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Assignment Report FOR INTERNAL USE PP/1979-8Q/1/4.3/10 NOT FOR GENERAL DISTRIBUTION Contribution to the development of infrastructures and training of personnel for technical and vocational education
REPUBLIC OF IRAQ
VOCATIONAL SECONDARY EDUCATION IN ELECTRONICS, RADIO AND TELEVISION
by T. Ortman
United Nations Educational, Scientific and Cultural Organization
Paris, February 1980
This report represents the views of the author and not necessarily those of Unesco or the Government of Iraq
Serial No.: FMR/ED/STE/80/102
Technical Report PP/1979-30/1/4.3/10 FMR/ED/STE/80/102(Ortman) 29 February 1980
Table of Contents
Page
The School System in Iraq 1
INTRODUCTION 3
SECONDARY ELECTRICAL TECHNICAL SCHOOL, BAGHDAD 3
The scholastic year 4
Comments on the present syllabus . . . 4
Staff-student situation 4
Workshop facilities 4
SEMINAR ON TEACHING METHODS FOR ELECTRONICS 5 (23-25 October 1979)
Objectives 5
Programme 6
Outcome of the Seminar 6
Comments 7
RECOMMENDATIONS 7
APPENDICES
1. Proposed syllabus for electronics, radio TV . . . . 9
2. Seminar Papers 13
3. Persons contacted by the consultant 25
The School System in Iraq
P r-- m a ry school (5 y e a r s )
Inte rmedi ate ¡•̂ school
(3 y e a r s )
X
Secondary school 3 years
Academi c
Vocati onal
Centres of Vocational Trai ni ng
Un i ve rs i t;
^
XI
T e c h n i c a l Ins t i tu tes (2 y e a r s )
( M i n i s t ry of I n d u s t r y )
- 3 -
INTRODUCTION
Under the Participation Programme of Unesco 1979-1980, a consultant mission was undertaken to Iraq with the following terms of reference:
(a) to study the present syllabi for the subjects of radio and television theory and practice of the secondary industrial schools, and suggest modifications in order to improve these syllabi based on modern trends and on the needs of Iraq;
(b) to conduct, with the co-operation of the Government, a short training workshop for Iraqi teachers of those subjects mentioned in (a) above.
The consultant was in Iraq from 2 to 30 October 1978.
The consultant was based at the Secondary Electrical School, Baghdad. All information needed to enable the consultant to fulfil his assignment was written in Arabic. Information about the school system, curriculum, syllabus, staff and students was therefore obtained mostly by questioning Iraqi counterparts. The Iraqi counterparts were very co-opeative and hospitable. The consultant found the mission to be a very pleasant experience.
ELECTRONICS (RADIO/TV) SECONDARY ELECTRICAL TECHNICAL SCHOOL
Curriculum
Subjects
Religion
Sport
English
Arabic
Social study
Mathematics
Physics
Chemistry
Technical Drawing
Electronics Theory
Practical Work
Total
Total
Hours weekly 1st, 2nd, and 3rd year
Class Workshop
45 min.
45 min.
1 h. 10 min.
1 h. 10 min.
35 min.
1 h. 45 min.
1 h. 10 min.
1 h. 10 min.
2 h. 10 min.
3 h. 30 min.
14 h. 10 min
18 h.
18 h.
- 4 -
The scholastic year
1 September - 30 September
1 October - 14 January
15 January - 31 January
1 February - 14 February
15 February - 14 May
15 May - 31 May
1 June - 30 June
1 July - 31 July
Comments on the present syllabus
Preparation for teachers
Teaching
Mid-year examination
Holiday
Teaching
Final examination
Preparation for teachers
Holidav
The total time for the course in electronics is about 2,000 hours. The training is divided into two parts:
electronics theory - 315 hours (15%)
practical work - 1,720 hours (85%)
The theory has a very small percentage of the course. 30-40% theory and 60-70% practical work would be more suitable.
