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BCD switches as a clock source

  1. Aug 23, 2010 #1
    Can anyone please explain to how one can use a set of BCD switches on a PCB and use them as a clock source?

  2. jcsd
  3. Aug 24, 2010 #2


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    Staff: Mentor

    Doesn't make sense on the face of it. A clock source would have to be an active circuit. A switch is generally a passive electromechanical device.
  4. Aug 24, 2010 #3
    If you need to recover a clock signal from 1-2-4-8 BCD signals, put a debouncer on the "1" signal (if it is a mechanical switch) and then a x2 multiplier (exclusive OR with a delay in one input).

    If you want to recover a clock signal from the "carry" output of the BCD, put the "8" signal and the "1" signal into an AND circuit. This signal goes TRUE at "9" and FALSE on the next input clock signal. You also can use the "8" signal alone and carry on the negative transition.

    Bob S
    Last edited: Aug 24, 2010
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