Urgent Help Please - Newbe out of control!

Discussion in 'The Projects Forum' started by usdiggs, Dec 4, 2006.

  1. usdiggs

    Thread Starter New Member

    Dec 4, 2006
    8
    0
    Hi, I need some help to design what sounds like a simple project. All it needs to do is count up or down (displaying on 7 segment displays) when a button is pressed. I have been trying to use Ic's SN74192 as the counter and SN74247 as the display driver. It only need to be up to 99.

    As well as this I also want to have another display that counts down (MM:SS) from 2 minutes. Once it has counted down to zero, then it resets to blank state or just stays at zero.

    Any help here would be much appreciated.

    Thanks, Dazed & Confused
    :confused: :eek:
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    How about posting your circuit design so far. This will give the members a starting point in assisting you with your design.

    hgmjr
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    That's 99 hex, not decimal, right? Converting hex to BCD takes a lot more than two chips...
     
  4. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
  5. usdiggs

    Thread Starter New Member

    Dec 4, 2006
    8
    0
    Thanks Hgmjr, I have started by trying to get one 7 segemnt display working as I under stand the cascading to add more on. I have attached a jpeg of my little mess.

    Thanks
     
  6. nomurphy

    AAC Fanatic!

    Aug 8, 2005
    567
    12
    The LOAD signal has no source, it is not driven, neither is it pulled up or down (this also affects the NAND gate inputs).

    Also, the CLEAR and preset lines A-D need to be terminated appropriately.

    ALWAYS terminate any unused inputs to the appropriate state.
     
  7. usdiggs

    Thread Starter New Member

    Dec 4, 2006
    8
    0
    Ok, Thanks. Now what does that mean? Sorry I am very new to this. Are you able to edit the jpg? or sketch it si I can see what you mean. Thanks
     
  8. nomurphy

    AAC Fanatic!

    Aug 8, 2005
    567
    12
    See attached:
     
  9. usdiggs

    Thread Starter New Member

    Dec 4, 2006
    8
    0
    Thanks sooo much. You have been a huge help & a lot of progress has been made.

    Thanks Again

    Aaron:D
     
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