Download Q. What material is used in wiring of motherboard?

Q. What is Multivibrator and what are Astable, monostable, bistable
Multivibrators?
A multivibrator is an electronic circuit used to implement a variety of simple two-state systems such
as oscillators, timers and flip-flops. There are three types of multivibrator circuits depending on the
circuit operation:

astable, in which the circuit is not stable in either state —it continually switches from one state to
the other. It functions as a relaxation oscillator.
 monostable, in which one of the states is stable, but the other state is unstable (transient). A
trigger pulse causes the circuit to enter the unstable state. After entering the unstable state, the
circuit will return to the stable state after a set time. Such a circuit is useful for creating a timing
period of fixed duration in response to some external event. This circuit is also known as a one
shot.
 bistable, in which the circuit is stable in either state. It can be flipped from one state to the other
by an external trigger pulse. This circuit is also known as a flip flop. It can be used to store
one bit of information.
Applications: in systems where square waves or timed intervals are required.
Q. What is Cache Memory?(CPU memory),
1. is random access memory (RAM) that a computer microprocessor can access more quickly
than it can access regular RAM.
2. The basic purpose of cache memory is to store program instructions that are frequently rereferenced by software during operation. Fast access to these instructions increases the overall
speed of the software program.
3. As the microprocessor processes data, it looks first in the cache memory; if it finds the
instructions there (from a previous reading of data), it does not have to do a more timeconsuming reading of data from larger memory or other data storage devices.
Q. What material is used in wiring of motherboard?
Copper wire
Q. what is Charge?( electric charge)
is a characteristic of a unit of matter that expresses the extent to which it has more or fewer
electrons than protons. In atoms, the electron carries a negative elementary or unit charge; the
proton carries a positive charge. The two types of charge are equal and opposite.
What is ion
A "charged" atom is called an "ion."
What is electricity?
a form of energy resulting from the existence of charged particles (such as electrons or protons), either
statically as an accumulation of charge or dynamically as a current.
Potential?
The electric potential of a point may also be defined as the work done in carrying a unit positive
charge from infinity to that point.
The electric potential at a point is equal to the electric potential energy (measured in joules) of any
charged particle at that location divided by the charge (measured in coulombs) of the particle
Current?
An electric current is a flow of electric charge. In electric circuits this charge is often carried by
moving electrons in a wire.
Voltage?
is the electric energy charge difference of electric potential energy transported between two points.
Voltage is equal to the work done per unit of charge against a static electric field to move the charge
between two points.
Energy?
is a property of objects, transferable among them via fundamental interactions, which can
be convertedinto different forms but not created or destroyed. The joule is the SI unit of energy, based
on the amount transferred to an object by the mechanical work of moving it 1 metre against a force of
1 newton.[1]
Some examples of different kinds of energy:
Forms of energy
1.
Type of energy
Description
Kinetic
(≥0), that of the motion of a body
Potential
A category comprising many forms in this list
Mechanical
The sum of (usually macroscopic) kinetic and potential energies
Mechanical wave
(≥0), a form of mechanical energy propagated by a material's oscillations
Chemical
that contained in molecules
Electric
that from electric fields
Magnetic
that from magnetic fields
Radiant
(≥0), that of electromagnetic radiation including light
Nuclear
that of binding nucleons to form the atomic nucleus
Ionization
that of binding an electron to its atom or molecule
Elastic
that of deformation of a material (or its container) exhibiting a restorative force
Gravitational
that from gravitational fields
Intrinsic, the rest energy
(≥0) that equivalent to an object's rest mass
Thermal
A microscopic, disordered equivalent of mechanical energy
Heat
an amount of thermal energy being transferred (in a given process) in the direction of decreasing temperature
Mechanical work
an amount of energy being transferred in a given process due to displacement in the direction of an applied force
Power?
In physics, power is the rate of doing work. It is equivalent to an amount of energy
consumed per unit time. In the MKS system, the unit of power is the joule per second (J/s),
known as the watt in honor of James Watt, the eighteenth-century developer of the steam
engine.
Q. Resistance: (electrical component)
Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits
Capacitor?
1. Passive two-terminal electrical component used to store energy electrostatically in an electric
field.
2. Capacitors are widely used in electronic circuits for blocking direct current while
allowing alternating current to pass.
3. When used in any electric circuit , opposes the change in voltage across it.
Inductor?
1.
2.
Two-terminal electrical component which resists changes in electric current passing through it.
When the current flowing through an inductor changes, the time-varying magnetic field induces
a voltage in the conductor, according to Faraday’s law of electromagnetic induction, which
opposes the change in current that created it.
Transistor?
1. a semiconductor device having two junctions.
2. In this an N-type semiconductor is sandwiched between two P-type semiconductors or vice
versa, forming two junctions.
3. Various combinations of voltages can be applied to obtain specific purpose of the transistor.
4. Used as amplifier.
5. BJT: bipolar junction transistor
6. FET: field effect transistor.
7. JFET: Junction Field effect transistor
7.1 N-Channel FET, P-Channel FET
8. IGFET: Insulated gate field effect transistor
Depletion type
Enhancement type
9. MOSFET: Metal Oxide Semiconductor Field effect transistor
9.1 the body (or substrate) of the MOSFET is often connected to the source terminal, making
it a three-terminal device like other field-effect transistors
9.2 The main advantage of a MOSFET transistor over a regular transistor is that it requires very
little current to turn on (less than 1mA), while delivering a much higher current to a load (10 to
50A or more). However, the MOSFET requires a higher gate voltage (3-4V) to turn on.
9.3 N-Channel MOS, P-Channel MOS
9.4 IGFET is a MOSFET implementing an insulator at gate other than oxide.
10. CMOS: Complementary metal oxide semiconductor Field effect transistor
Triode?
A triode is an electronic amplifying vacuum tube consisting of three electrodes inside an evacuated
glass envelope: a heated filament or cathode, a grid, and a plate (anode)
Today, their main remaining use is in high-power RF amplifiers in radio transmittersand industrial
RF heating devices.
CIRCUIT COMPONENTS
Classification[edit]
A component may be classified as passive, active, or electromechanic. The strict physics definition treats
passive components as ones that cannot supply energy themselves, whereas a battery would be seen as
an active component since it truly acts as a source of energy.
However, electronic engineers who perform circuit analysis use a more restrictive definition of passivity.
When only concerned with the energy of signals, it is convenient to ignore the so-called DC circuit and
pretend that the power supplying components such as transistors or integrated circuits is absent (as if each
such component had its own battery built in), though it may in reality be supplied by the DC circuit. Then,
the analysis only concerns the AC circuit, an abstraction that ignores DC voltages and currents (and the
power associated with them) present in the real-life circuit. This fiction, for instance, lets us view an
oscillator as "producing energy" even though in reality the oscillator consumes even more energy from a
DC power supply, which we have chosen to ignore. Under that restriction, we define the terms as used
in circuit analysis as:

