Kirchhoffs 2nd

law (Current Law)Objectives: At the end of the experiment the student should be able to understandthe condition of parallel connection of resistors resulting in current divider.

Theoretical Background: From the 2 nd Kirchhoffs law which states thatin a closed loop, the sum of the products of the current and resistance of each part of thecurrent and resistance of each part circuit equals the resultant e.m.f in the circuit whenresistances are connected in parallel, we have a current divider while the same voltageflows into each branch as in fig. 6.1

Apparatus: TPS 3321, Power Supply, a Multimeter and ResistorsProcedure:

1. Make sure the TPS 3321 is switched off.2. Connect the circuit as shown in fig 6.2 with the multimeter set to measure current

connected in series with the 1k which is R1.3. Allow the supervisor to crosscheck the connections.4. Then turn on the TPS 33215. Adjust the power supply voltage to +3V6. Check the reading for IR5 (1K )7. Record your readings8. Reconnect the circuit to fig 6.3 so as to read the meter for IR4 (5.1k)9. Check if IR5/R4=IR4/R5 exist and10. Verify if IR4*R4=IRS*R511. Connect as in fig 412. Justify the law Sum of all currents that enter a point in electrical circuit equals to

zero check if IT-IR4-IR5=0

Diagram:


+

-V R 1 R 2

I

I1

I2

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Fig 6.1

Readings :Tabulate your readings as shown below

IR4IR5IT

Exercises:

What does the formula in step 10 calculate?

Verify if IT=IR4+IR5 and make your comment.


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Experiment 7

Title:

Resistivity of MaterialsObjective: At the end of the experiment, the student should be able to establish thatthe resistivity of a material is directly proportional to its length and inversely proportionalto its cross sectional area.

Background Theory: The resistance of a material (conductor ) is directly proportional to its length and inversely proportional to its cross sectional area. Therelationship exists that

And resistivity is derived from the relation where is the resistivity therefore

= where A is constant.

Apparatus: Potentiometer, Multimeter,Procedure:

1. On the Potentiometer, measure using its meter rule, 0.3m.2. Set the Multimeter to Ohms range3. Place one Probe of the multimeter at the beginning of the constantan wire on the

potentiometer, and the other probe directly on the point of 0.3m.4. Take the reading on the Meter


L(m) 0.0 0.1 0.2 0.3 0.4 0.5 0.6R()

Exercises:Plot the graph of Resistance against lengthCalculate the slopeWhat does the slope suggest?From the experiment, draw your conclusions.


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COURSE TITLE/CODE:

ELECTRONICS 1

COURSE CODE/EEC 124


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Experiment 1

Title:

Physical Identification Of A PN-JunctionDiode And Test Of Its Functionality.

Objective: At the end of the experiment the student should be able to identify pn- junction diode physically and test for its functionality.

Background Theory: The pn-junction diode is formed by growing onecrystal, (it must be continous) of semiconductor, material and doping separate butadjacent layers of it with the appropriate impurities. At equilibrium, a depletion layer is

formed at the junction that is void (depleted) of loosely held charge carriers. Whenconducting leads are attached to a pn-junction, the device exhibits a useful characteristicsand is called a PN-junction diode.

Apparatus: 1. Multi-meter 2. Semiconductor diode type IN4007.

Diagram:


P N

+ + + - + - - -+ + + - + - - -+ + + - + - - -+ + + - + - - -

P NP N

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Procedure:

1. Identifying the PN-junction diode physically

2. The Semiconductor diode IN4007 looks cylindrical in shape3. Identify the cathode by locating the end with a white stripe around it as shown inthe diagram

4. The other end with no white stripe is the anode5. Test of Functionality using a multi-meter 6. Switch on the multimeter 7. Select the semiconductor test mode on the digital multimeter 8. Connect the red probe to the anode as earlier identified.9. Connect the black probe to the cathiode10. Observe what happens11. Connect the balck probe to the anode

12. Connect the red probe to the cathode13. Observe what happens

Results:Resistance reading

Forward biasReverse bias


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Experiment 2

Title:

Determination Of Transistor (Npn)Characteristic Curve

Objective: At the end of the experiment the student should be able to measure anddraw the output characteristic curve of an NPN transistor.

