School of Engineering & Technology
Introduction to Electronic Systems
4ENT1025 (HIBT) and 4ENT1028
Experimental Investigations
This booklet belongs to:
Semester A 2017/18
Contents page
SECTION A: ADVICE ON PROCEDURES AND PRACTICE 1
SECTION B: LABORATORY EXPERIMENT SHEETS
1. BASIC MEASUREMENTS 4
2. MESH ANALYSIS OF A RESISTIVE NETWORK 6
3. DIODE CHARACTERISTICS 8
4. NPN TRANSISTOR CHARACTERISTICS 10
Please read through this document as soon as you receive it.
Preparatory reading and self-study will be necessary before you attempt each
laboratory experiment.
The practical parts of each investigation are intended to be completed within a
timetabled two-hour period.
You MUST maintain a logbook which records all the work you undertake in the
laboratory, your logbook will be assessed.
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Advice on Procedures and Practice
1. Introduction
The experiments described in this booklet are intended to support material covered in your lectures
throughout semester A.
Each time you attend a laboratory session you must remember to bring this booklet and your
laboratory logbook with you. You will work in pairs whilst in the laboratory. A class list detailing you
laboratory and tutorial group will be published normally at the start of the course.
You are expected to spend time reading through and studying each lab-sheet and its associated
material before attending each laboratory session.
If it is not possible for you to complete an experiment in the time allocated, you should discuss this
with the lecturer before the end of the laboratory session.
2. Assessment
Assessment will be based on attendance and achievement. All your results and observations must
be recorded in a laboratory logbook along with any preparatory work done before each lab session.
You must ensure your log-book is signed by one of the supervising staff before you leave the
laboratory at the end of your timetabled session.
You will be assessed with referring to what is recorded in your log-book and a formal report that you
will be asked to write once you have completed all 4 experiments. More details of the assessments
for this module are given in the module guide, posted on StudyNet, along with this booklet.
3. Equipment
Each experiment will require the following items of general test equipment;
Breadboard,
Interconnecting leads,
Digital Multimeter (DMM),
Variable voltage DC supply.
Remember to connect up each circuit under investigation in a systematic manner by arranging all
the interconnecting wires as neatly as possible. Use a suitable colour code for all the main interconnections;
e.g. +5 volts = red, 0 volts (ground) = black.
4. Safety and Good Lab Practice
It is strongly advisable that before the beginning of any work in the Lab that you familiarise yourself
with the location of the circuit breaker and know how and what to do in case one of your colleagues
needs help.
Also familiarise yourself with posters and leaflets that are displayed in labs or notice boards in case
of help or Lab injuries.
In case of someone receiving an electric shock in the Lab try to immediately turn off the power without
coming into contact with the electrical power.
Take extra care when inserting or removing a plug. Never remove a plug by pulling on the cord.
Always keep power off when making connections or changing connections. Do not touch bare
wires or parts.
Use equipment with three -wire power cords and should be provided with a properly grounded case.
Section A IES 4ENT1025/28
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Never work when your skin is wet and remove all metallic objects such as rings, bracelets,
necklaces…etc. while working in the lab.
Always make sure to switch off and unplug all the equipment that you have used and dismantle your
setups at the end of each Lab work.
5. Your Laboratory Logbook
You MUST have a NEW logbook for this module.
Failure to use a logbook at all times will result in marking penalties. Pieces of scrap or loose-leaf
paper will not be accepted.
PRINT your name (in full), with your course code and module name on both the outside and inside
of your logbook.
Set up an INDEX on the first page, if one is not provided. ALL pages in your logbook will therefore
have to be numbered.
EVERY lab session that you attend must show logbook entries for the work done in that session.
This will form part of the assessment for this module.
For every NEW session, start a new page with your name, your partner’s name or group number, a
Title for the work and the date of the lab session.
Your log-book is not intended to be a ‘work of art’ but a record of what happened at the time, hence
do not cross out or obliterate mistakes as these are part of the learning process. A short note of what
went wrong or what worked well is all that is required.
Your logbook report/content must be written in the third person, past tense. It must contain the
following essential details;
date and title of the experiment
clear evidence of any preparatory work.
brief notes to explain any particular procedures or other details not explained, or
referred to on the lab-sheet.
tables of recorded results, including incorrect results (although do give the reasons
why certain of your results are incorrect!).
tables of calculated results along with sample calculations.
graphs, sketches of observed waveforms, etc. Remember to clearly label all axes and
show scales.
a brief conclusion and analysis of results.
