SMD LED identification

Discussion in 'General Electronics Chat' started by Reon636, Sep 13, 2017.

  1. Reon636

    Thread Starter New Member

    Jul 1, 2017
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    Hi everyone, can someone identify what kind of SMD LED is this in the picture? I need to find one that must be the same or very similar. Thanks 21742151_1831985726817113_715443535_o.jpg

    EDIT: the light that comes from it is directed towards the inner side of the plastic pcb
     
  2. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    It would appear that the LED is the white rectangle at the top of the board. Very generic, and should be easy to find and replace. Some such LED's have their element reflects to one side so as to act like a light projector to cast its illumination into a plastic light guide such as a cover over an LCD display.

    SMT LED.jpg
     
    Last edited: Sep 13, 2017
  3. Reon636

    Thread Starter New Member

    Jul 1, 2017
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    Yes the LED is the white rectangle, and as I said it's oriented towards the inner side of the circuit, casting the light in the "inside", where there was a plastic screen which diffused the light homogeneously. This said, I don't know what model/code the LED is!
     
  4. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    You might have to search one of the electronics suppliers to find something comparable. Depending on the color, you'll want to understand the characteristic forward voltage drop (Vf) and come close. LED's have a Vf that differs with color. There are some pretty standard numbers for differing colors and you can probably google it and find something close to what you have now. For instance: You can expect a yellow LED (super bright) to be around 2.1 Vf. If you were to put a red LED in its place the Vf would be lower, as would its ability to handle current. Since we know nothing about your device all we can do is guess. But looking through someone like DigiKey (not an endorsement) could help you find the part that would most likely fit. They also come in different sizes, so you'll need to learn more about what you have and how to size it properly. Sorry, on that subject I lack experience and wouldn't be able to provide reliable direction.

    Some devices are designed to stand on their side, casting its light energy directly into the defuser. But judging from your picture, it appears the device is mounted through the PCB. I have very little experience with surface mount LED's. Especially one that is mounted through the board. I've SEEN them. But can offer no practical advice on that subject.
     
  5. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    Can you take a clearer picture of just the LED?
     
  6. Reon636

    Thread Starter New Member

    Jul 1, 2017
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    I tried to but it's so small that the camera can't focus it. Maybe you can try crop the one I previously posted. Anyway the LED is white and I measured 2.77V forward voltage drop on the working one.
     
  7. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    Hold the camera further away so it can focus. Use the zoom feature to get a close-up. Should work nicely. I do that all the time when I want to photograph a small subject.
     
  8. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    Measuring a working unit is a good place to start. However, whatever you replace the other one with - you're going to need to know what its working Vf is. It MAY be 2.8 Vf, it could be higher. Or lower.
     
  9. JUNELER

    Member

    Jul 13, 2015
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  10. Reon636

    Thread Starter New Member

    Jul 1, 2017
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  11. Reon636

    Thread Starter New Member

    Jul 1, 2017
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    Could it be a "335" SMD LED?
     
  12. Tonyr1084

    Well-Known Member

    Sep 24, 2015
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    All my years in the electronics manufacturing business I've never seen an LED like that. Nothing like the picture I drew for sure. The CLOSEST thing I've seen to that was a PTH LED that had a rectangular plastic body with an open lens only on the top. It COULD be mounted sideways, but I don't think what I recall using some 25 years ago would be available. Obviously what you have is more modern than mine was.

    Have a look through e-bay and see if someone appears to have a lot of different ads selling LED's. Contact them with your picture and see if they can provide something equivalent. Oh, and you might want to take another picture with something else in the shot to provide scale. Maybe even a tape measure or a 6 inch pocket scale. Use the millimeter scale, as LED's are most often rated in size by mm's. (not M&M's)
     
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