BJT vs FET ( JFET, MOSFET )

                  _____BJT - Bipolar Junction Transistor_____                                                    

   

   

  

Three terminal active electronics device

  Used for amplification and switching








Important Points 

• The current flow through the transistor occurs due to holes and electrons 
• John Bardeen, William Shockley, and Walter Brattain are the inventors of  transistor
• In 1956 they won Nobel prize for the invention
• The first transistor radio was made in 1954 ( Regency TR1 )  

     Doping

             
      The process of adding controlled amount of impurities to a semiconductor is called doping     

• The 3 terminals are named Collector, Emitter, and Base
• Emitter    :-     Heavily doped
• Collector :-     Medium doped
• Base        :-     Lightly doped 

     Configuarions 

1. Common Base                -  Used as constant current source
2. Common Collector         -  Voltage follower ( buffer )
3. Common Emitter            -  Voltage and power amplifier

           

            Parameter                       CB                        CE                 CC

• Input impedance              Very low               Low               Very high
• Output impedance           Very high              Medium          Very low
• Current gain                    Less than 1           High               Higher than CE
• Voltage gain                     High                    High               Less than 1
• Leakage current               Very small            Very high         Very high

     Operating regions

 

1. Cut off region    -   Both input and output are reverse biased
2. Active region  -  Normal region of operation, input forward and output reverse biased
3. Saturation region - Both input and output are forward biased

_____FET - Field Effect Transistor_____ 

    Classisfication

1. JFET
2. MOSFET

    JFET - Junction Field Effect Transistor 

    Classification

1. N - type
2. P - type

    MOSFET- Metal Oxide Semiconductor FET

   Classification

1. Enhancement type
2. Depletion type

BJT vs FET

                        BJT                                       FET

• Biploar                                                Unipolar
• Current controlled                              Voltage controlled
• Less input impedance                         High input impedance
• More noise                                          Less noise
• Difficult to fabricate                           Easy to fabricate
• High gain-bandwidth product             Small gain-bandwidth product

        

RFID - Radio Frequency Identification

RFID ( Radio Frequency Identification ) is an 

emerging technology for the purpose of tracking and 

identification of objects.

RFID technology has two parts :-

1. Tag
2. Interrogator ( Reader )

Important Points

•  The tag consist of a microchip and an antenna coiled around it  
• The microchip is used to store a unique identity and other information 
• The interrogator emits radio waves to activate the tag

OPERATION

   

When an RFID tag is passed through an electromagnetic zone that is produced

 by the interrogator, it detects the activation signal. The reader ( interrogator )

decodes the data encoded in the tag for processing.

CLASSIFICATION

RFID tags are classified into two based on the power source

1. Active tags :- contains internal power source
2. Passive tags :- depends upon the power of the radio waves

 Another classification is based on the programming

1. Class 0 :- Pre-programmed
2. Class 1 :- Can be programmed once
3. Class 2 :- Can be programmed many

RF Frequencies used

1. Low frequency:    125 - 134.2 KHz
2. High frequency:   13.56 MHz
3. UHF :                    2.4 - 2.5 GHz 

Secret mobile phone codes

Nokia codes

• *#3370#           -          Enhanced Full Rate ( activate / deactivate )

• *#06#               -          IMEI

• *#7760#           -          Manufacture code 

• *#92702689#    -          All details about the model ( manufacture data, model, used time etc ) 

• 12345              -          Default password

• *#3283#           -          Manufacture date

• *#7370#           -          Restore factory settings

Sony ericson codes

•  *#0000#               -         Reset English menu

• 904059+>             -         Phone test  ( 3+< to exit )

• >+>>*<*               -         Secret menu

• <**<                     -         Network info

How to remove Recycle Bin from desktop

Step1

• Click Start- Run

• Type gpedit.msc and press Enter or Click OK

         Group Policy window will appear on the screen.