You do not need to repeat information or instructions already given on the instruction sheet. Use the
page margin of your logbook to cross reference to the numbered sub-sections of the instruction
sheet.
If a lab session requires preliminary preparation before the session, this MUST be included in your
logbook entry section for that lab before going to the lab. This will be checked and assessed at the
start of the session.
Your logbook MUST be available at both the start AND the end of any lab session, for scrutiny by
academic staff if required. You must ensure your log-book is signed by one of the supervising staff
before you leave the laboratory at the end of your timetabled session.
TAKE PRIDE IN YOUR WORK AND IN THE PRESENTATION OF YOUR RESULTS.
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6. REPORT WRITING
When you are required to write a ‘formal report’ on one of your laboratory investigations, your report
must be prepared using the Arial 10 point font and must contain the following sections, in the
following order:
1: A title page which includes your student registration number.
2: An abstract
3: A contents page listing all the sections of your report with page numbers.
4: An introduction or overview to the topic. This will be PAGE ONE of your report.
5: A number of sections and subsections, which must all be correctly numbered and
should include:
a description of the preparatory work (i.e. before the lab),
results taken during the lab to verify your design,
your analysis (carried out during and after the lab), including any error
analysis.
6: Summary and Conclusions.
Did your circuits work as expected? If you obtained unexpected results,
why was this the case?
7: Appendices:
At least 2 specific references, which must be correctly referred to in your report.
A bibliography which lists all the books, magazines, journals, etc. you have
consulted whilst preparing for the laboratory investigation and report.
Here are some guidance points to help you prepare your report:
1. Your report must be written in the third person, past tense.
2. Whilst you may cross-reference your report to the original laboratory sheet, brief notes to explain any
particular procedures or other details not explained or referred to on the lab-sheet should be given.
3. Where appropriate tables of calculated results along with sample calculations must be given. Excel
can be used to make tabulated calculations if appropriate.
4. Tabulate your results legibly and note alongside each set of readings the expected accuracy of the
test equipment in use. Component tolerances and other possible sources or error must also be
included. This data will enable you to estimate the overall accuracy of your results.
5. Tables of recorded results may be presented using an Excel spreadsheet or the table function of
Word.
6. Do NOT hand draw your graphs if Excel can produce the graphical information you need. Remember
to clearly label all axes and show scales.
7. Do give a clear, concise set of conclusions with an analysis of results and errors.
8. Presentation is important. Aim to create a good impression with your reader. Type neatly without
using strange combinations of fonts or irrelevant clip art. Submit your printed work in a plastic folder
that keeps all the pages together whilst allowing the reader to easily view all your work. With on-line
submissions, check the PDF copy has compiled as you expect.
9. Leave yourself enough time to double-check for spelling mistakes, poor grammar, etc. Use the Word
spell and grammar checking tool!
10. Be professional in your style of presentation and in your approach to completing the assessment
requirements. Imagine you are going to show your work to a potential employer at a job interview.
11. Give yourself enough time to print the final copy; it always takes longer than you think!
12. Back your work up regularly – lost files due to a computer crash is not an acceptable excuse.
Section B IES 4ENT1025/28
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1. Basic Measurements
1. Objectives
To perform a series of simple measurements on a number of series and parallel resistive networks.
To provide confidence when using test equipment and breadboard as a circuit prototyping medium.
2. Equipment
A selection of resistors to include 2 at 220, 1 at 330 1 at 470
3. Preparation BEFORE the Lab
For each of the circuits illustrated (in Figs 1, 2 & 3) calculate in each case: the total single equivalent
resistance (RT), the total current drawn from the supply (IS) and the voltage drop across each
individual resistor.
Ensure that all your calculations are recorded in your log book and that it is signed-off by supervising
staff at the start of the lab.
4. Experiment Details: Series Circuits
1. Using a breadboard, construct the circuit shown in figure 1. Set the power supply to 20 V.
Figure 1
2. Using a Digital Multimeter (DMM) measure the voltages at the points VF1 and VF2 with respect
to the negative side of the power supply. Note that the earthing point shown in figure 1. It is
not needed in your built circuit as the power supply is already earthed. Carefully record each
of your results in your logbook.
3. Now measure the total current flowing through the series network by inserting a DMM, set to
an appropriate current range, into the network between resistors R1 and R2. Repeat your
measurement between R2 and R3. Carefully record each of your results in your logbook.
4. Using your results, calculate the actual resistor values for the three resistors of figure 1.
Compare and comment upon the differences between your calculated answers and the
nominal values of each resistor. Are your results as expected?
