What is this?

Discussion in 'General Electronics Chat' started by timelessbeing, Nov 27, 2011.

  1. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    I found this little guy in a box of random parts.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    If you can say what gadget the board is out of or if you can send a wide view photo of the board that may help.
     
  3. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    Unfortunately that's all I have. Possibly a printer or scanner. There is a stamp on the back of this PCB fragment that says CMKD-P3X and a date 2003.6.2. I looked it up and came up with nothing.

    Some kind of EPROM?
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    Then my guess is that it is the sensor from an optical mouse.
     
  5. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    It looks like some light sensitive sensor.
    This company has a lot of those "see through" chips:
    http://www.taosinc.com/

    Bertus
     
  6. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    I'm positive I've never taken apart a mouse. But the part could have many uses.
     
  7. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    Good eye! It looks a lot like their ambient light sensors.
    [​IMG]
    I wonder if there's a part number on the bottom.
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Dark strip looks like a fingerprint reader.
     
  9. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I think that the black strip is to small for a fingerprint reader.
    Where the fingerprint readers available in 2003?

    Bertus
     
  10. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    The PCB definitely was not exposed to user fingers.
     
  11. THE_RB

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    Feb 11, 2008
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    It's a simple light sensor, probably with "light to frequency" output. The sensor component only has 2 wires going to the chip, so it is a simple monochrome photodiode or LDR.

    If you power the board up you will probably find one of the chip pins is a frequency output that changes freq according to light level.
     
  12. Adjuster

    Well-Known Member

    Dec 26, 2010
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    The device we are assuming to be a sensor appears to have only one bond wire contacting it, and a common connection. Is it not more likely to be a single photodiode?

    Edit: Oops, someone got there an hour ago.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    From what little I can figure out, the board came from a DVD player.

    I believe that the IC you have there was used to determine the position of the laser head.
     
  14. thatoneguy

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    I stated that it "looks like" the fingerprint readers found in notebooks and other electronics today. Not enough connections to actually be one, though I should have added that in my post above.
     
  15. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    I never took apart a DVD player.
     
  16. THE_RB

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    Interesting! Do you know that or it it a guess? I've never seen a sensor of this type used for laser head positioning, normally they position by finding focus on the ident track on the DVD and some units may have an optical interruptor sensor on the mechanicals.

    I still think it's an ambient light sensor (and yep that's a guess!). :) Some appliances have autodimming of the display at night and the ambient light sensor is used for that. In which case it probably would have been on the front panel PCB with a little window.
     
  17. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I agree with Sgt. Wookie and The_RB. It could be used in a DVD player, CD player, or it could be used to calibrate a laser printer. I've seen them on all sorts of electronic devices, all of which have something to do with a laser. Optical Mice usually have one built into a larger chip, used to decode the signal. I haven't once seen one in a mouse separate from the other components. My money is on the CD player or the calibration circuit for a laser printer.
     
  18. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    There's a very good chance it came from a laser printer. I DO remember disassembling one. Since there's an IC, does that mean output would be digital?
     
  19. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    No, just different voltages out on the two wires connected to it depending on which horizontal "ribbon cell" section the laser hits. I'm assuming that if you look very closely, you'll see hundreds or more small lines across the narrow side from top to bottom. Each is a photocell that will output a slightly different voltage when illuminated, so the output of it will "say" where the light is pointed at on it by a different voltage.
     
  20. timelessbeing

    Thread Starter New Member

    Jul 5, 2011
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    I see, so it might be useful for trying to align something.
     
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