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12 LED Also used with 220VAC? — Parallax Forums

12 LED Also used with 220VAC?

prof_brainoprof_braino Posts: 4,313
edited 2013-01-16 11:25 in General Discussion
Recently I ordered from EBAY
10W High Power Bright White/Warm White 800-900LM DC12V Led light Lamp bead

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=321024520278&ssPageName=ADME:L:OU:US:3160

Instead of getting warm white, I received bright white.

Also, instead of being labeled "12v 3 watt" they were labeled "AC220-240V 3 Watt". I assumed somebody put the wrong sticker, but the email reply was:
?
About the voltage , the LED chip can be used under AC220v or DC12v , there is no difference for the led chip about the working voltage . please trust us , we are professional and regular LED light manufacturer in China .
?

So I take it they mean it can be connected directly to 220VAC mains current. I'm a little iffy about this. Do I understand this correctly? If it can work from 220VAC, can it also work from 120VAC mains? Will it be half as bright? The LED module is just an array of nine LEDs on an aluminum circuit board, there are no passives or IC that I can see.

I'm worried about the magic smoke getting out.

Comments

  • lanternfishlanternfish Posts: 366
    edited 2013-01-15 16:24
    ?
    About the voltage , the LED chip can be used under AC220v or DC12v , there is no difference for the led chip about the working voltage . please trust us , we are professional and regular LED light manufacturer in China .
    ?

    Why do I find that hard to believe?
    Is the LED 'module' you have the same as the one in the ebay image?
    Are there any identifying figures on the LED?
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2013-01-15 17:53
    Video tape the 'experiment' and send it to them for your replacement LED. :smile:


    PS - wear eye safety
  • TinkersALotTinkersALot Posts: 535
    edited 2013-01-15 17:58
    Beau Schwabe (Parallax) wrote: »
    PS - wear eye safety

    the magic smoke might come out -- there may be a snap-crackle-pop too....recommend the "most inside" this experiment is done is a garage (better outside imho)
  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2013-01-16 10:53
    They probably have a switching regulator that can take a wide input voltage. That's actually not that hard with newer Power Factor Correction circuits. However, for it to accept that wide of an input range, it probably won't be terribly efficient.

    When you get it, take a picture and post it. See if you can draw up a bit of a schematic, but I wouldn't count on it.
  • stamptrolstamptrol Posts: 1,731
    edited 2013-01-16 10:57
    It is possible the LED unit has a constant current supply as part of the device. In essence, regardless of the input voltage, the current fed to the LED array is controlled/limited to a safe value.
    Hook it up to a Variac and monitor input current as the voltage is increased.

    Cheers,
  • prof_brainoprof_braino Posts: 4,313
    edited 2013-01-16 11:06
    lanternfish wrote: »
    Why do I find that hard to believe?
    Is the LED 'module' you have the same as the one in the ebay image?
    Are there any identifying figures on the LED?

    It's the one in the picture, only marks on its are the + and the - etched in the aluminum circuit board.
    At 12 volts dc it draws 0.3 amp. It doesn't get warm, but I have it on a heat sink using the thermal grease that was applied top the back before shipping.
  • Heater.Heater. Posts: 21,230
    edited 2013-01-16 11:13
    My experience with bright white LEDs is that running them on 12 volts AC produces an lot of annoying flicker.

    If that ali plate has nothing on it but LEDs I see no way it won't explode connected to 120/220 volts.
  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2013-01-16 11:25
    Ok, I didn't think to look at the picture in the auction - definitely no SMPS there. I don't know what they're talking about.

    You may want to get one of these: http://dx.com/p/900ma-10w-power-constant-current-source-led-driver-85-265v-42745
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