LABORATORY MANUAL FOR EXPERIMENTS IN ELECTRONIC WORKSHOP PART 1
OF BACHELOR OF ENGINEERING (HONOURS DEGREE) ELECTRONIC
ENGINEERING AT NUST
E. MAKUMBE
No part of this book may be used or reproduced in any manner whatsoever without
written permission from the authors except from its intended learners at NUST. The
contents are subject to reviews from time to time as laboratory resources and
consumables change.
LESSON 1
CONTENTS
About authors
Preface
1.) Introduction
2.) General Occupational Safety and Health regulations
3.) Departmental electrical safety rules
4.) Factories and works act in Zimbabwe
5.) Environmental and Health issues in the workshop
6.) Types of fire extinguishers
LESSON 2
Lab1 Evaluating Resistors
Lab2 Using a Multimeter in measuring amps , volts and ohms
Lab3 Testing Capacitors with Multimeter
Lab4 Testing Capacitors in Series and in Parallel
Lab5 Measurement of Capacitor values using reactances
Lab6 Diode VI characteristics curve
Lab7 Waveshaping by forward biased diode
Lab8 Half wave rectifier output without smoothing capacitor
Lab9 Half wave rectifier with smoothing capacitor
Lab10 Zener diode shunt regulator
Lab11 Final semester project on soldering
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About authors
Preface
The manual contains instructions given to Part 1 Course of Electrical Engineering
Workshop semester 1 and that of Electronic Engineering workshop in semester 2.
Introduction
A place called workshop is an area where hand tools and power tools are utilized for
the purpose of skill development .The main workshop at NUST is mainly of
electronic engineering involved in design, testing and fabricating of electronic
gadgets. The learner that has to go through this workshop have to appreciate
safety regulations involved with all types of workshop. It has been deemed not
enough to expose the learner to only electronic workshop safety but to arouse his /
her awareness of safety at all types of jobs. Therefore international safety
regulations of Occupational Safety and Health Acts (OSHA) are discussed first and
its compliment of factory and works regulations in Zimbabwe promulgated by
National Social Security Authority are enlightened to the learner .Since the learner
is coming into an engineering work and its associated risks, these regulations are
met to arouse safety awareness at an early stage. The work done in the electronic
workshop is met to develop confidence and competence in tackling engineering
work by the learner. At the end of each experiment a laboratory report should be
submitted as expected in a technical report, results discussed, deviations and
recommendations given for future improvements. The learner is encouraged to
keep a record of the work done for each lab experiment in a logbook. The idea of
keeping a logbook of engineering work is important at accrediting a learner as a
professional engineer in their career life and logging work done at an early stage
helps the learner to remain focused on important tasks.
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2.) Occupational Safety and Health Act
This guidance document is not a standard or regulation, and it creates no new legal
standards. The recommendations are advisory in nature, informational in
obligations. It contains recommendations as well as descriptions of mandatory
safety and health content, and are intended to assist employers in providing a safe
and healthful workplace.
The international Occupational Safety and Health Act( OSHA) requires employers
to comply with safety and health standards and regulations promulgated by OSHA
or by a state with an OSHA-approved state plan. In addition, the Act’s General
Duty, requires employers to provide their employees with a work-place free from
recognized hazards likely to cause death or serious physical harm.
Generally there are four occupational hazards that are common in electrical
workshop and electronic Laboratories . These are
2.1) Chemical Hazards involving chemical fumes encountered when fabricating
and developing Printed Circuit Boards (PCB). The processes often include chemical
etching and safe chemical waste disposal.
Chemical cautions: Do not pour water into acid , wearing plastic gloves when
handling chemicals, read labels to acquaint yourself with expiry dates.Eating,
drinking, and smoking are not allowed near hazardous chemicals like cleaning
liquids .
2.2) Physical Hazards are encountered by the noise generated by drilling
machines when making components holes on the PCB .Today there are small noise
free drilling machines.(N.B. The term physical means relating to things perceived
through the senses as opposed to the mind; tangible or concrete.)
Physical cautions: check for flying objects when drilling, identify noisy areas and
protect your ears and eyes.
2.3) Ergonomic Hazards: These are hazards that deal with body mechanics while
working on a task . e.g how to lift heavy things strategically without causing
damage to your body. How comfortable is your body is while sitting in an office
The term “Ergonomics” means the study of how equipment and furniture can
be arranged in order that people can do work or other activities more efficiently and
comfortably.
Ergonomic cautions: length & type of ladders is important, Aluminum ladders ,
wood ladders and the safest height to width ladder’s ratio is 4 to 1. In offices the
sitting arrangement should be comfortable, the order of furniture arrangement
should not be a threat to dangerous falling items.The lighting in the room should
not casue eye sore. Cables should not be hanging around the place for the can
cause somebody to stumble over them and fell.
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2.4) Electrical Hazards. The use and handling of electricity is important when
dealing with circuits and experiments.
Electrical caution: wet hands are dangerous, remove conductive bands, watches
and rings when handling high voltage, remove hanging necklaces, Ladies ought to
tie their hair at the back.
The Occupational Safety and Health Act requires employers to comply with safety
and health standards and regulations promulgated by OSHA .
The Act’s General Duty of employers is :