Active components rely on a source of energy (usually from the DC circuit, which we have chosen to
ignore) and usually can inject power into a circuit, though this is not part of the definition. [1] Active
components include amplifying components such as transistors, triode vacuum tubes (valves),
and tunnel diodes.

Passive components can't introduce net energy into the circuit. They also can't rely on a source of
power, except for what is available from the (AC) circuit they are connected to. As a consequence they
can't amplify (increase the power of a signal), although they may increase a voltage or current (such
as is done by a transformer or resonant circuit). Passive components include two-terminal components
such as resistors, capacitors, inductors, and transformers.

Electromechanical components can carry out electrical operations by using moving parts or by using
electrical connections
Most passive components with more than two terminals can be described in terms of two-port
parameters that satisfy the principle of reciprocity—though there are rare exceptions.[2] In contrast, active
components (with more than two terminals) generally lack that property.
Active components[edit]
Semiconductors[edit]
Diodes[edit]
Conduct electricity easily in one direction, among more specific behaviors.

Diode, Rectifier, Bridge rectifier

Schottky diode, hot carrier diode – super fast diode with lower forward voltage drop

Zener diode – Passes current in reverse direction to provide a constant voltage reference

Varactor, Tuning diode, Varicap, Variable capacitance diode – A diode whose AC capacitance varies
according to the DC voltage applied.

