decade counter

Discussion in 'Homework Help' started by Energetic, Feb 23, 2011.

  1. Energetic

    Thread Starter Member

    Jan 3, 2011
    33
    0
    My task is to design a circuit on multisim which will count from 0-9 on a 7 seg CA display. I am going to use a 555 timer chip at 1Hz and have ben advised to used a 74LS47. Also should include a latching facility.

    Please assume i am keen to learn but am a complete idiot (fully qualified electrician) when it comes to electronics.

    i have attached what i have so far. (embarrassingly little)

    Any advice on where to start would be much appreciated.

    Thanks....
     
  2. n1ist

    Active Member

    Mar 8, 2009
    171
    16
    Look at the data sheets for the chips. They will tell you what each pin does. Years ago, the common lineup was a 7490 counter feeding a 7475 quad latch feeding a 7447 decoder.

    There are a bunch of circuits out there; google "555 74ls90 74ls47" to find some.
    /mike
     
  3. Energetic

    Thread Starter Member

    Jan 3, 2011
    33
    0
    Thanks for the tip, i have had a go and have attached it below. It looks good (to me) but still doesn't do anything... Any advice on what's wrong would be great!!!!

    Cheers...
     
  4. jepoy

    New Member

    Oct 1, 2010
    15
    0
    the problem might be on the clock pulse.
    try using this scheme to get the 1Hz pulse.

    [​IMG]

    and I think pin 7 and 10 are not connected.
    I dont see no "dot".

    ( :
     
    Last edited: Mar 1, 2011
  5. Energetic

    Thread Starter Member

    Jan 3, 2011
    33
    0
    Thanks! The clock is now working. I have a nice pulse coming out. Sadly the rest is still not working... nothing on the display...

    Below is my latest effort...
     
  6. Energetic

    Thread Starter Member

    Jan 3, 2011
    33
    0
    Any ideas, anyone????
     
  7. Energetic

    Thread Starter Member

    Jan 3, 2011
    33
    0
    Sussed it, the 3,4,5 on the 7447 had to be tied high. counting away now...

    Thanks for the help guys...
     
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