electronics ii lab manual

ELECTRONICS II LAB. MANUAL

2013 2014 SPRING Prepared by Res. Asst. Erinc Topdemir

Student Information

Name :

Surname :

ID :

This page initially left blank

TABLE OF CONTENTS

Page i

Contents

Lab rules & Tips __________________________________________________________________________________________ ii

Guideline for Lab manual (Notebook) _________________________________________________________________ iv

Safety Information________________________________________________________________________________________ v

Grading ___________________________________________________________________________________________________ vi

Experiment 1 Introduction to Differential Amplifiers _______________________________________________ 1

Experiment 2 Operational Amplifiers & Their Usage ________________________________________________ 6

Experiment 3 Active Filters with Opamp ___________________________________________________________ 11

Experiment 4 - Frequency Response of Common-Emitter Amplifiers _____________________________ 14

Experiment 5 Power Amplifiers (Push-Pull) _______________________________________________________ 18

Experiment 6 Oscillators _____________________________________________________________________________ 21

Experiment 7 Voltage Regulators ___________________________________________________________________ 27

Appendix A Datasheets ______________________________________________________________________________ 32

BC237 BC238 BC239 NPN Silicon Amplifier transistor__________________________________________ 33

2N3904 NPN General Purpose Silicon Amplifier Transistor ________________________________________ 35

LM741 Operational Amplifier _________________________________________________________________________ 37

1N4001 ~ 1N4007 Silicon Diode ______________________________________________________________________ 39

TIP122 NPN Darlington Transistor ___________________________________________________________________ 40

Appendix B - Other Components ______________________________________________________________________ 42

Appendix C - Resistor Codes ___________________________________________________________________________ 43

Appendix D - Capacitor Readings _____________________________________________________________________ 44

Appendix E - Electrical Symbols _______________________________________________________________________ 45

Notes ____________________________________________________________________________________________________ 50

LAB RULES & TIPS

Page ii

Lab rules & Tips

LAB RULES

1. Students are allowed in the laboratory only when the lab instructor is present. Otherwise you have

to have some permit from lab assistants or people who is (are) responsible from laboratories regular

class hours.

2. For hours after 18:30 or weekends you need permit from Deans office (or secretary). But do not

forget to inform people who are responsible for lab to get components or cables.

3. Open drinks and food are not allowed near the lab benches.

4. Report any broken equipment or defective parts to the lab instructor. Do not open, remove the cover,

or attempt to repair any equipment.

5. When the lab exercise is over, all instruments, must be turned off. Return components and cables to

the designated location. Your lab grade will be affected if your laboratory station is not tidy when you

leave.

6. University property must not be taken from the laboratory, even for your lab project(s).

7. Do not move instruments from one lab station to another lab station, even for your lab project(s).

8. Anyone violating any rules or regulations may be denies access to these facilities.

TIPS FOR EXPERIMENTS

Read the lab manual.

Don't come late. Do not attend other lab sections. Who doesn't sign the attendance sheet will be

considered absent for the respective lab session. Assistants may take several attendances whenever

they think it is necessary. In some conditions, your lab quiz may be used as your attendance.

Do not forget to make pre-lab sections. There are pre-calculation parts in almost all of your lab

experiments. These parts are shown with bold calculation notifications. You may not allow to

attend lab sessions or may lose points if you do not make these calculations.


Come prepared. Make sure you have read the experiment instructions and read the relevant section

from the course book or your class notes. It is advised that you underline those parts where you

should take measurements or write comments. This way you don't skip a part and complete the

experiment faster. Make sure you understand what is being asked from you. If not, ask the assistant.

Don't copy what your friend has done.


There is no brake during the lab. You may take a break by yourself. Try to be not too generous to

yourself.

Safety is the most important point. Follow the lab safety rules. Never make practical jokes to your

friends with your tools.


LAB RULES & TIPS

Page iii

Make sure you use the right components. Check every resistor with your Ohmmeter. Be warned that

not every resistor you take from 1kOhm box is surely a 1kOhm.

Never ask the assistants what the next step of the experiment is. Everything you need to know (and

you have to know) is written in your lab manual. Wrong answers to these questions is not the

responsibility of the assistant.


If you are faced with a problem, try first to solve it by yourself. An important part of your education

is to analyze problems and to find solutions to it. To 90% of all problems you can find a solution by

yourself. Be sure you have followed the correct steps in the correct order. Check all connections and

supply voltages. Check all the components in the problematic are and be sure they have the correct

values. Only after then, if you cannot solve the problem, ask your assistant for help.

Do not forget to read the textbook.

GUIDELINE FOR LAB MANUAL (NOTEBOOK)

Page iv

Guideline for Lab manual (Notebook)

The laboratory notebook is a record of all work pertaining to the experiment. This record should be

sufficiently complete so that you or anyone else of similar technical background can duplicate the

experiment and data by simply following your laboratory notebook. Record everything directly into

the notebook during the experiment. Do not use scratch paper for recording data. Do not trust your

memory to fill in the details at a later time.

INFORMATION ABOUT SOME NOTATIONS

VAB : means voltage between points A and B. put positive side of voltmeter to point A, and negative side

to point B.

VC : means voltage of point C (usually collector) respect to the ground

VR1 : this means voltage of the resistor with number 1

IC : this means current of collector

Vp or Vpk or Vpeak : peak voltage. Maximum value of an AC signal

VPP : peak-to-peak voltage. Difference between maximum and minimum value of an AC signal

Vamp : amplitude voltage. If there is no offset (DC) voltage inside the signal it is equal to Vp

RE : usually refers to resistor at the emitter side

CS : capacitor at source side

RL : resistor of load

RC : usually resistor at collector side

Q : letter to describe BJT transistors

D : letter to describe diode

R : letter to describe resistor

C : letter to describe capacitor

L : letter to describe inductor

M : letter to describe MOSFET or JFET

VS : voltage of source (usually AC)

SAFETY INFORMATION

Page v

Safety Information

The danger of injury or death from electrical shock, fire, or explosion is present while conducting

experiments in this laboratory. To work safely, it is important that you understand to minimize the risks and

what to do if there is an accident.

Electrical Shock:

Avoid contact with conductors in energized electrical circuits. Electrocution has been reported at the voltages

as low as 42 volts. Just 100 mA of current passing through the chest is usually fatal. Muscle contractions can

prevent the person from moving away while being electrocuted.

