DIY LEDs - The write-up

[marc111]

Ok I have been reading through the entire thread and I Ok on the electronics mix of LED's etc.

I would like some advise on the number and density of LED's to go with.

My tank is 72 in long by 24 in front to back by 31 in tall. With the sand in place this leaves 26 1/2 inches from the water surface to the sand surface.

The lights can be up to 10 in above the water surface. Assume the tank is mostly SPS with some soft corals on the botttom. I would like to be able to keep SPS and or a clam from the surface to about 20 in under the surface.

There are two tank braces so I am thinking 3 physical light assemblies.

What would you advise for:
a) spacing of the LED's?
b) number of LED's per assembly?
c) optic or mix of optics to use?

Given that its a custom build I am considering having a portion of the LED's on a slanting heatink so as to keep light off the front glass.

Thanks,
Mark

 

[kcress]

I do the drill thing too. Yes it is fun. The point of doing it is so hopefully all the TVs, and radios, and baby monitors, in the neighborhood don't freak out whenever your hood is on.

Skeptic_07; Look into the plastic flexible conduit. There are four major types. (None are the standard PVC electrical conduit that's rigid.)

1) Spiral wrap. It's just a spiral wrapping that has memory and wants to get back to its shape which is like a long coil spring. Its the easiest of them all to use. You just hold it up to the wire bundle and kind of pinch them together while wrapping. You can still see the wires inside from outside but it looks very neat and tidy. It's also nice because a wire can exit anywhere you want it to from the bundle. It's very insensitive to the wire bundle size.

2) Split plastic. This type has rings molded around it that are to keep it in a cylindrical form. Then a single straight slice is run down the entire length. You pry the split open with your fingers and shove the wire bundle in. You won't see the wires at all. It's harder to extract a single wire as it will open the split in an slightly un-appealing manner where a wire exits. You absolutely cannot add one extra wire over the bundle size that it's made for. Go pop the hood on your 2000 or newer car and you will see this stuff running hither and yawn.

3) Nylon webbing. This a a tube of woven nylon. Picture cutting the end off of your tube sock and shoving a wire bundle thru it. You have to lay the webbing down and run the bundle all the way thru it. No side exits. Since it has no inherent rigidity it pretty much follows what the bundle wants to do. To me the biggest down side is that it comes flat with a razor sharp pair of creases running down the sides. Those creases are permanent! So it doesn't look great to me.

4) Water tight flex conduit. This is a spiral ribbed high gloss flexible solid conduit. It's gorgeous but if you want a muted look it is really eye catching black shiny material. You generally need to use the special matching end fittings. The conduit screws with its spiral ribs onto the end fittings that then have an outer screw fitting that comes with the fitting. The other end of a fitting has a waterproof fitting that is just like the normal conduit ends. (Think easy mount to a flat panel with a hole in it.) No side exits! But it is completely waterproof. Done correctly you could probably submerge it.

5) Standard Liquidtite. This is the stiff running from heavy machinery to its power source. It would be a real pain in the butt to use and would try to shove your fixture all over place. Forgetaboutit.

 

[ReefEnabler]

These:

They are for ballast quick disconnects in with the wire nuts.

Stu

Thanks... some googling turned up they are called "LIGHT-N-LOK" so its easier to find for others... meant for solid wire but I bet a tinned stranded wire works fine. Seems like what I'll go with to wire up all my fans without a huge mess.

Kcress, what Drill thing are you talking about? must've missed it but your post was the only in the last 2 pages that used the word drill....

Skeptic_07, let me know if you find the hdmi female plugs... at first I thought you were interested in HDMI to cut off the ends and just use it as a multi-conductor cable... can be got very cheap on amazon. I got a whole bunch 6' cables for 1 penny each a few months ago I'm with you on the whole cringing at store HDMI prices thing.

 

[kcress]

I said twist them. dnahas said, "use a drill":

http://www.reefcentral.com/forums/showpost.php?p=16713238&postcount=2020

I'm just agreeing with him.

You just take the two wires and stuff them into the chuck and tighten it. Run the dill until you have some reasonable twist. Un-chuck and cut off a few inches of mangled wire.

A variable speed cordless is the best tool.

I would hand make the cables and NOT use HDMI or some other cable because you may find that long cables don't work at all! If you made your own you can also make/shorten them more easily.

 

[DFason]

Hey guys,
I am about to start soldering my LED's. They are not pre-tinned. Will I need to put a small amount on the star first and then apply wire and then a little more?

Any advice would be great or even a video

-Dave

 

[der_wille_zur_macht]

What would you advise for:
a) spacing of the LED's?
b) number of LED's per assembly?
c) optic or mix of optics to use?

You probably want to be in the 140 - 160 range for LED count. 700mA or 1000mA drive current thanks to your deep tank, and 40 or 60 degree optics.

For spacing, just figure your heatsinks to come within a few inches of the area for each of your openings, and space the LEDs evenly across them.

 

[der_wille_zur_macht]

Hey guys,
I am about to start soldering my LED's. They are not pre-tinned. Will I need to put a small amount on the star first and then apply wire and then a little more?

Any advice would be great or even a video

-Dave

If they're not well tinned from the vendor, tin them while they're still on the metal sprues, or at least before you screw them to the heatsinks. Get your iron good and clean and keep the tip clean and tinned. Touch the iron to the pad for a few seconds, then touch the solder to the pad until the solder begins to flow. If you have a reasonable iron it should just take a second or two. If it's taking longer, your iron is garbage, or your tip is dirty, or you're not getting good tip/pad contact (I like a small chisel tip for this, since it lets you get a lot of surface contact on the pad).

