9 to 0 down counter with 7 segment display

Discussion in 'The Projects Forum' started by Doruk öztürk, Aug 7, 2017.

  1. Doruk öztürk

    Thread Starter New Member

    Aug 7, 2017
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    Hello everybody,

    I have a project which is to make a system that counts backwards from 9 to 0 (9 - 8 - 7 ... 0 etc.) with 1 sec periods. I can't use arduino or coding stuff so I just need to use some integrated circuits, so far I though to make a system with 74ls47(decoder), 555 (timer) and I should find an integrate which is able to count down that might be 73hc192 or 73hc193? can't decide which one to use and if I use one can't really decide how to connect them to each other.

    Also when I am connecting these integrates, the clock leg should be connected to 555 right ? since it is the one giving away the # signal ?. Coulnd't really find detailed info on backward counters so also some general info would be great, thanks beforehand!.
     
  2. bertus

    Administrator

    Apr 5, 2008
    19,799
    4,107
    Hello,

    I think you mean the 74HCT192 and 74HCT193 in stead of the 73's.
    Both are up/down counters.
    The 192 is a BCD and the 193 is binairy.

    Bertus
     
  3. freak101

    Member

    Aug 7, 2017
    37
    0
    Why don't you use 4-bit ripple down counter that starts from 9 ? You'll require 4 negative edge triggered JK flipflops and 555 IC for clock. You can search on youtube for more details.
     
  4. Doruk öztürk

    Thread Starter New Member

    Aug 7, 2017
    6
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    Yep I meant to write 74, but which one is to be used and why ? both of them have the same datasheet so I guess it doesn't really matter ?
     
  5. Doruk öztürk

    Thread Starter New Member

    Aug 7, 2017
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    Yeah I also though to use FF with 555IC but I guess using a integrated circuit would be better and easier I guess ?
     
  6. Reloadron

    Distinguished Member

    Jan 15, 2015
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    For your project either of SN54192, SN54193, SN54LS192, SN54LS193, would work just fine and you really only need the 192 chip for count down 9 to 0. The 555 can be used as your clock and the 7447 as your seven segment display driver. This also sounds like school assignment work. You have a clock chip, the 555 timer, followed by a synchronous 4 bit up/dn counter followed by a decoder driver for your display. The 74192/74193 data sheet I linked to explains everything you need to know.

    Ron
     
  7. Doruk öztürk

    Thread Starter New Member

    Aug 7, 2017
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    Yeah it is exatcly as you said, so right now I have the system works fine while counting up from 0 to 9, how can I reverse it, do you know which connections should change ?

    I have changed the 4th and 5th legs of those connections (one is down and the other is up). Other than those is there anything needs to change ? Bcs when I change those connections it doesn't count backwards just stays at 0. But as I said the normal counting is just fine.

    Alsi how can I alter the counting speed. Thanks in advance !!
     
  8. Reloadron

    Distinguished Member

    Jan 15, 2015
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    Your clock in goes to either the Up or Down input pin while holding the other (unused) pin at a logic high. Page 5 of the data sheet I linked to shows the count sequence clearly.

    Ron
     
  9. Doruk öztürk

    Thread Starter New Member

    Aug 7, 2017
    6
    0
    Ok, I got to do it, Thank you very much!!!
     
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