LDR Protection

Discussion in 'General Electronics Chat' started by RodneyB, Apr 8, 2015.

  1. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    I have made a light sensitive switch. I have drilled the LDR into the side This works really great for a couple of days then almost oxidizes and wont work any more. How can I protect the LDR from this happening
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    get a good one, or put it behind a plastic window inside the housing out of the weather. some actually are potted in clear plastic.
     
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  3. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
    633
    13
    If I covered it in clear silicon would that do the same job
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    chedck it after you coat it, some coatings block or absorb the light the ldr works on.
     
  5. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
    633
    13
    thank you
     
  6. #12

    Expert

    Nov 30, 2010
    16,314
    6,818
    The most common of that substance releases acetic acid (bad).
     
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  7. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
    9
    the GE Silicone-II product is acid free, found that out while doing some roofing with steel panels, panel maker said that the silicone would eat the paint of the panel, but the Silicone-II product does not have acid in it.

    w/o a nice even coat i suspect a coating like that will mess up the functionality, and, silicone will not stay nice for very long outside (wont break down but will collect dust/dirt and may fade in color). a UV stable clear epoxy would be better.
     
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  8. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
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    The cadmium in a LDR is extremely toxic, so the active surface should be at least securely coated with laquer, many manufacturers either potted them in water-clear resin, or even encapsulated them in windowed TO5 type cans.

    Some early types were even encapsulated in a glass envelope like valves.

    Cadmium poisoning causes osteoporosis and a very slow and painful death.
     
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