Do not touch someone who is being shocked while still in contact with the electrical conductor or you may

also be electrocuted. Instead, unplug cables or turn switches off (located near the door to the laboratory).

Make sure your hands are dry. The resistance of dry, unbroken skin is relatively high and thus reduces the

risk of shock. Skin that is broken, wet or damp with sweat has a low resistance.

When working with an energized circuit, work with your one hand, keeping your other hand away from all

conductive material. This reduces the likelihood of an accident that results in current passing through your

heart.

Fire:

Transistors and other components can become extremely hot and cause severe burns if touched. If resistors

or other components on your proto-board catch fire, turn off the power supply and notify the instructor. If

electronic instruments catch fire, unplug cables or turn switches off (located near the door to the laboratory).

Explosion:

When using electrolytic capacitors, be careful to observe proper polarity and do not exceed the voltage rating.

Electrolytic capacitors can explode and cause injury.

GRADING

Page vi

Grading

Note: Do not forget to make pre-lab sections. There are pre-calculation parts in almost all of your

lab experiments. These parts are shown with bold calculation notifications. You may not allow to

attend lab sessions or may lose points if you do not make these calculations.

GRADES

Laboratory session is part of your Electronics II course. It is normally %20 of your course, unless

announced otherwise. Your lab session includes experiments, quizzes (each week), lab project

(individually done) and lab final.

Experiments Quizzes Project Final Total

6 4 5 5 20

Experiment and quizzes

There will be 8 experiments and quizzes which will be graded over 3 each week (including the very

first week).

If you successfully done with your experiment then you will get 3,

If you missed some parts are made some wrong calculations or measurements then you will

get 2,

If you attend but not seem at class or do not show some work to make experiment, or you

really do not understand experiment and made almost everything wrong then you will get

only 1.

If you do not attend lab session then you will get 0 for that week. Lab assistant may accept

you to the experiment part if you miss quiz. But you will still get 0 from quiz not experiment.

There will be no excuse or make up experiments. Attendances are just taken for proofing you

are really there. You will not fail from lab because of you do not attend or miss some week(s).

Project

You have to make your lab project individually and present it at the last two weeks of semester with

making appointment with your lab assistant.

At project demonstration

You have to show your circuit on breadboard. You may make PCB or use soldered board if

you prefer, but it is optional not necessary.

You must show your circuit diagram.

GRADING

Page vii

You have to explain how circuit works, how long does it take to build, how you decide to make,

what changes have been occurred since you choose project, where can this circuit can be

used.

You do not need to prepare a PowerPoint presentation or a report. Just prepare yourself to

answer to above questions. Some further questions can be asked by lab assistants.

Your circuit does not need to work well if you really explain why and what happens. In this

condition you will credit up to 4 from your project

Final

You must attend your lab final at your own lab section. Your lab final will be 1 hour exam that include

both calculations and building circuit and measurements. Probably it will be a circuit design

question.

There will be no make-up exam for lab final. If you really have some situation please inform your lab

assistant. We are also human beings as you know

Exemptions

If you had taken Electronics II course in last three semester, you can ask for exemption for lab

session. If also course instructor accept it you will get your old credit. Your course instructor may

want to attend to just lab final or do some project instead.

If you had taken course more than one time in last three semester then the newest grade will be

count as your final grade.

EXPERIMENT 1 INTRODUCTION TO DIFFERENTIAL AMPLIFIERS

Page 1

Experiment 1 Introduction to Differential Amplifiers

OBJECTIVE To investigate the differential amplifier in the difference and common modes of operation and to determine the common mode rejection ratio (CMRR)

TOOLS AND EQUIPMENT REQUIRED

10 k x 2 3.3 k x 1 BC 239 (or any NPN) x 2

THEORY AND DESCRIPTIONS

Op-amp consists of three stages: differential amplifier, voltage amplifier and the output amplifier as shown in figure. The input stage to an op-amp is differential amplifier. Differential amplifiers can be operated in either of two manners: the input signal can be different, or the input signal can be identical. If it is different, the amplifier is operating in difference mode. This means that the output voltage will be proportional to the difference in the two input signals. If the inputs are same amplifier is operating in common mode.

The op amp responds only to the difference signal v2 v1 and hence ignores any signal common to both inputs. That is, if v1 = v2= 1 V, then the output willideallybe zero. We call

this property common-mode rejection, and we conclude that an ideal op amp has zero common-mode gain or, equivalently, infinite common-mode rejection.

Benefit of common mode is the elimination of noise is present at both inputs. Ideally, any noise voltage that is present at both inputs is cancelled out by phase inversion of the two sides of the amplifier. The common mode rejection ratio (CMRR) is a ratio of signal gain to noise gain, that is, how well the amplifier amplifies the wanted signal and cancels the unwanted noise. The single-ended CMRR is a ratio of the single-ended difference-mode voltage gain to the single-ended common-mode voltage gain. The double-ended CMRR is a ratio of the double-ended difference-mode voltage gain to the double-ended common-mode voltage gain. Typically, the CMRR is extremely high (75 to 100dB is not common)

Figure 1.1 Parts of an OpAmp


Page 2

EQUATIONS

Differential input: = 1 2

Common input: =1

2(1 + 2)

Output voltage: = , where Ad is differential-mode gain and Ac is common-mode

gain.

Common-Mode Rejection Ratio: =

or (log) = 2010

in (dB)

Common-mode gain: =

=

+2(+1)

Difference-mode gain: =

=

, =

=

2

Apply opposite polarity inputs to find Ad. 1 = 2 =

Apply same polarity inputs to find AC. 1 = 2 =

CIRCUIT & COMPONENT DRAWINGS

Vi1 Vi2

Vo2Vo1

Q1 Q2

RC1 RC2

RE

VCC

VEE

Figure 1.2 Diagram of an NPN Transistor

Figure 1.3 Pin diagram of transistor (BC239)

Figure 1.4 Pin Diagram of LM741 OpAmp Figure 1.5 Circuit schematic for Pre-Calculation and Procedure 1


Page 3

For all steps of Pre-Calculation and Procedure 1: Using RC1=RC2=10k, RE=3.3k, Q1=Q2=B239C

(or any NPN) set up the above circuit. Be careful about connecting VCC to +15V, VEE to -15V and

ground to 0V.

