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Building a Countdown Timer with a 555

  1. Oct 16, 2008 #1
    Im trying to do just that, that is build a timer that countsdown accurately to the minute. Ideally this device should have a range of about 5 second countdowns to 36 hour countdown. I'd like to add a 7-segment LED display wired to count as well but Im not sure I think i can do that with a 555 without a crystal oscillator. What im thinking might work is using a crystal oscillator in tandem with a microcontroller that will know the number of clockcycles a second are before decrementing the value on the LED display where at T=0, it should send a high voltage pulse to the output terminals, preferably high enough power such that it can accomodate turning a small dc motor on. Thanks for your help and valuable insight.
  2. jcsd
  3. Oct 17, 2008 #2
    Much better to use a 4060 chip and a watch crystal. Accurate to a fraction of a second without any adjustment.
  4. Oct 17, 2008 #3
    Thanks for the honest feedback, however where can I find these types of parts? Ive found so many different brands of ICs with so many specs most of which mean absolutely nothing as of now to me... What should i be looking for when purchasing a viable IC for my application?
  5. Oct 17, 2008 #4
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