Background Information: Every bipolar junction transistor have base (B),an emitter (E) and a collector (C) as its electrodes. However, when the transistor isconnected such that the emitter is common to both the base-emitter side and the collector-

emitter output side, then the configuration is said to be common emitter configuration.The output or collector characteristics plots of the output current (Ic) versus outputvoltage (Vce) for fixed values of input current, Ib.

Apparatus: TPS 3321,and Multimeters,

Procedure:1. Connect the circuit as shown above.2. Output characteristics3. Adjust the input resistance R1 and R2 until Ib = 0A initially.

4. Turn R3 to increase Vce in steps of 1V, starting from 0V to 10V, measure andrecord corresponding values of Ic using table1.5. Follow the procedure in step 1 and set Ib =20A to 80A for each fixed value of

Ib, repeat step 2 and complete the table.


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Diagram:

Results:Table 1

Ib(A) 0 20 40 60Vce(V)0123456

78


A

Vce

A

100K R1

R2 1M

5V

Ib

0 100mA

0 30mA

Ic

100

10V

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Experiment 3

Title:

Operation Of Zener Diode As VoltageRegulator

Objective: At the end of the experiment the student should be able to understandregulation in power supplies and measurements in linear voltage regulators.

Background Information: The zener diode is the basic component inregulation circuits. The zener diode is a diode operated in the reverse breakdown region.It is made from a heavily doped PN junction and reverse breakdown voltage or zener

voltage is specified by the manufacturer.

Apparatus: TPS 3321, Multimeters, Banana wires.

Procdure: 1. Implement the circuit as shown above2. Turn the trainer 3. Change Vi and fill the following table

Diagram:

Results:

t 1 2 3 4


Vi Vo

1K IN4001

Meter 1

Meter 2

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Vi 7V 8V 9V 10VVo 4.33 4.42 4.49 4.52 VoSv

Exercises: Vo (t) = Vo (t+1) Vo (t)Plot graph of Vi against VoCalculate the regulation coefficient for each columnSv = Vo/ VinDetermine the zener voltageState your observationsDraw your conclusions


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Experiment 4

Title:

Output Characteristics Of A Common SourceFet

Objective: At the end of the experiment the student should be able to understandthe operation of a field effect transistor and draw its output characteristics.

Background Information: The field effect transistor is a three terminalunipolar device, the FET is a voltage controlled device used in digital and analoguecircuits for control and switching. It has three terminals, the Gate, the Drain and the

Source. A plot of the drain current against the gate source voltage yields the outputcharacteristics.

Apparatus: TPS 3321, Voltmeters and Ammeters.

Procedure:1. Connect the TPS 3321 trainer to the power supply and the power supply to the

mains.2. Implement the diagram shown above3. Turn on power supply

4. Change V GG according to the following table and register the measured values of VGS, V D and V S

Diagram:


VGG

VG

5.1 K

1 K 1 M

+ 12V

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Results:

No 1 2 3 4 5 6 7 8 9 10 11VGG (V) 3 2.5 2 1.5 1 .5 0 -0.5 - 1 - 1.5 - 2VG (V)VD (V)VS (V)VGS (V)ID (mA)IS (mA)VDS (V)

Exercises:

Calculate V GS for every V GG value according to the following formulae:VG = V GGVGS = V G - V SID = (V DD V D)/ R DVGS, = V S/R SCalculate V PO and I DSS of the component.Plot I D against V GS.

COURSE TITLE/ELECTRICAL


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Mea surement and instrumentation I/EEC128

Experiment 1

Title:Measurement of Resistance using OhmmeterObjective: At the end of the experiment the student should be able to:Identify ResistorsMeasure Resistance using an Ohmmeter andDetermine resistance values using colour codes

Background Theory: Resistor is a component, which determines the currentmagnitude in an electric circuit according to Ohms law, depending on the resistor value

and the voltage passed through it. The most commonly used resistors come in cylindrical packages with 4 colour rings. Three are close to each other while the last one is slightlyfar away. The three close rings indicates the value of the resistor and the fourth itstolerance.

Apparatus: Multimeter, resistors- A J and connecting leadsProcedure:

1. Place the Multimeter on the table and adjust the Pointer to zero


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2. Set the selector switch to Ohms range3. Short the two terminals of the meter by bringing the two probes to touch each

other 4. See that the pointer turns to infinity5. Pick resistor A and connect the two leads to the two ends of the resistor

6. Take the reading on the Ohms Scale (Be sure to select an appropriate ohms range)7. Record your reading in the table provided8. Repeat the same for the remaining resistors B - J

RESULTS:RESISTORS VALUE FROM OHM METER ABCDE

FGHIJ

EXERCISES:What are the other units of resistance?

