NOT Gate Using SN74HC04 IC
Build a NOT gate (inverter) using the SN74HC04 hex inverter IC—six NOT gates in one chip!
Overview
While building logic gates from discrete transistors teaches you how they work internally, real digital circuits use integrated circuits (ICs) for reliability and convenience. The SN74HC04 contains six independent NOT gates (inverters) in a single 14-pin package. This project shows you how to use IC-based logic gates—the building blocks of modern digital electronics.
Components Needed
- 1x Switch
- 1x LED
- 1x SN74HC04 IC
- 1x 10kΩ resistor
- severalx Wires
Instructions
Gather Your Components
Collect the SN74HC04 IC, one switch, one LED, a 10kΩ resistor, wires, breadboard, and 5V power source. The IC is the small chip with legs on both sides.
Identify the SN74HC04 IC
Look at the IC closely. The notch or dot marks pin 1. Pin 7 (bottom left) connects to ground, and pin 14 (top left) connects to 5V power. Each of the six inverters uses two pins—one input and one output.
Wire the Circuit
Place the IC on the breadboard straddling the center gap. Connect pin 14 to 5V and pin 7 to ground. Connect the switch output to pin 1 (input of first inverter). Connect pin 2 (output of first inverter) to the LED through the resistor. Use the 10kΩ resistor as a pull-down on the switch.
Test: Switch OFF → LED ON
With the switch in the OFF position (to the right), the input to the inverter is LOW. The NOT gate inverts this to HIGH, turning the LED ON. This demonstrates the inversion—LOW input produces HIGH output.
Test: Switch ON → LED OFF
Flip the switch to the ON position (to the left). Now the input is HIGH, and the NOT gate inverts it to LOW, turning the LED OFF. The inverter is working correctly!
Challenges
- Use two inverters in series—what happens to the output?
- Build an oscillator using an odd number of inverters in a ring
- Use all six inverters simultaneously with six switches and LEDs
- Compare the switching speed to your transistor-based NOT gate