Derive the Boolean expression and construct a truth table for the switching circuit shown in Fig. $11.6$.
Figure 11.6]
The parallel circuit $I$ to 2 and 3 to 4 gives $(\Lambda+\bar{B})$ and this is equivalent to a single switching unit between 7 and 2 . The parallel circuit 5 to 6 and 7 to 2 gives $C+(A+\bar{B})$ and this is equivalent to a single switching unit between 8 and 2 . The series circuit 9 to 8 and 8 to 2 gives the output
$$
\boldsymbol{Z}=\boldsymbol{B} \cdot[\boldsymbol{C}+(\boldsymbol{A}+\overline{\boldsymbol{B}})]
$$
The truth table is shown in Table 11.3. Columns 1 , 2 and 3 give all the possible combinations of $A, B$ and $C$, Column 4 is $\bar{B}$ and is the opposite to column 2. Column 5 is the or-function applied to columns 1 and 4 , giving $(A+\bar{B})$. Column 6 is the or-function applied to columns 3 and 5 giving $C+(A+\bar{B})$. The output is given in column 7 and is obtained by applying the and-function to columns 2 and 6 , giving $Z=B \cdot[C+(A+\bar{B})]$