Step2

• Select User Configuration  

• Click Administrative Templates, below to User configuration 

• Double click on  Desktop option on the right side of the window 

• Or click on the  '+' at the left of Administrative Templates and then click on Desktop option 

• Or double click on Administrative Templates and select Desktop  

• Double click on the option - Remove Recycle Bin icon from desktop 

• Click on Enable  option on the window appear to remove Recycle Bin from desktop

• To restore Recycle bin, do all the steps mentioned above and select  disable option at the last step

What is a diode

•  It is the first active electronic device  
• Diode is a two terminal active semi-conductor 
  
• Conducts only in forward biased condition 
• Mostly used for switching and rectification 
• The first semiconductor diodes, called cat's whisker diodes, developed around 1906

• Forward bias :-  +ve to Anode (A) and -ve to Cathode (K).

• Reverse bias :-   +ve to Cathode (K) and -ve to Anode (A).

• Forward voltage drop :- 0.7V.

• PIV :- Peak Inverse Voltage - ( Max. Voltage can be apply in reverse bias ).

• DC resistance : Vd / Id

• AC resistance : ⌂Vd / ⌂Id

Used for

•      Rectification
•      Switching 

Inventions related

• 1904 - Vac cum diode  - JA Fleming

• 1906 - Cat's whisker diode 
• 1938 - Shotkey diode ( hot carrier diode ) - Walter H Shotkey 
• 1958 - Tunnel diode -Leo Esaki
• 1963 - Gunn diode - Gunn

Check a diode

• Reverse bias   : High resistance ( more than 2000K typ ).
• Forward bias   : Low resistance ( 500R - 800R typ ).

How to make a variable power supply using LM317

 

        LM317 - 3 Terminal Positive Adjustable Regulator

• Output range             -        1.2V - 37V 
• Current capacity       -         1.5A 
• Vout                           -        1.25 (1 + R2 / R1) + I adj * R2.                   ( I adj * R2 is neglected ) 
• Package                     -        TO220 
• Line regulation          -         0.01% 
• Load regulation         -         0.1%                           

       *reference voltage - 1.25V

       Circuit

*C2 - 10uf - 470uf 50V is better.( Electrolytic capacitor )
*C1 - 0.1uf - Ceramic capacitor.

*R1 must be 240R.( 0.125W)
*R2 linear potentiometer.

*Diode 1N4007 can be connected across Vout and Vin. 
  ( A of 1N4007 to Vout and K to Vin. )
 

RUN commands in Windows

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Accessibility Controls	access.cpl
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Automatic Updates	wuaucpl.cpl
Basic Media Player	mplay32
Bluetooth Transfer Wizard	fsquirt
Calculator	calc
Ccleaner ( if installed )	ccleaner
C: Drive	c:
Certificate Manager	cdrtmgr.msc
Character Map	charmap
Check Disk Utility	chkdsk
Clipboard Viewer	clipbrd
Command Prompt	cmd
Command Prompt	command
Component Services	dcomcnfg
Computer Management	compmgmt.msc
Compare Files	comp
Control Panel	control
Create a shared folder Wizard	shrpubw
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Display Properties	desk.cpl
Display Properties (w/Appearance Tab Preselected )	control color
Dr. Watson System Troubleshooting Utility	drwtsn32
Driver Verifier Utility	verifier
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Fonts Folder	fonts
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Group Policy Editor ( xp pro )	gpedit.msc
Hearts Card Game	mshearts
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Hyperterminal	hypertrm
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Iexpress Wizard	iexpress
Indexing Service	ciadv.msc
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Internet Setup Wizard	inetwiz
IP Configuration (Display Connection Configuration)	ipconfig /all
IP Configuration (Display DNS Cache Contents)	ipconfig /displaydns
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MS-Dos FTP	ftp
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Netmeeting	conf
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Network Connections	ncpa.cpl
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Notepad	notepad
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Object Packager	packager
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Opens AC3 Filter ( if installed )	ac3filter.cpl
Outlook Express	msimn
Paint	pbrush
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Pinball Game	pinball
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Printers and Faxes	control printers
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System File Checker Utility ( Set Cache Size to Size x )	sfc /cachesize=x
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Zoom Utility	igfxzoom