Light-emitting diode (LED) – A diode that emits light

Photodiode – Passes current in proportion to incident light
 Avalanche photodiode Photodiode with internal gain
 Solar Cell, photovoltaic cell, PV array or panel, produces power from light

DIAC (Diode for Alternating Current), Trigger Diode, SIDAC) – Often used to trigger an SCR

Constant-current diode

Peltier cooler – A semiconductor heat pump
Transistors[edit]
Transistors were considered the invention of the twentieth century that changed electronic circuits forever.
A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.

Transistors
 Bipolar junction transistor (BJT, or simply "transistor") – NPN or PNP
 Photo transistor – Amplified photodetector
 Darlington transistor – NPN or PNP
 Photo Darlington – Amplified photodetector
 Sziklai pair (Compound transistor, complementary Darlington)

Field-effect transistor (FET)
 JFET (Junction Field-Effect Transistor) – N-CHANNEL or P-CHANNEL
 MOSFET (Metal Oxide Semiconductor FET) – N-CHANNEL or P-CHANNEL
 MESFET (MEtal Semiconductor FET)
 HEMT (High electron mobility transistor)

Thyristors
 Silicon-controlled rectifier (SCR) – Passes current only after triggered by a sufficient control
voltage on its gate
 TRIAC (TRIode for Alternating Current) – Bidirectional SCR
 Unijunction transistor (UJT)
 Programmable Unijunction transistor (PUT)
 SIT (Static induction transistor)
 SITh (Static induction thyristor)

Composite transistors
 IGBT (Insulated-gate bipolar transistor)
Integrated circuits[edit]

Digital

Analog


Hall effect sensor –senses a magnetic field
Current sensor – Senses a current through it
Optoelectronic devices[edit]

Optoelectronics
 Opto-Isolator, Opto-Coupler, Photo-Coupler – Photodiode, BJT, JFET, SCR, TRIAC, Zerocrossing TRIAC, Open collector IC, CMOS IC, Solid state relay (SSR)
 Opto switch, Opto interrupter, Optical switch, Optical interrupter, Photo switch, Photo interrupter
 LED display – Seven-segment display, Sixteen-segment display, Dot-matrix display
Display technologies[edit]
Current:

Filament lamp (indicator lamp)

Vacuum fluorescent display (VFD) (preformed characters, 7 segment, starburst)

Cathode ray tube (CRT) (dot matrix scan, radial scan (e.g. radar), arbitrary scan (e.g. oscilloscope))
(monochrome & colour)

LCD (preformed characters, dot matrix) (passive, TFT) (monochrome, colour)

Neon (individual, 7 segment display)

LED (individual, 7 segment display, starburst display, dot matrix)

Flap indicator (numeric, preprinted messages)

Plasma display (dot matrix)
Obsolete:

Filament lamp 7 segment display (aka 'minitron')

Nixie Tube

Dekatron (aka glow transfer tube)

Magic eye tube indicator

Penetron (a 2 colour see-through CRT)
Vacuum tubes (valves)[edit]
A vacuum tube is based on current conduction through a vacuum (see Vacuum tube).

Diode or rectifier tube
Amplifying tubes

Triode

Tetrode

Pentode

Hexode

Pentagrid

Octode

Microwave tubes
 Klystron
 Magnetron
 Traveling-wave tube
Optical detectors or emitters

Phototube or Photodiode – tube equivalent of semiconductor photodiode

Photomultiplier tube – Phototube with internal gain

Cathode ray tube (CRT) or television picture tube

Vacuum fluorescent display (VFD) – Modern non-raster sort of small CRT display

Magic eye tube – Small CRT display used as a tuning meter (obsolete)

X-ray tube – Produces x-rays
Discharge devices[edit]

Gas discharge tube
Obsolete:

Mercury arc rectifier

Voltage regulator tube

Nixie tube

Thyratron

Ignitron
Power sources[edit]
Sources of electrical power:

Battery – acid- or alkali-based power supply

Fuel cell – an electrochemical generator

Power supply – usually a mains hook-up

Photo voltaic device – generates electricity from light

Thermo electric generator – generates electricity from temperature gradients

Electrical generator – an electromechanical power source

Piezoelectric pressure - creates electricity from mechanical strain

Physically carrying electrons - Van de Graaff generator or essentially creating voltage from friction
Passive components[edit]
Resistors[edit]
Pass current in proportion to voltage (Ohm's law) and oppose current.

