to help little circut

Discussion in 'General Electronics Chat' started by M.Naeem, Dec 24, 2007.

  1. M.Naeem

    Thread Starter New Member

    Dec 24, 2007
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    dear .i want use 3 bulb each is 12v 4A.But i am using battery 12v 4.5 AH dry battery.some relay or circut to help my circut not much load apply on battery thx. Naeem
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    Deepest apologies dear, but I do not understand your requirements.
     
  3. Dave

    Retired Moderator

    Nov 17, 2003
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  4. thingmaker3

    Retired Moderator

    May 16, 2005
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    I suggest either using smaller bulbs or bigger batteries.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    Definitely bigger battery, with the bulbs in parallel.
     
  6. David Bridgen

    Senior Member

    Feb 10, 2005
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    If I understand correctly, you want to use the 12V 4.5Ah battery to power three 12V 4A bulbs.

    You also want a "relay or circuit" which will reduce the load of those bulbs on the battery.

    If you want the bulbs lit continuously at their full power there's nothing you can do to reduce the power drain from the battery.

    The only way to reduce power from the battery is to reduce the power taken by the bulbs, either by switching them on and off rapidly, or less satisfactorily by putting resistance in series with each bulb (which is wasteful).
     
  7. BlueDevry

    Member

    Dec 26, 2007
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    Could a SCR be used to do the switching ?
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Well, you could use an SCR to turn the lamps ON, but you wouldn't be able to turn it OFF unless you:
    1) Disconnected the battery
    2) Used an inductive kick to momentarily bring the voltage across the SCR to zero, allowing it to turn off.
    3) Wait for the battery to be dead. (Don't worry, in this scenario you won't have long to wait. :rolleyes:)
     
  9. thingmaker3

    Retired Moderator

    May 16, 2005
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    One option for using an SCR would be to run a motor with the battery and run an alternator with the motor. Then the SCR could be used to control the AC. Rube Goldberg would be proud.

    PWM would be simpler, less expensive, and more compact.
     
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