How to make Automatic circuit for street light

This circuit allows automatically on and off the street light during day and night
How it works
The working principle is very simple during day hours the ldr offers little resistance due to this the voltage flows from +12 to the base of transistor through R3and mixes with negative voltage which is already present there due to this it becomes zero volt no current flows through transistor it flows only when there is negative voltage present on base of transistor as it is a PNP transistor and conducts only when ever negative voltage is present on the base pin
During night the ldr offeres high resistance so no voltage flows through ldr to base pin and the negative voltage is present there in this way the transistor conducts and current flows through the emitter to collector and energized the relay

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Resistance

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