Any ideas on a DIY timer/dimmer? - The Planted Tank Forum
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post #1 of 7 (permalink) Old 12-06-2012, 08:57 PM Thread Starter
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Any ideas on a DIY timer/dimmer?

Since I'm running two of the 36" Ray II LED's on my tank, I've noticed when the timer kicks them on in the AM, it's like the Sun blasting the tank all at once. I was thinking about a auto-controlled dimmer that would hook between the timer and lamps to bring the light level up slowly so the fish don't drop fins when it comes on. Any ideas or plans would be appreciated...

I did look at some of the home automation stuff. But the info shown is not very clear about how well it would work for my purposes. Plus the programming looks serious complicated.


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post #2 of 7 (permalink) Old 12-06-2012, 09:43 PM
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i am running a similar light set up and have contemplated the same dimmer option.

I will be watching this thread as well for ideas.


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post #3 of 7 (permalink) Old 12-06-2012, 10:49 PM
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Sorry guys but a typical dimmer won't work to solve your problem. Led fixtures operate differently than old fashioned incandescent light bulbs. Leds require a certain voltage threshold to be reached before current will begin to flow through them, where as incandescent bulbs will happily glow with the reduced voltage that the dimmer provides. Leds can only be dimmed by varying their current level not voltage.

You'll either have to replace you led lighting fixture with a fixture that already has a built in dimmer function-OR- it may be possible to "hack" the one you have to make dimming possible. Whether or not your fixture can be hacked depends on what type of constant current driver is being employed. It's possible that the electronics needed are already there, and the addition of a few strategically placed wires and a micro-controller will provide the dimming capabilities that you're looking for. I've hacked a few of the earlier led fixtures to do just that, but I'm not familiar with the "guts" in the fixtures that you're using now. You may also want to contact the manufacturer and see if they have any "off the shelf" options for you.

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post #4 of 7 (permalink) Old 12-06-2012, 11:27 PM Thread Starter
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Thanks, O2! Appreciate the input. I guess I need to hit up Finnex to see if there's a way to make the Ray II'2 dimmer "friendly"... Thanks again. And if I get any info, Chad, I'll let you know...

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post #5 of 7 (permalink) Old 12-06-2012, 11:53 PM
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Add another light. You can have it in the room sort of near the tank, does not have to be directly over the tank.
Make that one on the timer/dimmer. Incandescent, of course.
Set it to start coming on 15 minutes before the tank lights, then it can go off once the tank lights are on.
At night, reverse. It comes on while the tank lights are still on, and when the tank lights go off this light slowly dims, replicating sunset.

Other solution:
If you have a fixture that has several levels, that is, not all the lights come on at once, then set it so the smallest number can come on, then a few more, then all the fixture, over a 15 minute period. Reverse at night.
If all the bulbs are wired to come on at once this won't work.

Other solution:
Manually fix it:
Put a piece of cardboard between the tank and the light.
When the light comes on only one row of bulbs are uncovered to shine into the tank.
Over the next 15 minutes take away the cardboard, uncovering one more row... then one more row... until all the bulbs are exposed.

Other solution:
Keep the tank near enough to a window that the rising and setting sun can be seen. Time the fixture to be on only when the sun is up. That way the sun starts rising, slowly increasing the light, then the tank light comes on. In the late afternoon the tank light goes off during the day, then the setting sun 'dims' the tank.
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post #6 of 7 (permalink) Old 12-07-2012, 01:49 AM
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the way i sort of do that without shocking the fish is i have the room light go on first and sort of add a dimmer light to the tank then like 30 minutes later have the fish tank light kick on. it seems to work

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post #7 of 7 (permalink) Old 12-08-2012, 08:35 AM
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or just tell your fish to deal with it...Q.E.D

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