DIY LEDs - The write-up

[stugray]

laverda,

"I was thinking fluorescent light protector tubes might work."

That is exactly what you see in the picture.

They are ~$4 ea at HD 8 feet long and slip right over the channels.
If you look closely you can see the extra nylon screws that keep the tube from touching the emitters.

Running at 700mA with 12 LEDs ea., there is no cooling on them.
They run warm to the touch.

Stu

 

[Skeptic_07]

I had an idea for a collimator in lieu of individual optics. Could we use a Fresnel Lens!

Me being a fool decided to buy 3.5mm LEDs XP-Gs and XP-Es which do not have the flood light type optics that the XR-Es have. dammit self, there are ~40 deg optics available but I wanted more spread then that, I guess. Ideally, we would want to be able to change the focus, no? Why would we want to be locked into 40 or 60 degree FWHM? More flexibility would be better than less right?

This sparked some lateral thinking on my part which had initially failed miserably. I was thinking about using some not-for-LED acrylic optics mounted on a piece of acrylic rigged up in a way that would allow me to move the optics closer or further away to increase or decrease the focus of the light using some threaded rods, washers and wing nuts. the problem is that this would be very inefficient because the LEDs do not focus light on their own and probably 75% of the light would not hit any of the optics. most of it would spill out the sides and hit the acrylic areas in-between the lenses. So I decided to go search some DIY projects to see if that could spark something, and it did.

I saw a video of some kid using a pair of fresnel lenses to project the image from his iphone onto the wall. It worked surprisingly well! Then i searched 'fresnel lens' to see what others were using them for and it turns out the favourite use for these things is to make 'death rays' by focusing sunlight to a point that gets hot enough to burn 2x4s and melt pennies and silly things like that. It basically works like a giant magnifying glass.

Then I remembered what many of the optics we use look like on the surface; kind of like mini-fresnel lenses. So i thought, hey why not flip one of these huge ones over and use that to collimate the light? If one side focuses a beam (like the suns rays) into a point source , the other side should be able to take light from a point source like an LED and collimate it into a parallel beam.

So, then i ordered some cheap-o lenses off of amazon, you know, the ones that people use to read maps and fine print, etc.. and quickly wired up some extra LEDs I had lying around and a buckpuck from an older project that I took apart and started messing with the lenses and it kindof works! I can move the lens closer or further away from the LED's to get a more or less focused beam of light. What is even cooler is that the collimated spot is very even and you can even get it to come out the same shape as the lens itself (although a bit bigger). It is still inefficient, though, as quite a bit of light still misses the lens unless you put the LEDs very close to the lens but the result from that is the beam isn't much different than if you didn't even have the lens there. I'll have to post a video when i get home later tonight so you can see what I'm talking about. The idea isn't perfect by any means but maybe with a few more minds throwing some ideas out there... hint hint..

 

[stugray]

Skeptic_07,

I had a similar idea....

Go to ebay and look up: 'jewler loupe'


Youll see the cheap ones where you get one for ~$1 ea. from China.

They are even mounted to aluminum and adjustable.
If I knew the focal length & teh diameter of the lense I coudl do some quick calcs to see if they woudl work.

Stu

 

[Skeptic_07]

another great idea from Stu. you meant 'jeweler loupe' (or so ebay told me). This would certainly reduce the light spill problem. I wonder if it would be terribly difficult to line the insides of those with some reflective material. That would REALLY up the efficiency.

here is a place I found that has all sorts of fresnel lenses. http://www.bhlens.com/fresnel_lens.aspx

edit: this jeweler lens idea makes me wonder if using some of those cheap lenses for point and shoot cameras would work. you know, the cheap ones that screw on like a filter made by companies like targus, sakar, or merkury. they're already threaded... ahh probably too expensive at ~$10 each. or maybe something like http://www.dealextreme.com/details.dx/sku.22880

 

[der_wille_zur_macht]

Maybe I'm missing it by why all the side-exploration instead of purpose-built optics?

What's the efficiency on the stuff you guys are referencing?

 

[Skeptic_07]

Maybe I'm missing it by why all the side-exploration instead of purpose-built optics?

What's the efficiency on the stuff you guys are referencing?

I guess just some outside the box thinking. I found that I am limited to 40 degree optics with the LEDs I chose and wanted to use a wider angle optic. Also I thought it would be cool to not be limited to the angle of the optics chosen and to have something adjustable.

I'm pretty sure the efficiency is squat for the fresnel idea though.. :sad1:

 

[stealle]

I've often wondered if there is anything better than the cheap optics made for these LEDs. Not that I want to spend a bunch of money on optics, but if there is something worth the money then...

dealextreme has various "reflectors" that are made for use with flashlight LEDs. I don't know if it is possible to retrofit any of those. Also, the new reefbrite LED strips appear to use a T5 reflector in which they punch out holes for the LEDs. It seems like you could use a high end reflector such an ATI or IceCap. You could purchase 72" long reflector and cut them into strips of desired lengths to fit your application. This will definitely give you wider spread, Skeptic 07. Appears to work really well with the reefbrites.

These reefbrite LED strips are putting out a ton of PAR as you can see here: (see post #29) http://reefcentral.com/forums/showthread.php?t=1760115&page=2

 

[Santoki]

I've often wondered if there is anything better than the cheap optics made for these LEDs. Not that I want to spend a bunch of money on optics, but if there is something worth the money then...

dealextreme has various "reflectors" that are made for use with flashlight LEDs. I don't know if it is possible to retrofit any of those. Also, the new reefbrite LED strips appear to use a T5 reflector in which they punch out holes for the LEDs. It seems like you could use a high end reflector such an ATI or IceCap. You could purchase 72" long reflector and cut them into strips of desired lengths to fit your application. This will definitely give you wider spread, Skeptic 07. Appears to work really well with the reefbrites.

