Discussion/Interpretation of results
For this experiment, the group will now be working with DC
power supply circuits. An example of such a circuit is a rectifier
where in the rectifier converts an AC voltage into a DC voltage.
This is where the diode clipper or limiter will be used. Also, the
group will also demonstrate the difference between a half-wave
and full-wave rectifier. Furthermore, the group shall also show
how a filter affects the output of the rectifier. The experiment is
divided into three parts. Part A is focused on the half-wave
rectifier while part B is for the full-wave bridge rectifier. And
finally, part C is for the filter.
So, for part A, the group connected the circuit using the given
diagram in the manual. The diodes were connected to a half-
wave rectifier. The circuit is comprised of one diode and one
resistor with an input peak to peak voltage of 10V and a
frequency of 1kHz. This resulted to an output voltage of 5V and
the frequency remained the same. The frequency did not change
since only a half-wave rectifier was used. These types of
rectifiers work by converting an AC sine wave into a pulsating
DC wave during the positive half-cycle of the input wave. That
is why the output waveform was cut in half since the rectifier
removed the AC input signal to make into a DC level.
Furthermore, an observation was made where in the direction of
the diode was reversed which resulted to the changing of the
positive half-wave into a negative half-wave.
Now for part B, the group connected the components into a full-
wave rectifier circuit. The components are made up of 4 diodes
serving as the rectifiers, a resistor, and a transformer. In this
case, the input peak to peak voltage is set to 20V with an input
frequency of 100 Hz. The resulting measurement of the primary
voltage shows that it is 20V and that the secondary voltage is
25.8V which means that the transformer used was step-down. A
notable change in the output of this part of the experiment is that
the output voltage was almost reduced in half while the
frequency was doubled. This is due to the fact that the rectifier
used was a full-wave bridge type. The output waveform shows
only a positive half-cycle. It looks like the negative part was
trimmed however, in actuality, the negative half-cycle was
instead converted into a positive half-cycle as well. This can be
attributed to the characteristic effect of a full-wave rectifier
where it converts both polarities of a waveform into pulsating
DC.
And for part C, the group will be observing a capacitor filter and
its effect on the output of a bridge rectifier circuit. In this set-up
the output waveform looks like a ripple since the filter reduced
the variation of the rectifier output signal. This ripple effect is
also caused by the continuous changing and discharging of the
capacitor filter in the circuit. Moreover, the relationship between
the resistance of the load and the voltage supplied was seen. The
resistance of the load decreases as the voltage supplied
decreases which shows a direct relationship between the two.
Lastly, when the frequency in this circuit is increased, there is an
observed increase in the overall output waveform on the display.
Conclusion
In this experiment, the main objective was to demonstrate the
operation of a half-wave rectifier, full-wave rectifier, a capacitor
filter, and the use of the Zener diode as a voltage regulator.
These objectives are broken down into three main parts:
The first part is showing the operation of a half-wave
rectifier in actual connections. As seen from the results, the
group was able to manifest the characteristics of a half-
wave rectifier such as the reduction of output voltage and
the same value for the frequency since it is only a half-
wave rectifier. Furthermore, the output wave showed that
the negative half-cycle was converted into positive which is
also a trait for half-wave rectifiers.
Next part is all about showing the operation of a full-wave
bridge rectifier using actual connections. Once again, the
group is able to achieve this objective. The full-wave
bridge rectifier’s effects were showcased by the reduction
of the voltage and the doubling of the frequency. In this
instance the negative half-cycle of the output waveform
looks like it was trimmed but it was instead converted into
a positive half-cycle which coincides with the effect of this
rectifier where the waveform is converted into a pulsating
DC no matter the polarity.
The last objective is all about the capacitor filter. In this
case, the group achieved the objective since they were able
to show the output waveform that made a ripple since the
filter reduced the variation of the rectifier output signal
effectively cleaning up the output.
And with the realization of all 3 sub-objectives, the group
was able to use the Zener diodes as voltage regulators while
showing the various operations of rectifiers and filters.
References:
https://en.wikipedia.org/wiki/Rectifier
https://en.wikipedia.org/wiki/Clipper_(electronics)
https://www.dummies.com/programming/electronics/diy-
projects/how-rectifier-circuits-work-in-electronics/
