line powered filament LED lamps...

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  • eccerr0r
    Solder Sloth
    • Nov 2012
    • 8701
    • USA
    #1

    line powered filament LED lamps...

    I was playing with one of those "filament" LED lamps. I noticed it seemed to flicker a bit...so I tried powering it with different things to try to extract information about it - noticed it seems to be 100% LED - no droppers, no PSU, no rectifiers, nothing - the LED "filaments" are hooked straight to the contacts!

    Wondering what's the distribution of how "filament" LED lamps are driven? Do any have capacitive droppers? rectifiers? CC PSUs?

    ---

    Found another "filament" LED that does have a PSU in it, seems to be a capacitive dropper type, possibly CC as well. Runs better than the first one - does not flicker.

    ---

    On another note, found a little multichip LED (has 24 1206(I think) SMT LEDs in it on two crossed PCBs) all in a unit about 1" long and ⅜" diameter (12VAC/DC, about 1W dissipated) that contains its own tiny switching PSU in it, can see a SOT23-5 IC(?) and a coil in it, and of course rectifier diodes. All embedded in silicone. Wonder how much these cost to make...
    Last edited by eccerr0r; 09-21-2021, 10:04 AM.
    Tags: None
    • PeteS in CA
      Badcaps Legend
      • Aug 2005
      • 3581
      • USA, Unsure of Planet
      #2
      Re: line powered filament LED lamps...

      With traditional incandescent light bulbs, brightness is average voltage dependent. LED brightness is current dependent.

      Hooking a simple series string of LEDs across the line would result in an uncontrolled current and therefore uncontrolled brightness. And since LEDs are diodes, conduction would only occur on the appropriate half cycle. Or so it would seem to me.

      At the other extreme of LED lighting, LED street lamps are driven by a switching power supply that regulates output current rather than output voltage.
      PeteS in CA

      Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
      ****************************
      To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
      ****************************

        Comment

        • eccerr0r
          Solder Sloth
          • Nov 2012
          • 8701
          • USA
          #3
          Re: line powered filament LED lamps...

          I'd imagine street lights, since aesthetics doesn't matter too much, use standard high reliability LEDs. I suspect that the LEDs could then be binned unlike "filament" LED strips.

          The first "filament" LED seems to contain two sets of LEDs in inverse paralled to deal with AC.

            Comment

            • Per Hansson
              Super Moderator
              • Jul 2005
              • 5895
              • Sweden
              #4
              Re: line powered filament LED lamps...

              Big Clive makes lots of videos on LED lights, just browse through or search and you will find several on filament LED's too

              https://www.youtube.com/c/Bigclive/videos
              "The one who says it cannot be done should never interrupt the one who is doing it."

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