Resistor – fixed value
 Power resistor – larger to safely dissipate heat generated
 SIP or DIP resistor network – array of resistors in one package

Variable resistor
 Rheostat – two-terminal variable resistor (often for high power)
 Potentiometer – three-terminal variable resistor (variable voltage divider)
 Trim pot – Small potentiometer, usually for internal adjustments
 Thermistor – thermally sensitive resistor whose prime function is to exhibit a large, predictable and
precise change in electrical resistance when subjected to a corresponding change in body
temperature.[3]
 Humistor – humidity-varied resistor
 Photoresistor
 Memristor
 Varistor, Voltage Dependent Resistor, MOV – Passes current when excessive voltage is present

Resistance wire, Nichrome wire – wire of high-resistance material, often used as a heating element

Heater – heating element
Capacitors[edit]
Capacitors store and release electrical charge. They are used for filtering power supply lines, tuning
resonant circuits, and for blocking DC voltages while passing AC signals, among numerous other uses.

Capacitor
 Integrated capacitors





 MIS capacitor
 Trench capacitor
Fixed capacitors
 Ceramic capacitor
 Film capacitor
 Electrolytic capacitor
 Aluminum electrolytic capacitor
 Tantalum electrolytic capacitor
 Niobium electrolytic capacitor
 Polymer capacitor
 OS-CON
 Electric double-layer capacitor
 Nanoionic supercapacitor
 Lithium-ion capacitor
 Mica capacitor
 Vacuum capacitor
Variable capacitor – adjustable capacitance
 Tuning capacitor – variable capacitor for tuning a radio, oscillator, or tuned circuit
 Trim capacitor– small variable capacitor is usually for slight internal adjustments made with a
small screw driver turned into the right position.
 Vacuum variable capacitor
Capacitors for special applications
 Power capacitor
 Safety capacitor
 Filter capacitor
 Light-emitting capacitor
 Motor capacitor
 Photoflash capacitor
 Reservoir capacitor
Capacitor network (array)
Varicap diode – AC capacitance varies according to the DC voltage applied
Magnetic (inductive) devices[edit]
Electrical components that use magnetism in the storage and release of electrical charge through current:

Inductor, coil, choke

Variable inductor

Saturable Inductor

Transformer

Magnetic amplifier (toroid)

ferrite impedances, beads

Motor / Generator

Solenoid

Loudspeaker and microphone
Memristor[edit]
Electrical components that pass charge in proportion to magnetism or magnetic flux, and have the ability to
retain a previous resistive state, hence the name of Memory plus Resistor.

Memristor
Networks[edit]
Components that use more than one type of passive component:

RC network – forms an RC circuit, used in snubbers

LC Network – forms an LC circuit, used in tunable transformers and RFI filters.
Transducers, sensors, detectors[edit]
1. Transducers generate physical effects when driven by an electrical signal, or vice-versa.
2. Sensors (detectors) are transducers that react to environmental conditions by changing their
electrical properties or generating an electrical signal.
3. The transducers listed here are single electronic components (as opposed to complete
assemblies), and are passive (see Semiconductors and Tubes for active ones). Only the most
common ones are listed here.

Audio (see also piezoelectric devices)
 Loudspeaker – Magnetic or piezoelectric device to generate full audio
 Buzzer – Magnetic or piezoelectric sounder to generate tones

Position, motion
 Linear variable differential transformer (LVDT) – Magnetic – detects linear position
 Rotary encoder, Shaft Encoder – Optical, magnetic, resistive or switches – detects absolute or
relative angle or rotational speed
 Inclinometer – Capacitive – detects angle with respect to gravity
 Motion sensor, Vibration sensor
 Flow meter – detects flow in liquid or gas

Force, torque
 Strain gauge – Piezoelectric or resistive – detects squeezing, stretching, twisting
 Accelerometer – Piezoelectric – detects acceleration, gravity

