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Long life lights

Discussion in 'Electronic Design' started by Tim Williams, Aug 24, 2008.

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  1. Tim Williams

    Tim Williams Guest

    I've got a problem. I happen to carry the distinction of being the one
    responsible for changing lights. Much as that's a problem in itself, the
    biggest problem is.....the front porch light (surprisingly, it's not a
    stairway light, eh?), which happens to be a hanging, upside-down, enclosed
    fixture. And they put two screws in the thing, so it's almost impossible
    for a single person to replace the bulb thus inserted. Really quite
    remarkable how no one thought of this.

    Besides modifying it, which I may consider because it's just that bad, in
    the mean time I need something that'll last. We've already tried the "ten
    gajillion hour" CFLs, which died in all of, you know it, three months. I'm
    guessing something high voltage (130V+?) and incandescent. Any
    recommendations?

    Tim
     
  2. JeffM

    JeffM Guest

  3. 1. How about CFLs suitable for such things?

    a) - wide temperature range, outdoor: Philips 15 watt "Outdoor". My
    experience is that they mosty last more than a year in outdoor enclosed
    fixtures in/near Philadelphia.

    b) - as far as I know, the "ultimate" high temperature environment CFL:
    Philips 15 watt "Marathon" triple-arch

    That one may run dim in cold weather, even if it is enclosed.

    Be patient with warmup times for wide temperature range CFLs,
    especially in weather cold enough to depend on an enclosure. That can be
    quite a few minutes.

    2. The longest life common variety of incandescent I know of (other than
    indicator lamps for electronic equipment) is "traffic signal lamps". Most
    are rated to last an average of 8,000 hours. Keep in mind that they
    produce about 65% as much light as "standard" incandescents of the same
    wattage. They also mostly come in oddball wattages such as 117 and 92
    watts.

    There are 130V versions of some of these - designed to last 8,000 hours
    at 130V.

    You may have to get them by the case.

    Also, check the fixture's wattage rating. If there is none, it can
    easily be 60 watts.

    3. Incandescent with a series diode, preferably with the incandescent
    of a vibration resistant / "Rough Service"/"industrial service" type.
    And I would have some overkill choice of diode so that it lasts
    through most of the line voltage surges - as in at least a 1KV one rated
    a few amps.

    Be prepared for low light output. Also, power consumption is reduced
    about 40% rather than 50% since the filament's resistance has a positive
    temperature coefficient.
    Furthermore, it may be prudent to choose a lamp whose wattage does not
    exceed the fixture's rating, without relying on the diode not failing
    short to stay within the rating of the fixture.

    - Don Klipstein ()
     
  4. Blarp

    Blarp Guest

    Most CFL's die prematurely because they are placed in a luminaire
    designed for incandescants. I.e. with no cooling.

    Incandescents can stand heat, CFL's respond very badly to (internal)
    heat levels > 100C - mostly the caps die prematurely.

    Solution:

    - Extra cooling holes (and now spiders, insects etc. crawl in)

    - Use a PL lamp with external ballast.

    - 2 incandescents in series (long life, poor efficiency - some
    soldering required?)
     
  5. Brass does not conduct heat better than aluminum.

    - Don Klipstein ()
     
  6. My experience is that diodes do help a lot.

    Keep in mind that the filaments in blinking marquee lights have a much
    greater temperature swing than the filament of a lamp in series with a
    diode.

    - Don Klipstein ()
     
  7. Of course, a 120V incandescent with a diode in series is equivalent to
    a 170VAC incandescent, so you'll get shorter life, but a less "red"
    light, and better efficiency at creating visible light.

    You used to be able to buy button diodes that screwed into the bottom
    of a light socket.
    Best regards,
    Spehro Pefhany
     
  8. Wouldn't you use a pair in antiparallel?

    Thanks,
    Rich
     
  9. Heat kills CFL's, they are not rated for use in enclosed housings.
    No air flow in enclosed space = hot = short life.
    The XXXXX hours rating on the box are usually free-air ratings.

    I've started switching to Envirolux T5 circular fluro's with a
    separate electronic ballast, they run much cooler.

    Dave.
     
  10. There are integral-electronic-ballast CFLs that are sufficiently
    heat-resistant to be rated for use in recessed ceiling fixtures. My
    experience suggests that enclosed fixtures don't get much worse than
    recessed ceiling fixtures.

