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UFO (undentified flat object)

Discussion in 'General Electronics Discussion' started by NuLED, Jun 19, 2013.

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  1. NuLED

    NuLED

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    Jan 7, 2012
    Hi folks,

    I suppose it is not unusual for us to be curious about things and disassemble them right? I did that to and old cheap USB hub and found an interesting item.

    It looks like a flat whitish glass thingie with four leads.

    Is it some kind of capacitor?
     

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    Last edited: Jun 19, 2013
  2. NuLED

    NuLED

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    Jan 7, 2012
    Also, what are those black dots that I see on many PCBs? They appear to be a dot of plastic that is covering up an IC or something?

    It is on a PCB attached to an LCD display.

    I am also interested to figure out how the LCD display works. I assume I need to power the tiny conductive lines on the film (not sure with what voltage).
     

    Attached Files:

  3. davenn

    davenn Moderator

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    the first item is it a sheet of glass with a layer of white plastic on each side ?
    does it sit behind the LCD panel shown in your second post?
    It may be the backlight for the LCD panel

    those black blobs have IC's under them the blob of silicon/other material is the protection as the chip has no other casing.... its a pretty common thing

    Dave
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    That big black dot (blob of epoxy) hides under it a chip. It is wired directly to the board and does not come in a package with leads. They're very common in devices that are cheap and high volume because you can shave off a couple of cents from the price per unit.

    The big white thing above? A battery?

    edit: davenn's probably right about the white thnig. I assumed (for some reason) that the device didn't have a display.
     
  5. NuLED

    NuLED

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    Jan 7, 2012
    Hi guys - yes I think Dave must have got it right because I seem to remember it has a kind of backlight. Interesting, I wonder how it works. There are no other LEDs in the thing.

    What kind of voltage and how should I wire it up to test? There are four leads into it.

    (How does it work?? interesting).

    (The 3 leads and 1 Vcc; the 3 leads are wired into SMD capacitors right? They say 101 on them in the photo).
     
  6. davenn

    davenn Moderator

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    who know's ... I have no idea what that first thing is ... do you?



    they are SMD resistors 100 Ohms each

    Dave
     
  7. NuLED

    NuLED

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    Jan 7, 2012
    you guessed it already. the backlight. i recall there was a backlight for this hub.
     
  8. NuLED

    NuLED

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    Jan 7, 2012
    IDEA: Maybe those 3 leads have something to do with color selection. I know that is a long shot but I am thinking, RGB. Well, I will experiment and report back to see what happened. The thing is a USB hub so I am assuming it will use 5V generally, and with those 100 Ohm resistors, I will try to replicate that current. Maybe try 3xAA = 4.5V and then use a potentiometer to turn the current up slowly on one of the leads.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    I'd just start with a 1k resistor in series.
     
  10. NuLED

    NuLED

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    Jan 7, 2012
    ok will do. thanks
     
  11. BobK

    BobK

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    Electroluminescent panel.

    Bob
     
  12. NuLED

    NuLED

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    Jan 7, 2012
    Thanks for enlightening me! :)

    I will test it out maybe tomorrow and take photos for you guys if it is especially pretty.
     
  13. BobK

    BobK

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    Jan 5, 2010
    If it is an EL panel it would need 100V AC to drive. Based on the driver board, I think it might not be after all.

    Bob
     
    Last edited: Jun 19, 2013
  14. NuLED

    NuLED

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    Jan 7, 2012
    Ah ha!!

    :D

    5V. I think it's just a bunch of LEDs embedded inside a plastic slab.
     

    Attached Files:

  15. BobK

    BobK

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    Jan 5, 2010
    Very cool! That is a particularly nice takeout part.

    Bob
     
  16. Harald Kapp

    Harald Kapp Moderator Moderator

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    From the way these panels are lit, I'd assume that there are only a few LEDs at the top of the slab and the plastic acts as a light guide to distribute the light across the slab's surface.
     
  17. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Very nice! You could make a nice constantly changing colour display with that. Make three sinewave or triangle wave oscillators all running at different very slow frequencies, and use them to control the brightness of the three colours.
     
  18. NuLED

    NuLED

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    Jan 7, 2012
    I saw a huge pile of stuff that neighbors piled up down the street this morning. It is a real shame. Lots of televisions, some other appliances. If I had the space at home I'd bring some back to disassemble. It pains me that it is all going to the landfill.
     
  19. NuLED

    NuLED

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    Jan 7, 2012
    Yes that's basically how it works. I think the sides are silvered to help reflect back to the white paper, which mostly dissipates it for a softer glow.

    Later I will try to use this in something. I am mucking around with PIC these days but there are big gaps in my basic electronics knowledge, so I am trying to come at it from both directions (programming + electricity).
     
  20. NuLED

    NuLED

    294
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    Jan 7, 2012
    Oh yes, I tried to connect the cathodes in parallel but only one of them would light up at any one time. I haven't taken a real close look at how the LEDs themselves are arranged.

    How do I measure + calculate their optimum voltage levels? (I don't have an oscilloscope but would that be the best way, alongside a very accurate adjustable voltage source?).
     
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