"Is your Laboratory a TURN-OFF?"
Alun Evans, Timothy Davies & Stephen Wilks
Department of Electrical and Electronic Engineering,
University of Wales Swansea.
ABSTRACT
"Laboratory coursework is one of the highlights of your Degree Scheme of study": how often
have we seen this, or words to that effect, in the literature advertising or describing an
engineering degree course? This paradox has faced generations of students who have
discovered, too often, that laboratory experience is the least satisfactory aspect of reading
engineering. It is a regular comment from employers of engineering graduates that new
employees are deficient in basic laboratory skills, yet the problem persists and unquestionably
leaves serious expositors of the subject with a feeling that more should be done in this area.
Some three years ago the authors decided a serious effort was needed to address these issues
in our own Department. The vehicle chosen was the Level 1 Circuit Design Course. Our
paper will describe the strategy adopted to overcome the perceived weaknesses of our
previous Laboratory Course as measured by a quality audit of student reactions.
Three years of operating the new laboratory have been sufficiently encouraging to give the lie
to the question posed by the title of the paper.
INTRODUCTION
Laboratories distinguish vocational subjects from academic ones. Getting to grips with the
practicalities of an engineering discipline is conceded by most engineering students as the
motivating factor that attracted them to read the subject in the first place. Yet it is one of the
paradoxes of reading engineering that many students derive the least satisfaction and a sense
of achievement from the formal laboratory content, certainly in the early years. It is only
when they embark on their final year project that this satisfaction is rediscovered; but by that
time, of course, too many students have been "turned off" practical work altogether and are
careful to select projects with no practical content. Staff can aid and abet in this process by
offering fewer projects which include design and a practical build content. How often have we
seen projects that stop at simulation only? We firmly believe that departments must be alive
to the growing trend of steering away from design and practical content in formal laboratory
instruction. What we shall describe in this paper is our modest attempt to address some of
these often contentious issues.
BACKGROUND
Our previous Level 1 Electronics Laboratory was founded on a well established series of setpiece experiments designed by staff in support of their respective courses. A laboratory
structured this way may suffer from a number of technical and administrative failings:
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Experiments tend to be of variable quality in the challenges they pose and the
degree to which they successfully work.
The experiments were prepared by a variety of authors so it is unlikely that the
originator of an experiment is on hand to supervise his/her experiment all the
time.
Once in place, staff can be reluctant to review regularly and update an
experiment and going into the Laboratory becomes a chore rather than a
challenge. This indifference is sensed by postgraduate demonstrators and
undergraduates alike so that the whole atmosphere of the Laboratory suffers in
consequence.
There was never a guarantee that students had full covered the relevant
theoretical material from a lecture module before undertaking an experiment
because of lecture-module scheduling-constraints.
Having so many different experiments tended to proliferate the amount of
different equipment employed. Familiarity with equipment by demonstrating
post-graduates, in particular, is always problematic.
The Laboratory lacked a consistent design theme: yet this is a strong desire of
the Professional Institutions that Design is given greater prominence.
A NEW APPROACH
The old concept of a number of set-piece experiments prepared by individual staff members
where students, operating in pairs, are routed from one experiment to another in a series of
laboratory sessions has been abandoned. In its place is a goal-based approach where all
students participate in the "same experiment" week-in week-out at the same time working
toward a single target. This was done to change the atmosphere of the laboratory from the
often "let's get some quick results and get out" to a more participatory role. A greater
emphasis was placed on "Design" by revision of the Laboratory Title and a complete revision
of the Laboratory Handbook. A modern engineering course can reasonably be described as
having the minimum three essential elements;
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Theory & Design
Simulation
Practice
The colour coded Laboratory Handbook, in which these elements are central, sets out in an
uninhibited way to reflect this. The essential theory behind each experimental process is
given. The process is investigated through Simulation (first-half of a Laboratory Session)
followed by the "bread-boarding" of practical circuits on which measurements are made
(second-half of a Laboratory Session). Only then can conclusions be drawn- if an element is
missing then the results are of limited value. A block schematic of the Laboratory process is
shown in Fig.1.
The Laboratory Module begins with the simplest of concepts, maintaining a progressive
build-up with an end product in mind. The end product is a Waveform Generator built on a
printed circuit board with clearly defined objectives (i.e. meeting a specification). In short, the
Laboratory Module closely parallels the philosophy of the theoretical modules, which
traditionally start from the simplest of concepts to build up in depth and complexity. We are
of the opinion that so much of the disenchantment we detect is born of many seemingly
unrelated parts (the different experiments). A block schematic of the generator is shown in
Fig.2 followed by a schematic diagram in Fig.3 and Printed Circuit Layout in Fig.4.
It consists of three sections; a hysteresis switch, integrator and low-pass filter. The hysteresis
switch and integrator combine in a loop to form an oscillator, generating square and triangle
waveforms respectively. The low-pass filter lies outside the loop, depressing harmonics of the
triangle-wave and leaving, for practical purposes only a sine-wave. The build-up to an
understanding of the design and operation of this circuit is covered in a series of sessions of a
combined duration of thirty hours in total
• Session 1 Model characteristics of Resistors and Op-Amps.
• Session 2 Model characteristics of Capacitors and Inductors.
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Session 3 RC networks and the Op-Amp in the Time Domain
Session 4 RC networks and the Op-Amp in the Frequency Domain
Session 5 Applications of Diodes, Zener Diodes and Op-Amps.
Session 6 Building and Testing the Waveform Generator.
