This colorful back light gives natural appearance to the Aquarium tank. The circuit automatically turns on at sunset and gives changing White, Blue and Green color display to make the aquarium attractive. In the morning the light turns off
The circuit uses LDR as light sensor for automatic switching of the circuit. During day time LDR has very low resistance so that IC1 remains stand by. In the night, LDR offers high resistance and the reset pin 12 of IC1 becomes low. This activates IC1. CD4060 is a binary counter with ten outputs. The outputs of IC become high one by one based on the frequency of counting determined by C1, R1 andR2. In the circuit, strings of LEDs are connected to the collector of switching transistors T1 through T3.When the IC triggers, oscillations starts and the output Q6 turns on after 5 minutes and stays on for another five minutes to light Blue LEDs. After 10 minutes Q7 output becomes high and Green LED turns on. They remain on for 10 minutes. After half time, Blue LEDs also turn on. This gives a mixture of Blue and Green colors for 5 minutes. After 20 minutes Q9 output becomes high and White LEDs turn on. They remain on for 20 minutes. During this period, Blue-White, Green-White and Blue-Green-White color combination develop. This gives beautiful color display to the background of the Aquarium tank.
Aquarium Light Circuit
Note: Keep LDR in a position at which it illuminates in day light but dark in night