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Electrical Engineering
and Telecommunication
ELEC3106
Electronics
Objective
The objective of this laboratory task is to give the students experience with a small open-ended
design problem in which they can benefit from the knowledge gained throughout the course.
Components
For this laboratory exercise, you will need
2 Probes
1 Bread-board
LEDs
Logic gates
Resistors
Capacitors
Transistors
Other components
Wires
Lab-book
Components available from the school workshop (or equivalent substitutions) may be used in
this design project. Use of other components require the permission from the course coordinator.
Requirements
In this laboratory exercise, you need to, in pairs of two students, design and characterise a metal
proximity detector which makes use of an air coil as a sensor. For example: the specific coil
showed in Figure 1(a), which has a diameter of about 5cm, has an inductance of 5µH; when a
sheet of metal is placed just next to this coil (parallel to the coil plane), the coil inductance drops
to 3.5µH.
The designed metal proximity detector must be able to detect a 5cm× 5cm metal sheet held
next to (but not touching) the sensor coil and indicate to a user – for instance by means of an
LED – the presence of the metal sheet. The metal priximity detector may make use of laboratory
signal generators and power supplies.
Other than these, there are no requirements to the design – but you may want to consider
how to exceed the basic requirements by for instance 1) using a 3 V power supply as the only
laboratory equipment emulating battery operation 2) measuring and displaying the distance to
the metal sheet with 2 or more bits resolution or 3) making a very sensitive detector that can
detect a “small” piece of metal or a metal sheet “far away”.
TL/lab-project-23/February 9, 2023
ELEC3106/lab-project-23 p. 1/3
Pre-lab work
It is essential that you do your circuit designs before each laboratory class, complete with initial
component values: there will only be enough time during the class to measure, optimise and
debug your circuit, not designing it. Use your lab time wisely and start design early. It is
probably a good idea to also assemble the circuit on your bread-board before the class. You will
likely need to do some experimentation in the lab to implement a good solution or try out ideas,
so be prepared for that. Think about the requirements. How do you sense the coil inductance?
How do you make the sensed signal into a form that you can further work with? How do you
drive your proximity indicator?
Measurements
In your laboratory session, carry out the measurements in this section in pairs of two students to
characterise your circuit. Make sure that you show your result to the laboratory demonstrator,
and that both of you record everything neatly in your lab-book. In your last design laboratory
class (week 10), you must demonstrate your design to your laboratory demonstrator. Your test
set-up should look somewhat like what is shown in the figure below:
(a)
function
generator
power
supply
metal
detector internal nodes
for observation
probe
display
detector
coil
metal
sheet
(b)
Figure 1: Air coil (a). Metal proximity detector measurement set-up (b).
Characterisation
To verify that your circuit meets the specified requirements, your circuit characterisation need
to include the measurements that answers the following questions: What is the circuit power
consumption? What is longest distance D (see Figure 1(b)) between coil and metal sheet you
can reliably detect? How many different distance (D) can you reliably detect? What is the range
of input supply voltages over which the circuit operates? You must capture CRO waveforms of
voltages on suitable nodes in your circuit that demonstrate the circuit operation. It is up to you to
identify which voltages waveforms on which nodes to capture to best demonstrate your design.
You may want to do further characterisation, making sure that you collect suitable evidence of
your characterisation.
ELEC3106/lab-project-23 p. 2/3
Report
A short report (5 pages max) on the laboratory exercise must be prepared and uploaded as a
.pdf-file on the course Moodle site by Monday week 11. The report should include answers
to all questions asked above, and brief comments on the results. It should also include a brief
explanation of your circuit design and reasoning for choice of component values. Make sure you
point out any clever designs ideas you have employed. The full schematic of your circuit must
be included in the report, not counting towards the page limit. Submit one report per two-student
group and make sure that both student’s names and student ID appear clearly on the report.