LED's explained please?

Discussion in 'Electricians' Talk' started by teabreak, Apr 12, 2014.

  1. teabreak

    teabreak Screwfix Select

    Hi all,
    I have been ordering some LED bulbs to replace my old type. I hate CFL's thank goodess LED,'s seem to be taking off now.
    I have noticed that some are like little bulbs while others seem to be a series of cream/yellow plates, can anyone explain the differance between them please?
     
  2. unphased

    unphased Screwfix Select

    Yes. The clusters of little yellow plates are called SMD (surface mounted devices) and these can give a better spread of light. They are being successfully used around tubes as well, known as 'cobs' as they resemble sweetcorn cobs. Single LEDs are generally one large discrete diode whereas SMDs which are clusters of smaller plates. The principle is the same in that the LED is emitting light. The electronics behind it is very technical and I don't know much about it. :)
     
    Last edited: Apr 12, 2014
  3. teabreak

    teabreak Screwfix Select

    Ah!Thanks unphased. So if I were able to see inside the little bulbs they would have a small single yellow plate too the the others are just multiples of the same thing.Is that right?
     
  4. unphased

    unphased Screwfix Select

    Pretty much, yes. By using larger clusters of smaller SMDs they can be made brighter.
     
  5. teabreak

    teabreak Screwfix Select

    Cheers! thanks for the quick reply:)
     
  6. joinerjohn1

    joinerjohn1 Screwfix Select

    Last edited: Apr 12, 2014
  7. unphased

    unphased Screwfix Select

    I purchased some SMD LED GU10 replacements off eBay that came from China and they have no protective cover! I have used them but I thought the same, ie if anyone touched the SMDs are they 'live', enough to exert a lethal shock? I didn't realise they had no cover until they arrived. :( They are out of reach, just, but I certainly wouldn't buy any in future if they had no lens cover.
     
  8. Biochef

    Biochef Member

    Every day is a school day :)
     
  9. Cheburashka

    Cheburashka Active Member

    I've found some of the cheap ones with exposed chips also have low frequency flicker and it gives me a headache just like fluorescent lights do.

    What I would like to have seen is how much voltage was at the point where he was getting the reading from as we all know current is only half the equation to getting a shock.
     
  10. stateit

    stateit Screwfix Select

  11. teabreak

    teabreak Screwfix Select

    How about in a bathroom:eek::eek::eek:
     

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