Hold Relay for 5 seconds

Discussion in 'The Projects Forum' started by Chirantha, May 22, 2010.

  1. Chirantha

    Thread Starter New Member

    May 22, 2010
    2
    0
    Hi,

    I ran into this http://forum.allaboutcircuits.com/showthread.php?t=16210 on Google.

    Post 4 is what I exactly need but I don't know what resistors or transistors to use.

    I just need to hold a 12V relay for 5 seconds even after losing power. The circuit will be operating on a 12VDC power source.

    Help Me, :(
    Thanks
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    The first line of post #4 that you are referring to tells you the formula to get the time constant.

    Read the rest of the thread, they explain it for 5 seconds, giving the resistor and CAP values.
     
  3. Chirantha

    Thread Starter New Member

    May 22, 2010
    2
    0
    Ok I fried four D400 transistors and one C828.

    Can someone tell me why B C E are in different location on different books? :S

    I'm so confused

    I have a 16V 1000uf Cap! someone please guide me.
     
  4. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Different transistors have different pin outs. They can change from manufacture to manufacture, even model to model.

    One thing that will drive you nuts, some wiring diagrams show the layout as you are looking through the bottom of the board, and some the top. This is often labeled on the schematic, but often not.
     
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