Construction of SCR

Silicon controlled rectifier is an electronics devices which is true electronics switch is known as rectification .
Constructions details:
It is solid state semiconductor devices with the three terminals.It consists of one pn diode and other npn transistor in the single crystal.It is pnpn semiconductor in the single .First p-type material is named as anode terminal (A) ,last n-type material is named as cathode terminal (K) and third p-type material is named as gate terminal (G).It is must popular devices in controlled manner.This devices is used in many electronics devices when gate controlled switching is needed.
Anode terminal is connected in high positive potentials with respect to cathode terminal whereas gate is connected little high positive potential with respect to cathode terminals.

Here gate potential is used to controlled to the flow of current from anode terminal to the cathode terminal .This construction is same as Shockley diode but is has three terminal and different applications.

SCR

Introduction:
It is invented in 1957.Its full form is Silicon Controlled Rectifier .It is very very important electronics element after diode and transistor elements.It is an electronics devices which is used in switching circuit in the electronics devices.It is used in switching circuit as rectification,inversion and regulations of power flow .It has wide range of application in the electronics and communication field ,by which world beings so advanced or huge revolution.Silicon controlled rectifier has more importance because it can be handle several thousand of amperes and up to more than 1kV voltages.
It is true electronics switch in the many electronics circuit .It is used in very fast electronics switching system .It is used in the circuits as in a.c and d.c ,rectification of a.c to the controlled d.c and converting d.c to the regulated a.c. etc.
Its name is different depended upon the costumer such as thyristor,thyroid transistor.In this devices , there are three terminal which are named as anode ,cathode and gate.It is a proper construction of pn diode and npn transistor in the single crystal.

Working principle of Transister

PNP transistor:

When common base connection of a NPN transistor.In the forward bias connection of the first PN junction ,it causes the majority charge carrier(holes) in the P-type ,flow from emitter to the base region .This constitutes the emitter current (Ie) in the transistor.As these majority carrier (hole) cross in to N-type base .They are combine with the electron .Only the few hole (i.e less than 5%) combine with the electrons ,because the base of this transistor is lightly doped and very thin .Expects those holes ,all other i.e More than 95% cross in to the collector region.This constitutes collector current (Ic). In this process ,almost the whole emitter current (holes) flows into the collector region .So in this transistor ,current conduction in the circuit is by holes.

Ie=Ic+Ib
Where ,
Ie=emitter current,
Ic=collector current and
Ib=base current

NPN transistor:
When common base connection of a NPN transistor .In the forward bias connection of the NP junction,it causes the majority charge carrier(electrons)in the N-type ,flow from emitter to the base region.This constitutes the emitter current(Ie) in the transistor.As these majority carrier(electrons)cross in to the P-type base.They are combine with the holes.Only the few electrons(i.e less than 5%) combine with the holes ,because of this transistor is lightly doped and very thin.The remainder i.e more than 95% cross into the collector region.This constitutes collector current (Ic).In this way the whole emitter current (electrons)flows into the collector region .So in this transistor, current conduction in this circuit is by electrons.

Transister

Transistor is an electronics devices which has wide range of applications in electronics and communication field .Before the discover of the solid state semiconductor transistor ,vacuum tube transistor or mercury value are used to make the transistor .It is bigger in size ,low accuracy or efficiency ,difficult to make it, high cost etc .So when semiconductor transistor is discovered in 1948 by American scientists .From this time above type of transistor was replaced by semiconductor because it overcome the drawback of those type of transistor.It contains P-type of semiconductor and N-type of semiconductor in proper quantity.There are two type of semiconductor transistors:

1. P-N-P type transistor
2. N-P-N type transistor

It is used in the place of triode.
In P-N-P type of transistor N-type semiconductor of thin slice is sandwich between P-type semiconductor crystals.In this transistor left P-region is emitter,middle plates is base and last P-region is collector.Emitter is connect to the positive potential and collector is connect to the negative potential with respect to base terminal.Here left side of PN junction is forward bias that means high resistance .The direction of current is as shown below.

In N-P-N type of transistor P-type semiconductor of thin slice is sandwich between N-type semiconductor crystals.In this transistor left N-region is emitter,middle plate is base and last N-region is collector .Here emitter is connected to negative potential where as collector is connected to positive potential with respect to base .It just opposite to the P-N-P type semiconductor .The direction of current is opposite to P-N-P transistor.