    Examples of such CFLs: Philips "Marathon" triple arch, of wattages 15,
    20 and 23 watts (but not 25), and only non-dimmable versions. I have seen
    them at Home Depot. Use the 15 watt one when you can.

    The hour rating is median life expectancy in a 25 degree C ambient at 3
    hours per start.

    - Don Klipstein ()
     
  11. Right, this one is from my kitchen, failed early,
    ftp://panteltje.com/pub/philips_9_watt.jpg

    Sorry bad photograph, but if you look close you will see many soldering joints
    sort of worked lose due to thermal stress.
    This bulb was just upside down in in the ceiling, but in free air, like this.

    --------------------
    [ ]
    ||
    ||

    Not sure what is wrong, or even if it is the soldering, it has 2 chips in it.
     
  12. Mark

    Mark Guest

    no.... the solder joints were probably bad from the start

    Mark
     
  13. neon

    neon

    1,325
    0
    Oct 21, 2006
    This might require a little ingenuity and labor. LEXON lights are 7w dissipation or less the size of a dime LEDS that can make those 25 w lights brightness as very dim. I haven't actualy used them myself but my porch light is 25 LEDS superbrights that makes a 15 watts blush. run them directly from 120 ac diode resistor power dissipation about 2 watts total. break a bulb and have fun.
     
  14. I do not think so :)
     
  15. legg

    legg Guest

    A shorter life?
    I found a sidac in one of these buttons. Claimed to reduce inrush.
    Can't see how, as inrush is a simple function of cold element
    impedance. Can't imagine the semiconductor - basically a self-firing
    triac, would last long in that kind of thermal environment - one that
    is not improved by extra crap shoved into the lamp base.

    RL
     
  16. Shorter than a 230VAC bulb on 120VAC, of course.


    See, for example, US 3617766, US 4229680

    Sounds like it would cause nasty RFI continuously.
    Best regards,
    Spehro Pefhany
     
  17. For really long life (and low efficiency), maybe two 120VAC bulbs in
    series with a diode. Yeah, 2 bulbs 1 diode.

    Best regards,
    Spehro Pefhany
     
  18. For 42 volts RMS across each lamp?

    How extreme do you want to go? Put two 300W 120V lamps and a diode in
    series, and power consumption will be about 170 watts. And light output
    will be about 120 lumens. The light output exponent is more than 3.4-3.5
    when voltage is that low.

    A 230V lamp or two 120V ones in series should last long enough. I have
    heard -13 and -14 for that life expectancy exponent, and at times worked
    out -12 for myself. Even if it is -12, a 750 hour 230V lamp would have
    median life of 210 years at 120V.

    - Don Klipstein ()
     
  19. For 42 volts RMS across each lamp?

    How extreme do you want to go? Put two 300W 120V lamps and a diode in
    series, and power consumption will be about 170 watts. And light output
    of both combined will be about 200 lumens - about that of a "standard" 25W
    120V lamp. The light output exponent is more than 3.4-3.5 when voltage is
    that low - figure more like 4 for that hot-running lamp, 4.1 on average
    for others.

    A 230V lamp or two 120V ones in series should last long enough. I have
    heard -13 and -14 for that life expectancy exponent, and at times worked
    out -12 for myself. Even if it is -12, a 750 hour 230V lamp would have
    median life of 210 years at 120V.

    If you want really extreme, you don't need diodes - just put a few
    lamps in series. 3 should be overkill, with mean life expectancy
    (in the unlikely event filament evaporation is still the limiting factor)
    in the 10's of millennia or more.

    - Don Klipstein ()
     
  20. So, and since it was open anyways, I took the good old soldering
    iron and soldered all the bad looking connections again.
    Plugged it in, not expecting much.
    Light!

    So, the small coil that is in there, seemed to be the part that gets hottest,
    and it's pins looked sort of lose, could have been it.
    Could have been some of the other connections too.
    That sort of breaking solder joints due to temp stresses I
    have seen many times in TV repair, ofter with coils, sometimes
    with connectors, like in the Philips K12 chassis.
    Sometimes you get sparking at those joints, sometimes even burning holes in the PCB.
    And that was with 60/40 solder.
    So I am not blaming it on the new solder, merely on temperature.
    Anyways, now I have a spare bulb :)
     
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