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Step|A|B|C
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1   |0|0|1
2   |1|0|1
3   |1|1|0
4   |1|0|0

From the truth table above, I can not find the equivalent boolean expression hence I can not create the logic circuit. Does it have any?

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  • 2
    \$\begingroup\$ Is this a truth table or a transition table? \$\endgroup\$ – The Photon Jun 24 at 23:21
  • \$\begingroup\$ My question came from a job interview. After I thought about it, this is more likely a transition table. Thanks for the hint. If it is a transition table, can it be translated to a digital circuit? What subject should I learn to solve this problem? \$\endgroup\$ – Ηλεκτρολόγος Μηχανικός Jun 24 at 23:40
  • \$\begingroup\$ The table was used to drive a DC motor. \$\endgroup\$ – Ηλεκτρολόγος Μηχανικός Jun 24 at 23:41
  • \$\begingroup\$ A and B are the outputs of some sensor. \$\endgroup\$ – Ηλεκτρολόγος Μηχανικός Jun 24 at 23:43
  • \$\begingroup\$ If \$C\$ is the output and \$A\$ and \$B\$ are inputs, then you seem to only need to generate the \$C\$ output. This is pretty easy. Just use an RS FF and include an NOR and an AND gate. That's all there is. Do you see why? \$\endgroup\$ – jonk Jun 25 at 4:20
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I'm not entirely clear on the question you are asking. But I think the following satisfies the requirements:

schematic

simulate this circuit – Schematic created using CircuitLab

It's just an RS FF (two NOR gates) preceded by an AND and a NOR gate. See if that works for you.

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