What difficulties did you encounter while taking the readings?What precautions did you take?Give two instances where resistors are used.


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Experiment 2Title:Determination of Errors in MeasurementObjective: At the end of the experiment the student should be able to determineerrors in measurements.

Background Theory: Measurements are prone to errors which may ariseeither from meter variances, temperature differences and other factors. It is hereby

possible to determine the Absolute error and the relative error by calculations.

Apparatus: Multimeter, resistors- A J and connecting leadsProcedure:

1. Place the Multimeter on the table and adjust the Pointer to zero2. Set the selector switch to Ohms range3. Short the two terminals of the meter by bringing the two probes to touch each

other 4. See that the pointer turns to infinity5. Pick resistor A and connect the two leads to the two ends of the resistor 6. Take the reading on the Ohms Scale (Be sure to select an appropriate ohms range)7. Record your reading in the table provided


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8. Repeat the same for the remaining resistors B - J

RESULTS:RESISTORS NORMINAL

VALUE, RNMEASUREDVALUE,RM

ABSOLUTEERROR

RA=RN-RM

RELATIVEERROR

=RA/RMABCDEFGHIJ

EXERCISES:Calculate the Absolute and Relative errorsHow can you minimize the errors in your measurement?What precautions did you take?

Experiment 3

Title:Ohms Law (1)

Objective: At the end of the experiment, the student should be able to determinethe relationship that exists between Current and Resistance.

Background Theory: The current that flows through a resistor in a d.c.circuit is Inversely proportional to the resistance of the resistor for a constant voltage. i.e.I1/R.


Diagram:


+

-R V

I

I

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Procedure:1. Connect the TPS 3321 to power supply2. Switch On the power supply3. Turn the power supply control knob until you obtain 5V4. Connect the red probe of the meter to positive terminal of the power supply5. Connect the black probe of the meter to a terminal of the resistor R5 (1K )6. Connect the second terminal of the 1K resistor to ground.7. Measure and record the current in the circuit through the ammeter and record as

shown below.8. Repeat the procedure (5) (7) for resistors 1M, 91K, 10K, 1K, 100.

Result/Analysis:

Tabulate your readings as shown below;

R Vs(V) Resistance I(mA)1 52 5

3 54 55 56 5

Exercises:Plot the graph of Current against Resistance


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From the experiment, draw your conclusions.

Experiment 4

Title:Ohms Law (2)

Objective: At the end of the experiment, the student should be able toDetermine the value of an unknown resistor using the Rheostat,Determine the relationship that exists between Current and Voltage across a resistor.

Background Theory: the value of an unknown resistor could be determined by using the Rheostat with the arrangement below. By taking various readings for voltageand current, plotting the graph and calculating the slope. The Slope value is the unknown

resistance.

Apparatus: Ammeter (0-10mA), Voltmeter (0-10V), Rheostat (920, 0-3A)Power Supply Unit, (d.c. 10V), Resistors A-J, banana wires.

Procedure:1. Connect the above Circuit


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2. Set the power supply to 10V and energize the circuit.3. Adjust the rheostat to obtain a reading of 5V on the Voltmeter 4. Record both Voltmeter and the ammeter readings5. Repeat the procedure for 1-9V by adjusting the rheostat6. Tabulate the results as shown below


Exercises:

Plot the graph of voltage against current and calculate the slope.What can you say about the shape of the graph?Comment on the accuracy of this method.

Department Of Electrical Engineering, The Federal Polytechnic, Ilaro Ogun State.

Voltage (V) Current I (mA) Resistor Value1234

56789

32

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COURSE TITLE / CODE

ELECTRONICS II/EEC 234

Experiment 1

Title:

Performance Of A Common EmitterAmplifier.

Objective: The student at the end of the experiment should be able to determine therelationship between the base current and the collector current in a common emitter Amplifier


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Background Theory:For a transmitter amplifier circuit to function correctly, it should be properly fed with ad.c voltage source. In other words, the circuit must be correctly biased. This means the

base, emitter and collector of the transistor in the amplifier circuit must be at a certainvoltage values either relative to ground or relative to one another.

Apparatus:TPS - 3321, Multimeters, stabilizer power supply.

Procedure:1. Connect the circuit as shown below using banana wires as provided in the training

kit.2. Switch on the power supply.