Thermal
 Thermocouple, thermopile – Wires that generate a voltage proportional to delta temperature
 Thermistor – Resistor whose resistance changes with temperature, up PTC or down NTC
 Resistance Temperature Detector (RTD) – Wire whose resistance changes with temperature
 Bolometer – Device for measuring the power of incident electromagnetic radiation
 Thermal cutoff – Switch that is opened or closed when a set temperature is exceeded

Magnetic field (see also Hall Effect in semiconductors)
 Magnetometer, Gauss meter

Humidity
 Hygrometer

Electromagnetic, light
 Photo resistor – Light dependent resistor (LDR)
Antennas[edit]
Antennas transmit or receive radio waves

Elemental dipole

Yagi

Phased array

Loop antenna

Parabolic dish

Log-periodic dipole array

Biconical

Feedhorn
Assemblies, modules[edit]
Multiple electronic components assembled in a device that is in itself used as a component

Oscillator

Display devices
 Liquid crystal display (LCD)
 Digital voltmeters

Filter
Prototyping aids[edit]

Wire-wrap

Breadboard
Electromechanical[edit]
2 crystalline type oscillators
Piezoelectric devices, crystals, resonators[edit]
Passive components that use piezoelectric effect:

Components that use the effect to generate or filter high frequencies
 Crystal – a ceramic crystal used to generate precise frequencies (See the Modules class below
for complete oscillators)
 Ceramic resonator – Is a ceramic crystal used to generate semi-precise frequencies
 Ceramic filter – Is a ceramic crystal used to filter a band of frequencies such as in radio receivers
 surface acoustic wave (SAW) filters

Components that use the effect as mechanical transducers.
 Ultrasonic motor – Electric motor that uses the piezoelectric effects
 For piezo buzzers and microphones, see the Transducer class below
Terminals and connectors[edit]
Devices to make electrical connection

Terminal

Connector
 Socket
 Screw terminal, Terminal Blocks
 Pin header
Cable assemblies[edit]
Cables with connectors or terminals at their ends

Power cord

Patch cord

Test lead
Switches[edit]
Components that can pass current ("closed") or break the flow of current ("open"):

Switch – Manually operated switch.
 Electrical description: SPST, SPDT, DPST, DPDT, NPNT (general)
 Technology: slide switches, toggle switches, rocker switches, rotary switches, pushbutton
switches

Keypad – Array of pushbutton switches

DIP switch – Small array of switches for internal configuration settings

Footswitch – Foot-operated switch

Knife switch – Switch with unenclosed conductors

Micro switch – Mechanically activated switch with snap action

Limit switch – Mechanically activated switch to sense limit of motion

Mercury switch – Switch sensing tilt

Centrifugal switch – Switch sensing centrifugal force due to rate of rotation

Relay – Electrically operated switch (mechanical, also see Solid State Relay below)

Reed switch – Magnetically activated switch

Thermostat – Thermally activated switch

Humidistat – Humidity activated switch

Circuit breaker – Switch opened in response to excessive current: a resettable fuse
Protection devices[edit]
Passive components that protect circuits from excessive currents or voltages:

Fuse – over-current protection, one time use

Circuit breaker – resettable fuse in the form of a mechanical switch

Resettable fuse or PolySwitch – circuit breaker action using solid state device

Ground-fault protection or residual-current device – circuit breaker sensitive to mains currents passing
to ground

Metal oxide varistor (MOV), surge absorber, TVS – Over-voltage protection.

Inrush current limiter – protection against initial Inrush current

Gas discharge tube – protection against high voltage surges

Spark gap – electrodes with a gap to arc over at a high voltage

Lightning arrester – spark gap used to protect against lightning strikes
Mechanical accessories[edit]

Enclosure (electrical)

Heat sink

Fan
Other[edit]

Printed circuit boards

Lamp

Waveguide

Memristor
Obsolete[edit]

Carbon amplifier (see Carbon microphones used as amplifiers)

Carbon arc (negative resistance device)

Dynamo (historic rf generator)

