need recomendation for what sensor i can use

Discussion in 'The Projects Forum' started by outmuddin, Feb 8, 2010.

  1. outmuddin

    Thread Starter New Member

    Feb 8, 2010
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    I am making a project that will need to be some kind of switch that can detect a person not moving just standing there 0-3 feet.
    no motion at all just close to the sensor. if the person walks away the sensor switches. if the person is close in the range of 0-3 it switches or waits a few seconds to switch. any ideas out there. please help. does this type of sensor exist?
    thank you
     
    Last edited: Feb 8, 2010
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    What kind of project is it?
     
  3. outmuddin

    Thread Starter New Member

    Feb 8, 2010
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    this my sound silly but here it goes. a sensor on a wall in restroom toilet area that senses a person and activates a exhaust fan to come on.
    i would like to do this with out movement at all by person. a motion switch could work and just set the timer but thats not what im looking for.
    a non movement sensor.
     
  4. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    The obvious thing that comes to mind is an IR detector which would detect the presence of a warm body. I'm envisioning two detectors viewing in a horizontal plane with the detectors 90 degrees apart, one facing the person and one looking at the person from the side. The question is whether a cheap passive IR sensor (e.g., a photodiode) can reliably detect the human's IR radiation over the room's background radiation.

    Another approach is to use light beams that get tripped when someone moves into the area being monitored. You can use IR beams so that they're not visible.

    Unless you explain your design problem more, I can't see why you wouldn't purchase a commercial sensor/switch unit and tune it to make it work the way you wish.
     
  5. outmuddin

    Thread Starter New Member

    Feb 8, 2010
    3
    0
    if such a sensor exists, it could be installed inan item like a mirror with lights surrounding it. when she stands in front of it the lights stay on with no movement. when she walks away the lights in this portable mirror go off.
    the sensor would have to be b mounted in the mirror frame. all components would have to be mounted in the frame of the mirror that is just hanging on the wall. this mirror could be moved to another location later. just explaining that the components needed for this need to be mounted in front of person activating it.
    the sensor in automatic urinals in the bathrooms that sence you there and then you leave it flushes, what sensor is that.
    that sensor would work if a range could be 0-3 feet. help!!!!!!
     
    Last edited: Feb 8, 2010
  6. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    most public restrooms have sensors on toilets and urinals that detect human presence and switch on when the presence has moved away from it, these sensors are IR based sensors, basically consist of an IR emitter and an IR detector.... here is an example of an aftermarket one to convert an existing toilet to automatically flush... >>> http://www.parish-supply.com/autoflush_specifications.htm

    You can use the same IR detection scheme to activate a fan if the sensors detects a person, you can have a timer to delay the sensors output so it won't trigger the fan if the person is only there for a moment (possibly doing a #1 instead of a #2, lol).

    I had used a PIR sensor to detect a person entering the room and used a pressure sensor on the seat to determine if the exhaust should turn on or not, and I also employed a humidity sensor to automatically turn on the exhaust fan when some steam builds up when someone showers.....

    here is the project I worked on with this concept, it is all uc controlled (Pic32MX), the only thing different is that I used a different touch sensor IC than what is in the picture...

    [​IMG]

    You can see more of it here >> http://www.morse-code.com/id155.htm


    My .02
     
  7. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    You can use an IR of the type used outside to detect people and turn on the lights.
     
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