simple voltage reduction

Discussion in 'The Projects Forum' started by busterstratton, Jun 9, 2006.

  1. busterstratton

    busterstratton Thread Starter New Member

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    hello glad to have found this board I need some help I want to use a battery that is 12 volts to power a 6 volt light that has a rechargable battery(naturally also 6 volts).
    This battery (deep cycle marine) is also used to power our automatic gate opener and is charged through both a 12volt solar panel and a 300 ft run of 16 gauge low voltage wire from the shed
    I want to build a circuitboard that will supply the 6 volts to the light and also electrically trip to come on only when the gate is under power please help thank you
  2. Gadget

    Gadget Distinguished Member

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    As the whole system is solar powered, then obviously efficiency is a concern. Instead of a simple linear regulator I would suggest a basic PWM system. If you remove the 6 volt battery and charging circuit from the light then its only powering a light, so exact regulation isn't important.
    I would suggest a 555 timer supplying a 50/50 squarewave at several kHz to drive a MOSFET, in turn driving the lamp. This will halve the voltage without wasting very much power in the conversion.
    Powering this from the relay contacts that drive the gate motor should be all that is needed to ensure that it only works when the gate motor is working and doesn't draw any standby current when not operating.

    Now, heres an even more revolutionaty idea......
    Remove the electronics and battery from the 6 volt light. Replace the bulb with a 12 volt bulb. Power it directly from the relay output to the motor.
    Cant get much more efficient or simpler than that.
  3. busterstratton

    busterstratton Thread Starter New Member

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    0k gadget I had exactly the same plan earlier but would like to run the 6 volt light off off the relay only need something in the circuit to drop the voltage going to the 6 volt light. Thought mabey a zenner would do just that so that the voltage would go positive to the zenner at 12 volts then 6volts out of the zenner to the light, viola is this not possible???

    Just looking for as simple a circuit as possible (not much maintainance that way).The gate has an aux circuit for the purpose of lights but it is 12 volts and thats why this post exists just need the voltage comming from the relay to drop to 6 volts as simply as possible thank you
  4. Gadget

    Gadget Distinguished Member

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    Not that simple, and like I say, a Linear regulator will waste as much power as it regulates..(6 volts @ "x" amps in lamps, same again in waste heat across the linear regulator)
    What wattage is the lamp... ? A Zener wont do without a series pass transistor...(again a Linear regulator)
    I still recommend replacing the 6v bulb with a 12 volt bulb. Simple, cheap, and 50% of the power isn't being wasted. Is there a good reason why this cant be done..?
  5. busterstratton

    busterstratton Thread Starter New Member

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    ok will replace 6 volt lamp with 12 volt halogen hope not to melt down the reflector thanks gadget thought it would be a simple fix but will listen to you for that is why i am here thanks very much , Buster
  6. Gadget

    Gadget Distinguished Member

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    If you use a 12v bulb of the same type with same or similar wattage, then it should run at a similar temperature.
  7. radiosmoke

    radiosmoke Member

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    You could use two 6volt bulbs in series, just keep the one bulb in the reflector and add another reflector or just hang it in a box.
  8. mrmeval

    mrmeval Distinguished Member

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