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Count up/down?

Discussion in 'Electronic Basics' started by Zucker, Jul 18, 2003.

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  1. Zucker

    Zucker Guest

    I would like to be able to count the number of people entering (count up)
    and leaving (count down) a room. I was thinking about using two photocells
    driven by two small lasers, spaced 6" to 12" apart, to detect if a person is
    entering or leaving. If photocell A was tripped before photocell B, the
    counter would count up. If photocell B was tripped before photocell A, the
    counter would count down. My problem is that I'm trying to come up with a
    circuit that can detect the AB or BA pattern. May be a circuit that can
    detect the lag between the two photocell voltages? I don't know.

    If anyone has a suggestion for this circuit or any other ideas, I would
    appreciate it.

  2. Zucker

    Zucker Guest

    Sorry for the identical posts. My Outlook is acting up.
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