TWO TRANSISTORS AND PHOTOSENSITIVE CIRCUIT WITH LDR SCHEMATIC CIRCUIT DIAGRAM

When the ambient light is illuminated in the light sensitive circuit, the voltage generated on the LDR decreases. T2 switches to cut, T1 switches to transmission. Relay contacts change position. When the environment becomes dark, the voltage falling on the LDR increases. T1 transmission is T2 cut. This process is due to the change of the resistance of the LDR element to the light.

DIAGRAM OF THE PHOTOSENSITIVE CIRCUIT WITH LDR SENSOR

Electronic circuit diagrams were extracted from various sources (pdf, doc etc.) shared on the internet and transferred to the site. Thanks to the people who prepared the work.