Help identify this component..

Discussion in 'General Electronics Chat' started by bushrat, Feb 28, 2015.

  1. bushrat

    Thread Starter Member

    Nov 29, 2014
    97
    23
    Hello everyone,

    I have few of these parts, and I have no idea what they are.
    They look like oversize transistors (TO-18)
    Writing on the side says SD7014, but I cannot find any datasheet for it.

    IMAG1371.jpg

    Microscope zoom.
    IMAG1372.jpg
     
  2. debe

    Well-Known Member

    Sep 21, 2010
    961
    186
    Posibly light sensitive transistor, seen them in old Photocopiers as optical sensors.
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
    4,567
    804
    Its the same typical appearance as a large area photodiode - at least that's a search term you can eliminate, or otherwise.
     
  4. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,426
    364
    Possibly an old product from Advanced Photonix.
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    910
    Does it have a window over the presumed "active area?"

    If it has a window on it, then it is probably a light detector. If there is no window, it may still be a light detector, but it may also be a pressure detector. In the 1990's, I got several similar looking sensors form Electronic Goldmine that were from radiosondes. I will pick one up on my next trip to Cleveland.

    John
     
  6. Lundwall_Paul

    Active Member

    Oct 18, 2011
    222
    19
    My best guess is-- phototransistor is a light-sensitive transistor. A common type of phototransistor, called a photobipolar transistor, is in essence a bipolar transistor encased in a transparent case so that light can reach the base–collector junction.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
    4,567
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    If its intended application was known - that might clear things up.

    Photodiodes are very fast - phototransistors are a lot slower.

    The case style can be inconclusive - photodiodes often have 3 leads to conform to a case style standard and to prevent reversed insetion, phototransistors sometimes don't have a base lead brought out of the case.

    With the 6-pin DIL opto-couplers; most use a photo transistor, all the pins are there but the base pin isn't connected on some versions.
     
  8. bushrat

    Thread Starter Member

    Nov 29, 2014
    97
    23
    The base pin (or the middle pin) is connected to the case.
     
    Lundwall_Paul likes this.
  9. ian field

    Distinguished Member

    Oct 27, 2012
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    The first thing to do is use a DMM Ohms range to check for any path between the case pin and either of the other pins.

    Then check the other pins for any resemblence to a diode - bear in mind you might get different results depending on whether the active area is exposed to light.
     
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