3. Four resistors are provided for the base resistance R bx; determine using the color codes the value of these four resistors and record your readings in the table below.

4. For each of the base resistance given R bx , measure V b and V c and record as shownabove.

Results:


A A

R BX

R C=

1K

R E=100

Vb

VCC

=12V

VC

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S/N R bx VB VC VRB VRC I b(mA)

Ic(mA)

Hfe(10 -2)

Comments

123

4

Exercise:Plot the graph of V b against V c. State what you deduced from this graph

Experiment 2Title:Determination Of Gain/ Frequency CurveObjective: The student at the end of the experiment should be able to determine therelationship between the gain of an amplifier and its frequency of operation, calculate the

bandwidth of the amplifier and understand what is meant by frequency response of anamplifier.

Background Theory:An importance characteristic of an amplifier is that it does not amplify an input signalequally at all frequencies. Thus, the voltage gain of an amplifier is frequency-dependent.


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The frequency response of an amplifier is a plot of gain versus frequency ( at manyfrequency points).

Apparatus:1. Signal generator 2. Oscilloscope3. Power supply4. Multimeters5. An experimental board (with transistors, resistors and capacitors).

Diagram:

Procedure:1. Connect the single stage amplifier circuit as shown in the diagram using the

experimental board.2. Connect the input of the amplifier to the signal generator and the output to the

multimeter to measure the amplitude of the signal.3. Connect another multimeter set to measure frequency to the input. Start at 700Hz

and measure the corresponding voltage peak to peak, and record your results in

the table below

Results:


VCC

=10V

BC109 22F

80F

56K

5.6K

22F

1K

1K

22F

0.1F

VO

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Frequency (Hz) 700 1K 2K 3K 4K 5K 6K 7K 8K VinVoA=20log 10(Vo/Vin)

Exercise:Using the data in table above, plot the frequency response curve on a single semiloggraph paper.Determine the bandwidth of the amplifier from the frequency response curvesWhat is meant by the frequency response of an amplifier?

Experiment 3

Title:Application Of Negative Feedback To

Amplifiers.Objective: At the end of this experiment, the student should be able to understandThe effect of negative feedback on amplifier voltage gain,the effect of negative feedback on input and output impedances of an amplifier.

Background Theory:


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The voltage gain of an amplifier is reduced over all the frequency range when a negativefeedback is applied to it. If the amplifier gain without feedback is A , and is thefeedback factor, then the overall gain is reduced by a factor of (1 + A).

Apparatus:1. Sine wave oscillator 2. Oscilloscope3. stabilized d.c power supply, training kit TPS 3321.

Procedure:Without negative feedback (i. e C E is connected across RE)

1. Connect the circuit as shown below with the decoupling capacitor connected.2. Apply an input sine wave Vi from the signal generator to the amplifier.3. Measure and record the amplitude of the corresponding undistorted output signal,

Vo as provided in the table below.

Results:

V in(V)

Iin(A)

Vout(V)

A=20log 10(Vo/Vin) Zin Commen onstability of

amplifier

With negative feedback (i.e. C E not connected across R E):


80F

Vcc= 12v

OscilloscopeV

O

1K 10K

5.6K 91K

V

i

SIGNALGENERAT

OR

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Repeat steps 1 (ii) and tabulate your result as in table 1

Exercise:Calculate the gain for each Vin settingDetermine the input impedance for each Vin setting .Comment on the stability of each type of amplifier.State your observations and conclusions.

Experiment 4

Title:Operation Of Lc Oscillators.Objective: The student at the end of the experiment should be able to understandoperation of the colpitts oscillator circuit and determine the value of the unknowninductor using the frequency measured from the output of the oscillator.

Background Theory:


X1

X2

X

3

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Based on the proofs:For oscillation occur, (i) the reactance X 1 and X 3 must be of opposite sign and (ii)X1+X 2+X 3=0For oscillation to be maintained 1+hfe= -(X 1/X 3).

Oscillation type X 1 X2 X3Colpitt L C CHartley C L L

For colpitts, X 1= L, X 2= (1/jC 2) and X 3= (1/jC 3)f= 1/2 {LC 2C3/ (C 2+C 3)}1/2

Apparatus:1. TPS 33212. Multimeters3. Oscilloscope.

Procedure:1. Connect the circuit as shown below using banana wires.2. Connect the output of the oscillator to the oscilloscope.