•To provide their employees with a work-place free from recognized hazards likely
to cause death or serious physical harm
•To make a health & safety policy document
•To organize a health & safety Management system
•To maintain equipment and keep them safe for operation.
The Act’s General duties of Employees:
•Take care of your own safety and that of your fellow employee
•Take care of Personal Protective Equipment (PPE)
•Inform the employer of any health and safety risks
•Right to leave a workplace if they believe there is danger
2.5.) Hierarchy of Controls
Occupational safety and health professionals use a framework called the “hierarchy
of controls” to select ways of dealing with workplace hazards. The hierarchy of
controls prioritizes intervention strategies based on the premise that the best way
to control a hazard is to systematically remove it from the workplace, rather than
relying on workers to reduce their exposure. The types of measures that may be
used to protect laboratory workers, prioritized from the most effective to least
effective, are:
•engineering controls;
•administrative controls;
•work practices; and
•personal protective equipment (PPE).
Most employers use a combination of control methods. Employers must evaluate
their particular workplace to develop a plan for protecting their workers that may
combine both immediate actions as well as longer term solutions. A description of
each type of control for non-production laboratories follows.
2.5.1)Engineering controls are those that involve making changes to the work
environment to reduce work related hazards. These types of controls are preferred
over all others because they make permanent changes that reduce exposure to
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hazards and do not rely on worker behavior. By reducing a hazard in the workplace,
engineering controls can be the most cost-effective solutions for employers to
implement.
Examples include:
•Wearing Chemical Fume Hoods; and
•Biological Safety Cabinets (BSCs).
2.5.2)Administrative controls are those that modify workers’ work schedules
and tasks in ways that minimize their exposure to workplace hazards.
Examples include:
•Developing a Chemical Hygiene Plan; and
•Developing Standard Operating Procedures for chemical handling.
2.5.3)Work practices are procedures for safe and proper work that are used to
reduce the duration, frequency or intensity of exposure to a hazard. When defining
safe work practice controls, it is a good idea for the employer to ask workers for
their suggestions, since they have firsthand experience with the tasks as actually
performed. These controls need to be understood and followed by
managers,supervisors and workers.
Examples include:
•No mouth pipetting; and pouring water into an acid can cause an explosion but
pouring acid into water is safe.
•Chemical substitution where feasible
(e.g.,selecting a less hazardous chemical for a specific procedure).
2.5.3.a)Storage
Stacking materials can be dangerous if workers do not follow
safety guidelines. Falling materials and collapsing loads can crush or pin workers,
causing injuries or death.
•Height must not exceed three times the width
•Read Labels to acquaint yourself with expiry dates of stored materials
2.5.3.b) Housekeeping
•Leave your work area as you would expect to find it!
•Store PPE,tools, equipment and material in correct places.
•All work surfaces / areas must be clean and safe.
•DO NOT LITTER
•Clean up spills immediately, this will prevent fire hazards , slipping and falling risks
as well as damage to the environment.
•Keep walk ways free of obstruction
2.5.3.c) Ergonomic Hazards
These include how do you lift heavy equipment and how do you carry equipment
and tools
•When lifting a heavy object from the floor area it is important to keep the back
straight.
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•When carry equipment make sure it be carried with two people .
2.5.4) Personal Protective Equipment
Personal Protective Equipment (PPE) is protective gear needed to keep workers
safe while performing their jobs. Examples of PPE include respirators, face shields,
goggles and disposable gloves. While engineering and administrative controls and
proper work practices are considered to be more effective in minimizing exposure to
many workplace hazards, the use of PPE is also very important in laboratory
settings.
It is important that PPE be:
•Selected based upon the hazard to the worker;
•Properly fitted and in some cases periodically refitted (e.g., respirators);
•Conscientiously and properly worn;
•Regularly maintained and replaced in accord with the manufacturer’s specifications
•Properly removed and disposed of to avoid contamination of self, others or the
environment;and
•If reusable, properly removed, cleaned, disinfected and stored
Assignment 1
Q1. Identify FOUR hierarchy controls in the safety framework and give at least ONE
example that can be implemented to promote safety of a worker.
[12]
Q2. Which Act or regulation which compliments OSHA act in Zimbabwe?
[2]
Q3.What is the importance of keeping a logbook in engineering work.
[2]
Q4.State FOUR types of occupational hazards common in electrical work.
[8]
Q5.What precautions are required in these hazards stated above Q3.
[8]
Q6.Describe the danger involved in the following instances
(i)
Material stacking
(ii)
Lifting heavy equipment by one worker
(iii)
Working in an untidy environment
(iv)
Pouring water into acid
[8]
TOTAL 40 MARKS
Homework 1{due next lesson }
Research over internet to identify the type of personal protective equipment that
should be worn in the following situations
1) Walking on slippery floors
2) Working in dirty areas
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3) Working with a drilling machine to protect the eyes
4) When handling electrical wires
5) When working in noisy environment
6) For protection of the head against falling objects
7) When climbing over heights or working on scaffolds
8) For protection against fumes or dust
Department of Electronics Engineering
ELECTRICAL SAFETY
for Staff and Students in the Instructional Laboratories
WORK NEVER ALONE

