DIY LED Lighting Fixture

[DoctaQ]

you can run them in parallel to get the higher current. which is why i am saying to run 3 per string
then dim them by using a switch to turn one or two drivers off

http://www.nano-reef.com/forums/index.php?showtopic=227131

 

[keno]

DoctaQ;

Thanks for the clarification and the link. When I get a free moment I am going to figure out what the cost difference would be for my little 20 gallon long and my 200 gallon tank. Sounds like an option. I could also find fans that run on ac, so I wouldn't need a dc supply.

 

[keno]

DoctaQ;

I was doing some math on those AC drivers, I wanted to have you check my math. I am looking to create a circuit that has 12 CREE LED's and can get as close to 1 amp using the PA38 LED 27~42V DC 320mA Constant Current Driver Circuit which has a cost of $7.47.

Here are my assumptions:
The AC driver can handle up to 12 Watts.
Each of the Cree XR-E Q5 Emitters are 3.7 watts at 1 amp. I will not be able to get 1 amp exactly so for the purpose of this exercise I will use 3.5 watts.
12 watts / 3.5 = 3.4 so I will go with 3 LED's per AC driver. Now I need 3 AC drivers to get up to around 900ma.

So if need to power 12 LED's I am going to need 3 AC drivers per set x 4 for a total of 12 AC drivers. At a cost of $7.47 each x 12 that would be $89.64.
I can get a Meanwell power supply for $39.95 (on sale - normally $49.95) which would power all 12 of my LED's at 1 amp. If I am lucky based of what others have found I most likely would be at 850ma with the AC drivers. Plus 12 AC drivers take up a lot of space and the wiring is much more involved.

Did I do the math correctly or did I miss something?

 

[DoctaQ]

you would need 3 of them to get to 900ma, so about 20 dollars, vs 40 for a meanwell, but with the meanwell if you dim depending on the model you will either have to make a pwm module or supply a reference voltage of 10v, for the P or D models respectiveley.
dont go by wattage because you ended up getting that you need 12 drivers to power 12 leds?

3 drivers per 12 leds will get you up to 900ma

each driver can power 12 leds, and supply 300ma, run them in parallel to keep the voltage the same and multiply the current.

 

[keno]

DoctaQ;

I was forgetting about the wattage increase also, so yes the wattage would increase by a factor of 3. Still I think with three of these AC drivers in parallel would have a hard time powering 12 CREE LED's. 10 CREE LED's would most likely be the maximum that I would feel comfortable with.

Still it maybe an alternative.

 

[DoctaQ]

you are absoluteley correct, for some reason i accounted for 3.5vf which would work if you were only driving two of them together for 600ma but at 900ma the vf would be closer to 3.6-3.7 in which case the max should be 11 leds.

 

[Slappy*McFish]

Interesting thread. I may just give this a try in the near future.

 

[planted_noob]

Wow!!! that's a nice looking tank. I'm just getting into the planted tank stuff. I think I'm going to start with mosses mostly.

I'd love to see how you laid out your fixture.

 

[keno]

planted_noob;

Thanks...

If you are going to start with mosses, I would suggest Christmas, Weeping and Willow mosses.

I did a 5 part series on my DIY LED Light Fixture for Planted Tank. This is the link to part I. I suggest you start at part I and work you way thru the series...

If you have any questions just ask....

 

[DoctaQ]

i am doing a similar build for a friend of mine, i plan on using 16 leds to get the better coverage on the ends of the tank. i also plan on using that driver i linked to. what do you think?
what is your distance between leds back to front? i see you used a 5.5 inch heatsink so im thinkin 3-4 inches between them?