Light Measuring Circuit

Discussion in 'The Projects Forum' started by ferno101, Mar 3, 2011.

  1. ferno101

    Thread Starter New Member

    Jul 30, 2010
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    Help.. we're making a light measuring circuit as part of our thesis project.

    I need a circuit which can convert the amount of light received into a voltage level.

    I tried using light dependent resistors but it lacks sensitivity because we are measuring underwater in dark conditions and we are using an optical filter which only lets light around 680 nm wavelength pass..

    I'm out of ideas.. :(
     
  2. Kerim

    Member

    Mar 3, 2011
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    What about using a photodiode for 680 nm (red)?
     
  3. Kerim

    Member

    Mar 3, 2011
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  4. John P

    AAC Fanatic!

    Oct 14, 2008
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    Photodiode and transimpedance amplifier.
     
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
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    If your light levels are very low, you may find that photo-diode dark current may be significant. The effect of this can be minimised by operating the device at zero bias, providing that you have a device which will operate in this condition.

    As suggested by a previous poster, a transimpedance amplifier is useful - it will keep the detector voltage constant.

    Really low light levels may lead you to use some kind of shutter to cal out the dark condition.
     
    Last edited: Mar 4, 2011
  6. DickCappels

    Moderator

    Aug 21, 2008
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    Kerim likes this.
  7. Kerim

    Member

    Mar 3, 2011
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    Thank you Dick for sharing your simple but interesting idea.

    Off topic, may I ask you how (or when) one can add on a new solution the expression "Copyright 20xx”? Sorry if it sounds a silly question :)

    Kerim
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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