CSCI 235 Digital Circuit Design

Laboratory Exercise 2 – Logic Gates

Part 1. AND Gate

This first circuit is simply a 2-input AND gate. A 7408 IC contains 4 independent AND gates. The chip must be powered with a 5V supply. Plug a 7408 IC into the breadboard and connect the power supply pins as shown below.

Apply high and low voltages to the inputs of one of the AND gates. Using a volt meter, measure the voltage on both input pins and on the output pin for each input combination. Connect the negative (black) meter probe to the low bus for all measurements.

AND Gate

A / B / VA (volts) / VB (volts) / VX (volts) / X
0 / 0
0 / 1
1 / 0
1 / 1


Part 2. OR Gate

The 7432 IC contains 4 independent OR gates. Using the breadboard and meter, power a 7432 IC, and test its functionality.

OR Gate

A / B / VA (volts) / VB (volts) / VX (volts) / X
0 / 0
0 / 1
1 / 0
1 / 1

Part 3. Inverter

The 7404 IC contains 6 independent Inverters. Using the breadboard and meter, power a 7404 IC, and test its functionality.

Inverter

A / VA (volts) / VX (volts) / X
0
1


Digital Circuits Episode IV: A Larger Circuit.

Just recently

In this galaxy

A young Jedi learned to build a circuit

You’ve taken your first step into a larger world

Analyze the circuit below, and complete the truth table.

A / B / C / X
0 / 0 / 0
0 / 0 / 1
0 / 1 / 0
0 / 1 / 1
1 / 0 / 0
1 / 0 / 1
1 / 1 / 0
1 / 1 / 1

Then, build the circuit and complete the table below.

A / B / C / VM / M / VN / N / VX / X
0 / 0 / 0
0 / 0 / 1
0 / 1 / 0
0 / 1 / 1
1 / 0 / 0
1 / 0 / 1
1 / 1 / 0
1 / 1 / 1

Should you measure M at the output of the AND gate, or the input of the OR gate?

Should they be the same voltage?

Are they the same voltage?