How would I go about designing a dark sensor circuit using an LDR and transistors? The LDR value for light is around 7k ohms and when its dark it is around 1M ohm. The transistors are 2N3904. The circuit has a 5V buzzer and a 2V (10mA) LED. The circuit should work as follows: when there is sufficient light falling on the LDR, the transistor should be in saturation and the LED should be lit and when there is not sufficient light falling on the LDR then that transistor is in cutoff and the LED is not lit and the buzzer should sound. How would I go about designing this circuit? Any help is greatly appreciated