If you are working with energized circuits or equipment over 50 volts peak,
make sure that at least one other person can see you and hear you.
VOLTAGE RULES


All Instructional Laboratories lab kit voltages are 240 volts rms. (OSHA
permits “unqualified persons” to work on such circuits with “awareness-type”
training.)
If you intend to work on a project, you must secure permission and receive
specific training from your Instructor, TA, or Lab Technical Personnel
before any work on the project begins.
PREVENT ACCIDENTS: FOLLOW THIS ADVICE
1. Never hurry. Work deliberately and carefully.
2. Connect to the power source LAST.
3. If you are working with a lab kit that has internal power supplies, turn the
main power switch OFF before you begin work on the circuits. Wait a few
seconds for power supply capacitors to discharge. These steps will also help
prevent damage to circuits.
4. If you are working with a circuit that will be connected to an external power
supply, turn the power switch of the external supply OFF before you
begin work on the circuit.
Further advice
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1. Check circuit power supply voltages for proper value and for type (DC, AC,
frequency) before energizing the circuit.
2. Do not run wires over moving or rotating equipment, or on the floor, or
string them across walkways from bench-to-bench.
3. Remove conductive watch bands or chains, finger rings, wrist watches, etc.,
and do not use metallic pencils, metal or metal edge rulers, etc. when
working with exposed circuits.
4. When breaking an inductive circuit open the switch with your left hand and
turn your face away to avoid danger from any arc which may occur across
the switch terminals.
5. When using large electrolytic capacitors be sure to wait long enough
(approximately five time constants) for the capacitors to discharge before
working on the circuit.
6. All conducting surfaces intended to be at ground potential should be
connected together
BASIC ELECTRICAL SAFETY PRACTICES
The Institute requires everyone who uses electrical equipment to understand these
safety precautions to comply with the OSHA Electrical Safety-Related Work
Practices standard and NUST's electrical safety policies. The following safe work
practices can prevent electrical shock. Contact your supervisor for additional safety
training if your job involves repairing, installing or working on energized parts.
A. Safe Work Practices

Turn off and unplug equipment (instead of relying on interlocks that can fail)
before removing the protective cover to clear a jam, replace a part, adjust or
troubleshoot. Ask a qualified person to do the work if it involves opening
equipment and creating an exposure to energized parts operating at 50 volts
or more.

Don't use an electrical outlet or switch if the protective cover is ajar, cracked
or missing.
Only use DRY hands and tools and stand on a DRY surface when using
electrical equipment, plugging in an electric cord, etc.
Never put conductive metal objects into energized equipment.
Always pick up and carry portable equipment by the handle and/or base.
Carrying equipment by the cord damages the cord's insulation.
Unplug cords from electrical outlets by pulling on the plug instead of pulling
on the cord.




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





Use extension cords temporarily. The cord should be appropriately rated for
the job.
Use extension cords with 3 prong plugs to ensure that equipment is
grounded.
Never remove the grounding post from a 3 prong plug so you can plug it into
a 2 prong, wall outlet or extension cord.
Re-route electrical cords or extension cords so they aren't run across the
floor, under rugs or through doorways, etc. Stepping on, pinching or rolling
over a cord will break down the insulation and will create shock and fire
hazards.
Don't overload extension cords, multi-outlet strips and wall outlets.
Heed the warning signs, barricades and/or guards that are posted when
equipment or wiring is being repaired or installed or if electrical components
are exposed.
B. Check for Unsafe Conditions (either before or while you're using equipment :)
1. Is the cord's insulation frayed, cracked or damaged, exposing the internal
wiring?
2. Are the plug's prongs bent, broken or missing, especially the third prong?
3. Is the plug or outlet blackened by arcing?
4. Was liquid spilled on or around the equipment?
5. Are any protective parts (or covers) broken, cracked or missing?
6. Do you feel a slight shock when you use the equipment?
7. Does the equipment or the cord overheat when it is running?
8. Does the equipment spark when it is plugged in or when switches or controls
are used?
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FACTORIES AND WORKS ACT IN ZIMBABWE
In Zimbabwe there are general laws which are promulgated by National Social
Security Authority (NSSA) stated in factories and works act.
What are the laws surrounding Health and Safety in the Workplace in
Zimbabwe?
REF: https://mywage.org/zimbabwe/decent-work-check/health-and-safetylaws/health-and-safety-regulation
At a general level occupational health and safety laws that are applicable to all
employers and employees across sectors are the Labour Act, Chapter 28.01 and
NSSA (Accident Prevention) (Workers Compensation Scheme) Notice No. 68 of
1990
At a secondary level there is the Protection from Smoking (Public Health) (Control
of Tobacco) Regulations S.I.264 of 2002 that prohibits smoking in enclosed public
places including workplaces and the Labour Relations (HIV and AIDS) regulations
S.I.202 of 1998 which prohibits discrimination on the ground of AIDS/HIV status,
including:

Prohibition of mandatory testing for HIV as a precondition of employment

The duty to respect the confidentiality of HIV status of employees

The provision of protective clothing and other safety devices to prevent the
spread of AIDS/HIV at the workplace, including mandatory education and
information sharing programmes
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There are also sectoral occupational health and safety laws. These are laws specific
to a particular sector whose objective is to supplement the general laws. These laws
cover the mining, industry and agricultural sectors.
Mining Sector
The provision for workplace safety are awarded under the Mines and Minerals Act,
Chapter 21:05 and its regulations:

The Mining (Management & Safety) Regulations S.I 109 of 1990

The Mining (Health & Sanitation) Regulations S.I. 185 of 1995
Industrial Sector
The main pieces of legislation covering industry are the Pneumoconiosis Act
(Chapter 15;08) and the Factories and Works Act, Chapter 14.08 and its
regulations:

Factories and Works (General) Regulations S.I 263 of 1976

Factories and Works (Registration and Control of Factories) Regulations S.I
262 of 1976

Factories and Works (Machinery) Regulations S.I 302 of 1976

Factories and Works (Electrical) Regulations S.I 304 of 1976

Factories and Works (Building, structural and Excavation Work) Regulations
S.I 264 of 1976

Factories and Works (Elevator and Escalator) Regulations S.I 263 of 1976
Agricultural Sector
There is no specific health and safety law for the agricultural sector. However, the
Environmental Management Act, (Chapter 20:27) provides that every worker has a
right to work in an environment that does not endanger his or her safety. The Act
and its regulations also control usage, storage, labelling and disposal of hazardous
substances and articles.
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The collective bargaining agreement for the agriculture industry S.I 323 of 1993
requires employers to provide their employees with appropriate protective clothing
and such devices to protect them from harmful substances.
ENVIRONMENT AND HEALTH ISSUES IN THE LABORATORY
ENVIRONMENTAL PRACTICES
These include Material handling
1) Material handling
• A Material is hazardous if it can cause harm to people and the environment
•Eating ,drinking and smoking are not allowed near hazardous chemicals
• Labels-Identifies the content, effects on your health, special instruction, PPE,
basic first aid?
•Read labels before commencing work?
2) Disposal of chemical etchant
Etchant is a chemical used for fabricating electronic circuits.
The use of acids was common during the old days but its not environmental safe
and hence ferric chloride etchant is the only chemical which is environmentally
favoured but it has its drawbacks. The drawbacks of ferric chloride, [Iron (III)
chloride] is a suitable way of disposing the etchant after use in an environmental
friendly way. The disposal of salts of copper is poisonous to fish environment and
the disposal of ferric chloride waste can permanently stains the sink basin.
How to dispose of ferric chloride etchant
When ferric chloride was used as an etchant it ate away the copper to produce
copper(II) chloride a greenish substance . Cupric chrolide is actually a faster
etchant which will result into copper (I) chloride a brownish in colour .
An environmental friendly way of disposal of ferric chlodide is to add washing soda (
sodium carbonate ) which can be obtained cheaply for supermarkets.The reaction of
ferric chloride with washing soda will produce carbonates of copper and iron .
copper carbonate is insoluble solid blue in colour and iron carbonate precipate is
greenish in colour . The products can easily go down the drain and harmless to the
environment.
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2FeCl3
+ 2Cu
+ 2H2 O
=
2 CuCl2 +
Fe(OH)2
+ FeCl2
+ H2
etching processing
CuCl2 + Cu = CuO
etching process.
+ Cl2
Further etching process
cupric chloride the
To dispose the etching liquids add washing soda ( sodium carbonate)
2Cu +
FeCl3
+
Na(OH) + CuCl2 + H
Na2CO3 +
H2O
=
CuCO3
+ FeCO3
+ NaCl +
Methods of Waste Disposal
( C 2.1)Landfill
The Landfill is the most popularly used method of waste disposal used today. This
process of waste disposal focuses attention on burying the waste in the land.
Landfills are found in all areas. There is a process used that eliminates the odors
and dangers of waste before it is placed into the ground. While it is true this is the
most popular form of waste disposal it is certainly far from the only procedure and
one that may also bring with it an assortment of space.
This method is becoming less these days although, thanks to the lack of space
available and the strong presence of methane and other landfill gases, both of
which can cause numerous contamination problems. Many areas are reconsidering
the use of landfills.
( C 2.2)Incineration/Combustion
Incineration or combustion is a type disposal method in which municipal solid
wastes are burned at high temperatures so as as to convert them into residue and
gaseous products. The biggest advantage of this type of method is that it can
reduce the volume of solid waste to 20 to 30 percent of the original volume,
decreases the space they take up and reduce the stress on landfills. This process is
