Скачать или смотреть Laser Security Alarm System

A laser security alarm using an LDR (Light Dependent Resistor) and transistors works by creating a light-sensitive switch: when the laser beam hits the LDR, its resistance drops, keeping the transistor OFF (no alarm); but when someone blocks the beam, the LDR's resistance rises, turning the transistor ON, which completes the circuit to sound a buzzer and light an LED, signaling intrusion. This setup uses a voltage divider with the LDR and a fixed resistor to control the transistor's base, activating an alarm upon beam interruption.
Key Components
Laser Diode: Emits a continuous laser beam.
LDR (Light Dependent Resistor): Resistance decreases with light, increases in darkness.
Transistors (e.g., BC547, BC548): Act as switches.
Resistors: Set voltage levels (e.g., 10kΩ, 330Ω).
Buzzer & LED: Alarm indicators.
Power Supply: Battery (e.g., 9V).