Breakdown mechanism

This process is must useful to know about diode function and operate of it .If the reverse bias voltage is made to high ,the current through the PN junction increases rapidly at Vz. The voltage at which this happens is known as Breakdown Voltage or Zener voltage .There are two mechanism which cause this Breakdown .This two mechanism are as followings:

1. Zener Breakdown
   
2. Avalanche Breakdown

When reverse bias voltage is increased the electric field at the junction also increase.At some stage the electric filed becomes so high ,then it breaks the covalent bonds creating electron hole pairs .Thus a large number of carriers are generated . This cause a large number of current to flow .This mechanism is known as Zener breakdown.

At high reverse voltage due to high electric field ,the minorities charge carrier ,While crossing the PN junction acquires very high velocities .These by collision breakdown the covalent bonds generating more charge carriers .A chain reaction is established giving rise to high current .This mechanism is known as Avalanche breakdown.

The covalent bonds where the junction breakdown liberating large number of electron pair .Then the reverse current is increase highly to high amount .This avalanche breakdown may damage the PN junction .This phenomenon is used to zener diode and used in voltage regulator.

PN Junction

When a pieces of p-type and pieces of N-type material are joined in such a manner that crystal structure remain continuous at the boundary ,then a PN junction is formed .This type of junction is known as PN junction diode.
The negative ions on the P-type S/C and positive ions on the N-type S/C are immobile .The majority hole carrier from the P-side diffuse into the N-side,and the majority electrons from N-region diffuse into P-region.Due to the above ,the electrons and hole at the junction region combine and disappear,i.e covalent bond are completed.As a result, a layer of negative ions on the P-side and the layer of positive ions on the N-side is formed at the junction.In this region,due to recombination of electrons and holes depletion of charge carrier occur to this region is called depletion region .The charge density on the two sides of the junction (due to ions layer )The uncompensated ions layer in the depletion region generate an electric field in this region .The electric field points from N-side to P-side .This electric field prevent s further diffusion of holes from P-region .It also prevent further diffusion of electrons from N-side to P-side .The barrier electric field gives rise to a different of potential from one side to other side .this is known as barrier potential. For Silicon PN junction the barrier potential is about 0.7 V whereas for Germanium PN junction is about 0.3 V. For hole the potential on the N-type S/C is higher .Holes can not cross the depletion region because of this barrier potential.

TV

In radio communication there is only audio signal is transmit.So we can only listen the the sound signal .But in Television system we can listen and see video or picture. Here are two type of signal is used i.e sound signal and video signal.So it is so complex than radio communication system in both transmitter side and receiver side.It should transmit both sound signal and video signal and received both signal.In this system monitor is used to display the image or video signal , and loudspeaker is used in out put to produce sound signal.
Television means ,tele refer' far' and vision refer 'to see' .There are followings type of display units:

1. Cathode ray tube (monitor)
2. LCD(liquid crystal display)
3. Matrix display
4. Plasma type display

In cathode ray tube ,it contains electric gun to produce electron,accelerator ,deflection coil( i.e horizontal deflection and vertical deflection) to synchronize the the picture in the monitor ,phosphorous coatings to produce light according to input signal of it .It is cheaper than other display unit ,because it consume more power , picture quality is low ,low durable etc.
In LCD system it is very popular now a days ,Because of its properties i.e it consume low power ,high durable and good picture quality ,but its prise is high than cathode ray tube .It contains polarizing liquid ,crystal elements,LCD monitor internal power supply board contain bridge rectifier,Capacitor filter,schoctky diode,SMPs transformer ,output capacitor filter,fuse Ic power, optoisolator.
Matrix display is like calculator display using matrix technology .It is similar to LCD and plasma type display also.In this type of display overcome some of the drawback of both LicquidCrystal Displays and Cathode Ray Tubes .We can manufacture in large size (upto 50 inechs).Wide range of horizontal and vertical viewing angles, Although sharply focused image with the more colours ,it consume more voltage.

Radio

In science and technology field radio plays important role to develop the world in information and technology , advertisements, social work or activities , politics ,educations ,communications etc. There are two type of radio on the basis of working principles:

1. Tune- radio
2. Super-hetero dyne radio

Tune radio is an old type of radio system It connect only one channel at a time . Because of tune of RF signal process it has more distortion ,less efficiency ,more noise and interference .So this type of radio is not good in the broadcasting system .