Pre-Calculations

1. DC Analysis: Calculate IE, VC1 and VC2 for each base voltage (VB1 and VB2) at 0v.

2. Calculate the difference mode voltage gain.

3. Calculate the common mode voltage gain.

4. Calculate Vd, Vc, and Vo according Ad and Ac you had found in steps 2 and 3. Write values

that you choose for Vi1 and Vi2 for each step

5. Calculate CMRR using values of Ac and Ad that you found in step 4.

PROCEDURE 1 Differential amplifier with BJT

1. Balancing the differential amplifier: Connect Vi1 and Vi2 to ground (0V). Measure the

voltage between VO1 and VO2. This is called DCoffset voltage.

2. Determine the quiescent current (Q-Operating point): measure the DC currents of IC1,

IC2, IE3. Compare them with pre-calculation part 1

3. Difference mode: Set Vi1 to 1Vpeak at 1 kHz and ground Vi2. By this way you can define

VD. Measure voltage VO1 and VRC1 and VRC2 respect to ground.

4. Calculate IC1, IC2, IE from above values (calculate from values of step 3).

5. Common mode: Set Vi1 and Vi2 to 1 Vpeak at 1 kHz. By this way you can define VC.

Measure voltage VO1 and VRC1 and VRC2 with respect to ground.

6. Calculate IC1, IC2, IE from above values (calculate from values of step 5).

7. Apply opposite polarity to Vi1 and Vi2. Positive probe of AC source of 50 mVpk at 1 kHz to

Vi1 and negative probe to Vi2. (Like procedure 2 - part 5). Measure voltage VO1 and IC1 and

IC2 respect to ground. Is this difference mode or common mode?

8. Calculate AC using values you found at step 5 (common mode) and AD using values you

found at step 3 (difference mode).

9. Calculate Vo from values from 8. Use values of Ac and Ad you found at steps 3 and 5.

10. Calculate the CMRR in dB. Is it good or bad?


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For all steps of Procedure 2: Connect 4th pin of LM741 to -15V and 7th pin to -15V.

PROCEDURE 2 Measurement of CMRR of an op-amp

1. To measure offset voltage connect both inputs (inverting and non-inverting) to ground and measure output voltage.

2. Connect inverting input to 250 mVpk at 1 kHz while non-inverting still connected to ground. Measure output voltage.

3. Set both inputs to 1 Vpk at 1 kHz. Measure voltage VO. As shown in figure 6. 4. Apply opposite polarity to inputs. Positive probe of AC source of 250 mVpk at 1 kHz to non-

inverting input and negative probe to inverting. Measure voltage VO. As shown in figure 7. 5. Calculate Ac and Ad. 6. Calculate CMRR in dB. Is it good or bad?

Figure 1.6 Common Mode OpAmp Figure 1.7 Differenatial Mode OpAmp


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Name Surname: ID: Signature:

PRE-CALCULATIONS 1. VC1 = , IC1 = , VC2 = , IC2 = and IE = 2. Ad =

3. AC =

4.

a. Vd = selected Vi1 and Vi2 =

b. Vc = selected Vi1 and Vi2 =

c. Vo =

5. CMRR =

RESULTS FROM PART 1 1. VDCofset =

2. IC1 = , IC2 = , IE =

3. VRC1 = VRC2 = VO1 = and VD =

4. IC1 = , IC2 = , IE =

5. VRC1 = VRC2 = VO1 = and VC =

6. IC1 = , IC2 = , IE =

7. IC1 = IC2 = VO1 = mode:

8. AC = AD =

9. Vo = 2AdVs = Vo = AcVs =

10. CMRR (calculated values 13) =

Compare CMRR:

Comments and Conclusions: Describe what you learn from this experiment besides regular class.

RESULTS FROM PART 2 1. Voffset = VO =

2. VO =

3. VO = 4. VO = 5. Ac = Ad = VO = 6. CMRR (dB) =

Comment:

EXPERIMENT 2 OPERATIONAL AMPLIFIERS & THEIR USAGE

Page 6

Experiment 2 Operational Amplifiers & Their Usage

OBJECTIVE: To measure DC and AC voltages in linear op-amp circuits and to compute voltage gains of various op-amps


DMM (Digital Multi Meter)

DC Power Supply

Function Generator

Oscilloscope

22 k x 1

100 k x 3

LM741 op-amp x 1


The op-amp is a very high gain amplifier with inverting and non-inverting inputs. It can be used to provide a much smaller but exact gain set by external resistors or sum more than one input, each input causing a desired voltage gain.

INVERTING AMPLIFIER

As an inverting amplifier, the resistor are connected to the inverting inputs as shown in fig. 2.1 with output voltage

=

=

Figure 2.1

NON-INVERTING AMPLIFIER

A non-inverting amplifier is provided by the

circuit of fig. 2.2 with output voltage given by

=

+

= +

Figure 2.2

Ro

Ri

ViVo

Ro

RiVi

Vo

Figure 3 Pin diagram of LM741


Page 7

UNITY (BUFFER) AMPLIFIER

Connecting the output back to the inverting input as fig. 2.3 provides a gain of exactly unity:

VO = Vi

Figure 2.3

SUMMING AMPLIFIER

More than one input can be connected through separate

resistors as shown in fig. 2.4 with the output voltage then

Figure 2.4

2

2

VR

RV

R

RV O

O

O

DIFFERENCE (SUBTRACTOR) AMPLIFIERS

More than one input can be connected through separate resistors as

shown in fig. 2.5 with the output voltage then

If all resistors are same, then Vo = Vg1-Vg2

Figure 2.5

INTEGRATING AMPLIFIER

Circuit that integrate the input signal

Figure 2.6

ViVo

V1 Vo

Ro

R2

R1V2


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DERIVATIVE AMPLIFIER

Circuit that take derivative of

the input signal:

Figure 2.7

OPAMP AS COMPARATOR

Circuit that use opamp as comparator. Output voltage will either VCC or VEE in ideal. In practical these values are about VCC 1.5V and VEE + 1.5V.

The idea is comparing voltages at the input. If voltage at positive input is higher than voltage at negative input than output will be near to VCC. it will we near VEE otherwise.

