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O/T DC voltage help

Discussion in 'Uncategorized Threads' started by MGeslock, Dec 10, 2007.

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  1. MGeslock

    MGeslock TS Member

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    I want to hook up a set of battery lights to a wreath on the grill of my truck. The lights call for 2 C batteries that total 3 Volts. The truck is 12 volts. I did a test and of course the lights worked for 5 seconds before they burned out.

    Is there a resistor that can reduce the voltage to 3 volts?

    Thanks!
     
  2. pendennis

    pendennis Well-Known Member

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    This might work.

    Dennis
     
  3. Luigi

    Luigi TS Member

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    Try hooking a 12 Volt light bulb ( 1156 ) in series with your string of lights.
    When the motor is running and the Alt is charging the battery, you
    can have up to 14 to 15 Volts in the circurt.

    Luigi luifra
     
  4. MGeslock

    MGeslock TS Member

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    pendennis,

    Thanks, but I want to hook them into the head lights. I have thought of an inverter and just using AC lights. Not my first choice...
     
  5. cableguy

    cableguy TS Member

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    A ballast resistor 'might' work or, maybe two of them in series. An auto parts store. Older cars used to use them to reduce voltage in the ignition system. Good luck.

    Shawn
     
  6. Brian in Oregon

    Brian in Oregon Well-Known Member

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    Why do they have to be hooked into the headlights? Dennis has a good, simple solution.
     
  7. MGeslock

    MGeslock TS Member

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    I only want them to light up at night. I don't want extra wires running from the dash.

    cableguy, I thought about that. I think that the Chrysler's had them....I think that it dropped only 3 volts.

    Maybe I could use a few in line.....?
     
  8. Brian in Oregon

    Brian in Oregon Well-Known Member

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    Well, in that case, the simplest electronic ciruit is a zener diode voltage regulator. It has only two parts - a resister and a zener diode. The link shows the circuit. Understand that math is involved, as the resister and zener diode have to be matched to the voltage and load. One thing that's unknown is how much load your light string consumes. We know the voltage (3 vdc) but what is the current or wattage rating?
     
  9. MGeslock

    MGeslock TS Member

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    Brian,
    That just may work. I don't know tha watt rating. It will only be a strand of 15 Christmas lights. I will see if they are marked.
     
  10. dward

    dward Member

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    I'd go to Radio Shack and get a DC voltage reducer. They plug into a cigarette lighter and adjust voltage from 12 down to about a volt in 1.5 volt increments. You'll need to splice into the running light circuit with the female end of the plug in, and then plug the reducer to it and set to what ever voltage you want.
     
  11. bigbore613

    bigbore613 Active Member

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    Mark, maybe a real job would help? LOL Jeff
     
  12. MGeslock

    MGeslock TS Member

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    Jeff online at 10:22 AM.....I didn't think that they had PC's at your job... :)
     
  13. arrow

    arrow Member

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    Not sure what current you are drawing but if it is less the 1 amp
    al LM7803 should work. I checked and radio shack has a LM7805 but the 5 volts may be to much. The LM7803 is a series ragulator that will take anything from
    3 volts up to 40 volts in and put out 3 volt. LM7805 cost $1.59
    LM 7803 should be about the same if you can find one.

    Bryan
     
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