FAMILIARIZATION AND IDENTIFICATION OF ELECTRONIC COMPONENTS WITH SPECIFICATION- part 3
In electronics and electrical engineering, a fuse is a type of low resistance resistor to provide over current protection, of either the load or source circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, interrupting the circuit that it connects.
The relay is an electro-mechanical device. The most fundamental control of any equipment is the ability to turn it “ON” and “OFF. The easiest way to do this is using switches to interrupt the electrical supply
In telecommunications, RS-232 is a standard for serial communication transmission of data The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pin out of connectors. An RS-232 serial port was once a standard feature of a personal computer, used for connections to modems, printers, data storage, uninterruptible power supplies, and other peripheral devices. The RS-232 standard is commonly used in computer serial ports.
An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The connectors are also sometimes casually referred to as A/V jacks. The name "RCA" derives from the Radio Corporation of America, which introduced the design. It was originally a low-cost, simple design, intended only for mating and disconnection when servicing the console. Refinement came with later designs, although they remained compatible.
ACTIVE DEVICES
1.2.
ACTIVE ELECTRONIC COMPONENTS
Devices which are capable
of amplifying or processing electrical signals are called active electronic
components.
1.2.1.
SEMICONDUCTOR DIODE
Semiconductor diode is also called pn junction. Diode is
fabricated by joining together a P-type and N-type semiconductor. It conducts current in one direction only. This is utilized in rectifiers. The lead attached
to P-type is called anode and the lead attached to N-type is called cathode.
The polarity is indicated on the doide. The diodes are operated two modes forward
and reverse bias. The doide is said to be forward bias when positive voltage is
applied at the anode w.r.t cathode. When negative voltage is applied at the anode
of the diode becomes reverse biased.
BY126, OA79, 1N4001 to1N4007 etc. are
popular diodes in market. The symbol of the doide shown in the figure below. Leads are identified from the symbol marked on the body or white band is marked
on the body near the cathode.
The diodes are specified by :the type, peak
inverse voltage and current rating.
i)
POWER DIODE
The power semiconductor
diode, known simply as the Power
Diode, has a much larger PN junction area compared to its smaller
signal diode cousin, resulting in a high forward current capability of up to
several hundred amps (KA) and a reverse blocking voltage of up to several
thousand volts (KV).
The 1N4001 series (or 1N4000
series) is a family of popular 1.0 A (ampere) general purpose silicon rectifier diodes commonly used in AC adapters for common household appliances. Blocking voltage varies from 50 to 1000 volts. This
diode is made in an axial-lead DO-41plastic
package The 1N5400 series is a similarly popular series for
higher current applications, up to 3 A. These diodes come in the larger
DO-201 axial package.
i)
SIGNAL DIODE
These diodes are used in low
voltage and power applications. The maximum forward current ranges from 40mA to
250mA. OA79 is an example of signal diode. The electrodes are visible through
the trasparent cover. A red ring is marked on its body to indicate the cathode
i)
ZENER DIODE
Zener diodes make use of break down phenomena. In forward
biased mode, it functions as an ordinary diode. In reverse biased mode it
conducts at a particular voltage across the zener diode remains constant. Zener
diodes are used as voltage regulators.
i)
LIGHT EMITTING DIODE (LED)
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when
activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in
the form of photons. This effect
is called electroluminescence,
and the color of the light (corresponding to the energy of the photon) is
determined by the energy band gap of the semiconductor.
1.2.2.TRANSISTORS
It is basically a silicon or germanium crystal containing
three separate layers. It can also be considered as two diodes connected back
to back. Transistors are two types: NPN
and PNP. It has three layers; emitter base and collector.transistors are
classified as per the range of frequency they are used namely low frequency and
high frequency transistors and also classified as per power rating as low power
and high power transistors.they are specified by its type, power and frequency.
a)
FIELD EFFECT TRANSISTORS
( FET)
The field-effect transistor (FET)
is a transistor that uses an electric field to control the shape and hence the
electrical conductivity of a channel of one type of charge carrier in a
semiconductor material. FETs are also known as unipolar transistors as
they involve single-carrier-type operation. The FET has several forms, but all
have high input impedance. While the conductivity of a non-FET transistor is
regulated by the input current (the emitter to base current) and so has a low
input impedance, a FET's conductivity is regulated by a voltage applied to a
terminal (the gate) which is insulated from the device. The applied gate
voltage imposes an electric field into the device, which in turn attracts or
repels charge carriers to or from the region between a source terminal and a
drain terminal. The density of charge carriers in turn influences the
conductivity between the source and drain.
