This project is an automatic light-activated LED strip controller using an LDR, LM311 comparator, and NE555 timer. The LDR senses ambient light and, along with preset controls, sets the switching threshold. When the light level crosses the preset value, the LM311 generates a clean trigger signal that activates the NE555 timer. The timer ensures stable and noise-free operation, preventing false triggering due to sudden light variations such as temporary shadows.
The NE555 output drives a transistor stage that safely switches a 12V LED strip. An indicator LED shows the system status, and the circuit operates from a regulated 12V DC supply. This design provides reliable dusk-to-dawn automation with optional delay control for smooth operation.
Applications:
Suitable for automatic street lights, garden and pathway lighting, staircase illumination, decorative LED strip control, and energy-efficient security or perimeter lighting systems.