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
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