DIY LEDs - The write-up

[der_wille_zur_macht]

They don't sell good RBs or good optics. Nanotuners and rapidled are reasonably priced in smaller quantities.

 

[TheFishMan65]

Angling LEDs Part 2

Angling LEDs Part 2

I probably got lost being the last post of the page. I added the information for LED spread.

My plan is to mount the LED to a strip of aluminum and then bend the strip so that most of the light falls in the tank. So given a lens angle and how wide the LEDs cover (left to right or front to back) how do I design this. Here are some excel formulas I think work, but first let me explain the output:

OUTPUT - (3 columns by 12 row)
Lens Angle ........ 8.00 . degrees
Width ............ 48.00 . inches
LEDs to Edge ...... 2.00 . inches
Distance to tank . 96.00 . inches

Diameter ........ 344.89 . inches
ArcLength ........ 48.16 . inches
Deflection ........ 1.68 . inches

LED Separation ... 44.00 . inches
Point Separation . 31.75 . inches
Light Spread ..... 45.24 . inches


DESCRIPTION
Lens Angle: the angle of your lens
Width: how far your strip spands
LEDs to Edge: is how far in on each side
Distance to tank: How far above the tank are the LEDs

Diameter: where the LEDs will converge
ArcLength: how long to cut the strip to fit in your width
Deflection: how far the bar should bend to (if the strip fits in the opening this should be how far up the center is)

LED Separation: How far apart are the outer 2 LEDs
Point Separation: If the LEDs where a true point source how far apart are they when they hit bottom
Light Spread: If the lens was perfect what distance would it cover

FORMULAS
Please tell me if I am wrong, been a while since I had trig, but I think they are right.
B6 = B2/2*(TAN(RADIANS(B1/2))+(1/TAN(RADIANS(B1/2))))
B7 = PI()*2*B6*B1/360
B8 = B2/2*TAN(RADIANS(B1/2))
B10 = B2-2*B3
B11 = IF(B4<=B6,(B6-B4)/B6,(B4/B6)-1)*B10
B12 = TAN(RADIANS(B1))*B4+B11

Issue
Given a big enough angle the light spread by an LED will be more elliptical rather than round. The calculation for light spread do not take this into account - sorry I don't know the math. If some one asks nice I will see if I can figure it out.

DISCLAIMER :hmm4: : As I said above to the best of my knowledge this is correct, but I would try it and see if it is what you really want.

[EDIT]
If someone tells me (or I figure it out) I will post the spread sheet

[EDIT 2]
If I did this right the excel file should be attached

 

[OTCHU]

thanks der_wille_zur_macht

the XRE Q5 at dealextreme are good quality ?

I can use at work the temperature chamber ... I do plan next week to do some test with the CAT at extreme temperature (around 110degree F) ... will let you know

 

[Skeptic_07]

I was thinking about using ELN-60-24 to drive 3 parallel strings of 6 XP-E per string. thoughts? DWZM do you think i should just order some P models this time? I never even ordered the ALC i was planning on using, just ordered arduino. what sort of parts (fuses?) would I need to cover myself in case of failure?

The way my plan stands now I'll be driving 3 separate strings of 12 white XP-G using a ELN-60-48 for each string and 6 stings, 6 blue on each using 2 ELN-60-24. This way I can run all the drivers at full voltage and don't have to worry about blowing my LED's up (unless i have a failure) and still have some options for dynamic control.

 

[der_wille_zur_macht]

DISCLAIMER :hmm4: : As I said above to the best of my knowledge this is correct, but I would try it and see if it is what you really want.

Congrats on putting effort into the math. It's about time someone did it. Though, IMHO, there should be another disclaimer. Given the pure nature of the FWHM method used to "name" the optics, and the high variation regardless of the standard (not all "X" degree optics are the same), IMHO it's best to order a small number of the various pieces you're thinking about using and actually trying them in real life. Then you can adjust angles, height, spread, etc. to actually get the result you want. With the large variation inherent in these optics, making a big fixture based purely on the math might lead to disappointment.

thanks der_wille_zur_macht

the XRE Q5 at dealextreme are good quality ?

Should be good as any. Several people have bought from them. The only "problem" seems to be that shipping is not consistent. For some people it takes two weeks, for other people three months.

I can use at work the temperature chamber ... I do plan next week to do some test with the CAT at extreme temperature (around 110degree F) ... will let you know

Would be interesting to see those results!

DWZM do you think i should just order some P models this time? I never even ordered the ALC i was planning on using, just ordered arduino.

If you're planning on dimming with the Arduino, then the P is probably the better model to get. Though there has been a lot of speculation that there isn't really much difference between the two. Some people have applied < 10v analog signals to the "P" type and gotten the corresponding analog-like dimming you'd expect from the D type. Some other people have PWM'd the D's. So who knows.

I'll defer to others (kcress?) on parallel strings, since that's not something I'm really well versed in. Though it should be straightforward to do the math and see if it all adds up, then put a fuse on each driver's output that's a certain threshold above the current you expect to run at, but below the "failure" current you'd get if one string shut down from an LED failing open.

 

[SimonSKL]

Thank you to those who commented on my post. As far as heat dissipation I was comparing to someone who said he had adequate cooling by using a ~6"x8.5" heatsink with a fan for 24 LEDs which worked out to be about 7 sq in per LED. With the aluminum angle and spacing each LED about 3" apart, it worked out about 6 sq in per LED. But I agree with using U-channels will be better as I probably need more LEDs than the 48 originally planned as many of you suggested.

laverda
If I understand correctly your planning to have the L strips mounted above a thin sheet of plywood with holes in it. One concern about the plywood is, I think it will hinder the air flow. I would just but it all on top of a sheet of acrylic spaced far enough away to allow for optics. That should give more air flow and protect the LEDs and wiring from most of the moisture.

