Counting down timer

Discussion in 'General Electronics Chat' started by verouge, Mar 24, 2010.

  1. verouge

    Thread Starter New Member

    Mar 24, 2010
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    Hello guys.

    I would like to know if any of you know how to build a simple counting-down timer that counts up to 24hours and can be connected to a switch in order to automatically turn off an electrical gadget after 24hours. I want to set it by seconds.

    Thanks for your help,
    Regards,
    verouge
     
    Last edited: Mar 24, 2010
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Simpler than buying one?

    Do you want to build one or just find one?
     
  3. verouge

    Thread Starter New Member

    Mar 24, 2010
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    I want to build one.
     
  4. retched

    AAC Fanatic!

    Dec 5, 2009
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    Ok. Do you have any electronics experience? Or is this a project to get some experience?

    Do you want this to be battery powered, or do you have a transformer? (cell phone charger type wall plug in)
     
  5. verouge

    Thread Starter New Member

    Mar 24, 2010
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    I am a biomedical engineer, so I do have electronics experience but I've never built a timer. I need it to connect it to a "microanalyses particle sampler". I can easily afford a transformer.

    Thanks
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    Ok, good, so you know what a battery is. :)

    how accurate of a SECOND do you need? Crystal accurate or 555 accurate?
     
  7. verouge

    Thread Starter New Member

    Mar 24, 2010
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    Sure I know, hehehe..
    I believe 555 accurate is good enough since most of my sampling will be 24hours exactly, no hour fractions..
     
  8. Boo

    Member

    Oct 27, 2009
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    Do you want it to be digital or analogue, in the sense of Micro controller or 555 ?
     
  9. verouge

    Thread Starter New Member

    Mar 24, 2010
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    Digital. I don't want to program it on pc. Just a simple electrical board with no C-Language or Java-Language.
     
  10. Boo

    Member

    Oct 27, 2009
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    So something like this but 24 hours?
     
  11. verouge

    Thread Starter New Member

    Mar 24, 2010
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    with 2small variations:
    1. instead of giving sound, I want it to be connected to a switch to turn off another electrical gadget. (its alarm will turn off an equipment).
    2. I prefer to set the time manually (the guy here waits 5sec to stop it at 5, what if it was 86400sec=24hr?)
     
  12. verouge

    Thread Starter New Member

    Mar 24, 2010
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    Yes but with two differences:
    1. Instead of voice alarm, I want it to be connected to a switch to turn off my sampler automatically.
    2. I prefer to set the time manually instead of waiting until it's 24hrs to launch it.

    Thanks
     
  13. Boo

    Member

    Oct 27, 2009
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    Yup that can be done easily, p.s. I'm "the guy"
     
  14. verouge

    Thread Starter New Member

    Mar 24, 2010
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    :-D Mr. guy, so how can I make it? You got the electrical map, would u pls send me its link?
     
  15. Boo

    Member

    Oct 27, 2009
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    Your going to need to program a chip, specifically a PIC, thats what I used.
     
  16. verouge

    Thread Starter New Member

    Mar 24, 2010
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    Ok, thanks Mike. I will write a program for the chip.
     
  17. loosewire

    AAC Fanatic!

    Apr 25, 2008
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    What Is the name of the shipping port in Beirut,If I need to ship some thing to you.
    A transformer.
     
  18. verouge

    Thread Starter New Member

    Mar 24, 2010
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    You don't ship it to the shipping port. You ship it to my P.O.Box in Beirut. Why?
     
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