1) 9 V dc source
2) two LEDs (red and green)
4) few resistors (kilo ohm)
5) npn transistor
I need to build a circuit such that the red LED lights up only at night (0 light intensity) and the green LED lights up only during the day (maximum light intensity).
How can I do this? I found out how to achieve the results for only one LED. The follwing is a rough sketch for the task at hand.