Figure 2.8


Page 9

For all parts, VCC = 12 V and VEE = -12V. Use input signal Vi = 1V, at peak, and f = 10 kHz.

Pre-Calculations

1. Calculate the voltage gain for the amplifier circuit of fig. 2.1 for Ri = 22 k and Ro = 100 k.

2. Calculate the voltage gain of the non-inverting amplifier in fig. 2.2 for Ri = 22 k and Ro = 100 k.

3. Calculate the voltage gain of the summing amplifier in fig. 2.4 for R0 = 100 k, R1 = 100k, and R2 = 22 k.

4. Calculate the voltage gain of the summing amplifier in fig. 2.5 a. For all resistors with 100 k. Apply an input of V1 = V2 = 1 V b. Repeat but this time connect V1 to ground

5. Find and draw expected the output signal for the circuit of fig. 2.6 if you Apply an input of V1 = 1 V square wave

6. Find and draw expected the output signal for the circuit of fig. 2.6 if you Apply an input of V1 = 1 V triangle wave

7. For the circuit of fig. 2.8 with values R1 = 5 k (or 4k7) pot, R2 = 10 k, R3 = R4 = 22 k Calculate output signal for values when the pot is set to 1 k, 2 k, 3 k and 4 k.

PROCEDURE

1. Inverting Amplifier: Using an oscilloscope, measure and record the output voltage. 2. Non-inverting Amplifier: Using an oscilloscope, measure and record the output voltage. 3. Summing Amplifier: Using an oscilloscope, measure and record the output voltage 4. Subtraction Amplifier

a. For the summing amplifier in fig. 2.5 with inputs of V1 = V2 = 1 V. For all resistors with 100 k. Using an oscilloscope, measure and record the output voltage

b. Repeat but this time connect V1 to ground. 5. Op-Amp that takes Integral: Construct the circuit of fig. 2.6. Apply an input of V1 = 1 V

square wave, peak at f = 10 kHz. Using an oscilloscope, measure and record the output voltage

6. Op-Amp that takes Derivative: Construct the circuit of fig. 2.7. Apply an input of V1 = 1 V triangle wave, peak at f = 10 kHz. Using an oscilloscope, measure and record the output voltage

7. Op-Amp as Comparator: Construct the circuit of fig. 2.8. Change potentiometer from one end to other and record the output voltage.


Page 10


PRE-CALCULATIONS

1. Av (calculated) = 2. Av (calculated) = 3. VO (calculated) = 4.

a. VO (calculated) = b. VO (calculated) =

5. VO (calculated) = 6. VO (calculated) = 7.

Vi+ Vi- Vo

RESULTS FROM PROCEDURE

1. VO (measured) = AV (measured) = 2. VO (measured) = AV (measured) = 3. VO (measured) = 4.

a. VO (measured) = b. VO (measured) =

5. VO (measured) = 6. VO (measured) = 7.

Vi+ Vi- Vo

Compare and Conclusion: Describe what you learn from this experiment beyond regular class

EXPERIMENT 3 ACTIVE FILTERS WITH OPAMP

Page 11

Experiment 3 Active Filters with Opamp

OBJECTIVE: To calculate and measure the critical frequencies and to measure AC voltages as a function of frequency of various types of active filter circuits.


DMM (Digital Multi Meter)

DC Power Supply

Function Generator

Oscilloscope

22 k x 1

100 k x 3

LM741 op-amp x 1


Op-amps can be used to build active filter circuits for use as low-pass, high-pass, or band-pass filter operation. Filter operation provides the output of the filter drop-off as a function of frequency to 0.707 of the starting value at the cutoff frequency. This is a drop of 3 dB

In general, the frequency is determined with this formula =1

2 equation 3.1

LOW-PASS FILTER

A low-pass active filter passes frequencies below the filter cutoff frequency. The circuit of fig.3.1 shows the connection of an op-amp unit as a low-pass filter, the low-cutoff frequency determined by eq. 3.1 where R is R1 and C is C1. The output VO drops off at 3dB above the cutoff frequency.

HIGH-PASS FILTER

A high-pass filter, as shown in fig.3.2, maintains the output amplitude at frequencies above a high-cutoff frequency determined by eq. 3.1 where R is R1 and C is C1. The output VO drops off at 6dB/octave or 20 dB/decade above the cutoff frequency.

BAND-PASS FILTER OR BAND-STOP FILTER

A band-pass filter circuit passes the input signal only for the frequencies within a band of frequencies. The band-pass, low- and high- cutoff frequencies are then calculated using eq.3.1 for both low and high cut-off frequencies.

Figure 4 Pin diagram of LM741


Page 12

Figure 3.1 Figure 3.2

PRE-CALCULATIONS

1. For the circuit of fig.3.1 calculate the low-cutoff frequency and voltage gain AV using eq.3.1

RG = 1M, RF = 2.2 k, R1 = 330 , C1 = 10 nF.

2. For the circuit of fig.3.2 calculate the low-cutoff frequency and voltage gain AV using eq.3.2

for RG = 1M, RF = 4.7 k, R1 = 680 , C1 = 100 nF

3. What kind of configuration is needed to build a band-bass filter? Do you need a low-pass at

first then connect its output to high-pass filter as an input? Or vice versa?

PROCEDURE

For all parts, VCC = 15 V and VEE = -15V.

PART 1. Low-pass filter: Construct the circuit of fig.3.1 with RG = 1M, RF = 2.2 k, R1 = 330 , C1 = 10 nF.

a) Apply an input of 1V, peak. Vary the signal frequency from 50 Hz to 50 kHz while measuring and recording the output voltage in Table 3.1.

b) Plot the output gain-frequency response curve to a blank linear-log graph at the end of notebook.