Coherer
Bridge Rectifier?
A bridge rectifier is an arrangement of four or more diodes in a bridge circuit configuration
which provides the same output polarity for either input polarity. It is used for converting an
alternating current (AC) input into a direct current (DC) output.
Diode?
1.
two-terminal electronic component with asymmetric conductance; it has low (ideally
zero) resistance to currentin one direction, and high (ideally infinite) resistance in the other.
2. used to convert alternating current to direct current
Q. What is a Schottky Diode?
A Schottky diode( hot carrier diode),
1. has a low forward voltage drop and a very fast switching action.
2. A normal diode will have a voltage drop between 0.6 to 1.7 volts(0.7 for Si, 1.2 for Ge), while
a Schottky diode voltage drop is usually between 0.15 and 0.45 volts.
3. Better system efficiency and higher switching speed.
4. In a Schottky diode, a semiconductor–metal junction is formed between a semiconductor(n
type) and a metal(molybdenum, tungsten or chromium, platinum, thus creating a Schottky
barrier.
Applications:
1. As rectifiers in SMPS(switched mode power supply)
2. In standalone photovoltaic systems in order to prevent batteries from discharging through the
solar panels at night.
Zener Diode?
A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an
ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value
known as the breakdown voltage, "Zener knee voltage", "Zener voltage", "avalanche point", or "peak
inverse voltage".
Zener diodes are widely used as voltage references and as shunt regulators to regulate the voltage across
small circuits. When connected in parallel with a variable voltage source so that it is reverse biased, a
Zener diode conducts when the voltage reaches the diode's reverse breakdown voltage. From that point
on, the relatively low impedance of the diode keeps the voltage across the diode at that value.
LED
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a pn-junction diode, which
emits light when activated.[6]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.
LED uses fall into four major categories:

Visual signals where light goes more or less directly from the source to the human eye, to convey a
message or meaning.

Illumination where light is reflected from objects to give visual response of these objects.

Measuring and interacting with processes involving no human vision.[142]

Narrow band light sensors where LEDs operate in a reverse-bias mode and respond to incident light,
instead of emitting light.
PIN diode
A PIN diode is a diode with a wide, undoped intrinsic semiconductor region between a p-type
semiconductor and an n-type semiconductor region. The p-type and n-type regions are typically
heavily doped because they are used for ohmic contacts.
The wide intrinsic region is in contrast to an ordinary PN diode. The wide intrinsic region makes
the PIN diode an inferior rectifier (one typical function of a diode), but it makes the PIN diode
suitable for attenuators, fast switches, photodetectors, and high voltage power electronics
applications.
Photodiode:
A photodiode is a p–n junction or PIN structure. When a photon of sufficient energy strikes the diode, it
creates an electron-hole pair. This mechanism is also known as the inner photoelectric effect. If the
absorption occurs in the junction's depletion region, or one diffusion length away from it, these carriers are
swept from the junction by the built-in electric field of the depletion region. Thus holes move toward
the anode, and electrons toward the cathode, and a photocurrent is produced. The total current through the
photodiode is the sum of the dark current (current that is generated in the absence of light) and the
photocurrent, so the dark current must be minimized to maximize the sensitivity of the device.[2]
Darlington transistor
In electronics, the Darlington transistor (often called a Darlington pair) is a compound structure
consisting of two bipolar transistors (either integrated or separated devices) connected in such a way that
the current amplified by the first transistor is amplified further by the second one. [1] This configuration gives
a much higher common/emitter current gain than each transistor taken separately and, in the case of
integrated devices, can take less space than two individual transistors because they can use
a shared collector. Integrated Darlington pairs come packaged singly in transistor-like packages or as an
array of devices (usually eight) in an integrated circuit.
Silicon-Controlled Rectifier
A silicon-controlled rectifier (or semiconductor-controlled rectifier) is a four-layer solid
state current controlling device. The Silicon Control Rectifier (SCR) consists of four layers of
semiconductors, which form NPNP or PNPN structures. There are three modes of operation for an SCR
depending upon the biasing given to it:
1. Forward blocking mode (off state)
2. Forward conduction mode (on state)
3. Reverse blocking mode (off state)
Thyristor turn on methods[edit]
1. forward voltage triggering
2. gate triggering
3. dv/dt triggering
4. temperature triggering
5. light triggering
Application of SCRs[edit]
SCRs are mainly used in devices where the control of high power, possibly coupled with high voltage, is
demanded. Their operation makes them suitable for use in medium to high-voltage AC power control
applications, such as lamp dimming, regulators and motor control.
Seven-segment display
A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device for
displaying decimalnumerals that is an alternative to the more complex dot matrix displays.
Filters?
Electronic filters are analog circuits which perform signal processing functions, specifically to remove
unwanted frequency components from the signal, to enhance wanted ones, or both. Electronic filters can
be:

passive or active

analog or digital

high-pass, low-pass, band-pass, band-stop (band-rejection; notch), or all-pass.

