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2222a simple question

Discussion in 'General Electronics Discussion' started by elioacm, Jul 17, 2013.

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  1. elioacm

    elioacm

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    Jul 7, 2013
    im new to electronics, wondering how do i connect this

    i know that its E B C but i cant seem to find out the proper way to put it on a breadboard, ive seen some on the net, but their led is blinking and mine is not..

    can you help me how to input it on a breadboard? assuming i have a 9 voltage..
    and can u tell me how the diagram goes. (the two above npn an pnp) how it looks on a breadboard..

    the one below is what ive done and its not blinking.

    [​IMG]

    http://i1331.photobucket.com/albums/w581/michaelcaoile1/question2_zps98703a93.jpg


    thanks :)
     
  2. BobK

    BobK

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    Jan 5, 2010
    You need more than a transistor and resistor to make an LED blink.

    To drive an LED with an NPN transistor, the connections should be as follows:

    LED + to resistor to battery +
    LED - to collector
    emmiter to ground
    base to resistor to control voltage.

    Then the LED will be on if the control voltage is high and off if it is low, but it will not blink on it's own. You will need a circuit that switches the control voltage on and off at the desired blink rate.

    Bob
     
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    The traditional way to make an LED blink is the two-transistor astable multivibrator. See http://www.reprise.com/host/circuits/transistor_flasher.asp. There are two diagrams there; the left hand one uses NPN transistors and is the usual one.

    It says that the supply voltage range is 5~12V but that's wrong; it shouldn't be used above about 6V.
     
  4. elioacm

    elioacm

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    Jul 7, 2013
    i followed the schematics maybe im wrong cause its not blinking though the led is LIT
    can you show me how to put it on a bread board Kris?

    for bob same result its not blinking im wondering maybe my transistor isnt 2n2222 cause on the fron its just 2222a..
     
  5. BobK

    BobK

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    Jan 5, 2010
    Just about any NPN will work.

    Can you show us a photo of your circuit on the breadboad that allows use to check the connections?

    Bob
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
  7. BobK

    BobK

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    Jan 5, 2010
    How are you wiring it now?

    Bob
     
  8. elioacm

    elioacm

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    Jul 7, 2013
    hey bob here it is.
    [​IMG]
    <a href="http://s1331.photobucket.com/user/michaelcaoile1/media/IMG_20130721_171928_zps477abb55.jpg.html" target="_blank"><img src="http://i1331.photobucket.com/albums/w581/michaelcaoile1/IMG_20130721_171928_zps477abb55.jpg" border="0" alt=" photo IMG_20130721_171928_zps477abb55.jpg"/></a>

    as what kris showed something not right there, though the led is on ('assume'), maybe i need to buy more items, but ohm resistors here the lowest is at 1k ohm.

    and thanks kris. though i searched that already got some hard time reading schematics, just checking.. thanks btw . but a good presentation o n a bread board might help :) like the one on your first reply..
     
  9. BobK

    BobK

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    Jan 5, 2010
    Perhaps you misunderstood my first post. I was describing the circuit needed to turn an LED on and off via an electronic signal, not one that flashes it.

    Did you look at the astable multivibrator circuit linked by Kris in post #3? That is a circuit that will flash an LED. It needs 2 transistors and a lot of other components.

    Bob
     
  10. elioacm

    elioacm

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    Jul 7, 2013
    okay bob ill follow the circuit kris gave and if ive got problems ill post a pic :) and other with resistors, those are a little bit hard for me to understand, so there are much to be a trial and error here so hope both of you stay tuned

    ill repost after i followed kris circuit

    and btw,

    wheres the emitter when im holding the transistor flat surface facing me and round facing away..
    from left to right.. i know that base is the middle..
     
    Last edited: Jul 21, 2013
  11. BobK

    BobK

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    Jan 5, 2010
    The pins are identified as 1, 2, 3 from left to right when holding the flat side facing you and the pins down. Which pin is the E, B and C differs between different models.

    http://en.wikipedia.org/wiki/TO-92

    The PN2222 has 1 E, 2 B, 3 C

    Bob
     
  12. davenn

    davenn Moderator

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    Sep 5, 2009
    elioacm

    there are such things as blinking LEDs ya know ?

    Dave
     
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