Super-hetero dyne radio type of radio principle is modern type of technology .It contain mixer , local oscillator ,RF filter in one circuit which help to trap the RF constant frequency .at the out put of mixer .So it tune accurate channel . It reduce to RF signal return back from mixer through antenna.So it is high efficiency ,less distortion and less interference , low noise in this type of broadcasting.

It is a simplex communication system It means it transmit RF signal from transmitter site to receiver site. So we only able to listen but dose not reply from receiver site .So this type of communication is known as one way communication system.

Radio work at short wave(SW) frequency and medium wave (MW) frequency.

There are three type of signal in radio communication:

1. carrier signal
2. Modulating signal (audio signal or base band signal)
3. modulated signal

There are three type of modulation:

1. Amplitude modulation
2. Frequency modulation
3. Phase modulation

In amplitude modulation ,amplitude of carrier signal is change according to amplitude of modulating signal.Here other characteristics like frequency and phase remain unchanged .This type of modulation system is known as amplitude modulation.

In FM,frequency of carrier signal is varies according to the frequency of audio signal whereas other i.e amplitude and phase remain unchanged.This type of modulation is known as frequency modulation.

In PM,phase or angle of carrier signal is change according to phase of audio signal and other i.e frequency and amplitude remain unchanged.

Passive components

Passive components is that which characteristics is constant or dose not vary in all condition in the circuits.In electronics and communication field there are followings are the passive components :

1. Resister
2. capacitor
3. inductor

Resister is a electronics components which oppose the current in the circuit ,this property of resister is known as resistance.We can calculated this by using following formula:

1. R=V/I

Where,R=resistance in ohms
V=voltage in volts
I=current in amper
Capacitor is a electronics components which is used to store the electrical power is the circuit ,this property of capacitor is known as capacitance .We can calculated this by using following formula:

1. C=Q/V

where,C=capacitance in farads
Q=charge in coulombs
V=voltage in volts
There are two type capacitor which are followings:

1. Electrolytic
2. Non-electrolytic

Inductor is an electronics components which oppose the voltage in the circuit this property of inductor is known as inductance.

Diode

It is an electronic component .Before many years ago ,vacuum tube diode and transistor ,mercury arc values are used in many electronic devices.But they are in bigger in size,very difficult to manufacture and to make the electronics devices ,costly .So it can not be used in protable electronic devices ,it is not so efficient then solid state semiconductor devices .
When solid state semiconductor was invented then there are huge revolution in electronics and communications field because of their smallest in size ,very highly efficient ,easy to manufacture of it and very low cast . So it has wide range of application in this field and become very popular . It make help to invent the transistor and integrate circuit .

They are many type of diode but we are discussed only followings type of diode which are made by silicon and Germanium.

1. Normal diode
2. Zener diode
3. Light emitting diode(LED)
4. Power diode
5. Shocklcy diode
6. Photo diode
7. Varactor diode
8. Optocopler diode
   

Normal diode is used in mainly in rectifier circuits ,signal trapper circuits , power section etc. It conduct only one direction i.e from positive polarities to negative polarities.So it is work in forward bias connection .If it is connected in reverse bias system it may be damage.Silicon diode has 0.3 V breakdown voltage where as Germanium has 0.7 V. After this breakdown voltage it conduct the signal.

Zener diode component only work in reverse bias connection.It is used mostly in voltage regulator , inductor or coil protect circuits ,power section of electronics devices.It allow to pass constant voltage in regulator .After breakdown voltage it is ready to conduct or pass the constant voltage . Most of all electronics devices work in constant range of input power or voltage so is help for this purpose and become popular in this field .

Light emitting diode ,it beautiful diode components .It is work in forward bias connection.This type of diode is not made by Silicon andGermanium but by Galium ,Arsenic,phosphorus etc.Above those silicon and germanium diode change current in to heat But this diode change into light .Colour of light is depends upon the combination of elements in proper quantity.It is very usefully in lightnings system in required places.

Power diode ,it is used in power electronics equipment ,where high power is used .If other diode is used it can be damage so it is used in high power equipment and electrical equipments.It contain heat sink which observe the heat produce in this component.

Shocklcy diode,it is named by inventer.this is PNPN diode of two terminals diode .It is used in switching circuit.It consists of four layer of P- type and N-type of semiconductor in alternate ways.

Photo diode, this type of diode work in reverse -bias connection .It conduct reverse current when it is exposed in the light.

