Wavelength sensitive photoresistors

Discussion in 'General Electronics Chat' started by mikeross1830, Aug 25, 2010.

  1. mikeross1830

    Thread Starter New Member

    Aug 17, 2010
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    I have my students build a simple colorimeter using LEDs for the light source and have been using simple photoresistors as the detectors. I would like to add a blue LED as this range of the visible spectrum is more useful, but the simple photoresistors are not at all sensitive to those short wavelength photons. Does anyone have a suggestion for my use. I would prefer something that requires my students to build their own amplification circuit.
     
  2. Nik

    Well-Known Member

    May 20, 2006
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    Photo-transistors ?? IMHO, you don't need the speed of photo-diodes...

    IIRC, simple photo-resistors are more sensitive towards the red end of visible spectrum, happily detect infrared. Also, IIRC, they tend to be temperature and history sensitive, too.
     
  3. Markd77

    Senior Member

    Sep 7, 2009
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  4. timrobbins

    Active Member

    Aug 29, 2009
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  5. retched

    AAC Fanatic!

    Dec 5, 2009
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    Remember that a LEDs themselves can be used as photodetectors. AND they are already setup for their own wavelength.

    So use a blue LED to detect a blue LED's light.
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Exactly, and they work rather well. First time I heard of this I didn't believe it, had to hook a few different ones up to prove it to myself.
     
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