also known as thermal treatment where solid waste materials are converted
by Incinerators into heat, gas, steam and ash. Incineration is something that is
very in countries where landfill space is no longer available, which includes Japan.
( C2.3)Recovery and Recycling
Resource recovery is the process of taking useful discarded items for a specific next
use. These discarded items are then processed to extract or recover materials and
resources or convert them to energy in the form of useable heat, electricity or fuel.
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Recycling is the process of converting waste products into new products to prevent
energy usage and consumption of fresh raw materials. Recycling is
the third component of Reduce, Reuse and Recycle waste hierarchy. The idea
behind recycling is to reduce energy usage, reduce volume of landfills, reduce air
and water pollution, reduce greenhouse gas emissions and preserve natural
resources for future use.
Assignments
1)Describe the hazards that are general common in workshops and laboratories
[8]
2)State the duties of both the employer and the employees in Safety regulation
Act(OSHA)
[8]
3) Suggest a chemical hygiene plan that a person dealing with chemicals has to
follow to attain a health learner
[6]
4)When would it be necessary to use hand gloves and respirator in an electronic
lab
[4]
5) What could be an easier way to dispose Iron chloride etching liquid in the lab
[4]
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Four classes of fire and the type of fire extinguishers used
Types of fires
Class A fires- caused by combustion of solid matter e.g. papers, wood,cloth.
Class B fires-caused by flammable liquids e.g. petrol, paints, thinners, acetylene
gas
Class C fires- caused by flammable gases e.g hydrogen, methane, butane, LPG gas
And also electrical equipment like transformer, computers
Class D fires –caused by flammable metals like magnesium, aluminum, or
potassium .
Fire Triangle
The fire triangle is important to understand how fires can be prevented.
Removal of any of the three ingredients of fire can extinguish the fire.
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The triangle shows three elements a fire needs to get it ignited: fuel, fire ( heat)
and Oxygen to support combustion. Hence water can be used to put off the heat
but can also be inadequate for certain fires.Combustion is a chemical reaction that
feeds fire more heat and allows it to continue. So the removal of oxygen can force
it to extinguish . That’s why Carbon dioxide is used to extinguish certain fires but
still it inadequate for class D fires.
Fuel can be removed by lowering the concentration of flammable substances ,
that’s why dry powder is used or sand to prevent the flammable material from
burning .
1) Water Fire extinguishers
It is used for Class A fires only and it assumed a RED Colour.
2) Foam extinguisher
It is used for class A and B fires and it has a Label color CREAM
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3) Dry Powder extinguisher
It is also called ‘ABC’ extinguisher because it tackles class A, B and C fires including
electrical fires and Class D fires.
Label colour is BLUE
4) Carbon dioxide extinguishers
It is predominantly used for electrical fire risks provided for in computer server
room. They can also put out Class B fires ( flammable liquids , paints and
petroleum)
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY ONE
TITLE: Comparing standard resistors with its actual value.
AUTHORS:
DATE:
OBJECTIVE: At end of an investigation the learner should be able to recognise a
colour coded resistor quickly
EQUIPMENT: Multimeter, or OHMETER
MATERIALS: Resistor values;10 different resistors
METHOD :
1)Contsruct a table of results in which for each resistor write down the colour
coding and its Reading.
2) For each resistor above record the measured value by using a multimeter.
TABLE OF RESULTS
Colour coding
Colour coding
1St
Band
3rd Band
2nd
Band
Standard
Value
Measured
Value
4thBand
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DISCUSSION:
1) Does the resistor values fall within the limits of its tolerance.?
2) Why are the standard resistors not exactly equal to the measured values?
3) Any discrepancy in the experiment ?why ,if there is one?
4) Write down the expected colour coding of the following resistors given in the
table?
Standard Value
Colour coding
1St Band
680
+/-
470
+/- 10%
330
+/- 20%
1.8k
+/-
820
+/- 2%
2nd Band
3rd Band
4thBand
5%
5%
CONCLUSION: what skills or technical habits do think you have gathered for yo
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY TWO
TITLE: Using a multimeter in measuring Amps, Volts and Ohms.
AUTHORS:
DATE:
OBJECTIVE:
1) Understand the layout of a breadboard by using a continuity tester
2) Demonstrate the use of a multimeter in measuring amps, volts and ohms
EQUIPMENT: Multimeter,
MATERIALS: Resistor values;12k, 47K 56K ,jumping wires
METHOD :
1) in groups look at the following diagram, It consists of a battery and three
resistors
2) Look on figure 1.2 and try to see how all the components are connected
3) Open branch 2 circuit between R1 and R2 and place the multimeter in the
current range
4) switch the power and read the current passing through
5) Measure the voltage drop across R2 and across R1
