Shree P M Patel College, Electronics Devices I: Components Details

This assignment from Shree P M Patel College of Electronics and Communication, S.Y.B.Sc. Semester III, US03CELE21, delves into the fundamentals of electronic devices, specifically focusing on electronic components. It begins with an introduction to electronic components, categorizing them into active and passive types, and presents a block diagram. The assignment then provides a detailed exploration of resistors, including fixed and variable types, their construction (carbon composition, wire-wound, thin film, and thick film), and color coding. Following this, the document transitions to capacitors, explaining their function, units, and working principles. Different types of capacitors are discussed, including ceramic and film capacitors. The assignment offers a comprehensive overview of these crucial electronic components, essential for understanding and designing electronic circuits. This document is designed to aid students in their electronics studies, and is available on Desklib, a platform providing past papers and solved assignments.

Shree P M Patel College of Electronics and Communication, Anand
S.Y.B.Sc. Semester –III
US03CELE21 Electronics Devices – I
Unit – 1 Electronic Components
• Introduction
An electronic component may appear quite complicated and may be
capable of performing fantastic function. All electronic circuits, however
complicated contain a few basic components.
Generally speaking, there are basic five electronic components
which are used in mostly all electronic circuits. This component are of the
order of two different types either active component or passive
components.
Active components are the elements or devices which are capable of
providing or delivers energy to the circuit.
Passive components are the devices which do not require any
external source for the operation and are capable of storing energy in the
form of voltage or current in the circuit.
• Block diagram of electric components

• Difference between active and passive components
• Resistor
Resistors are components used to resist the flow of electric current
and have a stated value of Resistance. Many types of resistors are used
having different uses and construction. The most common types
have a fixed value of resistance so are often called fixed resistors. They
are shown on circuit schematic diagrams
The unit of resistor is ohm (ᾨ). The resistor are made in many forms
either fixed or variable resistor.
The two main characteristics of a resistor are its resistance, R, in
ohms and its power rating, P, in Watts. The resistance, R, provides the
required reduction in current or the desired drop in voltage.

The wattage rating indicates the amount of power the resistor can safely
dissipate as heat. The wattage rating is always more than the actual amount
of power dissipated by the resistor, as a safety factor.
Various types of fixed resistors are used in circuits, they are the most
numerous of all electronic components and their most common job is to
reduce voltages and currents around a circuit so that ‘active components’,
transistors and integrated circuits for example, that carry out tasks such as
producing or amplifying signals within the circuit are supplied with the
correct voltages and currents to work properly.
Resistors are also used in conjunction with other components such
as inductors and capacitors to process signals in many ways. Because
resistors are ‘passive components’ they cannot amplify or increase voltages
currents or signals, they can only reduce them. Nevertheless, they are a
most essential part of any electronic circuit.
There are two basic types of resistors.
1. Linear Resistors
2. Non Linear Resistors
Linear Resistors:
Those resistors, which values change with the applied voltage and
temperature, are called linear resistors. In other words, a resistor, which
current value is directly proportional to the applied voltage is known as
linear resistors.
Generally, there are two types of resistors which have linear properties.
1. Fixed Resistors
2. Variable Resistors

➢ Fixed Resistors:
As the name tells everything, fixed resistor is a resistor which has a
specific value and we can’t change the value of fixed resistors.
Types of Fixed resistors.
1. Carbon Composition Resistors
2. Wire Wound Resistors
3. Thin Film Resistors
4. Thick Film Resistors
1. Carbon Composition Resistors:
A typical fixed resistor is made from the mixture of granulated or
powdered carbon or graphite, insulation filler, or a resin binder. The ratio
of the insulation material determines the actual resistance of the resistor.
The insulating powder (binder) made in the shape of rods and there are two
metal caps on the both ends of the rod.
There are two conductor wires on the both ends of the resistor for
easy connectivity in the circuit via soldering. A plastic coat covers the rods
with different color codes (printed) which denote the resistance value.
They are available in 1 ohm to 25 mega ohms and in power rating from ¼
watt to up to 5 Watts.

