ELEC 105, Spring 2004
Prof. Rich Kozick

Laboratory 11
Design and Implementation of a Majority Voting Circuit

Three partners in a small company have hired you to build a circuit that will automate their voting. Each partner owns an equal share of the company, so decisions are made by majority vote. You are to design, build, and test the circuit. Please go through the following steps.

  1. Write the truth table for the majority circuit.

  2. Write a Boolean expression for the circuit in the standard sum-of-products form.

  3. Try to simplify the Boolean expression. We will help you with the simplification.

  4. Draw a logic diagram for your simplified Boolean expression using AND, OR, and NOT gates.

  5. Modify your logic diagram so that only NAND gates are used.

  6. Finally, connect your NAND gate design for the majority function. Use 7400 ICs, switches for the inputs, and an LED for the output. Test and demonstrate your circuit for all input combinations in your truth table.