Pn2222a

Discussion in 'General Electronics Chat' started by rvm.karthi, Feb 10, 2010.

  1. rvm.karthi

    Thread Starter New Member

    Dec 29, 2009
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    hI I AM MAKING A CIRCUR WHICH HAS PN2222A TRANSISTOR AS SWITCH... MY DOUBT IS HI=OW MUCH VOLTAGE REQUIR IT TO TURN ON....? ALSO FOR ALL OTHER GENERAL TRANSISTORS....?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    To be literal, about 700 mv will forward bias the transistor into conduction.

    You probably want to know the level of base current to operate the transistor as a saturated switch. Our Ebook may give you some guidance - http://www.allaboutcircuits.com/vol_3/chpt_4/2.html
     
  3. Wendy

    Moderator

    Mar 24, 2008
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  4. rvm.karthi

    Thread Starter New Member

    Dec 29, 2009
    13
    0
    Thankz u all.... Will be back with someother ....
     
  5. rvm.karthi

    Thread Starter New Member

    Dec 29, 2009
    13
    0
    Hi
    i am here with a new prob...i would like to turn on this transistor(2222a) using the o/p from IR phototransistor...i use 5vdc with 330 ohm reistor for IR phototransistor...also i like to turn on the 12vdc relay when the transistor(2222a) turned on....pl help me...
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,

    Can you post a schematic of the circuit that you have upto now?
    In that way we can have a look what needs to be changed.

    Greetings,
    Bertus