PART 2. High-pass filter: Construct the circuit of fig.3.2 with RG = 1M, RF = 4.7 k, R1 = 680 , C1 = 100 nF

a) Apply an input of 1V, peak. Vary the signal frequency from 1 kHz to 1MHz while measuring and recording the output voltage in Table 3.2.

b) Plot the output gain-frequency response curve to the same graph that you used in part 1

PART 3. Band-pass filter: Construct the circuit by connecting output of the high-pass filter to input of low-pass filter.

a) Apply an input of 1V, peak. Vary the signal frequency from 100 Hz to 300 kHz while measuring and recording the output voltage in Table 3.3

b) Plot the output gain-frequency response curve to the same graph that you used in part 1


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PRE-CALCULATIONS

1. fL (calculated)= AV = VO/VI (calculated)= AV-3dB = 2. fh (calculated)= AV = VO/VI (calculated)= AV-3dB = 3. explain:


1. Low-pass filter Table 3.1

f (Hz) 50 100 500 1k 2k 5k 10k 15k 20k 50k

VO (V)

AV (dB)

fL = AV = AV-3dB =

2. High-pass filter Table 3.2

f (kHz) 1k 2k 5k 10k 20k 30k 50k 100k 200k 500k 1M

VO (V)

AV (dB)

fH = AV = AV-3dB =

3. Band-pass filter Table 3.3

f (Hz) 100 500 1k 2k 5k 10k 20k 50k 100k 200k 500k 1M 2M

VO (V)

AV (dB)

fH = fL = AV = AV-3dB =

4. Explain what happens if you connect output of low pass to input of high pass with given values.

EXPERIMENT 4 - FREQUENCY RESPONSE OF COMMON-EMITTER AMPLIFIERS

Page 14

Experiment 4 - Frequency Response of Common-Emitter Amplifiers

TOOLS AND EQUIPMENT REQUIRED 2.2 k x2 3.9 k x1 10 k x1 39 k x1 BC238 or 2N3904 x1 1 uF x1 10 uF x1 22 uF x1


The analysis of the frequency response of an amplifier can be considered in three frequency

ranges: the low- mid- and high-frequency regions. In the low-frequency region the capacitors used

for DC isolation (AC coupling) and bypass operation affect the lower cutoff (lower 3-dB) frequency.

In the mid-frequency range only resistive elements affect the gain, the gain remaining constant. In

the high-frequency region of operation, stray wiring capacitance will determine the circuits upper

cutoff frequency.

Lower Cutoff (lower 3-dB) Frequency: each capacitor used will result in a cutoff frequency. The

lower cutoff frequency at the network is then the largest of these lower cutoff frequencies. For the

network of Fig. 4.1 the lower frequencies are as follows.

CS: the cutoff frequency due to the input (source) coupling capacitor is

=

(+) Where: Ri = R1 // R2 // re Eq.4.1

CC: the cutoff frequency due to the output (collector) coupling capacitor is

=

(+) Eq.4.2

CE: the cutoff frequency due to the emitter bypass capacitor is

=

Where: Re = RE // re Eq.4.3

Upper Cutoff (upper 3-dB) Frequency: In the high-frequency range the amplifier gain is affected

by the transistors parasitic capacitance as follows:

At input connection of circuit:


Page 15

=

Eq.4.4 Where RTH1 = R1 // R2 // re, and

= + + ( )

iwC , = input wiring capacitance

VA = voltage gain of amplifier at mid-band frequency

beC = capacitance between transistor base-collector terminals

bcC = capacitance between transistor base-collector terminals

At output connection of circuit:

=

Eq.4.5 where RTH2 = RC // RL and

= + + ( )

OWC , = output wiring capacitance

ceC = capacitance between transistor collector-emitter terminals

Keep in mind that the 3-dB cutoff frequencies are defined by 70.7% of mid-band gain, or 0.707

AV,mid. That is, once the mid-band gain is measured, the upper and lower cutoff frequencies are

measured at the points at which the gain drops to 0.707, the mid-band gain at either upper or

lower frequency.

=//

Eq.4.6

Figure 4.1 Common Emitter Amplifier Figure 4.2 Pin Diagram for BC237/238


Page 16

For all steps take CCV = 20 V, input AC signal, Vsig = 300 mVpp,

Cbc = 4.5 pF, Cce = 0.25 pF, Cbe= 8 pF, CW,O(Approximate) = 3.5 pF to 6 pF, CW,i (Approximate) = 9 pF

= any value from 200 to 450 if not given.

PRE-CALCULATIONS

1. Calculate values of DC bias voltage and current for the circuit of fig.4.1

2. Calculate lower cutoff frequencies due to coupling capacitors and due to bypass capacity 3. Calculate the upper cutoff frequencies and record below. 4. Calculate mid-band gain.

PROCEDURE

1. Assume that 10 kHz is your mid-band. Observe the input and output voltage using an oscilloscope at this frequency. Then find your mid-band voltage gain.

2. Vary the frequency from 50 Hz to 5 MHz then measure and record VO to complete Table 4.1 after measuring calculate gains in dB

3. Using semi-log (linear vs. logarithmic) paper, plot the gain in dB versus frequency over the full frequency range. Plot the actual points and connect to obtain the actual plot.

4. From the plot, obtain the lower and upper 3 dB frequency points and record.


Page 17


PRE-CALCULATIONS (SHOW YOUR ALL WORK)

1. VB (calculated) =

VE (calculated) =

VC (calculated) =

IE (calculated) =

re (calculated) =

2. SC

f (Calculated) =

CCf (Calculated) =

ECf (Calculated) =

3. iH

f (Calculated) =

OHf (Calculated) =

4. midVA , =


1. Vsig (measured) = VO (measured) = midVA , =

2. Output voltages and gains in dB

f (Hz) 50 100 200 400 600 800 1 k 2 k 3 k 5 k 10 k

VO (V)

AV (dB)

f (Hz) 20k 50 k 100 k 300k 500k 600 k 700 k 900k 1 M 2 M 5 M

VO (V)

AV (dB)

4. f 3dB (lower cut-off) = f +3dB (higher cut-off) =

Compare and Conclusion: Describe what you learn from this experiment beyond regular class

EXPERIMENT 5 POWER AMPLIFIERS (PUSH-PULL)

Page 18

Experiment 5 Power Amplifiers (Push-Pull)

OBJECTIVE

To calculate and measure the critical frequencies and to measure AC voltages as a function of

frequency of various types of active filter circuits.

TOOLS AND EQUIPMENTS REQUIRED

1 k x 2 10 k x 1

10 F x 3 1N4001 x2

TIP122 x1 TIP127 x1


A class-B amplifier draws no power if no input signal is applied.

As the input signal increases, the amount of power drawn from

the voltage supply and that delivered to the load both increase.

