Automatic Switching circuit

Discussion in 'General Electronics Chat' started by mahendra0707, Jun 28, 2011.

  1. mahendra0707

    Thread Starter New Member

    Jun 28, 2011
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    Hi
    Can anyone help me in designing a automatic switching circuit which opens and closes in between 20ms and 500ms for 12v and 30A rating.
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What will be the application?
    What is the load to be switched?

    Bertus
     
  3. mahendra0707

    Thread Starter New Member

    Jun 28, 2011
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    Hi thanks for your reply..
    To get the discharge characteristics of a dc battery.It is a resistive load.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What will be the repetition time for the 20 mSec to 500 mSec pulses?
    You could take some very heavy Mosfets that are pulsed.

    Bertus
     
  5. mahendra0707

    Thread Starter New Member

    Jun 28, 2011
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    0
    Initially the switch should be in open position after some time i,e 20ms switch should be closed and after 300ms it should be opened.I need to discharge the battery in different time intervals in the range 20ms to 500ms. What is the best switching timing circuit can be used.
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I would try to use two monostable multivibrators.
    One fixed at 300 mSec and one variable of 20 to 500 mSec.
    The circuits can be found in the thread of Bill_Marsden, who has written a lot about the NE555.
    Next Submission, 555 Monostable

    Bertus
     
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