When the LDR in the circuit will receive low light the circuit will produces beep and flashes the LED in the gap of few seconds. But the number of beep and flash will slowly increase as the sunlight will increase on the surface of the LDR.
The circuit is built around the popular NE 555 timer IC. The 1K variable resistor near the peizo buzzer is used to control the volume of the buzzer.
The circuit can be operated from 9 volt to 12 volt DC. But you can also operate the circuit with 6 volt. For operating the circuit with 6 volt decrease the value of the current limiting resistor of the LED from 470 ohm to 150 ohm.
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Here is a very interesting project of a morning / sunrise alarm circuit which will produce a beep-beep alarm sound and flashes an LED when the sunrises. Another interesting thing of the circuit is that the speed of beeping signal and flashing LED will increase gradually according to the rising of the sun.
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