Diagram:

Department Of Electrical Engineering, The Federal Polytechnic, Ilaro Ogun State. 411K

L

100 pF100pF

10K

12V

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Results:Measure and record the output frequency of the oscillator

Exercise:Calculate the value of the inductor using

f= 1/2 {LC 2C3/ (C 2+C 3)}1/2

Comment on your results.

Experiment 5

Title: Rectification.Objective: The student at the end of the experiment should be able to connect and

understand the action of a PN junction diode in rectification of AC signals and observethe output signals when connected as half wave and full wave rectifiers.

Background Theory:Since the most convenient and economic source of power is the domestic ac supply, it isadvantageous to convert this alternating voltage to dc voltage. This process of convertingac voltage into dc voltage is called rectification and is accomplished with the help of Rectifier Filter


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Voltage regulator circuits

Apparatus:TPS - 3321, multimeters, oscilloscope.

Procedure:Connect the circuit as shown below.Diagram:

Half wave rectifier circuit

1. Switch on the power supply, with SW 1 at the OFF position.

2. Channel 1 of the oscilloscope shows the output of the rectifier and channel 2shows the AC signal from the signal generator.

3. ON position: with the switch ON, the filter capacitor is connected to the output of the rectifier. Draw the wave forms observed.

Full wave rectifier circuit


C1

D1

SW 1

CH1CH2

SIGNAL

GENERATOR

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4. Connect the full wave rectifier as shown above and draw the waveform observed atthe output

COURSE TITLE / CODE


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MEASUREMENT ANDINSTRUMENTATION II/EEC 235

Experiment 1

Title:Measurement of voltage, current and

frequency using digital instrument.

Objectives: At the end of the experiment the student should be able to understandthe use of digital instruments to measure voltage, current and frequency.

Background Information: A digital voltmeter is used to measure the potential diffenrence across two points and is connected across the supply or in parallelwith the load. The ammeter measures the amount of current flowing through a load; it isconnected such that it is in series with the load.


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Apparatus:1. Digital multimeter 2. Digital Frequency meter 3. A.C. loads.

Procedure1. Connect the frequency meter as shown above across the load2. Connect the ammeter in series with the load across the volt meter 3. Connect the combination using a switch across the mains.4. Record your readings on the voltmeter, ammeter and frequency meter

Diagram:

Readings :Record your readings as shown below:

Voltage Current FrequencyLoad 1Load 2

Exercises:Calculate the power dissipated by load 1 and load 2 respectively


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Experiment 2

Title:Measurement of power using single-phase

wattmeter.

Objectives: At the end of the experiment the student should be able to measure power using a wattmeter and compare the readings with that obtained on voltmeters andammeters.

Background Information: The wattmeter works on the principle of electrodynamometer, it is used for measurement of A.C. and D.C. power The fixed coilin the wattmeter connected in series with the load such that the total current flowsthrough it. The movable coil is connected in series with a current limiting resistor acrossthe supply line.


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Apparatus:1. Single Phase Wattmeter 2. Voltmeter 3. Ammeter

Procedure:1. Connect the source to the load and main terminal on the wattmeter as shown

above.2. Connect the load terminal to the common terminal and then to the load3. Connect V2 to the neutral of the source and load4. Connect the ammeter in series with the load as shown5. Connect the voltmeter in parallel with the load as shown6. For each load record your reading for wattmeter, voltmeter and ammeter.

Diagram:


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Readings:

Record your readings in the table below:S/N Type of load Power

Measuredusingwattmeter

Voltagemeasured

Currentmeasured

Calculated power

Exercises:

Comment on the measured values.

COURSE TITLE / CODE


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TELECOMMUNICATIONS/EEC 244

Experiment 1

Title:Demonstration Of Amplitude Modulation

And Demodulation

Objectives: At the end of the experiment the student should be able to

Background Information: When the amplitude of the carrier wave is variedaccording to the modulating wave, it is called Amplitude modulation (A.M). This enablesinformation at low frequencies to be transmitted at much higher frequencies. When theA.M. signal is received at the receiving end it is fed into a diode detector whose output isa D.C. signal, which varies in amplitude as that of the modulating signal.


