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3 x 7 segment led countdown

Discussion in 'LEDs and Optoelectronics' started by Viad, Mar 6, 2012.

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  1. Viad

    Viad

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    Feb 9, 2012
    I want to build a countdown timer using 3 x 7 segment led displays
    I want it to count down from 120 to 0
    I shall provide the pulses to operate the counter , 1 pulse per second
    At the end of the countdown the counter can sit at 0 or reset to 120
    or be manually reset to 120 by a single operation/switch

    I apologise if this info is readily available but I can't find a circuit diagram for this.
    I see there is a circuit diagram for a 9 to 0 countdown on this site perhaps that could be modified, but I'm a novice and it's beyond me as yet.

    A circuit digram for the above or perhaps a book where I can find a suitable circuit would be a great help.

    thanks Alan
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Have you Googled for what people have done before?

    There are some good options you might consider as a base.

    Especially this one.
     
  3. Viad

    Viad

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    Feb 9, 2012
    Hi steve and thanks for your reply, yes I had seen the link you posted but the construction was rather daunting to me, it uses a programable chip does it not ? .
    I don't want to appear lazy but I don't have the time at present to study and understand the 'more complicated' circuits.
    Will I have to use a programable chip to obtain the features I want or can it be done using an expanded version of for example the 0 to 9 counter you describe on this site ?
    I can purchase a Velleman kit K8035 up down counter, for very little money, it does more than I require, however I don't think the reset to 120 can be easily achieved ie by an automatic reset or a single switch action.

    Am I wasting my time searching for a simple circuit diagram, will I have to use a programable chip, I would have thought what I'm looking for exists but I just can't find it
    Alan
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    A programmable chip is really what makes the resetting to 120 a relatively simple proposition.

    Doing it in discrete electronics (OK, using standard logic (counters, gates, flipflops etc) is possible, but would be rather more complex.
     
  5. Viad

    Viad

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    Feb 9, 2012
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Yep, that's an example of a device using a programmable chip (the PIC16C57).

    If you had access to the source code and enough experience, you could make it do what you want. As it it, I'm not sure that it does.
     
  7. Viad

    Viad

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    Feb 9, 2012
    Thanks for your help steve
     
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