Principles &
Applications of
Electronic
Year 13
Devices & Fahim
Mohammed
Circuits
Electronics and electronic devices are used in a huge variety of
manufactured products. From everyday popular items such as
cameras and thermometers to the robotic welding machines
used in industry, the use of electronics is continually growing.
Year 13
, Unit 35 Construction and Operation of Analogue Circuits Assignment 1
In this first assignment of this unit I will explain the purpose of two different types of diode,
each in a different electronic circuit application; as well as describe the operation of two
different types of transistor, one in an analogue & one in a digital circuit. Additionally, I will
build and test two different types of analogue circuit using
Operational amplifiers, & of course modify an existing analogue circuit to achieve a given
revised specification by selecting and changing the value of one of the components.
Firstly, a diode is an electronic device containing two components which are known as
cathode (negative end) & anode (positive end). Subsequently, the electrons within a diode
can flow in only one direction for example from cathode to anode; the diode offers the one-
sided conduction that is necessary for rectification.
Half Wave Rectifier
With the half wave rectifier, we can see from the diagrams below that the single rectifier
diode is positioned in series with the load across an AC supply; it translates the alternating
voltage into a single direction voltage using one half cycle of the applied voltage. Now, the
other half cycle being withheld as it conducts in one direction, except if there is an
inductance or battery in the circuit, then the current will be nil, thus, for half the time.
The half-wave
rectifier circuit uses
a semiconductor
diode with a load
resistance. The
diode is linked in
series with a
secondary signal
generator (or a
transformer) & the load resistance. Also, the primary of the transformer is connected to the
ac supply mains.
The AC voltage across the secondary fluctuates polarities after every half cycle of input
wave. During the positive half-cycles of the input AC voltage e.g. when upper end of the
secondary meandering is positive, its lower end, the diode is forward biased & conducts
current. If the forward resistance of the diode is predicted to be nil, the input voltage during
the positive half-cycles is directly applied to the load resistance making its upper end
positive. Additionally, the waveforms of the output current & output voltage are of the same
form as the input AC voltage.
Throughout the
negative half
cycles of the AC
voltage, the
lower end of
the secondary
winding is
positive &
upper end; the
diode is reverse biased therefore it doesn’t conduct. As a result, during the negative half
cycles of the input AC voltage, the current through & voltage across the load remains nil. The
P1 Fahim Mohammed