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Apparatus:1. Oscilloscope2. Training Kit TPS 3421

Procedure:Connect the output of the function generator to the A.M. input of the A.M. modulator stage.Connect the output of the modulator to the oscilloscope.With the function generator output at zero amplitude Vvar=0, observe and draw thewaveform seen (i.e. carrier wave)With Vvar=1/2Vmax(midway between zero and maximum), observe and draw thewaveform seen (i.e. modulated carrier)With Vvar=Vmax (maximum), Observe and draw the wave form seen.Connect the output of the modulator to the input of the diode detector and observe theoutput of the demodulator on the oscilloscope channel 2.

Draw the demodulated signal waveform.Record your observationsWrite your conclusions on the experiment.

Diagram:


Vvar

Pre - Amplifier AM/FM

Modulator

AM DiodeDetector

AudioAmp

Oscilloscope

Loudspeaker

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Readings :Record your observations

Exercises:Write your conclusions on the experimentDraw the waveforms seen in steps 4,5 and 6.

Experiment 2

Title:Determination Of Frequency Modulation

Objectives: At the end of the experiment the student should be able to understandhow the amplitude of the modulating signal is used to vary the frequency of the carrier.

Background Information: Frequency modulation is the process in whichthe frequency of the modulating carrier is varied while the amplitude is kept constant.The maximum deviation of the carrier is obtained when the cosine term inF=(Fc(1+KvmcosWmt) has its maximum value of 1 i.e. F=Fc(1=+/-KVm)

Apparatus:1. TPS 34212. Sescope Software on PC


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3. Multimeter

Procedure:Set up the circuit as shown in the diagramAdjust the potentiometer and see how the signal frequency varies accordingly.Record your readings in the table below

Diagram:

Readings :

No 1 2 3 4 5Vi

No of cycleT

F FKF

Exercises:


VCO

High

Low

AM/FMModulator

VVAR

AM

FM1

OscilloscopeOut

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For each measured voltage calculate FCalculate KF for each FDraw a graph of the frequency dependence on the VCO voltage

COURSE TITLE / CODE


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ELECTRICAL MACHINES/EEC 236

Experiment 1a

Title:Efficiency Of Transformers.Objective: The student at the end of the experiment should be able to measure theefficiency of a transformer.

Background Information:Transformers are electrical machines, which operates at a very high efficiency. The twomain losses experienced are attributed to copper and iron losses. Copper loss is the i 2R loss as a result of the resistance of the transformer windings while the iron losses are dueto hysteresis and Eddy-current loss. The eddy current loss is reduced by laminatingformer cores and the laminated surfaces vanished before assemblage.

Apparatus:1. E70 - A.C Service Module2. E73 Transformer Experimental Module


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3. E86 single phase power supply

Procedure:1. Connect E70 and E86 together using the provided 6-way wires2. Set the power supply E86 to 100v3. Also connect the E73, the transformer experimental module to E70 AC service

module4. Feed a voltage of 100v to the primary side of the transformer B.5. Place a 10 resistor connected in series with an ammeter across the secondary of

transformer B6. Take reading of the secondary side power, voltage and current.7. Take reading of the primary side power, voltage and current.

Results:PRIMARY SIDE SECONDARY SIDE

CURRENT (A)

VOLT (V)POWER (VA)

Exercise:Determine the efficiency of the transformer of the transformer B when feeding a load of 100V.

Experiment 1b

Title:Transformer Voltage Regulation.Objective: The student at the end of the experiment should be able to determine thevoltage at the secondary terminals of a voltage transformer.

Background Information:The transformer on electrical machine; operates mainly on the principle of mutualinductance. When the primary side is connected to supply, voltage is induced on thesecondary side as a result of the mutual flux linkage. However, the magnitude of theinduced voltage depends on the turns ration between the primary and secondarywindings.Equipment E73 comprises three different transformers labeled as A, B and C. The

primary sides of the transformers are internally connected to the supply input on E73.The supply input to each of the transformer can be measured by switching the channelselector on the supply; that provides a variable a.c supply to the service module E70.


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Apparatus:A.C Service Module E70, A.C supply E86, Transformer (bank) E73

Diagram:

Procedure:Connect transformer B to the supply ac supply E86 through the service module E70 asshown in fig 1Ensure the supply voltage is set to 100V.Using the voltmeter on the E70 AC service module, measure the various secondaryvoltages.Measure the voltages between terminals b1 and b2Measure the voltages between terminals b1 and b3Measure the voltages between terminals b2 and b3

Results:Set the supply voltage to 100V and measure the following secondary voltages.

b1 b2 b1 b3 b3 b2

Exercise:The primary winding has 500 turns, estimate the following:

No. of turns in section b1 b2 No. of turns in section b1 b3 No. of turns in section b3 b2

Determine the maximum flux in the magnetic circuit of the transformer.


