Reviewer in EST LEC AND LAB:

Digital electronics is a field of electronics involving the study of digital signals and the
engineering of devices that use or produce them. Digital electronics is the study of electronic
circuits that are used to process and control digital signals. In contrast to analog electronics,
where information is represented by a continuously varying voltage, digital signals are
represented by two discrete voltages or logic levels.
Example of Digital Electronics Computers understand only two numbers, 0 and 1, and do all
their arithmetic operations in this binary mode. Many electrical and electronic devices have two
states: they are either off or on. A light switch is a familiar example, as are vacuum tubes and
transistors.
Logic gate is a device that acts as a building block for digital circuits. They perform basic logical
functions that are fundamental to digital circuits. Most electronic devices we use today will
have some form of logic gates in them.

Logic gates are used to carry out logical operations on single or multiple binary inputs and give
one binary output. In simple terms, logic gates are the electronic
There are seven basic logic gates: AND, OR, XOR, NOT, NAND, NOR, and XNOR.
The AND gate is so named because, if 0 is called “false” and 1 is called “true,” the gate acts in
the same way as the logical “and” operator.

The OR gate gets its name from the fact that it behaves after the fashion of the logical inclusive
“or.” The output is “true” if either or both of the inputs are “true.” If both inputs are “false,”
then the output is “false.” In other words, for the output to be 1, at least input one OR two
must be 1.
The XOR ( exclusive-OR ) gate acts in the same way as the logical “either/or.” The output is
“true” if either, but not both, of the inputs are “true.” The output is “false” if both inputs are
“false” or if both inputs are “true.” Another way of looking at this circuit is to observe that the
output is 1 if the inputs are different, but 0 if the inputs are the same.

Logical inverter, sometimes called a NOT gate to differentiate it from other types of electronic
inverter devices, has only one input. It reverses the logic state. If the input is 1, then the output
is 0. If the input is 0, then the output is 1.

The NAND gate operates as an AND gate followed by a NOT gate. It acts in the manner of the
logical operation “and” followed by negation. The output is “false” if both inputs are “true.”
Otherwise, the output is “true.”
The NOR gate is a combination OR gate followed by an inverter. Its output is “true” if both
inputs are “false.” Otherwise, the output is “false.”

The XNOR (exclusive-NOR) gate is a combination XOR gate followed by an inverter. Its output is
“true” if the inputs are the same, and “false” if the inputs are different.

A circuit component which can deliver power or power gain in an electric circuit for infinite
duration of time is known as active component. A circuit element which only absorbs the power
and convert it in heat or stores in electric field or magnetic field is known as passive
component.
Active Components:
Those devices or components which require an external source to operate in a circuit are called
Active Components.
For Example: Diode, Transistor, SCR etc…
Explanation: As we know that Diode is an active component. Therefore, it requires an external
source to work and operate in a circuit.

Passive Components:
Those devices or components which do not require an external source to operate in a circuit
are called Passive Components.
For Example: Resistor, Capacitor, Inductor etc…

Explanation: Passive Components (such as resistors. Capacitors, inductors etc.) do not require
an external source to their operation.
Resistor (R or Ω)
Resistor is an electrical component that limits or regulates the flow of electrical current in an
electronic circuit. Resistors can also be used to provide a specific voltage for an active device
such as a transistor.
Capacitor
Capacitor, device for storing electrical energy, consisting of two conductors in close proximity
and insulated from each other. A simple example of such a storage device is the parallel-plate
capacitor.
The capacitance C of a capacitor is defined as the ratio of the maximum charge Q that can be
stored in a capacitor to the applied voltage V across its plates. In other words, capacitance is
the largest amount of charge per volt that can be stored on the device: C = Q V . C = Q V .

The capacitors are classified into two types according to polarization:

A polarized capacitor is an important electronic circuit component and is often termed an
electrolytic capacitor. These capacitors are used to achieve high capacitive density.
Unpolarized capacitors are preferred over polarized capacitors because it doesn’t get
destroyed by reverse voltage and can be used in pure AC circuits. They also find applications in
DC circuits as they don’t have positive and negative ends. The frequency of the unpolarized
capacitor is high, and the leakage current is low. After understanding the classification of
capacitors, let us learn about capacitor types.
Types of Capacitor

A ceramic capacitor is considered to be one of the most commonly used capacitors. The
material used in this capacitor type is dielectric. Also, ceramic capacitors are non-polar devices
which means that they can be used in any direction in the circuit.
Film capacitors are also known as a polymer film, plastic film, or film dielectric. The advantage
of film capacitors is that they are inexpensive and come with limitless shelf life. The film
capacitor uses a thin dielectric material with the other side of the capacitor metalized.
Depending on the application, the film capacitor is rolled into thin films. The general voltage
range of these capacitors is from 50 V to 2 kV.

Power Film Capacitors

Construction techniques and materials that are used in power film capacitors are similar to that
of ordinary film capacitors. Polypropylene film is used as a dielectric in a capacitor.
Electrolytic Capacitors

In an electrolytic capacitor metallic anode coated with an oxidized layer used as a dielectric.
These capacitors are polarized. Electrolytic capacitors are categorized based on their dielectric.
Paper capacitor is also known as a fixed capacitor in which paper is used as the dielectric
material. The amount of electric charge stored by the paper capacitor is fixed. It consists of two
metallic plates, and paper, which is used as a dielectric material, is placed between these
plates.
Transistor
Transistor is a miniature semiconductor that regulates or controls current or voltage flow in
addition amplifying and generating these electrical signals and acting as a switch/gate for them.
Word transistor is a combination of transfer and resistance. This is because it transfers the
resistance from one end of the device to the other end or we can say, transfer of resistance.
There are numerous differences between NPN and PNP transistors, even though both are
bipolar junction transistors. There are applications which make use of transistors as a device-
switch and amplifier. In a PNP transistor, the majority charge carriers are holes while in NPN,
the majority charge carriers are electrons. PNP switches ON by a low signal whereas NPN
switches ON by a high signal. In PNP transistors, the P represents the polarity of the emitter
terminal and N represents the polarity of the base terminal.

EST LABORATORY
Oscilloscope is a laboratory instrument commonly used to display and analyze the waveform of
electronic signals. In effect, the device draws a graph of the instantaneous signal voltage as a
function of time.

Oscilloscopes (or scopes) test and display voltage signals as waveforms, visual representations
of the variation of voltage over time. The signals are plotted on a graph, which shows how the
signal changes. The vertical (Y) access represents the voltage measurement and the horizontal
(X) axis represents time.
Coupling refers to the method used to connect an electrical signal from one circuit to another.
In this case, the input coupling is the connection from your test circuit to the oscilloscope. The
coupling can be set to DC, AC, or ground. DC coupling shows all of an input signal. AC coupling
blocks the DC component of a signal so that you see the waveform centered around zero volts.
“Success is no accident. It is hard work, perseverance, learning,
studying, sacrifice and most of all, love of what you are doing or
learning to do.”

― Pelé, Brazillian pro footballer

☺ Good Luck Future Engineer’s Padayon ☺