Small bulbs always burning out.

Discussion in 'Lighting' started by Peter Jason, Feb 9, 2013.

  1. Peter Jason

    Peter Jason Guest

    I have a truck with a plurality of lamps, of 12V,
    21W.

    They don't last long and replacing them is a
    tedious chore.

    I want to reduce the voltage to each bulb to take
    the load off the filament and so extend its life.

    They are bayonet fittings, and so I seek a small
    thin disk of some resistive material to put into
    the lamp socket to contact the center terminal, so
    that when the bulb is inserted this will act as a
    resistor so reducing the voltage by a small
    amount. Clearly the inserted bulb will hold the
    material in place.

    What can I use? Graphite, iron, lead, or some
    form of nichrome? Is there any other
    low-conductive material available in sheet or disk
    form?

    I am sick of replacing these bulbs, and they're
    not cheap!

    Please help, Peter
     
    Peter Jason, Feb 9, 2013
    #1
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  2. Peter Jason

    Guest

    Peter Jason <> wrote:
    > I have a truck with a plurality of lamps, of 12V, 21W.


    Sounds like the 1156 (ANSI number) that was popular in older US cars
    and trucks. Usually available for about $1 apiece, cheaper if you
    buy a box of 10 at NAPA. For a little more money you can get a "long
    life" version with approximately twice the rated life.

    > They don't last long and replacing them is a tedious chore.


    How's your electrical system? If you see much over 14.0 volts at the
    battery, or over about 12.8 volts at the fixture, with the engine
    running at 2000 rpm (gas/petrol) or, say, 1500 rpm (diesel), fix that
    first and your lamps will last longer.

    Were the fixtures installed by the manufacturer, or a later addition?
    If added later, how well are they mounted? Loose and floppy fixtures
    burn out lamps. Are they well sealed? Water leaking in will burn out
    lamps.

    > I want to reduce the voltage to each bulb to take the load off the
    > filament and so extend its life.


    This also makes it dimmer, which makes your truck harder to see.
    Dropping the voltage to 90% of rated voltage will make the lamps last
    about three times as long... but it will also cut their light output by
    about 30%.

    There are LED replacements available, but they usually send all the
    light in one direction, which is not a good match for the original
    lamp. The fixture will be highly visible from one direction only and
    hard to see from all other directions.

    > They are bayonet fittings, and so I seek a small thin disk of some
    > resistive material to put into the lamp socket to contact the center
    > terminal, so that when the bulb is inserted this will act as a
    > resistor so reducing the voltage by a small amount.


    Normally, if a voltage reduction is needed, it is done inline with the
    wiring to the fixture.

    Matt Roberds
     
    , Feb 9, 2013
    #2
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  3. Peter Jason

    Peter Jason Guest

    On Sat, 9 Feb 2013 09:38:43 +0000 (UTC),
    wrote:

    >Peter Jason <> wrote:
    >> I have a truck with a plurality of lamps, of 12V, 21W.

    >
    >Sounds like the 1156 (ANSI number) that was popular in older US cars
    >and trucks. Usually available for about $1 apiece, cheaper if you
    >buy a box of 10 at NAPA. For a little more money you can get a "long
    >life" version with approximately twice the rated life.
    >
    >> They don't last long and replacing them is a tedious chore.

    >
    >How's your electrical system? If you see much over 14.0 volts at the
    >battery, or over about 12.8 volts at the fixture, with the engine
    >running at 2000 rpm (gas/petrol) or, say, 1500 rpm (diesel), fix that
    >first and your lamps will last longer.
    >
    >Were the fixtures installed by the manufacturer, or a later addition?
    >If added later, how well are they mounted? Loose and floppy fixtures
    >burn out lamps. Are they well sealed? Water leaking in will burn out
    >lamps.
    >
    >> I want to reduce the voltage to each bulb to take the load off the
    >> filament and so extend its life.

    >
    >This also makes it dimmer, which makes your truck harder to see.
    >Dropping the voltage to 90% of rated voltage will make the lamps last
    >about three times as long... but it will also cut their light output by
    >about 30%.
    >
    >There are LED replacements available, but they usually send all the
    >light in one direction, which is not a good match for the original
    >lamp. The fixture will be highly visible from one direction only and
    >hard to see from all other directions.
    >
    >> They are bayonet fittings, and so I seek a small thin disk of some
    >> resistive material to put into the lamp socket to contact the center
    >> terminal, so that when the bulb is inserted this will act as a
    >> resistor so reducing the voltage by a small amount.

    >
    >Normally, if a voltage reduction is needed, it is done inline with the
    >wiring to the fixture.
    >
    >Matt Roberds


    Thank you. I've just realized I can wire suitable
    no of lamps in series and effect a reduction that
    way.
     
    Peter Jason, Feb 10, 2013
    #3
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