There is a need to improve the co-ordination between theoretical and practical teaching.
The present syllabi deal far too much with electron tubes at the expense of modern electronic technology.
The first two years of the course could be given a more general approach to electronics in order to enable training in other applications of electronics, radio and TV to be dealt with in the 3rd year as a specialization.
Example :
Basic
Electronics
(2 years)
Industrial Electronics
•Telecommunication
Radio and TV (Home electronics)
(1 year)
Staff-student situation
About 300 students in electronics (Radio/TV) graduate each year from secondary technical schools in Iraq.
- 5 -
The Secondary Electrical Technical School in Baghdad has approximately 1,000 students and 50 teachers. In the electronics department there are 5 teachers, teaching electronics theory, 11 teachers teaching practical work, and around 460 students. The teachers in theory have a fair theoretical background, a degree in engineering, and many of them have had the opportunity of overseas training.
The practical teachers generally have a very poor training in their profession; many are secondary school-leavers without any practical experience. The consultant did not meet one teacher in practical electronics who had formal training in teaching. Very little co-operation between the practical and theoretical teachers was shown. The practical teachers use 85% of their time for training in electronics.
Workshop facilities
At present, there are 5 secondary technical schools in Iraq with departments for electronics.
The Secondary Electrical Technical School in Baghdad was built in 1969. The consultant was told that this school is one of the best technical schools in Iraq for electrical/electronics training.
The electronics department of the school has 6 workshops, each designed for about 16 students, and one laboratory. The workshops and classrooms for theory are separated into different buildings. Due to bad workshop management, workshops and equipment are in bad condition.
There are some difficulties in purchasing electronics components. With assistance from the Foundation, it is possible to import what is needed. Some sophisticated equipment, trainers and instruments have been purchased and put into the laboratory.
There are 28 new technical schools under construction in Iraq. The schools are being built by a Finish company. The consultant had the opportunity to visit one of the new schools which was nearly completed and very impressive. This school was designed for 650 students.
SEMINAR ON TEACHING METHODS FOR ELECTRONICS (23-25 OCTOBER 1979)
The consultant arranged the laboratory at the school for the Seminar. Workbenches were put in, electricity supplied to the benches and instruments, which had never been used, were unpacked and put into working order.
A programme of 7 exercises (Appendix 2) was worked out. Existing equipment was used and 3 connection-boards were designed. A connection diagram was pasted on a sheet of wood, tacks knocked in and the circuits connected.
Objectives
To introduce teaching methods in electronics; to teach the use of semiconductors, transistors, UFT, SCR; to exercise the use of electronic instruments.
The Seminar was designed mainly to deal with modern techniques in electronics, new components, etc., which are likely to be included in a revised syllabus.
- 6 -
The approach to electronics practice consists at present of learning by rote. Due to lack of workshop management, equipment and the few instruments available were in very poor condition.
The practical teachers have received poor training. Most of them are secondary school-leavers without any practical experience. On the last day of the mission, the consultant was told that there exists a two-year course at the University for technical teachers, and that some of the staff at the school had completed this course. The consultant, however, could see no difference in the competence of these teachers.
The consultant drew the conclusion that it would be most beneficial for the staff if the Seminar were to contain an integration of electronics theory, teaching methods and workshop management. It was agreed that the Seminar should be of 3 days' duration. A programme for the Seminar was worked out with the intention of it being run in a similar way to how the practical work in electronics should be conducted in the workshops. Twenty-four teachers from different schools attended the Seminar.
Programme
1st Day
A. Teaching methods
(i) The objectives for practical work in electronics to prove the theory; to learn manual skill; to develop good working habits.
(ii) Types of practical work. Exercises in measurements integrated with practical explanations of the theory (examples of this type of work were demonstrated in the Seminar by exercises) , Learning manual skills e.g. soft soldering, connections, etc.
(iii) Project work. Manual skills integrated with theoretical knowledge and techniques of measurement. Example: Building and testing of amplifiers, rectifiers, oscillators, etc.