What is the percentage variation between your calculated and the nominal values?
What can you deduce from your results for the current flowing in the network?
5. Modify your circuit and add another 220Ω resistor, R4, in series with the three existing
components you have rearranged as shown in figure 2. Set the power supply to 10 V.
6. Using a DMM measure the voltages at the points VF1 and VF2 with respect to the negative
side of the power supply.
7. Using the voltage divider rule; calculate the voltage drops across R3 and R4, respectively.
Compare all your calculated results with those taken by measurement.
Are your results as expected?
Are the voltage drops across R3 and R4 identical? If not, why not?
Section B IES 4ENT1025/28
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Figure 2
5. Experiment Details: Parallel Circuits
1. Using your piece of breadboard, now construct the circuit shown in figure 3. DO NOT
CONNECT the power supply at this point.
Figure 3
2. Measure the total resistance of the network with a DMM set to the appropriate range and
connected across the points VF1 and VF2.
3. Next, connect up the power supply and use the DMM to measure the voltage between points
VF1 and VF2. Reconnect the DMM into the network to measure the total current (IS) drawn
from the supply and the currents flowing through R1 and R2, respectively.
4. Draw a circuit diagram of your network showing the actual resistor values by calculation and
all your measured currents and voltages. Compare your results with those obtained during
your preliminary calculations
5. Add a third resistor of your choice in parallel across R2 and repeat steps 1 – 4.
6. Sketch a circuit containing two series resistors connected to two parallel resistors. Now build
your circuit using a selection of resistors values already used in this experiment.
7. Repeat steps 1 – 4 for your series-parallel circuit.
6. Summary and Conclusions
Write a brief summary of all the work you have carried out during the laboratory investigation briefly
describing any problems or difficulties you had and how you overcame them.
Compare the relative accuracies of your measured results and theoretical analyses. Estimate the
percentage variations between your measured and calculated results in each case.
What was the easiest part of the experiment, and the most difficult, and why? What would you do
differently if you were to repeat this set of experiments?
Ensure that your log book is signed off by a member of staff before you leave the laboratory.
7. References
ELECTRONICS – a systems approach by Storey, Neil; 4th edition, published by Prentice Hall,
2009; ISBN: 9780273719182; Chapters 1, 2. (You may use 5th edition.)
R3 220 ohms
R1 330 ohms R2 470 ohms
Vsupply 10 V
VF1
VF2
R4 220 ohms
R1 1.2k
Vsupply 20 V
VF1
R2 3.3k
VF2
Section B IES 4ENT1025/28
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2. Mesh Analysis of a Resistive Network
1. Objectives
To perform a mesh analysis on a resistive network containing DC sources. To compare the results
of this analysis with measurements made on a corresponding practical network. The following
aspects of analogue engineering are applied:
application of resistor colour code
recognition of the possible errors in nominal resistor values
manual application of a formal network analysis method
use of breadboard as a circuit prototyping medium
use of twin DC power supplies
use of a digital multimeter (DMM) to measure direct current and voltage
2. Equipment
A selection of resistors to include 10k, 3.9k and 1k. Digital multimeter and DC power supplies.
3. Introduction
All theory and experimental work will be based on the DC resistive network shown in figure 1 below:
Ra = 10 k
8 V Rb = 1 k
Rc = 3k9
5 V
Figure 1.
4. Preparation BEFORE the Lab
Ensure that all your calculations are recorded in your log book and that it is signed-off by supervising
staff at the start of the lab.
Carry out a mesh analysis of the circuit shown in figure 1 and hence derive theoretical values for
the two mesh (or loop) currents shown. Also calculate the voltage (or potential difference) between
point X and ground.
All stages of your analysis must be shown in your log book and all calculated parameters illustrated
clearly on a circuit diagram.
X
I1 I2
Section B IES 4ENT1025/28
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5. Experiment Details
1 Select Ra, Rb and Rc from the resistors provided and connect up the network shown in figure
1 using the breadboard.
DO NOT CONNECT ANY POWER SUPPLIES YET!!!
What are the colour codes for 1 kΩ, 3.9 kΩ and 10 kΩ resistors?
2 Adjust one variable DC power supply to give 5 V and another to give 8 V as indicated by a
DMM.
Once adjusted to the required levels, SWITCH OFF the power supplies and connect them to
the appropriate points in the network.
Why adjust the power supplies before connecting them?
Why switch off before connecting power supplies?
3 Adjust each DMM to measure direct current of the order calculated in your preparation for I1
and I2 then connect the DMM’s in series with Ra and Rc.
