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Interfacing a synchronous counter - need ur help.

Discussion in 'Electronic Basics' started by nattynathan, Jul 26, 2005.

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  1. nattynathan

    nattynathan Guest

    hi friends,

    I need ur help. I am trying implementing a pyroelectric detector/sensor
    (dual element) which detects the movement of ppl in and out of a
    secured building. the link below shows the circuit diagram for the
    motion detector. only one person enters or leaves the building at a

    Now, I want to couple a counter which counts the number of ppl inside
    the building. so I have decided to use an
    UP/DOWN SYNCHRONOUS COUNTER, cud someone help me how to make this a
    continuous process, so that that counter increments and decrements wen
    someone moves in or out of the building.

    I need ur advise (asap!!) in the interface part. how shud I proceed to
    interface the above circuit whith the sync. counter.

    I wud really appreciate ur help. thank you.

  2. Mochuelo

    Mochuelo Guest

    I'll assume you have a circuit like this at the entrance and another,
    identical one, at the exit (because, of course, one single circuit
    like this cannot tell whether a person is entering or leaving the
    I would not use an up/down counter. I would use a small and cheap MCU
    (maybe even 8-pin), and get rid of the two relays, and the two CD4538
    ICs. If you need isolation, have it after the MCU, and with two
    optocouplers. The MCU can do the function of the 4538 (monostable),
    can count up/down and, if you choose it with internal EEPROM, can keep
    the count information even when there is no supply.
  3. Chris

    Chris Guest

    Hi, Natty. I would guess you're going to be waiting a while for Ur
    help. The city has been uninhabited since about 500 B.C.

    But you sound like you're in a big hurry, and can't wait for help from
    Ur (you must be positively frantic to be using cell phone text in a
    newsgroup). You should have a Velleman Multifunctional Up/Down Counter
    (K8035) Fed-Exed to your location as soon as possible, and just
    construct it yourself. They're $37.90 USD at Circuit Specialists, and
    are available from many distributors worldwide. Be sure to download
    the user manual, which explains the limitations and features of the
    counter. It's got four digits, will totalize up and down, has voltage
    as well as contact inputs, and will run off 9 to 12VDC at 150mA. Just
    use a 9VDC wall wart, and you're good to go.

    If you want a cool-looking, completed display, get the VM-107 kit,
    which includes a cute bezel for that finished look. I would guess
    they're a bit more expensive, and aren't available from as many

    If you're in a bigger hurry, just go down to the local Grainger and buy
    a totalizing counter. It'll cost you more, but you'll have a solution
    up and running today.

    Good luck with the fire
  4. nattynathan

    nattynathan Guest

    hiii friends,

    thank u for handy infos. will get back to you soon. thanx again.

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