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Does anyone make high efficiency ac/dc LED indicators

Discussion in 'Electrical Engineering' started by John Gilmer, Apr 29, 2006.

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  1. John Gilmer

    John Gilmer Guest

    With Google I found a company that has a line of LED indicator assemblies
    from 6 volts up to 24 volts. As far as I can tell from the power
    consumption data, they just take two LEDs in parallel and put in the
    appropriate resistor. At 24 volts, we are talking about 1/2 watt and that
    can get downright WARM.

    BUT, why couldn't "they" put several "tiny" LEDs in series and adjust the
    resistor so that the same light could be obtained with, say, 5 mA as
    compared to the more or less standard 20 mA.

    OR, for AC use, how reasonable would be it to use a capacitor or coil to
    drop most of the voltage.

    It would be "nice" to have a pilot lamp than can run cool and have a
    expected lifetime longer than whatever it is monitoring. At 120/240 neon
    based indicators just don't seem to last very long.
  2. John Gilmer

    John Gilmer Guest

    You can't.

    That's why:

    1) you "back up" the cap with a resistor which will help with the impulses.

    2) you "protect" youself with a "60 Hz, _% harmonics label.)
  3. Poor current regulation, particularly for the lower voltage assemblies.
    The more LED drop (with a negative Vf vs temperature characteristic) in
    the circuit, the more sensitive it will be to temp. variations.
    It all boils (no pun intended) down to cost. Most buyers are comparing
    these things to cheapo incandescent or neon units. As long as the lamps
    last a little longer than the warranty, the manufacturer doesn't care.
  4. Mike Lamond

    Mike Lamond Guest

    The LED lamps that IDEC sells for their industrial pilot lights have an
    resistor and what looks like multiple elements on a flat surface. They have
    bayonet base and are rated 20mA for 6, 12 and 24 volt models, and 10mA
    for 120 and 240 volt models. I think some of them are brighter than the 1
    watt incandescent, but none of them match a 3 watt 120MB lamp.

  5. Spokesman

    Spokesman Guest

    So far there is no LED lamp that can match the effieciency of an ordinary
    incandescent let alone being as efficient as a HPS lamp. Someday..
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