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Homework Help: Digital Electronics- logic gates problem

  1. Oct 7, 2014 #1
    • Warning! Posting template must be used for homework questions.
    A bulb in a staircase has two switches , one at the ground floor and the other one at the first floor. The bulb can be turn ON and also OFF by any of the two switches irrespective of the state of the other switches, then what is the logic of switching of the bulbs

  2. jcsd
  3. Oct 7, 2014 #2
    There can be two cases and truth table can be formed in two ways.If both the switches are in same state the output can be "ON State" or if both the output are in opposite state the output can be in "OFF State".

    Truth table does not seems to be correct.
    Last edited: Oct 7, 2014
  4. Oct 7, 2014 #3


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    Staff: Mentor

    Your truth table shows that if A=1 there is no way that B can turn the bulb off, yet specs say bulb status should be able to be set independent of other switch.
  5. Oct 8, 2014 #4

    rude man

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    Homework Helper
    Gold Member

    Change one line in your truth table.
    Last edited: Oct 8, 2014
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