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Re: need help to build a card for driving 17 relays

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  • xxxtoytech
    Look in the Files section of this group for a PDF document parallel.pdf along with PDF data sheets for most of the components required. This describes a
    Message 1 of 4 , Jan 9, 2004
      Look in the "Files" section of this group for a PDF
      document "parallel.pdf" along with PDF data sheets for most of the
      components required. This describes a simple interface for sending
      and receiving data via the parallel port. It doesn't cost too much
      and takes about an afternoon to build. You'll notice that not all 8
      bits of the control signal are used. You can use the unused bits to
      control additional IC's (look at the schematic to see how each IC is
      addressed). Depending upon your relays you may be able to drive them
      directly from the circuit given. The only caution is that you'll have
      to read the values from the sensors a bit at a time so if the values
      are rapidly changing it might present a minor problem. It also
      depends upon the resolution of the sensor (binary, 4-bit, 8-bit etc.)
      The programming is also described; you can used most popular
      programming languages including Java to access the parallel port. You
      can also use an old PC that has been discarded for experimentation.

      Regards
      xxxtoytech
      --- In home_electronics@yahoogroups.com, "SADI Kheir-Eddine"
      <mindoverflow@y...> wrote:
      > hi,
      >
      > well, i need to build an electronic card to drive 17 relays by pc
      and return
      > two values read from 2 sensors.
      >
      > could any body help me please?
    • SADI Kheir-Eddine
      hi, well, the real application of that project isn t to drive 17 relays but to drive 17 electromagnets to simulate a punched card, the photocell is used to
      Message 2 of 4 , Jan 10, 2004
        hi,

        well, the real application of that project isn't to drive 17 relays
        but to drive 17 electromagnets to simulate a punched card, the
        photocell is used to determine if the reader is reading the card or
        not. I think that the electromagnet can't function for a long time
        without taking a pause then i am planing to use a triger so that when
        the photocell's signal is moving from high to low, the electromagnets
        will be turned off and when it's moving from low to high, the
        electromagnets gets activated. what do you think about it? about the
        current sensor i think it's no more needed cuz we'll know if the
        reader is on or off by adding a timeout to the photocell, when it's
        reached the reader is considered as of until it sends that signal.
        then the pc will send 3 bytes containing wich electromagnets to
        activate and the board will send 1bit (in 1 byte) wich is sent when
        the photocell changes it's state and is used to synchronize between
        the pc and the reader. I'll write the software part.

        What do you think about all that? am i missing some thing?
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