(iv) Work with the ready product. Testing, tuning, trouble-shooting on radio/TV, etc.
B. Workshop management
Arrangement to tools, instruments, work-benches, etc.
2nd Day
Practical work
3rd Day
Practical work Evaluation
Outcome of the Seminar
The first day of the Seminar proceeded according to plan. The teachers exposed a weakness in electronics.
- 7 -
The second day, dealing with practical work, did not proceed as planned. The teachers had great difficulties in working from written instructions and in operating the instruments. Also, lack of theoretical knowledge, electronics and basic calculations created difficulties. For these reasons, the teachers were able to complete only one out of seven exercises.
The consultant changed the programme for the third day which was then used to train teachers in measuring frequencies and voltage with the oscilloscope.
The manager of the school and one representative from the Foundation were observers at the Seminar. They expressed great surprise that the standards of the teachers were as low as shown in the Seminar.
It should, however, be pointed out that the teachers showed great interest in the Seminar and some of the topics brought up were applied in the workshops several days later.
Comments
Unfortunately, 3 days was too short a time. A great interest for the Seminar was shown, however, and the consultant got the feeling that it was appreciated.
Appendix 2 refers to the papers prepared for the Seminar.
Recommendation s
1. In order to improve the training in electronics (Radio/TV), there is a need to revise the syllabus. The consultant has written a syllabus for a 3-year course in electronics (Radio/TV)(Appendix 1), which could serve as a guide for the revised syllabus. The consultant would like to point out that he had a very short time at his disposal for this consultancy and that the proposed syllabus therefore only deals with the main topics.
2. In order to be able to fulfil the intentions of the revised syllabus there is an urgent need to upgrade the teachers in practical work in modern electronics technology, in workshop management and in teaching methods. An initial one-year full-time course should be considered.
3. A secondary electrical technical school should be developed into a training centre for teachers in electronics and power electricity. The objectives for this training centre should be:
(a) To run in-service courses for teachers in the field.
(b) To train new teachers.
(c) To produce teaching aids (job instruction sheets, etc.).
(d) To give advice about suitable material for eaching (instrucments, trainers, etc.).
4. There is an urgent need to develop and use teaching aids to a greater extent in the teaching process.
5. A programme of in-service teacher training must be considered to upgrade the level of the existing staff, especially in teaching methods and the use of equipment for practical work.
- 8 -
6. The consultant wishes to recommend that the Iraqi Government seek Unesco's advice and assistance in preparing the technical teachers and instructors for the new schools under construction, and for the management of these new schools.
- 9 -
APPENDIX 1
Proposed syllabus for electronics, radio/TV Secondary Technical School
1st year
Topic
1. Electrical safety
2. Basic electrical installation
3. Soft soldering
4. Direct current DC
m
Techniques of measurement (1)
Theory
Electrical distribution
Why earthing? How electric current effects the human body
Wiring rules
Fuses Cables Plugs Outlets Basic installation
Solder Tools etc.
How electricity is produced
Volt Ampere Watt Electric circuit etc.
Voltmètres Ammetres Ohm metres Multimètres Oscilloscope Audio frequency Generators RLC bridges
Practical
Connection of plugs, outlets, lampholders, simple installation
Soldering on: net terminals printed circuits etc.
Measurement of current voltage power etc.
Exercises in the use of the listed instruments. To be integrated in other exercises.
Time T P
- 10 -
1st year t
1 Topic i
6. Alternating current
7. Mechanical work
8. Electronics (1)
9. Alternating current
10. Electronics
Theory
AC generation The sine vave Frequency Time Resistive AC circuit The transformer
Passive components: resistors capacitors terminals and contacts used in electronics wires and cables switches semiconductor diodes
Relays
Reactance Power factor Power in AC circuits RC circuits RL RLC LC Resonance
Transistors: germanium silicon
CE connection CB CC Special components: photo devices zener diode tunnel diode field effect transistor MOS transistors
Practical
Measurement with oscilloscope and meters : Time frequency U and RMS value PP
To determine the' characteristic for germanium diodes silicon diodes zener diodes The connection of simple rectifier circuits.