Ensure all connections are correct and double check that appropriate current ranges have
been selected on the DMM’s – then and only then switch on, measure and record the values
of the two mesh currents, I1 and I2.
Compare the magnitudes and directions of the current flow with the answers from the mesh
analysis you did as preparation before you started the lab (section 2.4).
4 Switch off, remove the DMM’s and re-connect your network.
Now use a DMM to measure and note the magnitudes and polarities of all potential differences
in the network.
Calculate the ACTUAL values of Ra, Rb and Rc in your network.
Are they exactly as you were led to believe by the colour codes? If not, why not?
5 Draw a circuit diagram of your network showing the actual resistor values and all measured
currents and voltages.
Compare this with the predictions obtained during your preliminary calculations.
6. Summary and Conclusions
Write a brief summary of the work you have carried out during the laboratory investigation briefly
describing any problems or difficulties you had and how you overcame them.
Finally, conclude your logbook notes for this experiment by commenting on the following points;
1. Compare the relative accuracies of your measured results and theoretical analyses.
2. Summarise the actual resistor values in your network, evaluate the % deviation from
the colour-coded value and comment on whether they are within the tolerance
specified.
Ensure that your log book is signed off by a member of staff before you leave the laboratory.
7. References
ELECTRONICS – a systems approach by Storey, Neil; 4th edition, published by Prentice Hall, 2009;
ISBN: 9780273719182; Chapters 2, 3. (You may use 5th edition.)
Electrical and Electronic Technology by Edward Hughes, 10th edition, published by Prentice Hall,
2008; ISBN: 978-0-13-206011-0; Chapters 3 and 4.
Section B IES 4ENT1025/28
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3. Diode Characteristics
1. Objectives:
To plot the forward and reverse characteristics of two types of semiconductor diode: a basic silicon
diode and a silicon zener diode.
2. Equipment required.
2 Digital multimeters. 1 Variable DC power supply, 0-25 V.
1 220 ±5% resistor, 0.25 W. 1 1.2 k ±5% resistor, 1 watt or more.
1 Board with mounted silicon diode 1N4148 or equivalent.
1 Silicon Zener diode, 10 volt, 400 mW (BXY88C10V or equivalent).
3. Procedure: Diode forward bias characteristics.
The circuit shown in Fig 1 forward biases the diode under test.
1. Connect the circuit as shown in Fig 1 taking care to check the connections as incorrect
connections may destroy the diode under test or may blow the fuse in the ammeter.
Ensure that meter M1 is set to CURRENT and M2 to VOLTAGE.
First, use the Silicon diode of the diode board.
NOTE: the currents given below are typical values but will vary dependent upon the
diode you are using.
– +
Variable
P.S.U.
0 – 25 V
1.2 k
Diode
under test
Anode
Cathode
R1
VF
R2
220R V
+
–
M2
A
+ –
M1
IF
Figure 1
2. Adjust the PSU output voltage until the forward current IF is 0.5 mA, measure and record the
forward voltage VF.
3. Increase the PSU output voltage gradually until VF has increased by 25 mV.
4. Measure and record IF. Keep increasing the PSU output so that VF increases by 25 mV steps,
recording IF and VF for each step. Continue until IF reaches about 20 mA.
5. Plot a graph of IF versus VF using suitable linear scales for both axes. Additional readings
may be plotted where appropriate.
You should plot all the graphs during the laboratory session and get them checked by the
lecturer supervising the laboratory before leaving.
6. Now repeat the procedure to plot the forward characteristics for the zener diode (you only need
to plot a few points for the forward characteristic of the zener diode because it is the reverse
characteristic which is important).
Section B IES 4ENT1025/28
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4. Procedure: Diode reverse bias characteristics.
1. Change the circuit to that shown in Fig 2. (R2 is removed, the PSU (+) and (-) terminals are
reversed and the position of the voltmeter is changed).
Figure 2
2. By adjusting the PSU output voltage, set the reverse voltage VR to 0 volts, then 1 volt, then 5
volts, for each value of VR, measure and record the reverse current IR.
3. Now adjust the reverse voltage VR up to 25 V in approximately 5 V intervals. Measure and
record IR for each value of VR. Note that the meters will register negative values.
4. Plot the reverse characteristics of the silicon diode on the same graph as the forward
characteristics but in the third quadrant using the negative voltage and current axes. Use
suitable linear scales which will be different from those used for the forward characteristics.
Don’t be surprised if the reverse current of the silicon diode is too small to measure.
