coll circuit

The design:

The fish aquarium LED light with timer circuit  presented here utilizes a standard fish aquarium LED light set-up design for the required illuminations. Two sets of LED colors are used, blue and white, which illuminate in tandem at an interval of 12 hours each. The switching is controlled through a simple IC 4060 timer circuit.

The white LEDs light up at 9 am and switch OFF at 9 pm, switching ON the blue LEDs. The blue LEDs remain illuminated from 9pm until 9am, when its again replaced by the white LEDs....the cycle goes on as long as power remains available to the circuit. A standard ratio of 1:6 is used for the LEDs, i.e. around 348 white LEDs and about 51 blue LEDs.

Circuit Description:

The diagram shows a simple circuit based upon the universal timer IC 4060 for implementing the sequencing operations of the involved LEDs.

The product of R2 and C1 determines the timing frequency, which must be set roughly for generating 12 hour intervals. C1 may be taken as 0.68uF, while R2 may be appropriately selected for generating the above time frequency through some trial and error.

A small value resistor say a 1K may be selected for R2 to check what time interval it generates, once we get this, the value for 12 hour may be easily calculated through cross multiplication..

If after a few days the time intervals seem to be drifting away from the set start/finish hours, the switch SW1 may be pressed for resetting the sequence. If required this can be done every morning at 9am for implementing accurate switching of the LEDs, and for maintaining a natural feel inside the aquarium habitat.

Lets assume the circuit is switched ON at 9 in the morning. The output pin#3 of the IC initiates with a logic low and the timer starts counting.

The low at pin#3 keeps T1 switched OFF, this creates a high potential at the collector of T1 which instantly triggers T3/T2 illuminating the white LEDs.

The white LEDs remains illuminated for so long the timer counts, and the moment the set time lapses, the output of the IC goes high (after 12 hours), this instantly switches ON T1 and the associated blue LEDs and switches OFF T2/T3 and the white LEDs.

The cycle repeats as long as the circuit remains powered.

C2 and C3 helps to illuminate the respective LED banks gently, in a cool fading manner.

Parts List

R1 = 2M2

R2/C1 = see text

R3 = 470 Ohms

R4 = 10K

T1,T3 = 8050

T2 = TIP122

C2/C3 = 470uF/25V

C4 = 1uF/25V

IC = 4060

SW1 = push to ON switch (push-button)

LEDs = Blue 51 nos, white 348 nos. (super bright, roughened at the surface through a grinder wheel)

The white LED bank is made by connecting 116 nos. strings connected in parallel. Each string consists of 3 white LEds with a 150 Ohms resistor.

The blue LED bank is also made in the above fashion using 51 nos. blue LED strings in parallel.