Time T P
2nd year •
- 11
2nd year
Topic
10.. Electronics
(cont.)
11. Techniques of measurement (2)
Theory
UJT transistors SCR Electrone tubes Integrated circuits IC, LSI
Rectifier circuits Stabilization Current limit Over load protect. Audio frequency
amplifiers Decibel Feedback Harmonic distortion Frequency range Operational amplifiers
Hf amplifiers: wide band amplifier selective amplifier band with Q factor
Modulation AM, FM Oscillators IF amplifiers Mixers Detectors AM, FM Power amplifiers Digital technique:
analog - digital pulses binary system logical functions AND, OR, NOR, etc. relaxation oscillator sequency circuit
Record player Tape recorder Superheterodyne receiver
Oscilloscope MF generators Frequency counters
Practical Time T P
12
Topic Theory
3rd year
Practical Time
12. Electronics
Antennas and transmission lines
Tape recorders FM receivers Tuning and measurement
on the discriminator curve etc..
Stereo amplifiers Stereo radio
TV, black and white
Colour TV, Basic.
- 13 -
APPENDIX 2
Internal resist,
of a battery
Transistor in
CE connection
Transistor in
CB connection
Transistor in
CC connection
Stab, circuits
using semicond.
Voltage régulât.
ÜJT and SCR
Prep, for demonstr.
Tuned circuits
Project work
•
SEMINAR PAPERS
RECORD FOR PRACTICAL WORK
Name:
- 14 -
Secondary Electrical Technical School
Baghdad Iraa
Information sheet The Internal Resistance of an Electrical Power Source
name
class
Every source of electric power can be represented by an Electromotive Force (E) which is constant, and an Internal Resistance (Ri) connected in series.
If the power source is unloaded, no current will flow, there will be no voltage drop across Ri, and the terminal voltage (U) will be the same as E.
If the power supply is loaded with a resistor (Rl), a current (I) will flow, and there will be a voltage drop across Ri (Uri)
I = Ri Rl
6^?
U
h Ú "i: _ 1 ~
With reference to equation A what will happen to the current I if Rl is decreased?
Answer:
The voltage drop across the inernal resistance (Ri) will be:
Uri = Ri B Ri + Rl
With reference to equation B, what will happen to Uri if Rl is decreased?
Answer :
If Kirchoff's Law is applied to the circuit
E - Uri - Uri = 0 C
With reference to equation C, what will happen to the terminal voltage Uri if Uri is increased?
Answer:
Exercise The terminal voltage of a battery was measured to 6V when the battery was unloaded. When the battery was loaded with a resistor of 2 ohm, the terminal voltage dropped to 4V. Calculate the internal resistance of the battery.
- 15 -
Secondary Electrical Technical School
Baghdad Iraq
Worksheet Measurement of the Internal Resistance of a Battery.
name
class
Objectives: To get a practical application on Ohm's Laws. To exercise the handling of the oscilloscope and the RLC bridge.
Material: 1. Oscilloscope with probe set
RLC bridge
Multimeter
Battery
Resistor
Procedure: 1. Measure the resistance of the load resistor with the RLC bridge.
Record the result: R =
Measure the terminal voltage of the battery when it is unloaded. Use the multimeter.
Record the result: U =
Repeat the measurement (2) but use the oscilloscope this time.
Record the result: U =
Connect the resistor across the battery terminals and measure the terminal voltage when the battery is loaded. Use the multimeter;
Record the result:
Conclusion: Now, all information needed to calculate the internal resistance is available.
Calculations:
Answer :
Remarks: In this exercise the power source was a battery. The same method can be used to determine the output or input impedance of an amplifier.
- 16 -
Secondary Electrical Technical School
Baghdad Iraq
Work sheet The transistor in GE connection
name
class
Theory: The GE connection has a rather high current and voltage gain. Consequently the power gain is high too.
