entry counting

Discussion in 'The Projects Forum' started by bwaley, Jun 10, 2008.

  1. bwaley

    Thread Starter Member

    Jun 1, 2008
    27
    0
    could somebody help me!
    I have apair of phototransistor and IrLED to enable me sense person entering and leaving a room. I would like to know occupancy by using updown counter fed by pulses from phototransistor cct due to intereference of IR LIGHT. How will I connect to obtain up down counting and know the presence of persons in a room. If possible send to me a circuit.
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,535
    The catch is Up and Down counting. How do you plan on knowing whether their coming or going, not to mention the case where two people cross each other at the threshold.
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Will you use an ordinary counter IC or a microcontroller to count the people?
     
  4. Digi Dave

    Member

    Apr 25, 2008
    26
    0
    The only solution is to have two beams across the entrance, one in front of the other about 100mm apart, so that if say beam 1 is broken first then beam 2, that will give you the direction. otherwise its just counting on one beam.
     
  5. bwaley

    Thread Starter Member

    Jun 1, 2008
    27
    0
    thanks Digi Dave


    to Mik3
    Im using an ordinary up down counter i.e 4510 and
    a D fliflop.CD4013
     
  6. bwaley

    Thread Starter Member

    Jun 1, 2008
    27
    0
    Is the choice of my ICs reasonable. I choose these because my supply is 12v. Otherwise advice.

    will having the beams 100m apart bring about quadrature encoding?
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Distance between beams will not determine quadrature encoding. Having two beams in one (and only one) mechanical path will make for quadrature encoding. IF you can get the humans to go through the path one at a time, or all in the same direction. Two humans in two directions at the same time will spoil it.
     
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