Introduction
The 74LS32 IC contains four independent OR gates. OR gates are basic logic gates that output a HIGH signal (1) if at least one of their inputs is HIGH. This experiment demonstrates how the 74LS32 OR gate works in a simple logic circuit.
Objective
The objective of this experiment is to build a logic circuit using the 74LS32 OR gate and to verify its behavior by testing different input combinations and observing the output.
Components Needed
- 1 x 74LS32 OR Gate IC
- 2 x Push Button Switches
- 1 x LED
- 1 x Resistor (220Ω for the LED)
- 2 x Resistors (10kΩ for pull-down on push buttons)
- 1 x Breadboard
- Connecting Wires
- Power Supply (5V)
Circuit Diagram
Procedure
- Place the 74LS32 IC on the breadboard.
- Connect pin 14 (VCC) to the positive 5V power supply and pin 7 (GND) to ground.
- Connect two push button switches to act as inputs to the OR gate. Connect one side of each button to the 5V supply and the other side to the inputs of the OR gate (for example, pin 1 and pin 2).
- Add 10kΩ pull-down resistors between the ground and the inputs of the OR gate to ensure a defined LOW state when the buttons are not pressed.
- Connect the output of the OR gate (for example, pin 3 if using the first OR gate) to the anode of the LED.
- Connect the cathode of the LED to ground through a 220Ω current-limiting resistor.
- Power the circuit with 5V. The LED should turn on if at least one of the push buttons is pressed, demonstrating the behavior of the OR gate.
Step 1: Input Configuration
Step 2: Output Configuration
Step 3: Testing the Circuit
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Results
The LED will turn on when either one or both push buttons are pressed, confirming that the 74LS32 OR gate functions according to the truth table of an OR gate. The LED will remain off if both buttons are not pressed.
Truth Table
| Input A | Input B | Output |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
Conclusion
This experiment demonstrated the basic operation of the 74LS32 OR gate. By testing different combinations of inputs using the push buttons, we confirmed that the OR gate outputs a HIGH signal when either or both of its inputs are HIGH. The behavior observed matches the expected truth table for an OR gate.
