reading signal lvl of a modulated IR source

Discussion in 'The Projects Forum' started by bignick270, Jan 25, 2011.

  1. bignick270

    Thread Starter Active Member

    Mar 25, 2009
    36
    0
    Is there a way to take a signal from a phototransistor, filter out non 40 kHz square wave signals and then be able to read the strength of the signal with an ADC?

    signal from phototransistor ---> filtering ---> if 40 kHz wave then read level of signal with adc as you would normal do with a phototransistor output
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    907
    That sounds doable, Vishay makes a sensor that might work off the shelf for what you want. The output pulse width is proportional to intensity. It should be easy to convert that to a voltage and feed an ADC, but it would probably be even easier to measure the pulse width directly with an MCU.

    http://www.vishay.com/company/press/releases/2010/100628irsensors/

    John
     
  3. bignick270

    Thread Starter Active Member

    Mar 25, 2009
    36
    0
    good find right there, although the way the detector is mounted in casing will not work for my application. I will take a look around to see if there are any similar items with other manufacturers.
     
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