discrete-time (sampled) or continuous-time

linear or non-linear

infinite impulse response (IIR type) or finite impulse response (FIR type)
Passive filters
Passive implementations of linear filters are based on combinations of resistors (R), inductors (L)
and capacitors (C). These types are collectively known as passive filters, because they do not depend
upon an external power supply and/or they do not contain active components such as transistors.
Active filters
Active filters are implemented using a combination of passive and active (amplifying) components, and
require an outside power source. Operational amplifiers are frequently used in active filter designs. These
can have high Q factor, and can achieve resonance without the use of inductors. However, their upper
frequency limit is limited by the bandwidth of the amplifiers.
Electrical resonance occurs in an electric circuit at a particular resonance frequency when the imaginary
parts of impedances or admittances of circuit elements cancel each other. In some circuits this happens
when the impedance between the input and output of the circuit is almost zero and the transfer function is
close to one
CFL (Compact Fluorescent Light)
electrons that are bound to mercury atoms are excited to states where they will radiate ultraviolet light as
they return to a lower energy level; this emitted ultraviolet light is converted into visible light as it strikes the
fluorescent coating on the bulb (as well as into heat when absorbed by other materials such as glass).
Latche Vs Flip Flop
Flipflops have clock signals whereas latches don't need clock input.
Google
Larry Page and Sergey Brin
Yahoo
Jerry Yang and David Filo
Wikipedia
Jimmy Wales (born 1966); Larry Sanger
Facebook
Mark Elliot Zuckerberg
Apple
Steve Jobs, Steve Wozniak, Ronald Wayne
Radar (RAdio Detection And Ranging)
Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or
speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor
vehicles, weather formations, and terrain. The radar dish (or antenna) transmits pulses of radio waves
or microwaves that bounce off any object in their path. The object returns a tiny part of the wave's energy to
a dish or antenna that is usually located at the same site as the transmitter.
The modern uses of radar are highly diverse, including air traffic control, radar astronomy, air-defense
systems,antimissile systems; marine radars to locate landmarks and other ships; aircraft anticollision
systems; ocean
surveillance systems,
outer
space
surveillance
and rendezvous systems; meteorological precipitation
monitoring;
altimetry
and flight
control
systems; guided missile target locating systems; and ground-penetrating radar for geological observations.
High tech radar systems are associated with digital signal processing and are capable of extracting useful
information from very high noise levels.
Frequency
Wavelength
Designation
Abbreviation[5]
3 – 30 Hz
105 – 104 km
Extremely low frequency
ELF
30 – 300 Hz
10 – 10 km
Super low frequency
SLF
300 – 3000 Hz
103 – 100 km
Ultra low frequency
ULF
3 – 30 kHz
100 – 10 km
Very low frequency
VLF
30 – 300 kHz
10 – 1 km
Low frequency
LF
300 kHz – 3 MHz
1 km – 100 m
Medium frequency
MF
3 – 30 MHz
100 – 10 m
High frequency
HF
30 – 300 MHz
10 – 1 m
Very high frequency
VHF
300 MHz – 3 GHz
1 m – 10 cm
Ultra high frequency
UHF
3 – 30 GHz
10 – 1 cm
Super high frequency
SHF
30 – 300 GHz
1 cm – 1 mm
Extremely high frequency
EHF
300 GHz - 3000 GHz
1 mm - 0.1 mm
Tremendously high frequency
THF
4
3
Doplar effect:
Frequency shift is caused by motion that changes the number of wavelengths between the reflector and the
radar.
Signal noise is an internal source of random variations in the signal, which is generated by all electronic
components. Noise typically appears as random variations superimposed on the desired echo signal
received in the radar receiver. The lower the power of the desired signal, the more difficult it is to discern it
from the noise. Noise figure is a measure of the noise produced by a receiver compared to an ideal
receiver, and this needs to be minimized.
LASER(Light Amplification By Stimulated Emission Of Radiation)
emits light coherently
Spatial coherence allows a laser to be focused to a tight spot, enabling applications like laser
cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over long distances
(collimation), enabling applications such as laser pointers. Lasers can also have hightemporal
coherence which allows them to have a very narrow spectrum, i.e., they only emit a single color of light.
Temporal coherence can be used to produce pulses of light—as short as a femtosecond.
A maser (/ˈmeɪzər/) is a device that produces coherent electromagnetic waves through
amplification by stimulated emission. The word "maser" is derived from the
acronym MASER: "microwave amplification by stimulated emission of radiation".
Solid state devices
Are electronic devices that are entirely built on semiconductor.
Eg. ROM, Flash RAM. Integrated circuits, LCD.
Satellite Communication
What Is a Satellite?
A satellite is an object that moves around a larger object.
Types
1. Fixed satellite service (FSS)
• Links for existing telephone networks
• Transmitting TV signals to cable companies.
2 Broadcasting Satellite Service (BSS)
• Direct to home (DTH) =Direct broadcasting satellites (DBS)
3. Mobile satellite service (MSS)
• Land mobile, maritime mobile and aeronautical mobile
4. Navigation satellite service (GPS)
• Global positioning system (S&R)
5. Meteorgolical satellite service (Weather Forecast)
6. Deep Space Satellites
LEO Satellite
Circular/slightly elliptical orbit under 2000 km
MEO satellite
Circular orbit at an altitude in the range of 5000 to 12,000 km
USES:
1.
2.
3.
4.
5.
6.
7.
Weather Forecasting
Radio and TV Broadcast
Military
Navigation
Global Telephone
Connecting Remote Areas
Global Mobile Communication
Modulation?
In electronics and telecommunications, modulation is the process of varying one or more properties of a
periodic waveform, called the carrier signal, with a modulating signal that typically contains information to
be transmitted.
Analog modulation methods
In analog modulation, the modulation is applied continuously in response to the analog information signal.
Common analog modulation techniques are:

Amplitude modulation (AM) (here the amplitude of the carrier signal is varied in accordance to the
instantaneous amplitude of the modulating signal)
 Double-sideband modulation (DSB)
 Double-sideband modulation with carrier (DSB-WC) (used on the AM radio broadcasting
band)
 Double-sideband suppressed-carrier transmission (DSB-SC)
 Double-sideband reduced carrier transmission (DSB-RC)
 Single-sideband modulation (SSB, or SSB-AM)
 SSB with carrier (SSB-WC)
 SSB suppressed carrier modulation (SSB-SC)
 Vestigial sideband modulation (VSB, or VSB-AM)
 Quadrature amplitude modulation (QAM)

Angle modulation, which is approximately constant envelope
 Frequency modulation (FM) (here the frequency of the carrier signal is varied in accordance to the
instantaneous amplitude of the modulating signal)
 Phase modulation (PM) (here the phase shift of the carrier signal is varied in accordance with the
instantaneous amplitude of the modulating signal)
Digital modulation methods
an analog carrier signal is modulated by a discrete signal. Digital modulation methods can be considered
as digital-to-analog conversion, and the corresponding demodulation or detection as analog-to-digital
conversion.
Fundamental digital modulation methods
The most fundamental digital modulation techniques are based on keying:

PSK (phase-shift keying): a finite number of phases are used.

FSK (frequency-shift keying): a finite number of frequencies are used.

ASK (amplitude-shift keying): a finite number of amplitudes are used.

QAM (quadrature amplitude modulation): a finite number of at least two phases and at least two
amplitudes are used.
In television
FM is used for audio
VSB-AM is used for Video
QAM is used for colour information
NTSC and PAL are video standards that are recorded on the cassette. These videos send
and electronic signal to the television, then only it can be viewed. In, India, PAL
video format is supported. NTSC is the video standard commonly used in North America
and most of South America.
The Fields Medal, officially known as International Medal for Outstanding Discoveries in Mathematics,
is a prize awarded to two, three, or four mathematicians under 40 years of age at the International
Congress of the International Mathematical Union (IMU), a meeting that takes place every four years.
Manjul bhargav ko mila is saal