The input power to a class-B amplifier is

Pi (DC) = VCCIDC = 2()

The power provided by the amplifier can be

calculated using:

() =

2()

=

2()

2=

2( )

8

The amplifier efficiency is calculated using:

% = 100()

()%

Figure 5.1 Pin diagram of TIP 122 and TIP127

Figure 5.2 Circuit Diagram for Push-Pull Amplifier


Page 19

For all steps +V = 10V, -V = -10 V,

RLoad = 56 , R1 = R2 = 1k and C1 = 10uF. Take = 500 for each transistor.

PRE-CALCULATIONS

1. Calculate the power ratings for a class-B amplifier, as shown in above figure 5.2. Take VL as 0.2 V.

2. Find Vin for VL = 0.2 V 3. Can you find operating range of this circuit? Try to find Vin range that will not distort output

voltage VO

PROCEDURE 1. Construct the circuit. Adjust the input signal (Vin) until VL = 0.2V, peak. Measure the AC

voltages of both input and output. 2. Sketch both input and output voltages to the same graph. 3. Measure the average DC supply current. 4. Measure the DC voltages of VO,VB1,VB2. 5. Using the measured values, calculate input and output power, and circuit efficiency. Compare

this values with your pre-calculated ones. 6. Adjust Vin until the output voltage distorted. Measure both output and input AC voltages. 7. Measure the DC voltages of VO,VB1,VB2. 8. Using the measured values, calculate input and output power, and circuit efficiency. These will

become your maximum values for this circuit. 9. What is the power dissipated on the amplifier for part 5 and 8 (at max. range)?


Page 20


PRE-CALCULATIONS (SHOW YOUR ALL WORK)

1. DC analysis

a. VO =

b. VB1 =

c. VB2 =

d. Pi =

e. PO =

f. % =

2. Vin =

3. Operating range: Vo (min) = and Vo(max) =


1. Vi = VO =

2.

3. IDC =

4. VO (DC) = VB1 = VB2 =

5. Power values and comparison

a. Pi =

b. PO =

c. % =

6. Vi(max) = VO(undistorted) =

7. VO (DC) = VB1 = VB2 =

8. Maximum power values and comparison

a. Pi =

b. PO =

c. % =

9. power dissipation

a. Pdissipated (according to step 5) =

b. Pdissipated (according to step 8) =

Conclusion: Describe what you learn from this experiment beyond regular class

EXPERIMENT 6 OSCILLATORS

Page 21

Experiment 6 Oscillators

TOOLS AND EQUIPMENTS REQUIRED

1 k x 2 1.2 k x 1

100 k x 3 LED x1

Potentiometer (50k) x 1 Potentiometer (1M) x 1

10 nF x 3 100 nF x1


Phase Shift Oscillator: Oscillator circuits can be built using op-amp with feedback to phase-shift the output signal by 1800. In a phase-shift oscillator, as shown in below figure, three sections of resistor-capacitor combinations are used. The resulting oscillator frequency can be calculated using

=1

26

Wien-Bridge Oscillator: A bridge network can be used to provide the 1800 phase shift as shown

in below figure. The circuits resulting frequency can be calculated from

=1

21122

Relaxation oscillators: This is a very common opamp oscillator circuit. You will measure a saw tooth-like waveform at (point A) node between capacitor and the resistor (or at node inverting input of the opamp), and a square wave at (point B) output. You can also adjust the duty cycle of the square wave output if you connect a serial potentiometer to the feedback resistor. The resulting oscillation frequency is simply calculated by

=1

2

Barkhausen criterion: It states that if A is the gain of the amplifying element in the circuit and (j)

is the transfer function of the feedback path, so A is the loop gain around the feedback loop of the

circuit, the circuit will sustain steady-state oscillations only at frequencies for which:

The loop gain is equal to unity in absolute magnitude, that is, and

Barkhausen's criterion is a necessary condition for oscillation but not a sufficient condition.

As you know, must be 29 when the oscillation starts.

Figure 6.1 Pin Diagram for LM741


Page 22

CIRCUIT DIAGRAMS

Tit le

Size Docum ent Num ber Rev

Dat e: Sheet of

A

1 1Friday , January 24, 2014

-

+

U1

LM741

3

26

7 14 5

Ri

1.2k

Rf 50 k pot

R11k

R21k

C1

10 nF

C2

10 nF

C3

10 nF

VEE -15V

VCC +15V

Figure 6.2 Circuit Diagram for Phase Shift Oscillator Figure 6.3 Circuit Diagram for a Common Oscillator

Figure 6.4 Circuit Diagram for Relaxation Oscillator with Double Source

Figure 6.5 Circuit Diagram for Relaxation Oscillator with Single Source

-

+

U1

LM741

3

26

7 14 5

Ri 1k

Rf 4.7 k pot

R1

1k

R2

1k

C1

10 nF

C2

10 nF

VEE -15V

VCC +15V

Figure 6.6 Circuit Diagram for a Wien-Bridge Oscillator


Page 23

Circuit 6.2: Ri = 1.2k, R1 = R2 = 1K, C1 = C2 = C3 = 10 nF and Rf = 50 k (at least)

potentiometer. VCC = 15V and VEE = -15V

Circuit 6.3: R1 = R2 = R4 = 100K, R3 = 1 M, R5 = 1k , C1 = 100 nF and D1 = LED. VCC = 9V and

VEE = Ground

Circuit 6.4: R1 = R2 = 10K, Rf = 100k , C1 = 10 nF. VCC = 15V and VEE = -15V

Circuit 6.6: R1 = R2 = Ri = 1K, Rf = 4.7k potentiometer, C1 = C2 = 10 nF. VCC = 15V and VEE = -

15V

PRE-CALCULATIONS

1. According to circuit fig. 6.2 calculate the oscillation frequency f1.




5. What will the value of potentiometer be to start oscillate and to give undistorted output for

circuit 6.2?

6. What will the value of potentiometer be to start oscillate and to give undistorted output for

circuit 6.6?

7. Why we need to connect extra 2 resistors to use same circuit with only one supply voltage?

8. Can you redraw circuits shown in figure 6.2 and figure 6.6 with single supply?

9. Can you redraw circuit shown in figure 6.3 with double supply?

PROCEDURE

IMPORTANT FOR ALL PARTS: Sometimes you can observe 50 Hz sinusoidal signal at your

oscilloscope. THIS IS NOT YOUR ANSWER. This signal is observed due to electrostatic noise in the

environment and if you still observe this signal while your oscilloscope probe is grounded then main

power cables are not well grounded. Anyway, as I said this 50 Hz signal IS NOT YOUR SOLUTION.

