Led fading aquarium?

I have a fish tank, and it has a TL light above it.
I made blue Led's above the fishtank.
My idea was:
- You get like from 8 AM. - 8 PM. the TL ligth (or some led's i have to make)
- From 8PM-10PM the blue Led's
- And then it all shuts off.
- And then the cycle goes aroud.
But the thing is, the TL is 220V and the leds are powered by a 8V AC powersupply,
I made a diode bridge, so it all works,
But my TL ligth will just shut off, becose it has a timer on it,
And i have to turn on/off the blue leds myself.
So, does anyone have an idea how to do this?
maby some extra white led's so i can power it from 1 cicuit?
Greetings. Ingmar

(Im from Holland, don't mind my shitty english)

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Aerospaced5 years ago
It sounds to me that you want to bring the lights up and down to simulate sun up and sundown conditions respectively.
Depending on your technical skill and ambition, i would suggest an arduino controller that would steadily change a PWM ( Pulse Width Modulation) to give you the dimming effect and overall timing as well.
It shouldn't be too hard to do really. You will need a FETs or series of FETs to handle the current and provide the switching function that you will need. If you use a FET that is twice current capacity, you wont have a lot of heat. however it is recommended to use a heat sink on it just in case.
If the arduino is too expensive, you can use the Texas Instruments Launchpad. They are much cheaper, but the lead time may be a while as they are super popular.

ingkiller (author)  Aerospaced5 years ago
i do have a arduino uno, and a arduino mini,
but im not a real pro at electronic stuff, i just know some basic stuff.
and i know how to solder. so maby you have a schematic for me so i can get the stuff at a local electronic store nearby.
maby if i show the shematic to them, they can help me immediately
OK. It looks like we can use pins 2-7 on the uno board. I need a few specs on your LEDs. how much current are they pulling? Or just give me a part# and quantity and what configuration are they in? You said you have a diode bridge, so I'm guessing you are using that to rectify the AC to DC. Meaning you have 4VDC out to the LEDs.
The out put from your board will go to a small gate array that will in turn fire the FETs. That board will be very simple. I will start an Eagle layout soon and make a screen grab to send to you.
This is starting to get fun :)
ingkiller (author)  Aerospaced5 years ago
so far i have 3 of these blue led's whit a 180Ohm resistor:
and 4 of these red led's whit a 270Ohm resistor:
the powersupply is now a 8V AC 200mA.
but i could buy an other one if it would be easyer to work with
This circuit should be more than capable. https://www.instructables.com/file/F0T5PZCGY9ZICB0/
This coupled with the code (modified) from the http://reefprojects.com/wiki/Functions should do the job.
This may do the trick!
ingkiller (author) 5 years ago
ok..now i have the 3 blue leds on a timer,
but the 4 red one's in the coconut i made, dont go on somehow..
i had a coconut and cleared it from the coco, and hot glued some red led's in.
it worked all fine, but after a few days they started to shine way less brigther then in the beginning. and now they are so fade out that i dont see them anymore,
i have a resistor to the leds thats more than nessasery, so there's not too much current or something..
how does this happen?
canucksgirl5 years ago
Could you get an inexpensive timer and use the parts to turn on/off the LED's?
ingkiller (author)  canucksgirl5 years ago
those things are sort of a relai,
so it wont be realy usefull.
pie R []ed5 years ago
or try this: https://www.instructables.com/id/ThrobbingFading-LED-with-555-Timer/
no idea if it could go slow enough, but worth a shot.
pie R []ed5 years ago
you could get a motor geared WAY down hooked up to a potentiometer as a voltage divider. onside had white LED's the other Blue. when the motor goes on it would slowly change the lights to dim it. then have it hit a switch to flip the polarity and reverse the direction. if you do it just right, the potentiometer would turn 1/2 turn every 6 hours, and the resistance would completely turn off the LED at 1/2 turn with this it would cycle back and forth. super sketchy, but it might just work.