Varactar diode, this is act as variable capacitor by its PN junction in reverse bias.

Optocupler diode, it is combination of LED and Photo diode in one crystal.

Antenna

In this world there are many type of antenna ,because it has wide range of application in broadcasting and communication field i.e radio broadcasting ,television broadcasting, mobile communication,microwave communication,satellite communication ,military communication etc.

We must have the knowledge about antenna type, characteristics, wave radiations pattern,installations of antenna.If you are going to installation of antenna then you must take attention about those and following parameters:

1. antenna gain
2. efficiency of antenna
3. impedance matching
4. input power
5. output power
6. bandwidth
7. polarizations

Fundamental theory of antenna is that it is a kind of transducer.Transducer is a electronics devices which convert one form of energy into other form of energy ,i.e non-electrical into electrical and vice-verse.

Antenna convert electrical signal into electromagnetic wave and vice-verse at output and input respectively.
Generally 73ohm impedance antenna is used in radio receiver. For commercial purpose 50ohm
antenna is used in receiver and for consumer purpose 75ohm antenna is used in receiver.
According to the construction of antenna they are following type:

• dipole antenna

• folded dipole antenna

• yagi antenna

• parabolic dish antenna

• helical antenna

• microwave antenna

According to wave radiations pattern they are following type:

1. uni-directional antenna
2. bi-directional antenna
3. Omani-directional antenna

In uni-directional antenna ,wave propagation is only one particular direction.

In bi-directional antenna,wave propagates in two opposite direction.

In Omani-directional antenna,wave propagates in all rounds or all direction.

Although those all are known ,you must know about wave propagation in the space.There are following type of wave propagation:

• ground wave propagation

• space wave propagation

1. straight wave propagation(line of sight i.e LOS )

• sky wave propagation

• 

HPF , BPFand BSP

Theory of high pass filter:
High pass filter allow to pass the wanted high signal and blocked to the low unwanted signal.
Explains of its:


It is just opposite to Low pass filter .It has capacitor in series and inductor in parallel .The capacitor allow to the high signal and blocked to the low signal .The inductor allow to the low signal and blocked to the high frequency .So its out put is high frequency signal.For this uses the proper value of capacitor and inductor .
Theory of band pass filter:
In LC band pass filter it allow to the certain bandwidth signal and blocked to the below and above to this bandwidth signal.
Explains of its:


Functions of cap actor and inductor it only allow to pass the certain bandwidth of frequencies.We must choose the proper value of these.
Theory of band stop filter:
It blocked to the certain wanted bandwidth of frequencies and allow to pass the below and above to it .


Note:There are other type of filter ,but their working principles is similar .If you are try to construct desire filter you must pays to attention about value of capacitor ,inductor ,resister, its cutoff frequencies, efficiency ,gain and uses of its.

Low pas filter Theory &explains

Theory :
It is used to pass the low signal which you wants and blocked the unwanted high signal .

Explains:


It consist of one inductor L and one capacitor C as shown in above figuer.Here inductor is used in series and capacitor is used in parallel to its input power . Inductor acts as closed circuit in low impedance where as it acts as open circuit in high impedance
If there is low frequency, inductor has low impedance and if there is high frequency, inductor has high impedance.So its allow to the low signal and blocked to the high signal.
Capacitor acts as closed circuit in low impedance where as it acts as open circuit in high impedance .If there is low frequency, capacitor has high impedance and if there is high frequency, capacitor has low impedance.So its allow to the high signal and blocked to the low signal .This two components working principle is opposite to each other.
If we used proper value of capacitor and inductor then we get desire output .

LC filter

Introduction:
In electronics and communication field many type of filter is used .Like RC(register capacitor)filter ,RL(register inductor ) filter,LC(inductor capacitor )filter all of those are passive filter and active filter like Op-amps using filter etc.Most of this filter LC filter is widely used in radio broadcasting ,and any other communication field electronics equipments .It is very important section of equipment.It is used after power section mostly.It is used to pass the wanted signal and blocked the unwanted signal .It is also used to removed the ac(alternative current) ripple and only pass the DC(direct current) that means continuous wave.It is widely used to minimized the wave distortions.Now inductor or radio coil (choke) is easily find or made in home so LC filter is more popular in this field .They are followings type of LC filter :

1. Low pass filter
2. High Pass filter
3. Band pass filter
4. Band stop filter
5. k-type constant filter

Note:This type is depends upon the location of inductor and capacitor i.e series or parallel to the input power and to those components.