If your oscillation does not start or you did not find anything beside 50 Hz:

a. re-check every connection

b. Rebuild your circuit.

c. You may (not necessary) change your opamp.

d. You can change potentiometer with a higher value one

e. If you still not found any oscillated signal after above steps you may skip this step

and you can come back after other procedures.


Page 24

PROCEDURE 1. Set-up circuit shown in fig. 6.2 and adjust potentiometer until it starts oscillation. Measure

oscillation frequency with oscilloscope. Compare it with your pre-calculated result. Also

check phase shifting (difference) between your (inverting) input and output.

2. After oscillation starts, measure value of feedback resistance (potentiometer) and calculate

voltage gain Av = Rf/Ri. Is this answer satisfy with Barkhausen criterion?

3. Set-up circuit shown in fig. 6.3 and adjust potentiometer until it starts oscillation. Measure









6. After oscillation starts, measure value of feedback resistance (potentiometer) and calculate

voltage gain Av = Rf/Ri. Is this answer satisfy with Barkhausen criterion?


Page 25


PRE-CALCULATIONS (SHOW YOUR ALL WORK) 1. Oscillation frequency f1 =

2. Oscillation frequency f2=



5. Approximate value of the potentiometer. Rpot =

6. Approximate value of the potentiometer. Rpot =

7. Explain:

8. Redraw circuit 6.2 and 6.6 with single supply configuration.

9. Redraw circuit 6.3 with double supply configuration.


Page 26


RESULTS FROM PROCEDURE 1. Oscillation frequency f1 =

Phase shift =

Compare:

2. Value of the feedback resistor (potentiometer):

Voltage gain Av = is it satisfy? Why?

3. Oscillation frequency f2 =

Phase shift =

Compare:


Phase shift =

Compare:


Phase shift =

Compare:

6. Value of the feedback resistor (potentiometer):

Voltage gain Av = is it satisfy? Why?

EXPERIMENT 7 VOLTAGE REGULATORS

Page 27

Experiment 7 Voltage Regulators

OBJECTIVE The operation of power supply circuits built using filters, rectifiers, and then voltage regulators. A steady dc

voltage is obtained by rectifying the ac voltage, then filtering to a dc level and, finally, regulating to obtain a

desired fixed dc voltage.

TOOLS AND EQUIPMENTS REQUIRED BC238 x2 LM741 x1

6.8V Zener x1 220 x1


A block diagram containing the parts of a typical power supply and the voltage at various points.

Filter Voltage Regulation and Ripple Voltage

The DC voltage derived from an AC source signal by rectifying and filtering will have some AC variation

(ripple). The smaller the ac variation with respect to the dc level, the better the filter circuits operation.

Consider measuring the output voltage of a filter circuit using a dc voltmeter and an AC (rms) voltmeter.

The DC voltmeter will read only the average or DC level of the output voltage. The AC (rms) meter will read

only the rms value of the ac component of the output voltage.

= = ()

=

()

100%

Figure 7.2 Graph of a Ripple

Figure 7.1 Block diagram of a Power Supply


Page 28

CAPACITOR FILTER

A very popular filter circuit is the capacitor-filter circuit. A capacitor is connected at the rectifier output, and

a dc voltage is obtained across the capacitor. The output voltage of a full-wave rectifier before the signal is

filtered. Notice that the filtered waveform is essentially a dc voltage with some ripple (or ac variation). It is

possible to further reduce the amount of ripple across a filter capacitor by using an additional RC filter section

The purpose of the added RC section is to pass most of the dc component while attenuating (reducing) as

much of the ac component as possible.

SERIES REGULATOR CIRCUIT

A simple series regulator circuit is shown below. Transistor Q1 is the series control element, and Zener diode

DZ provides the reference voltage.

Figure 7.3 a) Block Diagram for Filtered Rectifier circuit and b) output voltage graph on DC Load

Figure 7.4 Simple circuit diagram for Additional RC Filter

Figure 7.5 Circuit Diagram for Series Regulator


Page 29

IMPROVED SERIES REGULATOR

An improved series regulator circuit is in below figure. Resistors R1and R2 act as a sampling circuit, Zener

diode DZ providing a reference voltage, and transistor Q2 then controls the base current to transistor Q1 to

vary the current passed by transistor Q1to maintain the output voltage constant.

OP-AMP SERIES REGULATOR

Another version of series regulator is that shown in below figure. The op-amp compares the Zener diode

reference voltage with the feedback voltage from sensing resistors R1 and R2. If the output voltage varies,

the conduction of transistor Q1is controlled to maintain the output voltage constant. The output voltage will

be maintained at a value of

= ( +

)

Figure 7.7 Circuit Diagram for Series Regulator

Figure 7.6 Circuit Diagram for Improved Series Regulator


Page 30

PRE-CALCULATIONS 1. Draw a circuit diagram for full-wave rectification. Just use 4 diodes. Indicate AC input and DC output.

2. If you connect your circuit inside the block you see in figure 7.4, can you make some comment on the

voltages (AC and/or DC characteristics) and ripple(s) at points A and B?

3. How does the output voltage at point B changes for the circuit in figure 7.4 if you

a. Increase the value of C1

b. Increase the value of C2

c. Increase the value of R1

d. Increase the value of RL

4. Calculate the input voltage for the circuit you draw at part 1 if the output voltage is 20V

5. Calculate the output voltage for the given circuit in figure 7.5 for R = 220 , RL = 1k, and Vz = 9.6 V

Zener.

6. Calculate the output voltage for the given circuit in figure 7.6 for R1 = 3.3 k, R2 = RL= 2.2 k, R3 =

4.7 k, R4 = 10 k, and Vz = 9.6 V Zener.

7. Calculate the output voltage for the given circuit in figure 7.7

PROCEDURE 1. Build full-wave rectification circuit of 4 Diodes Bridge.

2. Adjust its input voltage from function generator until it gives 20V output.

3. Connect this output to the circuit shown in figure 7.4 for R1 = RL = 1k and C1 = 22 uF, C2 = 10 pF.

Measure the voltages at points A and B with oscilloscope.

