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Archive for December 20th, 2009

Photoresistors Aren’t Indestructable

Delaminated photoresistor

Delaminated photoresistor

So while testing the routine that measures light intensity using the technique described there, I discovered that:

  • The conductive layer atop the photoresistor doesn’t bond well to the base layer
  • The transparent top coating isn’t armor plating

I wanted to verify the extreme dark end of the response curve, where the resistance is the highest and the input voltage correspondingly the lowest. The fastest way to do that is to put a piece of black electrical tape across the photoresistor’s face; it worked perfectly.

Unfortunately, peeling the tape off the photoresistor also peeled the coatings apart. The resistance was unchanged, but I suspect moisture inside the layers isn’t going to do them the least little bit of good.

Drat & similar remarks…

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