2. Wire-wound Resistors:
Wirewound resistors are very variable in construction and physical
appearance. Their resistive elements are commonly lengths of wire, usually
an alloy such as Nichrome (Nickel/Chromium) or Manganin
(Copper/Nickel/Manganese) wrapped around a ceramic or glass fibre rod
or tube and coated in an insulating flameproof cement film.
They are normally available in quite low values of resistance (single
ohms to a few Kilohms) but can dissipate large amounts of power. In use
they may get very hot.
3. Thin Film Resistors:
Basically, all thin film resistors are made of from high grid ceramic
rod and a resistive material. A very thin conducting material layer overlaid
on insulating rod, plate or tube which is made from high quality ceramic
material or glass. There are two further types of thin film resistors.
1. Metal Film Resistors
2. Carbon Film Resistors
Metal Film Resistors:
These resistors are made from small rods of ceramic coated with
metal such as a nickel alloy or a metal oxide such as tin oxide. The value
of resistance is controlled firstly by the thickness of the coating layer; the
thicker the layer, the lower the value of resistance.

Also by a fine spiral groove cut along the rod using a laser or
diamond cutter to cut the carbon or metal coating effectively into a long
spiral strip, which forms the resistor.
Metal film resistors can be obtained in a wide range of resistance
values from a few Ohms to tens of millions of Ohms with a very small
Tolerance.
Carbon film Resistors:
It’s construction to Metal film resistors but generally with wider
tolerance (typically +/- 5%), shown in above Fig. mounted on paper strips
for machine insertion into printed circuit boards. Small resistors are
extremely inexpensive components and are also often sold in batches of
10s or 100s in this form for easier handling.
4. Thick Film Resistors:
The production method of Thick film resistors is same like thin film
resistors, but the difference is that there is a thick film instead of a thin film
or layer of resistive material around. That’s why it is called Thick film
resistors. There are two additional types of thick film resistors.
1. Metal Oxide Resistors
2. Cermet Film Resistors
Metal Oxide Resistors
By oxidizing a thick film of Tin Chloride on a heated glass rod
(substrate) is the simple method to make a Metal oxide Resistor. These

resistors are available in a wide range of resistance
with high temperature stability. In addition, the level
of operating noise is very low and can be used at high
voltages.
Cermet Oxide Resistors (Network Resistors)
In the cermet oxide resistors, the internal area contains on ceramic
insulation materials. And then a carbon or metal alloy film or layer
wrapped around the resistor and then fix it in a ceramic metal (which is
known as Cermet).
They are made in the square or rectangular shape and leads and pins
are under the resistors for easy installation in printed circuit boards. They
provide a stable operation in high temperature because their values do not
change with change in temperature.
➢ Variable Resistor:
The variable resistor means its resistance value can be adjusted
(similar to a potentiometer). There are a rotating shaft and a wiping contact.
Basically, there is a resistive semi-circular bar or coil and by wiping the
contact we change the effective length of the resistive element and hence
the resistance gets changed. One example of such resistors is rheostat.
Following are the further types of Variable Resistors
1. Potentiometers
2. Rheostats

Potentiometers:
Potentiometer is a three terminal device which is used for controlling
the level of voltage in the circuit. The resistance between two external
terminals is constant while the third terminal is connected with moving
contact (Wiper) which is variable.
The value of resistance can be
changed by rotating the wiper which is
connected to the control shaft.
Rheostats
Rheostats are a two or three terminal device which is used for the
current limiting purpose by hand or manual operation. Rheostats are also
known as tapped resistors or variable wire wound resistors.
➢ Color Coding of Resistors
Large resistors such as the wire-wound resistors or the ceramic-
encased power resistors have their resistor values and tolerances printed on
their cases. Smaller resistors, whether constructed of a molded carbon
composition or
a metal film,
may be too
small to have
their values
printed on the
component.
Instead, these
smaller resistors are usually covered by an epoxy or similar insulating

coating over which several colored bands are printed radially as shown in
Figure.
The colored bands provide a quickly recognizable code for
determining the value of resistance,
the tolerance (in percentage), and
occasionally the expected reliability
of the resistor.
The colored bands are always
read from left to right, left being
defined as the side of the resistor with the band nearest to it. The first two
bands represent the first and second digits of the resistance value. The third
band is called the multiplier band and represents the number of zeros
following the first two digits; it is usually given as a power of ten. The
fourth band indicates the tolerance of the resistor.