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Experiment 2

Title: Transformer Load Test.Objective: The student at the end of the experiment should be able to determine the

parameters of a transformer when it loaded.

Background Theory:When the transformer is loaded, the secondary current I2 is set up. The magnitude and

phase of I2 with respect to V2 is determined by the characteristic of the load. I2 is in phase with V2 if the load is resistive, it lags when the load is inductive and it lags whenthe load is capacitive.

Apparatus:E70 - A.C Service Module , E73 Transformer Experimental Module , E86 single

phase (1-) power supply

Diagram:


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Procedure:Connect E73 transformer experimental module to E86 through E70, the AC servicemodule.

Set E86 to 100VOpen SB and connect load resistors across the secondary as shown aboveArrange to measure the primary voltage V1, primary current I1, secondary voltage V2and secondary current I2.Interconnect the 10 resistors provided to achieve several values of the load resistor.For each value of the load resistor close SB and set the primary voltage at 100V.SA and SC should be offComplete the following table.

Results:LoadResistor ()

V1 (V) V2 (V) V1/V2 I2 (A) I1 (A) I2/I1

s51020e.t.c.

Exercise:Plot on the same scale a graph of V1/V2 against I2/I1 for the four values of the load

current.Why are the voltage and current ratios different and why are they dependent on loadcurrents?


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Experiment 3

Title: Determination Of No-Load Current

Componets.Objective: The student at the end of the experiment should be able to determine themagnetizing current (I m) and the core- loss current (I c) of a 1- transformer.

Background Information:The no-load current in a transformer is made up of two components namely, themagnetizing current (I m) which is responsible for the magnetic flux in the transformer.The other component is the core- loss current (I c) which is the current flow in the ironlaminations. The heat felt in the transformer core is partly due to the flow of this current.

Apparatus:1. E70 - A.C Service Module2. E73 Transformer Experimental Module


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3. E86 single phase (1-) power supply

Diagram:

Procedure:Connect E73 transformer experimental module to E86 through E70, the AC servicemodule.

Set E86 to 100VSwitch on transformer B and leave the secondary side on open circuit.Apply a variable voltage to transformer B in steps of 10V, from 10-100V and record thevalue of the no-load current for each voltage.

Readings:VOLT(V)

CURRENTIO (AMP)

IC=IO Cos I m=IO Sin

102030405060708090100The assumed power factor of the transformer is given that Cos = 0.75

Exercise:Plot a graph of I C against I m and determine the slope of the graph.Comment on your result


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Experiment 4

Title:Open Circuit And Short Circuit Test On A

TransformerObjective: The student at the end of the experiment should be able to determine the

parameters of a voltage transformer.

Background Information:Two tests are carried out on transformers to be able to determine their parameters. They

areOpen Circuit Test and (ii) Short Circuit Test.During the open circuit test, the primary or the high voltage side is on open circuit andthe rated voltage is applied to the secondary side. Readings of power, current and voltageare taken from the secondary or low voltage side. During short circuit test, the lowvoltage side is shorted by means of an ammeter and variable voltages applied to the highvoltage side until rated current flows in the low voltage side, the readings are taken.


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Apparatus:E70 - A.C Service ModuleE73 Transformer Experimental ModuleE86 single phase power supply 5A

Procedure:OPEN CIRCUIT TESTConnect transformer A to supply through E70, AC service module.Ensure the supply voltage is set to 100v.Keep the primary side of transformer B open circuit, by placing the toggle switchconnected to it in the OH positionMeasure the output voltage of transformer A.Feed the output voltage of transformer A to the secondary side of transformer B.Take the readings of power, voltage and current of transformer B whose primary side ison open circuit.SHORT CIRCUIT TEST

Use am ammeter to short circuit the low voltage (or secondary) side of transformer B.Vary the input voltage to the primary side of transformer B until a current o 1 Amp flowson the secondary side.Take readings of power, voltage and current flow on the primary side of transformer B

Results:

POWER (W)

VOLT(V)

CURRENT(A)

OPEN CIRCUIT TESTSHORT CIRCUITTEST

Exercise:Determine the parameters of transformer B and comment on your results.

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