Colour Detection Circuit

Discussion in 'General Electronics Chat' started by Mazaag, Dec 17, 2007.

  1. Mazaag

    Thread Starter Senior Member

    Oct 23, 2004
    Hey guys,

    I was wondering if there is a circuit that is capable of detecting different colours ( as a voltage or current or something) without using a camera or webcam?

    Are there cheap optical "band pass" filters for example that would pass only a specific frequency of light that I could possibly couple to 3 LDRs (RED , BLUE, GREEN) and somehow sum up the voltages or soemething and obtain a specific voltage for a specific colour ?

    Thanks guys
  2. cumesoftware

    Senior Member

    Apr 27, 2007
    You can resort to other solution. Use a dark chamber with three LEDs (red, green and blue) and one LDR. Emmit one light at a time and the LDR will read the reflected light.

    You can also use three colour filters in front of the respective LDRs, but you have to make sure they will not pick up other frequencies.

    One last solution is to use three LEDs as light sensors (as photo diodes). The LEDs will respond only to the frequency of light that they emit.
  3. HarveyH42

    Active Member

    Jul 22, 2007
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    Or try searching on "colorimetry".