BFW10
N-Channel FET with symbol
b)
UNI-JUNCTION TRANSISTOR
(UJT)
It is a single junction
transistor and it has three terminals namely emitter (E), base 1 (B1) and base
2 (B2). It is constructed by doping P-type impurity to a heavily doped silicon
bar. Two ends of the bar act as B1 and B2.
 |
| UJT with symbol |
1.2.3. INTEGRATED CIRCUITS
An integrated circuit (IC),
sometimes called a chip or microchip, is a semiconductor wafer on which
thousands or millions of tiny resistors, capacitors, and transistors are
fabricated. An IC can function as an amplifier, oscillator, timer, counter,
computer memory, or microprocessor.
 |
| How to read the pin numbers |
i)
REGULATOR CHIP
The 78xx (sometimes L78xx, LM78xx, MC78xx...) is a family of self-contained fixed linear voltage regulator integrated circuits. The 78xx family
is commonly used in electronic circuits requiring a regulated power supply due
to their ease-of-use and low cost. For ICs within the family, the xx is replaced with two digits,
indicating the output voltage (for example, the 7805 has a 5-volt
output, while the 7812 produces 12 volts). The 78xx line are positive
voltage regulators: they produce a voltage that is positive relative to a
common ground. There is a related line of 79xx devices which are complementary
negative voltage regulators. 78xx and 79xx ICs can be used in combination to
provide positive and negative supply voltages in the same circuit.
1.2.
MISCELLANEOUS COMPONENTS
i)
FUSE AND FUSE HOLDER
In electronics and electrical engineering, a fuse is a type of low resistance resistor to provide over current protection, of either the load or source circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, interrupting the circuit that it connects.
 |
Fuse
and fuse holder
|
i)
RELAY
The relay is an electro-mechanical device. The most fundamental control of any equipment is the ability to turn it “ON” and “OFF. The easiest way to do this is using switches to interrupt the electrical supply
iii)
CONNECTORS
a) USB CONNECTORS
The Universal
Serial Bus is a serial bus standard to interface device. It is
currently widely used among PCs, Apple Macintosh and many other
devices. There are several types of USB connectors, the most commonly used is
the (male) series "A" plug on peripherals, when the cable is fixed
to the peripheral. If there is no cable fixed to the peripheral, the peripheral
always needs to have a USB "B" socket. In this case a USB
"A" plug to a USB "B" plug cable would be needed. USB
"A" sockets are always used on the host PC and the USB "B"
sockets on the peripherals. It is a 4-pin connector, surrounded by a shield.
 |
| Male USB plug |
b)
RS232 MALE FEMALE
CONNECTORS
In telecommunications, RS-232 is a standard for serial communication transmission of data The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pin out of connectors. An RS-232 serial port was once a standard feature of a personal computer, used for connections to modems, printers, data storage, uninterruptible power supplies, and other peripheral devices. The RS-232 standard is commonly used in computer serial ports.
c) RCA CONNECTOR
An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The connectors are also sometimes casually referred to as A/V jacks. The name "RCA" derives from the Radio Corporation of America, which introduced the design. It was originally a low-cost, simple design, intended only for mating and disconnection when servicing the console. Refinement came with later designs, although they remained compatible.
d) BNC CONNECTOR
The BNC (Bayonet Neill–Concelman) connector is a miniature quick
connect/disconnect radio frequency connector used for coaxial cable. It features
two bayonet lugs on the female connector;
mating is fully achieved with a quarter turn of the coupling nut.BNC connectors
are used with miniature-to-subminiature coaxial cable in radio, television, and
other radio-frequency electronic equipment, test instruments, and video
signals. BNC connectors are made to match the characteristic
impedance of cable at either 50
ohms or 75 ohms. They are usually applied for frequencies below 4 GHz and voltages below 500 volts.
 |
| bnc connector |
iv)SWITCHES
In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to
another. The mechanism of a switch may be operated directly by a human operator
to control a circuit.
a) TOGGLE SWITCH
A toggle switch is a
switch that has just two positions. For example, light switches that turn a
light on or off are toggle switches. To
switch from one setting to another. The term toggle implies
that there are only two possible settings and that you are switching from the
current setting to the other setting.
 |
| Toggle switch |
b)PUSH SWITCH
Push switch is a momentary or non-latching switch which causes a temporary change in the
state of an electrical circuit only while the switch is physically
actuated. An automatic mechanism (i.e. a spring) returns the switch to its
default position immediately afterwards, restoring the initial circuit
condition. A push to make switch allows
electricity to flow between its two contacts when held in. When the button is
released, the circuit is broken. This type of switch is also known as a Normally Open (NO) Switch.
(Examples: doorbell, computer case power switch, calculator buttons, individual
keys on a keyboard)
 |
| push switch |
RESULT
The different electronic components used in an
electronics laboratory are studied.
