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logiccircuittruthtablecircuit-diagram

What's the truth table of this circuit

I'm trying to make a truth table of this electronic circuit:

enter image description here

How does this work? How can I know what the value of B is for example A = 0 and C = 0? Isn't this an infinite recursive structure? Or how does that work? I used Logism to simulate the circuit and found this truth table:

A = 0 C = 0 --> B = 1
A = 1 C = 0 --> B = 1
A = 0 C = 1 --> B = 1
A = 1 C = 1 --> B = 0

Now, is this correct? And what's the boolean expression for this circuit given A and C?

Solution

  • if C=1 -> the multiplexer select the A input, and then B=NOT(A)

    if C=0 the multiplexer select the NOT(B) input and then, B=NOT(NOT(B))=B. or the last value of not(A) just in the edge from 1 to 0 of C.

    if C=0 -> B holds your value. Whatever it is 0 or 1.

    So, if C=1 --> B=NOT(A) whatever is the A value. it is live a Flip Flip D, not Master-Slave, With D=A and B=not(Q). C=Clock

    If C=0 B is hold in the last value, Like a Flip Flop NOT master-slave said before.

    The truth table is:

    A C B

    0 0 B

    0 1 1

    1 0 B

    1 1 0

    Note that with C=1, B=not(A), and with C=0, B=not(not(B))=B, that show B holds the value it has. the NOT(A) just when C change from 1 to 0.

    It is a single Flip Flop D. Not Master-Slave, A=D, B=NOT(Q), C=Clock