The input impedance is around Ik in parallel with Rl.
The output impedance is around 10 k. in parallel with RC.
In this exercise you are going to measure the input and output impedance, the voltage - and current gain and adjust the bias to its correct value.
Material: 1. Connection board with transistor AC 122.
1. DC power supply (9V)
1. Audio frequency generator.
1. Double beam oscilloscope.
1. Multimètre
1. Decade resistor
Diagram:
£
\i—L
£c
• O f
Procedure : A. Biasing
1. Connect the power supply to 3 and 5 (positive to 5) Adjust to 9V.
2. Connect a voltmètre between 5 - 6 .
3. With the variable resistor, adjust the voltage between 5 - 6 to 4,5V.
Measure UBE and UCE, record.
UCE = , UBE =
Calculate IC:
IC
Mark the biasing point in the collector diagram Draw the load line.
- 17 -
The transistor in CE connection (Cont.)
B. The voltage gain
1. Adjust the frequency generator to 1,000 Hz and the output voltage to zero.
Connect to 1 - 2 (screen to 2)
2. Put the input selector switches of the oscilloscope in AC position.
3. Connect CHI input of the oscilloscope to 1 - 2 and the CH2 input to 4 - 5 (screen to 5)
4. Increase the output voltage from the generator until both peaks are distorted at the output of the amplifier.
5. Decrease the output voltage from the generator about 50%.
6. Measure the input and output voltage of the amplifier and record.
Uin + = PP
Uout PP
Calculate the voltage gain.
Answer:
C. The input impedance
1. Keep the same connection as used in R and connect a decade resistor in series with the generator.
2. Put the decade resistor to zero and read the output voltage from the amplifier.
Uout = PP
3. Adjust the decade resistor till Uout is half the value recorded in 2.
4. Read the resistance value of the decade resistor. This is the same as the input impedance of the amplifier.
Zin
What should happen to the input resistance if Rl was increased?
Answer :
Exercise;
Apply the same method as used in C and measure the output impedance of the amplifier. Draw the circuit diagram.
Zout =
- 18
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Sj
- 19 -
Secondary Electrical Technical School
Baghdad Iraq
Work sheet The Transistor in CB connection
name
class
Theory:
Material:
Connection diagram:
In CB connection the base is the common electrode for the input and output.
A transistor in CB connection can be used at higher frequency than if connected in CE. For that reason the CB connection is often used in radio and TV receivers.
The CB connection has high voltage gain, but no current gain.
The input impedance is low, the output impedance is high.
Connection board with transistor AC 122 in CB connection.
DC power supply (9V)
Audio frequency generator.
Double beam oscilloscope
Decade resistor or a variable resistor
Multimètre.
. a.
-c -
(Mf «JT
x
-a
-0 +
Procedure: A.
1.
2.
Biasing
Adjust the power supply voltage to 9V.
With the variable resistor, adjust UCE to 4V.
Measure and record the following voltage
UE = , ÜBE =
Calculate the collector current
UCE
- 20 -
The transistor in CB connection (cont.)
B. The voltage gain
1. Adjust the frequency generator to L 1,000 Hz and the output voltage to zero.
Connect to the input of the amplifier (1 2)
3.
Connect the CHI input of the oscilloscope to measure the input voltage to the amplifier, and CH2 to measure the output voltage.
Increase the output voltage from the generator until both peaks of the output signal is distorted, then decrease the input signal about 50%.
Measure and record:
Uin = PP
Uout PP
Calculate the voltage gain.
Voltage gain =
What, is the phase difference between the input and output signal?
Answer :
C. The input impedance
1. Connect as shown in diagram.
2. Put the decade resistor to zero ohm.
3. Read the output voltage from the amplifier at the oscilloscope.
Connect
Uout pp
Increase the resistance of the decade resistor until the output voltage from the amplifier is half the value recorded in 2. The input resistance of the amplifier equals the resistance value of the decade resistor.
