AND Gate Circuit

The AND Gate Circuit is a fundamental digital logic build that demonstrates the operational behavior of a logical conjunction using discrete hardware. At the heart of the setup is the 4LS09 Quad AND Gate IC, powered by a stable 5V power supply. The circuit utilizes two push buttons connected to the inputs of one of the internal AND gates to act as manual binary input switches. Pull-down resistors, specifically the 1K resistors, are configured with the inputs to ensure they remain at a definitive low logic state (0V) when the buttons are unpressed, preventing floating inputs that cause erratic switching. When a button is pressed, it pulls the respective input up to the 5V high logic state. The 100nF capacitors are placed across power rails to act as decoupling components, filtering out high-frequency noise and stabilizing the 5V supply to the sensitive transistor-transistor logic (TTL) IC. The output pin of the AND gate is tied to a current-limiting 220-ohm resistor, which safely drops the remaining voltage before driving a single LED. According to the AND gate truth table, the LED will only illuminate when both push buttons are simultaneously depressed, supplying high logic levels to both inputs. If either button or both buttons are released, the output falls to low, turning the LED off and visually confirming the logical AND operation.