6) Open branch 1,and place Multimeter in between to measure current passing
through R3
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.DIAGRAM
Branch 2
SW
Branch
1
R1 =12K
R3 =56K
9V
R2 =47K
FIGURE 1.2
RESULTS
MEASURED CURRENTS
VOLTAGE
CALCULATED
RESISTANCE
Branch 1
R3 =
Branch 2
R2 =
Branch 2
R1 =
Determine error% in the resistance for R1 ,R2 and R3
( Std value –calculated value ) X 100%
CONCLUSION
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY THREE
TITLE:
AUTHORS:
TESTING CAPACITORS
functionality
Investigation of capacitor values and their
DATE:
OBJECTIVES: 1. Comparing the standard value and measured value to ascertain
whether its value falls within a reasonable tolerance range.
2. Testing the functionality of Capacitors
EQUIPMENT: Multimeter, or OHMETER
MATERIALS: 5 Different capacitors
TECHNICAL NOTES:
You can test a capacitor using the OHM range of the Multimeter,.First disconnect at
least one end of a capacitor from the circuit and discharge the capacitor. You do
this by touching it with a piece of conducting wire. Now place the leads of the
multimeter over the capacitor
A capacitor that’s working properly should register an infinitely high resistance
value. This means that the capacitor is not allowing current to pass, which is what
a capacitor is supposed to do. A zero resistance reading means the capacitor is
short circuiting and must be replaced because it is faulty.
A leaky capacitor will show a high resistance value, but not quite infinity. This may
mean the circuit will not work properly.
Sometimes a capacitor works for a while and then not at all, and then later it works
again. This can be because the voltage from the power supply is too high, or
outside the operating range of the capacitor..
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METHOD :
1) Place each capacitor onto the breadboard
2) Measure the its resistance with a multimeter and record the value of each
resistance
3) Place the capacitor into a slot on the multimeter marked capacitor then record
the value
TABLE OF RESULTS
Complete the table
No. Measured
Resistance on
Capacitor
Printed Readings of
Capacitor
Capacitor
Measurement
from Multimeter
Error
value
1
2
3
4
5
DISCUSSION:
1) Does the capacitors values fall within the limits of its tolerance.?
2) State any experimental errors or any precautional
Experiment
3) Was there any malfunctional capacitor?
measures taken during the
CONCLUSION:
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY FOUR( changed to NETWORKs internal Resistance)
TITLE:
TESTING CAPACITORS CONNECTED IN PARALLEL AND SERIES
AUTHORS:
DATE:
OBJECTIVES:
1. Comparing the standard value and measured value to ascertain whether its
value falls within a reasonable tolerance range.
2. Testing the functionality of Capacitors
EQUIPMENT: Multimeter
MATERIALS: 10 Different capacitors
TECHNICAL NOTES:
You can test a capacitor using the OHM range of the Multimeter,.First disconnect at
least one end of a capacitor from the circuit and discharge the capacitor. You do
this by touching it with a piece of conducting wire. Now place the leads of the
multimeter over the capacitor
A capacitor that’s working properly should register an infinitely high resistance
value. This means that the capacitor is not allowing current to pass, which is what
a capacitor is supposed to do. A zero resistance reading means the capacitor is
short circuiting and must be replaced because it is faulty.
A leaky capacitor will show a high resistance value, but not quite infinity. This may
mean the circuit will not work properly.
Sometimes a capacitor works for a while and then not at all, and then later it works
again. This can be because the voltage from the power supply is too high, or
outside the operating range of the capacitor.
METHOD :
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1) Place TWO similar capacitors in SERIES onto the breadboard
2) Measure their total capacitance with a multimeter and record the total value
3) Place TWO similar capacitors in PARALLEL onto breadboard
4) Measure their total capacitance with a multimeter and record the equivalent
Value.
TABLE OF RESULTS
Complete the table
No. Measured
Resistance on
Capacitor
C1
C2
C3
Printed Readings of
Capacitor
Capacitor
Measurement
from Multimeter
Error % value
C1
Total
Series
series parallel
C2
C3
Total
parallel
1
2
DISCUSSION:
1) Does the capacitors values fall within the limits of its tolerance.?
2) State any experimental errors or any precautional
experiment
3) Was there any malfunctional capacitor?
measures taken during the
CONCLUSION:
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Cite as:Mr E Makumbe, course materials for TEE 1102. Electrical Engineering Workshop NUST(ZW) Dept of Electronics
Engineering
NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY FIVE( changed to NETWORKS )
TITLE: Measurement of Capacitance
Investigation of capacitor values using its reactance
DATE:
OBJECTIVES: 1.To calculate the reactance of circuit using voltage divider rule
2. To calculate the capacitor value by using its reactance
EQUIPMENT: Multimeter, AC Power supply or Function generator
MATERIALS: Capacitor 33nF
THEORY: The value of capacitive reactance will continuing drop down with increase
in frequency . Knowing the frequency over which the reactance is being measured
