In this video, I’ve made a simple laser security alarm using a BC547 transistor, LDR, buzzer, and a 3.7V battery. When the laser beam is blocked, the buzzer instantly turns ON, triggering the alarm. This is a great mini project for beginners to learn about light sensors and transistors.
Perfect for home safety, school projects, or electronics experiments.
⚡ Powered by a single 18650 cell and works without Arduino!
Components Used:
BC547 Transistor
LDR (Light Dependent Resistor)
Buzzer
1k Resistor
Laser Module (3V)
3.7V Battery