DIY Luxeon LEDs

[MAZ350SS]

I've been working on this project for about 3month Im on the home stretch but iv hit a wall now. I've research the issue but i have not been able to find an answer.

If I have a 10Watt 1ohm resistor is this the same as 1watt 1ohm resister. The information i got from research is yes they are the same but one is just rated for more watts. reason i ask is I'm only getting .45amps out of my Driver and i should be getting twice that. around 875 would work.

I'm also going to have Pix of the working LEDs using .45 amps later.

[Bill S]

OK, I have a lot of experience with LEDs, from replacing lighting on our boat. I just spent another $250 on LEDs this morning.

Are you using a driver like a buckpuck, or something else? What are you using the resistors for? Some pics would be cool. Your resistor should be fine, BTW.

[MAZ350SS]

I'm using a 50watt 24v 1.750 amp LED driver and I'm using the resistors because is suggested to from other web sites but if you got a reason for me not two Id be all for it.

and now if that resistors fine my next question is why there is so little amp going through. its not that i mind it so much but it makes the blue LEDs look almost royal blue, looks kool but i wanted a little more white.

[txav8r]

The resistor is acting as a voltage drop. A 10 watt resistor is very large. I don't think that you would need more than a .25watt resistor to run an LED. What is the voltage rating on the LED's that you are trying to drive? If its a blue LED and you are supplying enough power to see it starting to turn more white then you are getting close to the max voltage for that LED and it will be short lived.
Most small LED's have a voltage limit of about 3.2 vdc. Larger LED's and specialty LED's have a higher voltage range. you just have to look at the specifications for the one you are using.

[MAZ350SS]

Yeah these LED are rated for up to 1000mA and I'm just trying to get 875 out of the lights. I know the Resistor is over kill but from what im getting from other forums is that its fine still the same amount of ohms.

what I'm trying to get out of the LEDs are 3.9v and 875mA.

[Bill S]

Have you tried a buckpuck? They will take up to 32v in, and put out a constant 700ma (or whatever you need) for a whole bunch of LEDs. This eliminates the need for resistors.

[MAZ350SS]

I'm trying to be economical (cheap) and i shouldn't need it, i have a LED driver that is rated to put out that very amount when hooking in 2 parallel circuit.

[Bill S]

Well, I GUESS that makes sense. I'm cheap too. LOL!

However, I kind of figure if I'm going to spend $200 on LEDs, what the heck is another $50 to make sure they have a constant and correct output - thereby giving a long life AND suitable output. On the boat, I'm "lucky" - current is already 12v DC - not a constant 12v, but that's another story! I look at it as a protection of my LED investment.

Also remember that one of the reasons you are using LEDs is - I think - for less power and heat. A resistor is nothing but a tiny heater. It's great at converting current directly to heat. So, instead of using that current to light your tank, you are using it to heat your tank!

Also, in talking to the folks at ledsupply earlier today, they WILL make you custom stars - if that's any help. For instance, they will make you a Rebel Star with 2 white & 1 blue LED on the star. After buying a couple of hundred LEDs, I find out now...

[wesheltonj]

I would highly suggest using a premade driver, buckpuck being the cheapest. On my lamp in each puck are three leds 2 white and 1 blue.

[Bill S]

Yeah, the cool thing about these is that you can get a dimming puck, if you want:

http://www.ledsupply.com/wired-buckpuck.php

[MAZ350SS]

yeah that all works but I'm trying to power them at 875mA if i use a buckpuck it works with 350mA 700 mA and 1000mA.

700mA makes the blue lights look violet and 1000 is to close to the Max the lights can take.

has any one tried to use LEDs yet.

[MAZ350SS]

Promised Pix i tried to get more but technical problems also I'm not done, I'm hoping to make a detailed how-to when I'm done for those how are trying to use LEDs

http://maast.org/forums/picture.php?albumid=108&pictureid=802
Note: one Blue was removed and in its place a white. pattern also change blue, white, blue.

[Bill S]

Buy a dimmable buck puck. That way you can tune the color, based on current.

[wesheltonj]

I use LED on my tank. They work, but you will need an GOOD (not cheap) power supply and you need spead out the load or you will burn them up in short order. Do not try to have the motherboard regulate the load, that does not work, believe me. You also need a quality lens to spead the light. Both Bill and I have recommeded that to use a buckpuck to drive the lights. While my lights have different brand of drivers, making one yourself is a huge project. You need to drive indepently the whites and blues.

[MAZ350SS]

What type of LEDs to you use? (specs)

[wesheltonj]

This is what my light fixtures uses (per 12"):

LEDs:
Array: 8 Triple Lenses ( (2W x 1B) * 8) = 24 LEDs total

White: Quantity: 16
SSC: W42180
Cree: XREWHT-L1
Correlated Color Temperature (CCT): 6500K
Lens Angle: 40 degrees



Blue: Quantity: 8
SSC: B42180
Cree: XREBLU-L1
Dominate Wavelength: 460nm
Lens Angle: 40 degrees

[Bill S]

Those look to be similar to the Luxeons he's using (in color and output) - I just bought a whole bunch of Crees for the boat - looking for a warmer LED.

[MAZ350SS]

i just found out the problem i was having with the LEDs but it turns out i don't need a Resistor for LED drivers, thus the point of a LED driver, checked the amps and now it seems to put out more.

I do have another question, has anyone ever used heat sink besides on PC's?
I'm using some silicon heat sink compound and it doesnt seem to disipate heat well?

[Bill S]

Do you have your LEDs on stars? With mine, I mount them directly on top of a 1" square heat sink. I just use JB Weld - but I glue them in place WITHOUT any glue between the star and the sink - I put them on the heat sink, then glue them into position. They seem to run cooler that way than with a heat sink compound or glue.

[MAZ350SS]

no i did not i ended up using the silicon compound and I'm using an aluminum plate 12 1/2 x 12 1/2. and i dont think the adhesive I'm using is doing a great job i may be losing light due to heat.

[Bill S]

OK, I need to understand something. Are your LEDs mounted on boards/stars?

In any case, they need direct contact to a heat sink. You can either fasten them mechanically (screws) or via silver epoxy, or like I do where the star is put on the heat sink, and then kept down with epoxy (no epoxy between the star and the sink).

For many/most uses other than keeping your fish confined to your tank, silicone is a poor choice.

[wesheltonj]

The need a huge heat sink and you will need a fan to move air over the heat sink.

[QuickSilver525]

are led's as good as mh? or t5?

[wesheltonj]

If you are asking me, my answer is very bit as good, but way more expensive.