can help us to get the capacitor value .
DIAGRAM:
Rs = 680Ω
Vs
f= 2kHz
.f= 4kHz
.f= 8kHz
.f= 10kHz
Vc
C = 33nF
Figure 5.1 RC circuit supplied by Function generator
METHOD:
1. Connect the circuit on breadboard as shown in Figure 5.1
2. Set function generator for sinusoidal waveform
3. Set first frequency output at 2kHz
4. Set the voltage from function generator at 9 rms value using a multimeter
5. Measure the supply voltage (Vs ) and Capacitor voltage (Vc ) by a multimeter
and record it in table
6. Repeat step 5 for frequencies of 4kHz,8kHz and 10kHz
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TABLE OF RESULTS:
Frequency
Capacitor
Voltage
Reactance
Calculated
Capacitance
F=2kHz
F=4kHz
F=8kHz
F=10kHz
DISCUSSION:
1.Calculate the reactance for the frequencies from 2kHz to 10kHz
What happen to reactance as frequency increases?
2. Determine the capacitor value by using voltage divider rule from the reactances
given in the Table. Is the capacitor values obtained more or less the same ?
CONCLUSION:
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Cite as:Mr E Makumbe, course materials for TEE 1102. Electrical Engineering Workshop NUST(ZW) Dept of Electronics
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY FIVE
TITLE : Examining the diode VI characteristics & diode testing
AUTHORS:
DATE:
Aim: To determine the varying nature of transfer resistance across a forward
biased and reverse biased diode in it VI characteristics
Objective:
1) Learning to test a diode
2) Learning to take the forward biased measurements across a diode
3) Learning to draw a graph of results from the table
PART 1. Diode Test
a) Diode testing Scale
The diode-testing scale of a DMM can be used to determine the operating condition
of a diode. With one polarity, the DMM should provide “offset voltage” of the diode,
while the reverse connection should result is an “OL” response to support the opencircuit approximation.
Using the connections shown in fig1.2, the constant-current source of about 2 mA
internal to the meter will forward bias the junction, and a voltage about 0.7 V
(700mV) will be obtained for silicon and 0.3 V (300mV) for germanium. If the leads
are reserved, an OL indication will be obtained
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Fig 1.2
If an OL indication is obtained in both direction, junction is open.
Perform the tests of table 1.1 for silicon and germanium diodes.N.B germainium
diodes are not available in our Lab so skip the test for GE
Table 1.1
TEST
SI
GE
FORWARD
REVERSE
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Part 2. Forward-bias Diode Characteristics
Material: diode 14N007, resistor = 1k ohms
Equipment : variable power supply, multimeterX2
Note:
In this part of the experiment we will obtain sufficient data to plot the forward-bias
characteristics of the silicon diode on fig.1.4 ( Graph paper)
METHOD: Part 2
a) Construct the network of fig.1.3a and Measure proper value of 1kΩ resistor.
b) Increase the supply voltage (Vs) until Vr reads 0.1V.
c) Then deduce VD by subtracting Vr from Vs and insert its voltage in Table1.3.
d) Calculate value of ID using the equation shown in Table 1.3 (Vr/R)
e) Repeat step (b),(c ) and (d) for values of Vr reading 0.2 upto 0.8
f) Plot the values of ID( Y axes) vs VD (X axes) on graph paper given below in
Fig 1.4
DIAGRAM
DMM Vr
1KΩ Resistor
DMM Vs
(Vs)
variable
power
supply
Forward
biased
Diode
Fig 1.3a Forward bised Diode
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METHOD : Part 3
a) Construct the network of fig 1.3b
b) Increase the supply voltage Vs from 0.9V up until 5V
c) For each step record the value of VD
d) Calculate the value of the corresponding volatage (Vr) using the equation
shown in Table 1.3 (Vs –VD)
e) Calculate ID = Vr/R mA
1KΩ Resistor
DMM Vd
Vs
Reverse
Biased
Diode
Vs
Variable
Power
supply
Fig 1.3b Reverse bised Diode
TABLE 1.3 a Forward biased diode
VD versus ID for silicon diode
Vr
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Vd=Vs-Vr
Id=Vr/R(mA)
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TABLE 1.3b
Vs
Reverse the diode
0.9
1
2
3
4
5
Vd
Vr=Vs -Vd
Id=Vr/R(mA)
Discussion: Part 2 what can you say about forward biased diode with regards to
theoretical 0.7V voltage drop .How far is it attained ?
Discussion: Part 3 Is there any leakage reverse currents?
Conclusion :
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Fig 1.4
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF TECHNOLOGY
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
LABORATORY SIX
Title: Wave shaping by Forward biased Diode one circuit
Objectives: 1) learning to use Function generator and Oscilloscope
2)learning how diodes can reshape the form of a waveform
Materials and Equipment:
IN4148A signal diodeX2; 1.2kΩ resistor as RS; 2.2kΩ resistor as RL1; 4k7Ω
resistor as RL2; Digital oscilloscope ; and Function Generator,3 pairs of long wires
Method:
In this experiment, you will be required to build and make some tests on a diodes
that are forward and reverse biased in one circuit. Carry out the following steps for
this experiment:
1. Construct the circuit shown in Fig 6
2. Set the function generator at VS = 8V peak value with 2kHz frequency triangular
waveform.
3. Work with one branch first and the other second(a) square (b) triangular (c)
Sinusoidal
