Help with Optical sensor

Discussion in 'The Projects Forum' started by spelcaztr, Dec 19, 2011.

  1. spelcaztr

    Thread Starter New Member

    Feb 16, 2011
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    0
    Hi guys. I have been working on my project. Something that could detect incoming intruders in the house. is there a way to make an optical sensor to detect as far as 1m? I looked up some of the sensors in the market but a lot of them can only detect as far as 2mm. Or is there a better way? The sensor output should be able to activate a relay in so the output should be approximately 6v min.
    Thanks.

    i think this works but it functions as a sound/tone detector or something.

    http://www.aaroncake.net/CIRCUITS/irremote.asp?showcomments=all
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    488
    The receiver is tuned to only respond to incoming infrared light modulated at the specified frequency, since he says tone I assume it's audio frequency. It could work like a light barrier. Which brings us to a fundamental question.

    Do you want to detect someone approaching or do you want to detect someone passing through a light barrier?

    One works with reflection, the other one on interruption of a light beam (pulsed or continuous).

    Ambient light sources can be a quite challenging issue to resolve. Is this going to be installed where ambient light changes rapidly? (like direct sunshine with passing by clouds)

    Have a look at the SI1102. You might be better off with ultrasound modules.
     
  3. Adjuster

    Well-Known Member

    Dec 26, 2010
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    300
    I've seen barrier alarms working indoors really well using a sender and receiver pair pointing at a corner reflector (prism type, like the ones on vehicles). I think the optics use collimating lenses though. Security companies must use loads of these things.
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
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    Passive infra red, PIR, detectors are quite reliable, & good for several meters.
     
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