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How to use 555,2x 7490,2x 7447 to count 0 - 60?

  1. Aug 10, 2011 #1
    I can perform counting 0-99 but how do you stop it in 59 then 00 then back to 01?
    heres a sample
  2. jcsd
  3. Aug 10, 2011 #2
    heres a sample

    Attached Files:

  4. Aug 10, 2011 #3


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    Science Advisor

    You'd have to build yourself a different state machine that could do that. Or, being a CS type, you'd write a dozen lines of code for a microcontroller, providing BCD output to your 7-segment display drivers.

    On the assumption that you're looking for some kind of time-keeping device, you can also use an RTC (real time clock). Some even come integrated with crystals (or if not, you can find yourself a 32.768 kHz--2^15 Hz crystal). Heck, I've seen one which was basically an alarm clock on a chip (think it came from Maxim).
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