Transistor Basics

 

Transistor Basics

what is Transistor?

Transistor is a three semiconductor pin device it is invented by three scientists at the bell laboratories  in 1947. it is made by three layers of doped semiconductors and it constant three terminals 

 Before 1947 we used vacuum tube instead of transistor therefore the electronic devices had large size

for example : first computer in this world is very large because in it Big vacuum tubes are use instead of transistor and a large Equipments and energy was required to maintain these tubes...................

Types of Transistors :

There are basically two types of transistor these are:

1. PNP transistor
2. NPN transistor

PNP transistor

A pnp transistor is a transistor in which n type material is sandwich between two p type semiconductor materials In PNP transistor IE current is emitting from the emitter terminal.

NPN transistor

 A npn transistor is a transistor in which p type material is sandwich between two n type semiconductor materials. In NPN transistor IE current is Entering in the emitter terminal.

mostly npn transistors is used in Electronic Devices

Parts of Transistor :

There Are three important part of  Transistors:

1. Emitter:  Emitter is that comment of the transistor in which max.. current flow       IE>IC>IB
2. Base:      It is the smallest part of transistor and it is lightly doped in this parts IB Current  flow which is very small about in micro amperes
3. collector: Collector is that part of the transistor which is highly doped as compare to emitter and base  

important  Terms used in Transistor :

Important terms used in transistor are:

• Collector current                   IC
• Emitter current                       IE 
• Base current                           IB 
• Beta                                       B   
• Alpha                                     a
• Collector to emitter voltage   VCE
• Base Emitter voltage                       VBE  
• Collector Voltage                   Vcc
•  Emitter voltage                     VEE   

Note:

when diode is operating then emitter base junction is forward base and collector base junction is reversed based

  Configurationof transistor

transistor is used in the circuits in different way for achieve different purposes and these configurations are these:

1. Common base configuration
2. Fixed base configuration
3. Emitter base configuration
4. Voltage divider configuration
5. Common Emitter configuration
6. Feed back configuration

  Important Formulas used in  transistor are:

1.   IE = IB +IC  
2. IE=(B+1)  IB 
3. IE=IC   because IB  approximately zero
4. IC = BIB
5. VCE= Vcc-IBRB -IERE
6.   a=IC/IE

 Used of transistor

Transistor are used for many purposes some are these:

1. It is used as inverter 
2. it is also used for switch 
3. it is used for as amplifier

Thank You.....................................

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