4. Replace C1 and C2 with each other. Now measure voltages at points A and B again.

5. Connect the output of your full-wave rectifier to Vi at circuit shown in figure 7.5 for R = 220 , RL =

1k, and Vz = 9.6 V Zener. Measure Vo. Compare your result that you find in pre-calculation.

6. Connect the output of your full-wave rectifier to Vi at circuit shown in figure 7.6 for R1 = 3.3 k, R2 =

RL= 2.2 k, R3 = 4.7 k, R4 = 10 k, and Vz = 9.6 V Zener. You can use any NPN transistor (BC 237 or

2N3904). Measure Vo. Compare your result that you find in pre-calculation.


Page 31


PRE-CALCULATIONS (SHOW YOUR ALL WORK) 1. Bridge diode diagram

2. Voltages at points A and B

3. Voltage at point B depend on

a. C1

b. C2

c. R1

d. RL

4. Vinput =

5. Voutput =

6. Voutput =

7. Voutput = explain how this formula for the output voltage is found.


2. Vinput = when output is 20V

3. VA = and VB =

4. Replace C1 and C2, then measure VA = and VB =

5. Voutput = and compare

6. Voutput = and compare

APPENDIX A DATASHEETS

Page 32

Appendix A Datasheets

You can find more technical and electrical information about the components used in experiments

in following pages. At this pages you can find some selected behaviors of the components under

different situations (voltages, currents, temperatures). You can also find some sample circuit

diagrams for the given components.

Remember, these are common datasheets. Some conflicts and/or changes may occur. If something

is wrong with your experiment you can always check the new version from internet.

And some components that used in the experiments may not be included here. This is because a

different type of the same component can be used. The pin diagrams are often same. Otherwise

your lab instructor will inform you.

BC237 BC238 BC239 NPN SILICON AMPLIFIER TRANSISTOR

Page 33

BC237 BC238 BC239 NPN Silicon Amplifier transistor

BC237 BC238 BC239 NPN SILICON AMPLIFIER TRANSISTOR

Page 34

2N3904 NPN GENERAL PURPOSE SILICON AMPLIFIER TRANSISTOR

Page 35

2N3904 NPN General Purpose Silicon Amplifier Transistor

2N3904 NPN GENERAL PURPOSE SILICON AMPLIFIER TRANSISTOR

Page 36

LM741 OPERATIONAL AMPLIFIER

Page 37

LM741 Operational Amplifier

LM741 OPERATIONAL AMPLIFIER

Page 38

1N4001 ~ 1N4007 SILICON DIODE

Page 39

1N4001 ~ 1N4007 Silicon Diode

TIP122 NPN DARLINGTON TRANSISTOR

Page 40

TIP122 NPN Darlington Transistor

TIP122 NPN DARLINGTON TRANSISTOR

Page 41

APPENDIX B - OTHER COMPONENTS

Page 42

Appendix B - Other Components

ZENER DIODES

LEDS

POTENTIOMETERS

APPENDIX C - RESISTOR CODES

Page 43

Appendix C - Resistor Codes

EXAMPLES

Green-Blue-Black-Black-Brown

560 ohms 1%

Red-Red-Orange-Gold

22,000 ohms 5%

Yellow-Violet-Brown-Gold

470 ohms 5%

Blue-Gray-Black-Gold

68 ohms 5%

APPENDIX D - CAPACITOR READINGS

Page 44

Appendix D - Capacitor Readings

APPENDIX E - ELECTRICAL SYMBOLS

Page 45

Appendix E - Electrical Symbols

Ground Symbols

Earth Ground Used for zero potential reference and electrical shock

protection.

Chassis Ground Connected to the chassis of the circuit

Digital / Common Ground

Resistor Symbols

Resistor (IEEE)

Resistor reduces the current flow.

Resistor (IEC)

Potentiometer (IEEE)

Adjustable resistor - has 3 terminals.

Potentiometer (IEC)

Variable Resistor /

Rheostat (IEEE)

Adjustable resistor - has 2 terminals.

Variable Resistor / Rheostat (IEC)


Page 46

Trimmer Resistor Preset resistor

Thermistor Thermal resistor - change resistance when temperature

changes

Photoresistor / Light dependent

resistor (LDR) Photo-resistor - change resistance with light intensity change

Capacitor Symbols

Capacitor

Capacitor is used to store electric charge. It acts as short

circuit with AC and open circuit with DC.

Capacitor

Polarized Capacitor Electrolytic capacitor

Polarized Capacitor Electrolytic capacitor

Variable Capacitor Adjustable capacitance

Power Supply Symbols

Voltage Source Generates constant voltage

Current Source Generates constant current.


Page 47

AC Voltage Source AC voltage source

Generator Electrical voltage is generated by mechanical rotation of the

generator

Battery Cell Generates constant voltage

Battery Generates constant voltage

Controlled Voltage Source Generates voltage as a function of voltage or current of other

circuit element.

Controlled Current Source Generates current as a function of voltage or current of other

circuit element.

Meter Symbols

Voltmeter Measures voltage. Has very high resistance. Connected in

parallel.

Ammeter Measures electric current. Has near zero resistance.

Connected serially.

Ohmmeter Measures resistance

Diode / LED Symbols

Diode Diode allows current flow in one direction only (left to right).


Page 48

Zener Diode Allows current flow in one direction, but also can flow in the

reverse direction when above breakdown voltage

Schottky Diode Schottky diode is a diode with low voltage drop

Varactor / Varicap Diode Variable capacitance diode

Tunnel Diode

Light Emitting Diode (LED) LED emits light when current flows through

Photodiode Photodiode allows current flow when exposed to light

Transistor Symbols

NPN Bipolar Transistor Allows current flow when high potential at base (middle)

PNP Bipolar Transistor Allows current flow when low potential at base (middle)

Darlington Transistor Made from 2 bipolar transistors. Has total gain of the product

of each gain.

JFET-N Transistor N-channel field effect transistor

JFET-P Transistor P-channel field effect transistor


Page 49

NMOS Transistor N-channel MOSFET transistor

PMOS Transistor P-channel MOSFET transistor

Misc. Symbols

Motor Electric motor

Transformer Change AC voltage from high to low or low to high.

NOTES

Page 50

Notes

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