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Counter using 74LS90 and 74LS47

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by MattAyers, Mar 20, 2004.

  1. Lanzer

    Lanzer New Member

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    Yet another link on the 74ls90

    Just wanted to add a note here in case anybody else come across the need in playing around with 74LS90 circuits:

    http://travel.howstuffworks.com/digital-clock5.htm

    Gives examples of setting up divide-by-10 counters and divide-by-6 counters to create a digital clock.
     
  2. ccabrera

    ccabrera New Member

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    multisim project

    Okay i'm kind of new at this and I'm using multisim7. For my project I need some sort of timing device. After 5 sec, I need ouputs to change. Then after 23 sec, I need outputs to change again. Then after 25 seconds I need those outputs to change once more. I imagine I'll use a counter, but I'm really not sure how I go about making a truth table or hooking up multiple counters. I think counters like the 74192 or 7490 or 74161 could be used?? Can anyone help me out??? I'm kind of....clueless and I'd appreciate any help. Oh and I can only usre 74xxx series ICs.

    Thanks.
     
  3. ronak_dave

    ronak_dave New Member

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    Hi,
    I also build this counter and its works well, but I have one problem that when I switch on the power of counter its displays 8 rather than 0. Please help me in this metter if you know anything about it.
    Project diagram is received by http://www.aaroncake.net/circuits/counter.htm
     
  4. dave

    Dave New Member

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  5. ljcox

    ljcox Well-Known Member

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    The circuit needs 2 additions.

    1. Switch on reset so it starts at 0

    2. a 100 nF bypass capacitor across the counter supply pins. Strange results can occur otherwise

    Len
     
  6. Shadyman

    Shadyman New Member

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    74ls47 have open collector outputs, chances are your simulation software includes this in its models as well. This means you should tie them high using 1K pull up resistors and then use inverters between the 7447 output to your 7 seg display. Try it.
     
  7. rsgino7

    rsgino7 New Member

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    Counter doesn't work.

    Hey, I am building this counter right now and i can't get it running. :confused: Is there a switch required? And what do you with Pin 14 where it says "count in". Please if anyone can help me it would be great!

    BTW: there is not a youtube vid on building this, is there? Maybe someone could make one since everyone has trouble with this circuit :)

    Thanks in advance!
     
  8. Brook

    Brook New Member

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  9. gandapur

    gandapur New Member

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    Digital Cloooooooooock

    :eek:neeeeeeeeed digital clock complete circuit diagram:mad:
     
  10. AllVol

    AllVol New Member

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    The reason you had to use an inverter chip is because of a mis-match with your driver and display.

    That is also the reason many people have trouble with a simple counter.

    If your 7- segment display is a common cathode type, you must use a 7448 driver.

    If your 7- segment display is a common anode type, you must use a 7447 driver.


    Other points to watch:
    Liberally use capacitors between the + and - rails to avoid spikes and glitches.
    Use a regulated 5 volt power supply or fresh batteries totaling 4.5 to 5 volts with TTL chips (74xx series)
    Make sure the input to pin 14 of the 7490 is clean. Debouncing is mandatory if using a switch for single pulse.
    If you want multiple digits, you must use a 7447(8) for each display.
    Place 220R resistors between driver and each segment.

    I realize this thread dates back some 5 years, but there are always new people joining our group, hence the above information.
     
    Last edited: Mar 14, 2009
  11. chazie

    chazie New Member

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    can i have a schematic diagram of 74LS192 and 74LS47 with up/down counter???
     
  12. chazie

    chazie New Member

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    what is the function of 74LS192 and 74LS47
     
  13. ngekz

    ngekz New Member

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    74ls90 na d74ls145

    what is the use of 74ls90 and 74ls145?
    just reply on my ad vaughn101@gmail.com tnx
     
  14. ChitSu

    ChitSu New Member

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    I also built a digital clock using 74LS 161 and 74 LS47 IC. but I have one problem that is 74LS161 IC can not output . How to fed input that IC ? please answer to meeeeeeeeeeeeeeeeeeeeeeee.............
     
  15. shokjok

    shokjok Member

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    Your clock source could be just a resistor tied to VCC and the other end tied to a grounded pushbutton. I recall this project from the former Radio Shack in Canada. I had this particular Archer kit once, without a clock source I couldn't verify its operation.
     

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