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Help with setting up counter

Discussion in 'General Electronics Discussion' started by McDroogie, Jan 7, 2013.

  1. McDroogie

    McDroogie

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    Dec 25, 2012
    I would like to to set up some 4520s CMOS chips and attach them to a seven segment display and make them count or display numbers. The link for the data sheet is posted below. They came in a pack of two and say dual. What does this mean? Can they be used separately or must they be used together in order to make them function?

    http://www.nxp.com/documents/data_sheet/HEF4520B.pdf
     
  2. davenn

    davenn Moderator

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    Sep 5, 2009
    Dual in this case means there are 2 separate counters in the one package
    you can use one or both of them depending on circuit requirements

    like with all CMOS and logic chips, its a wise idea to ground to 0V rail any inputs of a section that are not being used. This stops all sorts of weird fault symptoms

    Dave
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

    9,230
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    Nov 17, 2011
    Here is an example for a single digit counter using the 4520.
    For an n-digit counter you need to cascade n counters, the datasheet tells you how to connect the counters for cascading.

    The 4520 is a binary counter. To display the count on a 7-segment display you will need an additional BCD-to-7Segment decoder, one for each digit.


    However, the 4520 is a binary counter, meaning it counts from 0...15, So you can't build a decimal counter from this chip and your display will show weird symbols once the count goes over 9.
    If you can find one, I suggest looking into the 4026 or 4033. These chips are not only decade counters, they already include the decoder to drive the 7-segment display.
    Or look into the 4510 which can not only count up but also count down. Here is a complete circuit to evaluate the 4510.

    Harald
     
  4. McDroogie

    McDroogie

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    0
    Dec 25, 2012
    Can I at least initiate a countdown or count up from 0-9? If so where can I start?
     
  5. Miguel Lopez

    Miguel Lopez

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    55
    Jan 25, 2012
    From the datasheet it seems that HEF4520 is just a count-up counter, so, there is no possibility to count down.

    You can start it at zero, fixing initial conditions at pins 7 and 15. If these pins goes HIGH, then the counters will be reseted to zero.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    You will still need a BC D to 7-segment decoder, though.
     
  7. McDroogie

    McDroogie

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    0
    Dec 25, 2012
    So is there a chip within that same family that acts as a decoder? And so I have to wire them with the counter and 7 seg display?
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

    9,230
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    Nov 17, 2011
    You could use a 4511. But I would use the 4510 counter with integrated decoder. Saves some wiring.
     
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