4. Using a Digital oscilloscope, observe and sketch the input voltage and the output
voltage..
[6mks]
5. Calculate the peak current flowing through diode D1 and Diode D2
.
[4mks]
Diagram:
RS
VS
D1
D2
RL1
RL2
VOUT
Fig 6.0
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6. Change the waveform input function into square waveform and sinusoidal
7. Justify your results with theoretical explanation
[10mks]
Discussion: From dealing with the oscilloscope and function generator what
control knobs are you now familiar with. Discuss how they work.
35
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OFTECHNOLOGY
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
Laboratory Practical 7a
Title :Half wave
rectifier
circuit
Objective: To determine how close is a practical rectifier is real with theory.
Theory:
Equipment
Oscilloscope1/13 ;Multimeter and Function Generator,2X BNC Coaxial cables-Male(
50Ω RG58 20AWG ),3 pairs of long wires
Materials
IN4148 signal diode; 2x1 kΩ resistor, 2X 2.2 µF Capacitor, 470µF capacitor
Procedure:
Carry out the following steps for this experiment:
1.Construct the Half wave rectifier circuit shown in Fig 1. Without Capacitor
connected.
2.Instead of Transformer use a Function Generator and
(i) Set its frequency to 2kHz.
(ii)Set input voltage to be 8V pk-pk
(iii) Select sinusoidal wave,
(iv) Select zero attenuator,
(v) Set DC offset to zero.
(vi) Connect BNC male to 50Ω/p BNC Female.
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3.For the Oscilloscope
(i)Set oscilloscope to Time base of 0.1ms,or 50µs,
(ii) Set magnitude of 2/div for both Ch1
(iii) Connect input voltage to CH1 and measure across AB terminals Fig 1
(iv) Connect Output voltage to CH1 and measure across CD terminals Fig 1
Diagram
Figure 1
Results
For stage 1: Rectifier RL without the Capacitor C
1) Using an oscilloscope Measure the peak Input voltage and peak output voltage
from CRO
And calculate the difference in peak Voltages between the TWO.
Question :
What is the cause for the drop in peak voltage ?
2) Sketch a well labelled the input voltage and the output voltage onto scaled
graph
Discuss: From the practical standpoint why is the waveform not perfect as it is
theoretically understood to be.
Conclusion statement:
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NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRONIC ENGINEERING
TEE 1102 – ELECTRICAL WORKSHOP
Laboratory Practical 7b
Title: Half wave
rectifier
circuit with capacitor
Objective: To determine effect of ripple content after RL value is reduced
To determine effect of ripple content after the Capacitance is increased.
Theory: See Electronic notes below
Equipment
Oscilloscope1/13 ;Multimeter and Function Generator,2X BNC Coaxial cables-Male(
50Ω RG58 20AWG ),3 pairs of long wires
Materials
IN4148 signal diode; 2x1 kΩ resistor, 2X 2.2 µF Capacitor, 470µF capacitor
Procedure:
Carry out the following steps for this experiment:
8. Construct the Half wave rectifier circuit shown in Fig 1. Without Capacitor
connected.
9. Instead of Transformer use a Function Generator and
(i) Set its frequency to 2kHz.
(ii)Set input voltage to be 8V pk-pk
(iii) Select sinusoidal wave,
(iv) Select zero attenuator,
(v) Set DC offset to zero.
(vi) Connect BNC male to 50Ω/p BNC Female.
10.For the Oscilloscope
(i)Set oscilloscope to Time base of 0.1ms,or 50µs,
(ii) Set magnitude of 2/div for both Ch1
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(iii) Connect input voltage to CH1 and measure across AB terminals Fig 1
(iv) Connect Output voltage to CH1 and measure across CD terminals Fig 1
11.Using an oscilloscope, sketch a well labelled the input voltage and the output
voltage.
For stage 1: Rectifier RL without the Capacitor C
For Stage 2: Rectifier RL with Capacitor C =2.2µF connected Fig 2
For Stage 3: Rectifier with two RL connected in parallel to Capacitor C
For Stage 4: Rectifier with One RL connected in parallel to two Capacitors
For Stage 5: Rectifeir with One RL connected to C=470µF
12.For each stage above Measure the ripple using the Oscilloscope and Compare it
to the calculated ripple content.
13.Further Electronic Tests: You can use a multimeter (DMM) connected to the
output to measure Vdc( switch DMM on DC voltage scale) and Vripple in rms (
switch DMM on A.C.Votage scale)
DISCUSSION
What is the effect on the ripple content over
(i)
Reducing Load resistor RL
(ii)
Increasing Capacitor C
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Figure 1
ELECTRONIC NOTES
ON RIPPLE VOLTAGE
The capacitor charges and discharges during each half cycle peak .As the output
voltage drops the capacitor discharges through the load and so the ripple appears
on the top of the half wave rectified signal .
The size of the ripple voltage depends on the load resistance, RL ,the size of the
smoothing capacitor ,C and the peak value of the output voltage, VPK. Given by
VRipple = (VPK / RLC) x ∆𝑡
Where ∆𝑡 is time taken between successive peaks of the output waveform from the
rectifier circuit. This will be 20ms if an ac frequency of 50Hz is used ( T =1/f ).
N.B. This formula ia an approximation and assumes the ripple voltage is small. If
the ripple voltage exceeds 10% of DC voltage level ( average output of the have
wave rectifier ) this formula becomes increasingly inaccurate.
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