➢ Capacitors
A Capacitor is a passive component that has the ability to store the
energy in the form of potential difference between its plates. It resists a
sudden change in voltage. The charge is stored in the form of potential
difference between two plates, which form to be positive and negative
depending upon the direction of charge storage.
A non-conducting region is present between these two plates which
is called as dielectric. This dielectric can be vacuum, air, mica, paper,
ceramic, aluminum etc. The name of the capacitor is given by the dielectric
used.
Symbol and Units:
The standard units for capacitance is Farads. Generally, the values
of capacitors available will be in the order of micro-farads, pico-farads and
nano-farads. The symbol of a capacitor is as shown below.
The Capacitance of a capacitor is proportional to the distance
between the plates and is inversely proportional to the area of the plates.
Also, the higher the permittivity of a material, the higher will be the
capacitance. The permittivity of a medium describes how much electric
flux is being generated per unit charge in that medium. The following
image shows some practical capacitors.
When two plates having same area A, and equal width are placed
parallel to each other with a separation of distance d, and if some energy is
applied to the plates, then the capacitance of that parallel plate capacitor
can be termed as
where, C = Capacitance of a capacitor
ε0 = permittivity of free space
εr = permittivity of dielectric medium
d = distance between the plates
A = area of the two conducting plates

Working of a Capacitor
A Capacitor can be understood as a two-terminal passive component
which stores electrical energy. This electrical energy is stored in
electrostatic field.
Initially, the negative and positive charges on two plates of the
capacitor are in equilibrium. There is no tendency for a capacitor to get
charged or discharged. The negative charge is formed by the accumulation
of electrons, while the positive charge is formed by the depletion of
electrons. As this happens without any external charge given, this state is
electrostatic condition.
The Capacitors whose value is fixed while manufacturing and cannot be
altered later are called as Fixed Capacitors.
Ceramic Capacitors
The common capacitors used among fixed type are Ceramic
Capacitors. The Ceramic capacitors are fixed capacitors that have ceramic
material as a dielectric.
These ceramic capacitors are
further classified as class1 and class2
depending upon their applications. For
instance, Class1 has high stability and
works best for resonant circuit
applications, while class2 has high
efficiency and gives its best for coupling
applications. These are available in the order of 1ηF to 100μF.
Film Capacitors
The Film Capacitors are the ones
which have a film substance as a dielectric
material. Depending upon the type of film
used, these are classified as Paper and
Metal film capacitors.

These film capacitors are both paper dielectric capacitors whereas a
paper capacitor uses a waxed paper while a metallic film capacitor uses a
metallized paper. The arrangement is almost same as shown above.
Paper Capacitors
Paper capacitors use Paper as a
dielectric material. Two thin tin foil sheets
are taken and placed between thin waxed or
oiled paper sheets. This paper acts as a
dielectric. Now-a-days paper is being
replaced by plastic.
These sheets are sandwiched and are rolled into a cylindrical shape
and encapsulated in a plastic enclosure. Leads are drawn out. The following
figure shows an example of Paper Capacitors. Paper capacitors are
available in the order of 0.001μF to 2μF and the voltage rating can be as
high as 2000volts.
Electrolytic Capacitors
The Electrolytic Capacitors are the
capacitors which indicate by the name that
some electrolyte is used in it. They are
polarized capacitors which have anode + and
cathode − with particular polarities.
A metal on which insulating oxide layer forms by anodizing is called
as an Anode. A solid or non-solid electrolyte which covers the surface of
the oxide layer, functions as a cathode. The Electrolytic Capacitors have
much higher Capacitance-Voltage CV value than the others, due to their
larger anode surface and thin dielectric oxide layer.