Semiconductor

Now science and technology are so advanced and world is diminished by it .Day by day new technology is invented. In semiconductor field , there are so advanced and new.S/C(semiconductor) is neither conductor nor insulator.It is depend upon the temperature.There are
many semiconductor devices like diode, transistors,IC(integrated circuit).Without semiconductor all electronics equipments was not invented and world not so developed.
These are solids in which the forbidden energy gap between the valence band and conduction band is small,of the order of 1eV.At zero kelven temperature,the valence band is completely filled and conduction band is completely empty .At 0K ,it behaves as an isulator (electron can not absorb infinite small energy because there is forbidden gap just above the top of the valance bands .At finite temperature ,some electron gain energy due to thermal motion and jumpe from the top of the valance bands to the conduction band .These electron contribute to the conductions of electricity in the S/C.
The forbiden gap in S/C is small 1eV.At finite temperature ,some valance electron goes to conduction band.Then the formlessly is in the middle of the gap . The energy gap in some S/C is as followings:
silicon=1.12eV
Germinium=0.7eV
Indium antimonide=0.7eV
Gallium arsenide=1.43eV
Tellurim=0.33eV
The energy gap decercase slightly with the increase the temperature.
Type fo Semiconductors

1. Intrinsic S/C
2. Extrinsic S/C

Intrinsic S/C is a pure form of S/C.The impurity must be les than 0.01 parts per millon . At low temperature all the valance electron are tightly bonded and no free electron is aviable for electrical conduction .So this type of S/C behaves as a prefect insulator at zero kelven temperature .If the temperature is increase then ,some of the electron may gain enough thermal energy and move away from the influnce of th nucleus i.e the covalent bond may be broken and it act as conductor.

There are two type of Extrinsic semiconductor ,one is P-type semiconductor and other is N-type semiconductor .Co valence element like Silicon(Si),Germanium (Ge)etc are used to made those two type of s/c.The proces of adding impurities to the S/C element is called doping.Mostly those two type of element is used mostly.If pentavalent element(from group V such as Arsinic ,antimony, phosphrous etc.) is doped in Silicon or Germanium in proper quantity then this type of semiconductor is known as N-type semiconductor where as if trivalent element(from III group such as Aluminium,Gallium,Indium etc.) is doped in proper quantity then this type of semiconductor is known as P-type semiconductor.The conductivity of extrinsic S/C is controlled by the amount of doping .In N-type semiconductor ,majority carrier is electron and minority carrier is hole where as in P-type of semiconductor,majority carrier is hole and minority carrier is electron.

Microphone and loudspeaker

It is a kind of transducer,which convert the sound signal into electrical signal.According to their characterstics ,size and applications they are many types, like dynamic microphone,capacitive microphone ,crystal microphone etc.According to those types their basic workings principles, theory are different.In the case of dynamic microphone its principles is that when sound is produced ,its diaphragm is vibrates according to sound signal and produced electrical signal.Micro
phone characterstics involves signal to noise ratio, bandwidth,distortion,their size etc.It is just opposite to loudspeaker.They are come together in applications field ,like radio broadcasting, public
addressing systems telecoms,mobile communications, or every communications field.It has wide range of applications or uses.Microphone plays important role to developed the world by new communications
technology.
Loudspeaker is a kind of transducer,which convert electrical signal into sound signal.According to their characteristics ,size and applications they are many types.This is more usable electronics equipment in communications field,advertising's system etc.

Objective

In this website we are able to find about your all electronics equipments . We are also able to enhanced your knowledge about new equipments.Day by day the world become close by new technology.To know about technology witch are used in new equipment like digital computer, PC5 , digital camera,camcorder etc.To find out circuits layout,PCB designs.To know about new software which are used in new equipments.To get new ideas to creates any electronics circuits. To know about electronics components,its manufacturing process, cost of components its quantities or number used in ckt.Many people try to gain new knowledge but they don't have any ideas about how to gain it in every time,it is one way to gain new things by website .This website help you to find or gain knowledge about electronics equipments and components.Now a day this is possible to learn new technology .Main things about this is that to get new process new theory ,new equipments are come out in market but we don't have any ideas to proper uses ,this website helps us to uses of its.Science and technology are change day by day so we are able to know about those science and technology.This website help you to downloads about new articles and ckts.