Once they're all tinned, examine your wire. If it's pretinned you're ready to go. Mount the LEDs, cut the wires such that they're a little long and put a slight kink in the middle. Then solder the same way you tinned, but work on the interface between the wire and pad instead of the pad itself - i.e. try to hold the tip such that it's touching wire and pad, and feed solder against the wire and pad together. You want the wire and pad to be nice and hot BEFORE you feed the solder in - you should notice the tinned solder on the parts liquify, then you can feed in the new solder.

Watch very carefully for solder bridges - several people (myself included) have accidentally bridged very fine wisps of solder from the joint to the MCPCB or a screw or the heatsink.

 

[stugray]

ReefEnabler,

"but I bet a tinned stranded wire works fine."
I tried that at first and it can be done but its a PITA. as long as you tin the wire so that some solder gets up under the insulation you'll have better luck.

DWZM,

"Touch the iron to the pad for a few seconds, then touch the solder to the pad until the solder begins to flow."

I have also found that while the solder is molten on the pad, rub the tip around a little.
You will feel it "squeak".

I have found that this allows the solder to "wet" the pad better giving complete coverage.

Stu

 

[DFason]

Thanks for the help guys. I fired my new Weller solder station up all the way and tried it out!

Does this look like success/correct?

-Dave

 

[der_wille_zur_macht]

I really can't see the quality of the solder job on this computer (teeny little low quality netbook with poor contrast) but it looks like you tinned 4 of the pads - you should only need two (one positive and one negative) assuming you're taking the traditional series approach.

 

[widmer]

Something fun-

I stopped into the local hydroponics supply store today because I was in the area and thought I would see how much the folks with their hydroponic herb gardens are embracing the LEDs these days...

I found on the little bulletin board there an advertisement for someone local who is making and trying to sell something he's calling the Omni-Hue LED Grow Light. According to the picture, it appears to be a CPU heatsink with 6 LED stars mounted on it (can't tell the make of the stars). His sheet claims that it consumes 40 watts and replaces a 200 watt high pressure sodium lamp. And the sheet says it's patent pending.

Oh, and he wants $325 for it. What a bargain at just over $50.00/LED :lol:

One thing I'm curious though, he claims that one of the LEDs mounted on it puts out 660 nm light, although I'm not familiar with any manufacturers which make an LED that does this. Anyone out there know if these really exist?

 

[akindbro4u]

http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=%2Fspecs%2Fr1330_specs.htm

here you go. not useful for us however

 

[akindbro4u]

at the University of Chicago, researchers discovered that the average wavelength of cell tissue in the human body ranged between 600 nanometers and 720 nm; 660 is the mid-point. So in essence, the reason a 660 nm works better than any other single frequency is because it is closer to the resonant frequency of cell tissue. The other reason is that 660 nm absorbs better in hemoglobin.

 

[widmer]

So in essence, the reason a 660 nm works better than any other single frequency is because it is closer to the resonant frequency of cell tissue. The other reason is that 660 nm absorbs better in hemoglobin.

Works better than any other single frequency for what? The unit I saw at the hydroponics place was for growing plants.. Also, thanks for posting a 660 nm LED but I was referring to a high output LED star that was advertised on this unit which puts out 660 nm. The one linked above only consumes a fraction of a watt.

 

[akindbro4u]

there is a 1w version manufactured by a Japanese company. Sorry my kanji is not so good, so not too sure on the full specs, but it comes in a smt package. 660 morks better for cell growth, and regeneration.

 

[akindbro4u]

http://www.roithner-laser.com/LED_HP_single_chip.html

here they have them on stars.

 

[der_wille_zur_macht]

660 morks better for cell growth, and regeneration.

What kind of cells?

 

[kcress]

Meat cells..

 

[akindbro4u]

and vegetable. So in theory it could be used in a reef tank. However I don't think anyone really wants that heat lamp look.

 

[widmer]

Gotta question about the drivers, if you don't mind. I believe the meanwell's can take a 120V input, right? But the buckpucks require the 24V input via a power supply. I assume you can run more than one buckpuck on the same 24V power supply (which is plugged into a 120V source), yes? Or is that a bad assumption.

the reason behind my question is that I want to be able to turn on ~6-8 LEDs at one time (as they're being used for dawn/dusk), but I'm thinking if I run buckpucks on one power supply, I lose my ability to turn them in such small intervals via the 120V Neptune DC8 controllers. Based on these thoughts, I'm thinking it would be cheaper to buy meanwells and run 8 LEDs on them instead of buying buckpucks each with a dedicated 24V power supply. Make sense?

You're correct about the power requirements of the separate drivers. Since the Cree LEDs will top out at 1000 mA drive current, this means that each buck puck driven string of them will take an amp. So for the case of the buck puck drivers, you need a power supply with appropriate amperage to handle the number of buck pucks you use. IE for 5 buck pucks ~ 5 amps you would want a ~6 amp power supply so that you are leaving some breathing room for it when everything is under full load.

The meanwells are like a buck puck with built in power supply so that they just plug into the wall. They are what folks are primarily using, as far as I know, if they want their lighting to be controlled by their reefkeeper etc...