Ph 490

January 6, 2005

Problem Set 11: Digital Electronics

1. Using only AND and OR circuits and inverters, design a logic circuit with two inputs, A and B, and an output Q, such that the output is given by

. (This is the function known as the exclusive or.) The AND, OR and inverter are shown below.

2. Make a truth table for the circuit of problem 1.

3. Now design a logic circuit to reproduce the function of problem 1, but using only NAND circuits.

4. Below is given a circuit for lighting a warning light if the seatbelts in a car are not fastened. It does not light if there is no one in the passenger seat.

Redesign this circuit using only NAND circuits.