5. Finally, repeat steps 1 – 4 using a zener in the circuit of figure 2. Vary the PSU output voltage
from 0 to 20 V in 1 V steps measuring and recording VR and IR at each step.
The reverse characteristic of the zener diode is important so take about 5 more measurements
around the “knee” of the reverse characteristic to obtain a good range of values of IR up to
about 20 mA.
5. Summary and Conclusions
Write a brief summary of the work you have carried out during the laboratory investigation briefly
describing any problems or difficulties you had and how you overcame them.
What were the easiest and most difficult parts of the investigation?
What would you do differently if you were to repeat the experiment?
Compare and contrast all the results you have obtained for the different diode types.
Ensure that your log book is signed off by a member of staff before you leave the laboratory.
6. References
ELECTRONICS – a systems approach by Storey, Neil; 4th edition, published by Prentice Hall, 2009;
ISBN: 9780273719182; Chapter 16. (You may use 5th edition.)
Electrical and Electronic Technology by Edward Hughes, 10th edition, published by Prentice Hall,
2008; ISBN: 978-0-13-206011-0; Chapter 19.
+ –
V
A
Variable
P.S.U.
0 – 25 V
1.2 k
Diode
under test
+
–
+ –
Anode
Cathode
R1
V M2 R
M1
IR
Section B IES 4ENT1025/28
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4. NPN transistor characteristics
1. Objective:
To investigate the d.c. characteristics of an NPN Bipolar Junction Transistor (BJT).
2. Equipment required.
2 Digital multimeters. 2 Variable DC power supply units,
1 220 k ±5% resistor, 0.25 W.
1 Mounted NPN transistor such as BFY 50 or 2N3053.
3. BJT input characteristic
1. Connect the circuit as shown in Fig 1, taking care to check the connections as incorrect
connections may destroy the transistor under test.
2. Measure VBE at IB = 10 A and at IB = 100 A.
3. Calculate the amount by which VBE increases for a factor of 10 increase in IB and state
whether these results are consistent with the base-emitter junction being a forward biased
silicon PN junction diode.
Figure 1, measuring the input characteristic.
4. BJT transfer characteristic
1. Connect the circuit as shown in Fig 2, taking care to check the connections as incorrect
connections may destroy the transistor under test. PSU2 should be a Farnell type L30 as the
output of this type can be varied smoothly right down to 0 V.
2. Set VCE (PSU2) to 5V using the meter built into PSU2.
3. Adjust PSU1 to give a base current Ib of approximately 10 A.
4. Measure & record the actual base current Ib and the corresponding collector current Ic.
5. Increase Ib in steps of approximately 10 A up to 50 A, measuring and recording Ib and Ic at
each point.
6. Plot a graph of Ic versus Ib and find the current gain hFE at each point. Is hFE independent of
Ic? At higher values of Ic, does Ic increase gradually with time? Why might this be? What
happens if you hold transistor, Q1 between your finger and thumb?
Section B IES 4ENT1025/28
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Figure 2, measuring the transfer characteristic.
5. BJT output characteristic
1. Set Ib to approximately 25 A then remove DMM1, connect R1 directly to PSU1 and leave
PSU1 output constant. Select d.c. voltage on DMM1 and connect it in parallel with the output
of PSU2 as shown in Fig 2.
2. Using DMM1 to measure VCE, set VCE to 10 V, measure and record Ic. Reduce VCE in steps
of 2 V down to 2 V, measuring and recording IC at each point. Make further measurements of
IC at VCE = 1 v and at several values of VCE between 0 and 1 V.
3. Plot a graph of IC versus VCE, labelling the saturation region. If the collector current at VCE
= 5 V is X mA, draw dotted lines on your graph showing what characteristic you would obtain
if Q1 were replaced with:
(a) a perfect X mA constant current source. (b) A resistor equal to 5/X k.
For the range of VCE between 1 and 10 v, is the output characteristic closer to (a) or (b)?
Figure 3, measuring the output characteristic.
6. Summary and Conclusions
Write a brief summary of the work you have carried out during the investigation briefly describing any
problems or difficulties you had and how you overcame them. Finally comment on the significance
of all the results you have obtained.
Ensure that your log book is signed off by a member of staff before you leave the laboratory.
7. References
ELECTRONICS – a systems approach by Storey, Neil; 4th edition, published by Prentice Hall, 2009;
ISBN: 9780273719182; Chapter 3. (You may use 5th edition.)
Electrical and Electronic Technology by Edward Hughes, 10th edition, published by Prentice Hall,
2008; ISBN: 978-0-13-206011-0; Chapter 21.