Zin =
- 21 -
The transistor in CB connection (cont.)
D. The output impedance !
1. Connection: ( ̂
2. Measure the output impedance, use the same method as used when the input impedance was measured.
Zout =
E. The current gain
Calculate the imput current:
Calculate the output current:
Calculate the current gain:
Lin =
lout =
Current gain =
O '+•
F. Determine the frequency range for the CB amplifier.
0 ¿IB , _ _
-^¿6.-
; | i i i | i i ' i i ' ' * i | i i ' » | i i F i | i | i i | | ' • i • f^i i t ; •
l<? O ICCO ißK lùOk IffOOk -5»
»CK iOOK. Hz
Voltage gain = dB = 20 log
Power gain dB = lo 10 log
Uout Uin
Pout Pin
- 22 -
Secondary Electrical Technical School
Baghdad Iraq
Work sheet The transistor in CC connection.
name
date
Theory:
Circuit diagram
Procedure :
The CC connection is called the emitter follower.
The emitter is the common electrode for the input and output signals.
The CC connection has a high current gain but no voltage gain.
The input impedance is high and the output impedance is low.
The CC connection is often used as an impedance transformer.
Z OL.
s-'l W"
I ^J? + In the theory it was stated that the collector is the common electrode for the input and output signals.
With reference to the diagram, explain that statement.
The imput is between 1 - 2 , and the output is between 7 - 8 .
Answer :
A. Biasing
Set the biasing to its correct value
Calculate IC.
C. Voltage gain
Determine the voltage gain,
'5-8
IC =
U gam =
D. Input and output impedance Measure the input and output impedance:
Z. in out
E. Calculate the current gain.
in out •r I
gaxn
- 23 -
Secondary Electrical Technical School
Baghdad Iraq
Worksheet Voltage regulation with UJT and SCR
name
class
Material: 1. Electronic Trainer VÉNETA with instruction book
I. Oscilloscope with probe set.
1. Frequency Counter, TAKEDA, TR-5142G with manual.
Procedure: Read the Instruction Manual for the Frequency counter, Chapter 2 specifications, chapter 3 Operating instructions.
Head the instruction book (Electronic VÉNETA) Page 163-164
Copy and study the circuit diagram. Circuit diagram:
Connect up the circuit on the board, assembling diagram page 166.
Contact the teacher for check up.
Test the function,
Put the variable resistor in the centre position, measure and copy the following curves, (use the oscilloscope) Measure the frequency with the frequency counter.
lie A
-^
*¿' A
-?-
U IS U 2. O
- 24 -
Secondary Electrical Technical School
Baghdad Iracr
Stabilizing circuits using semiconductors
name
class
Material: Electronic trainer, ELWE - FRANZ System with experiment book
Procedure: 1, Read in the experiment book, page 6-70.2 to 6-70.4.
2. Copy the circuit diagram and study the function. Circuit diagram:
Questions:
3. Connect and test the function.
1. What should happen to U„ if the zener diode was burnt and the contact between the anode and the cathode was interrupted?
Answer:
2. What should happen to (J if transistor T was short-circuited?
Answer :
3. What should happen to U_ if transistor T was short-circuited?
Answer :
- 25 -
APPENDIX 3
PERSONS CONTACTED BY THE CONSULTANT
Mr. Kaled Abdu Sallam Assistan Director, Foundation for Vocational Education
Mr. M.H. Al-Naib (Mr. Motheer)
The Manager of the Secondary Electric Technical School
Mr. S. Ibrahim (Mr. Saad)
Assistant Manager of Technical Affairs
Mr. R. Alansair (Mr. Rother)
Head of Electronics Department (Textbook author)
Mr. H. Al-Khattar Part-time teacher at the School and Director of the Institute of Electronics (Textbook author)
Mr. Clewestam Project Co-ordinator IRO/L 846 - Unesco/IBRD Education Project