LDR Protection

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

  1. RodneyB

    Thread Starter Well-Known 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 Well-Known Member

    Apr 28, 2012
    680
    15
    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 Well-Known Member

    Apr 28, 2012
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    thank you
     
  6. #12

    Expert

    Nov 30, 2010
    17,897
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    The most common of that substance releases acetic acid (bad).
     
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  7. DC_Kid

    Distinguished Member

    Feb 25, 2008
    709
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    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

    AAC Fanatic!

    Oct 27, 2012
    5,557
    984
    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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