The 7805 is a linear voltage regulator IC from the 78xx series. 78xx series → Positive voltage regulators. xx → Output voltage. So, 7805 = +5V fixed output regulator. It takes a higher DC input voltage (e.g., from your 12V 2A adaptor) and outputs a regulated +5V DC. ⚙️ Specifications Input Voltage: 7V to 25V (recommended). Output Voltage: 5V (fixed). Output Current: Up to 1A (with proper heatsink). Dropout Voltage: Needs about 2V higher input than output (so min. ~7V input). 📌 Pin Configuration (3 pins) Pin 1 (Input) → Connect DC input (e.g., 12V from adaptor). Pin 2 (Ground) → Common ground. Pin 3 (Output) → Provides regulated +5V DC. ⚙️ Working Principle Without regulator: If you power a circuit directly from a 12V adaptor, fluctuations or excess voltage may damage it. With 7805: It stabilizes the voltage at exactly 5V, protecting microcontrollers (like Arduino, PIC, or sensors) which require precise +5V. 🛠️ Circuit Example with 12V 2A Adaptor 12V Adaptor (+) ───► [Pin 1: IN 7805] GND ───────────────► [Pin 2: GND] [Pin 3: OUT 7805] ─► +5V regulated output Add 0.33µF capacitor at input and 0.1µF capacitor at output for stability. If load is high, use a heatsink with the 7805 (because it dissipates heat as (Vin – Vout) × Current). 🔋 Application Examples Powering Arduino boards, sensors, ICs from a 12V source. Used in CCTV cameras, routers, audio devices. Battery chargers and small electronic projects.