These reefbrite LED strips are putting out a ton of PAR as you can see here: (see post #29) http://reefcentral.com/forums/showthread.php?t=1760115&page=2

Just because the optics are "cheap", doesn't mean it's not doing a good job. Have you ever seen one in person? Perhaps taken it apart? What makes an Icecap or ATI reflector higher end? Price?
That's one of the beauties of this technology. It literally doesn't take much to direct the light to where you want it.
The optics are designed for these LEDs, and I would say doing a better job gathering/focusing the light where it needs to go when compared with the so called reflectors on the Reefbrights. It's analogous to those ricers supping up their Hondas with inferior aftermarket parts. It demonstrates a lack of understanding with the technology.
I think what many people still don't get that LEDs output light in a very different manner. The way they are mounted in that reflector does almost nothing to harvest light that would otherwise be spilling out the sides at 180˚ angles.
-R

 

[jjrreef]

what sizes wire do you guys use to put the leds togeder?
what watages soldering gun?

 

[customcolor]

i do beleave you can use 20-24ga wire (pretin it of coarse) and this is the soldering station i used....it solders the leds in 4 sec per solder!!!

i got this off ebay for $75 its the best soldering station i have ever had!!

 

[der_wille_zur_macht]

what sizes wire do you guys use to put the leds togeder?
what watages soldering gun?

Ideally you want high quality pretinned wire, 20 - 26 gauge, with insulation that won't start a fire if it melts. Pretinned wire is better protected from corrosion as well as being easier to work with. Something like this:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=A2015L-100-ND

Soldering iron wattage? As high as you can get. And you want an iron with good temperature recovery. Ability to pump heat into the pad on the star quickly is important.

 

[laverda]

What is the difference between?
Mean Well ELN-60-48D dimmable driver and Mean Well ELN-60-48P dimmable

The ELN-60-48D is dimmed by applying 0-10 volts DC to it. The ELN-60-48P is dimmed using a PMW signal.

 

[widmer]

i do beleave you can use 20-24ga wire (pretin it of coarse)

I used 24 awg wire for all connections between LEDs/drivers in my build, and it wasn't pretinned. Works great

 

[jjrreef]

ok so i have 6 white led Cree® XR-E LED and 6 Cree® XR-E LED.
2.- 3023-D-E-700PmA BuckPuck (one for the blues one for the whites)
will this power suply handle them?
POTRANS FS-15024-M
OUT PUT+24V 6.5A
it has two conections for two drivers

 

[customcolor]

I used 24 awg wire for all connections between LEDs/drivers in my build, and it wasn't pretinned. Works great

if you pre tin your wires first it will solder up faster and speed is the came when doing leds so you dont burn one up....dont get me wrong you can get away from not pre tinning but pre tinning is best in my eye

 

[der_wille_zur_macht]

ok so i have 6 white led Cree® XR-E LED and 6 Cree® XR-E LED.
2.- 3023-D-E-700PmA BuckPuck (one for the blues one for the whites)
will this power suply handle them?
POTRANS FS-15024-M
OUT PUT+24V 6.5A
it has two conections for two drivers

Yes, it will be more than adequate. You could get away with a smaller power supply since you'll only need about 2A. And FWIW, you can "stack" multiple wires on the same screw terminal - the pair of connections are just there as a convenience when you've got the thing loaded to the hilt.

if you pre tin your wires first it will solder up faster and speed is the came when doing leds so you dont burn one up....dont get me wrong you can get away from not pre tinning but pre tinning is best in my eye

I think we need to differentiate between pretinned wire, which comes fully tinned from the factory, and just plain tinning wire at home immediately before you use it. Pretinned wire has the advantage of being protected from corrosion up under the insulation - probably not a big deal to not have it, but it adds an extra measure of reliability, and it doesn't add a ton to the price of the wire. Plus, it eliminates the need to tin the stuff yourself, which saves a bit of time.

 

[widmer]

I think we need to differentiate between pretinned wire, which comes fully tinned from the factory, and just plain tinning wire at home immediately before you use it.

This is just what I meant when I said my wires weren't pretinned. I figured it was standard practice to do the tips before soldering pretty much anything

 

[jjrreef]

thank you der_wille_zur_macht

 

[OTCHU]

ok ... I need some help to confirm my leds lighting.
I have a 125G reef tank. Some SPS on the top and clam.
My actual light is 3x150MH and 4 x 96W compact

My light is right now at about 5inches from the top of the tank. I would like to put that higher for the maintenance. So I do plan to put my leds at about 10-15 inches

Because the 2 braquets I do have on my tank, I gonna make 3 modules of leds.

Questions:
1 - How many leds do I need for each module ?
2 - 50% cool white and 50% royal blue, is it right ?
3 - Do I need lenses for them (like I said, the modules will be at about 10-15 inches)

Something I don't understand: the color temperature for the XR-E Q5 is 6500K.
the Wavelength for the royal blue is 450nm
4 - what is the conversion nm to K ??
5 - in MH the color temperature is between 10000K and 20000K. How many % of power do I need to put on the cool white and the royal blue to have 10000K and the same for 15000K

Thank you very much guys for your help
Vincent

 

[OTCHU]

my tank is 72x18x23