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Project Help

Discussion in 'Homework Help' started by Bob Greenwich, Oct 23, 2016.

  1. Bob Greenwich

    Bob Greenwich New Member

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  2. JimB

    JimB Super Moderator Most Helpful Member

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    One way would be to use a 74145 to convert the BCD output from the 74190 to 10 individual outputs.

    JimB
     
  3. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Why do you want to use a chip that is likely to make the circuit more complex?
     
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  4. dave

    Dave New Member

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  5. Bob Greenwich

    Bob Greenwich New Member

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    There are no 4017 chips available, and my teacher suggested I use a 74190
     
  6. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    If you use the decade counter you will have all four steps but the whole idea of the 10 steps is the Green / red is on longer.. With the 74190 all four states will be the same length.... You could use 3 74190's cascaded 4 states red/green and 1 state yellow / red... 4 states green /red and lastly 1 state red yellow...
     
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  7. Colin

    Colin Member

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    There are no 4017 chips available, and my teacher suggested I use a 74190

    I just bought 500 x 4107 at 17 cents, so I must have bought the last of the chips IN THE WORLD.
     
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  8. absf

    absf Active Member

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    As 74190 uses 5V for Vcc, the circuit won't work with just 5V as there are 4 LED to lite on each branch. A 78L05 is needed to get 5V from 12V for the TTL to work properly.

    The outputs of 74LS145 (as suggested by Jim) are active low, so either 4 PNP transistors are needed as high side switches for the LED or the 12 LEDs have to be rearranged to fit the 74145 outputs.

    Allen
     

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