LABORATORY ADMINISTRATION
At the beginning of the Laboratory Assignment students are handed a laboratory pack
containing the following items
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Laboratory Handbook
Laboratory Diary Wizard
Viva-Voce Handbook
Quality Assessment Document
The Laboratory Handbook is colour coded into three sections; theory, simulation and practical
experiments. By combining all three elements in a single handbook the almost impossible task
of covering all relevant theory before an experiment takes place is circumvented and timetable
constraints are avoided.
The Laboratory is timetabled to run for the duration of five weeks towards the end of the
second term. An open-access policy has been adopted for five days a week with formal
supervision by staff and demonstrators on two afternoons. By running open-access, "catchup" time is available for students who have difficulty, for whatever reason, in completing the
work in the scheduled time. It also provides time for that rare enthusiast to explore outside the
confines of the module itself. Demonstrators are drawn from the postgraduate research school
and all go through a period of induction when they, themselves, complete the laboratory
assignment over a period of a week under staff supervision.
Students work in pairs and are required to alternate session-by-session who takes the lead in
simulation or build and test. An element of formal preparation outside scheduled laboratory
sessions has been introduced. Where a student fails to carry this out, he/she will be required to
leave the Laboratory until preparatory work is completed. This sanction is, reluctantly, felt
necessary because past experience suggests that lack of preparation lies at the heart of so
many of the deficiencies.
From the outset, we decided to make this a paperless laboratory by using the available
technology to record all results. This, in effect, meant keeping a diary on line and the diary
wizard is an aid to this process. It also has the indirect effect of adding format consistency to
results presentation with marking taking place along "wizard" guidelines.
The Viva-Voce Handbook forms part of a holiday assignment. It contains forty problems with
their solutions supporting the Laboratory module. Early in the third term students attend an
interview lasting half an hour with a member of staff when a series of ten questions based on
the Viva-Voce Handbook are asked to which verbal solutions are sought. This procedure is
intended to assess accuracy of the work undertaken and powers of verbal communication on a
one-to-basis. Marks are assigned to the answers and factored in with those from the
Laboratory Report Assessment, also drafted with the help of the Diary, during the course of
the holiday.
FEEDBACK
Assessing the quality of any new enterprise is now deemed essential. This requirement has
been addressed by providing a questionnaire which all participants are required to complete
anonymously. Fig. 5 shows the questionnaire used in this instance.
STUDENT REACTION
The reaction of the students to the New Laboratory Module has been very positive and
encouraging. Demonstrators, too, approach their work with renewed confidence and vigour.
Laboratory technician staff, as well, have played their part in what we modestly describe as a
genuine team effort. It has changed the atmosphere of the Laboratory and unquestionably
improved the work ethic. Observing what has happened some five minutes prior to laboratory
closure on an evening best captures this. Now the Laboratory is full, previously it would have
been comparatively empty. Students communicate with each other more, compare results and
on occasions help each other and work a great deal harder and with greater purpose than
hitherto. We are confident that we have struck the right note which has given us the
confidence to move forward on an upgrade path with the purchase of new instrumentation that
has a network capability so the testing of circuits and the capture of measurements and their
presentation is now entirely under keyboard control.
CONCLUSION
Modern Engineering, in its broadest context, is now built on the three pillars of Model
Theory, Simulation & Design and Practice. To count ourselves as modern and outward
looking we have aimed at embracing all three in an attempt to provide quality laboratory time
for our undergraduate students. What we have described is only a start, but an important one,
and the challenge that lies ahead is one of maintaining the impetus and bringing our newly
acquired experience to other laboratories as well.
Circuit made from
Ideal Circuit Elements
Physical Circuit made
from actual devices
Modelling
Measurements
Analysis
&
Simulation
Print Out
Agree?
Fig.1 Schematic of Laboratory Process
Vout
Low Pass
Integrator
Vin
Square
Filter (LPF)
Triangle
Sine
Fig.2 Block Schematic of Waveform Generator
+12V
R3
D1
1kΩ
D2
R10
3.9kΩ
ZD
D4
D3
8.2kΩ
Vsin
C3
10kΩ
8.2kΩ
10nF
Vtri
C1
R6
10kΩ
R5
R2
C2
1kΩ
-12V
R1
10nF
1kΩ
R11
R4
R8
R9
10kΩ
R7
10kΩ
10nF
10kΩ
Vsq
Fig.3 Schematic Diagram of Waveform Generator
Vtri
Fig.4 Printed - Circuit Layout of Waveform Generator
Introduction: This is your chance to provide us with vital feedback about the laboratory you
have just completed. We need this information to refine our procedures and improve the
content of the laboratory so that taking a few moments to complete the questionnaire will
benefit future students. Include any observations or comments you feel would be helpful in
allowing us to arrive at a thorough evaluation.
On a scale of 1 to 5 (1 lowest, 3 neutral or about right and 5 highest) tick one box only
against each question
Question
1
2
Score
3
4
(1) How well did the co-requisite modules
prepare you for the laboratory?
(2) Did you find the theoretical (white) section
of the handbook sufficiently comprehensive?
(3) Did you find the simulation (red) section
of the handbook clear?
(4) Did you find the practical (blue) section
of the handbook clear?
(5) How well did the simulation experiments
work?
(6) How well did the practical experiments work?
(7) How did you find the pace of the laboratory?
(8) How helpful was the demonstrator support?
(9) How challenging did you find the laboratory?
(10) Has the experience increased your interest
in practical work?
Comments: (over-page if necessary)
Fig.5 Quality Assessment of Level 1 Circuit Design (CD) Laboratory
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