EEN1016 Electronics I - Faculty of Engineering - Multimedia University

EEN1016 Electronics I: Appendices
Another wave shaping circuit, as shown in Figure 8, is the clamping circuit. The
capacitor is fully charged to the peak voltage of the AC source when the diode is forwardbiased.
(For simplicity, we have assumed the forward voltage drop of the diode is negligible.)
As the diode acts like a switch that is turned on, the output voltage taken across the diode is
zero when the AC waveform is at its peak. As soon as the AC voltage falls below the peak
value, the diode becomes reverse-biased by the voltage sum of the transformer and the
capacitor which is a negative value. The resulting waveform is an AC waveform that is
“clamped” down below zero volt. If the 0.6 V forward voltage drop of the diode is
considered, the capacitor is charge to (V m – 0.6) V and the average value of V o is – (V m – 0.6
) V. The V o peak voltage is 0.6 V above zero volt.
C
+
V m
V S
V S
~
V o
-Vm + 0.6
ωt
-
V o
Instructions
Figure 8
The lab is divided into two parts: Part A Theoretical Prediction and Part B Experiment.
Read through both parts carefully, attempt and prepared for all the questions in both parts.
Students must complete the theoretical predictions before attending the corresponding lab
session. During the processes of theoretical predictions, students should attempt to
understand the purposes of the experiments. The Short Report Form for Part A has to be
submitted to the Lab’s technician at least two days before the scheduled lab session. The
instructor will check your predictions and then return it back to you during your lab session.
Use the predicted results to verify your measured data. Students are required to submit the
Short Report Form for Part B, attached with Short Report Form for Part A
immediately after the lab session.
Cautions
Oscilloscope: Make sure the INTENSITY of the displayed waveforms is not too high,
which can burn the screen material of the oscilloscope.
Function generator: Never short-circuit the output (the clip with red sleeve), which may
burn the output stage of the function generator.
Sketching oscilloscope waveforms on graph papers
Refer to Appendix D for efficient waveform sketching.
Factors affecting your experiment progress
Your preparation before coming to the lab (your understanding on the theories, the
procedures and the information in the appendices; your planning to carry out the
experiments and to take data), attempt all questions before the lab.
Your understanding on the functions and the operations of the equipment (Your learning
on using the equipment during the Induction Program Lab Session; your understanding on
checking and presetting the equipment)
The technique you use to sketch waveforms on graph papers
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