Laverda, besides the 1/4" plywood that the L strips will be mounted on, I also have a acrylic sheet below to protect the LEDs. In a way, the LEDs are protected first by the acrylic sheet than by the plywood. It may be an overkill.

sammy113
What I'm doing is attaching the LEDs to an aluminum sheet that will have a few heatsinks on top to create more mass to remove heat.

Sammy, I like your LED layout for your corner tank. Where can you find such a large aluminum sheet with enough thickness to support the weigh of those heatsinks? Those I could find at the home centers are very thin. Weight is factor as I don't want to have too much weight on top of the canopy.


Thanks!

 

[bstohrer]

DISCLAIMER :hmm4: : As I said above to the best of my knowledge this is correct, but I would try it and see if it is what you really want.

I have to agree with DWZM on this. I did some simple math with different optics and angles and then decided I would just put it all together and adjust the angles of the aluminum bars/channels along with trying different optics right on the tank until I got a "look" I liked.

Bob

 

[TheFishMan65]

I realize it is not perfect, but maybe it can help someone rule out some choices.

bstohrer: Can you bend the 'L' and 'U' channels that are 1/8 thick?

Is anyone interested in a spreadsheet to show the intensity of the additive LEDs?

 

[SimonSKL]

I realize it is not perfect, but maybe it can help someone rule out some choices.

bstohrer: Can you bend the 'L' and 'U' channels that are 1/8 thick?

Is anyone interested in a spreadsheet to show the intensity of the additive LEDs?

I am interested!

 

[der_wille_zur_macht]

I realize it is not perfect, but maybe it can help someone rule out some choices.

bstohrer: Can you bend the 'L' and 'U' channels that are 1/8 thick?

Is anyone interested in a spreadsheet to show the intensity of the additive LEDs?

I applaud your efforts, but just wanted to suggest that people do some real-world experimentation before committing. You're right though, at the least, doing some math up front will put you in the ballpark.

The most important consideration though is that an "X" degree optic will, more or less by definition, have a fair portion of it's light outside the cone described by "X" degrees, since the optics' names are derived at the FWHM point. And since some optics have steeper curves than others, even two optics of the same "size" might look very different above a tank.

Plus, in the end, I find it really FUN to actually play with the parts in real life before doing a build, so I'm encouraging others to do that, too. It's pretty wild to run a small LED array and swap optics, change height, change angles, etc. all "live" while it's running over a tank. Really helps get my creative juices flowing.

 

[TheFishMan65]

I will see what I can put together, but does anyone know where I can get info on the CREE lenses. I found the increased illumination model for the 8 degree one, but not the other.

Thanks

 

[killarsox]

I've been reading through this thread and i've got to admit i'm completely confused. I was hoping someone out there might be able to give me a little help and steer me in the right direction. I'd like to make and LED fixture for my 34G Solana. I have no clue where to begin. If anyone's got a few extra minutes could you shoot mea PM with some pointers to get started. Thank You.

 

[der_wille_zur_macht]

Better to post in the thread so others can learn, vs PM. IMHO at least.

What are the dimensions of the 34g solana? How high above the tank will you place the fixture? What sort of livestock do you want (i.e. what intensity of light)? If you were going to go with MH or T5, what would you use? What color do you like?

 

[bstohrer]

I realize it is not perfect, but maybe it can help someone rule out some choices.

Your right! Thats what I did. I was able to rule out many of the tighter optics using math alone. I only ordered the few optics that mad mathmatical sense.

bstohrer: Can you bend the 'L' and 'U' channels that are 1/8 thick?

I have not tried intentionally - I did accidently bend some 12 foot channels that were 1"X1"X0.125". It really depends on how sharp the bend is and what aluminum alloy it is. For a really sharp bend, you may have to cut or notch the channel or L.

 

[TheFishMan65]

bstohrer

I need an arc about 6/10 up in the center over 18 inches total. That is why I was thinking strip.

 

[bstohrer]

bstohrer

I need an arc about 6/10 up in the center over 18 inches total. That is why I was thinking strip.

I'm having trouble visualizing. Are you wanting to bring the ends of the aluminum down and the center up to angle the LEDs on the ends away from the side walls and towards the center?

 

[TheFishMan65]

That is exactly what I want to do.

 

[bstohrer]

That is exactly what I want to do.

You could do it with channels and Ls if you made cuts through the vertical "fins" every 1-3 inches. It would be much simpler with strips. I'm probably going to have to use strips becuase I only have 3-3.5 inches of clearnce in my hood. I would like to bend like you are planning but not enough space. At least I'll still be able to angle the strips in the front toward the center of the tank and away from the front glass.

 

[killarsox]

The Solana is 20x20x20. I've currently got one setup, which I run a 150w Hqi with 20k bulb. I just purchased another, and I'm debating between another reef or a seahorse tank, but another reef is prevailing. Coral wise I'd be keeping a bit of everything only a few SPS pieces though. As far as height above the tank, i'd like to use some sort of hanging kit, to attach to the fixture to the stand rather than the ceiling. LED color wise, I'd like something that gives good growth but at the same time makes the corals colors pop. I'm thinking about a planted reef tank, i'd like to incorporate some nice marine plants/macros into the tank.

 

[Skeptic_07]

So who knows.

hopefully I will know soon enough

I'll defer to others (kcress?) on parallel strings, since that's not something I'm really well versed in. Though it should be straightforward to do the math and see if it all adds up, then put a fuse on each driver's output that's a certain threshold above the current you expect to run at, but below the "failure" current you'd get if one string shut down from an LED failing open.

I think it adds up fine. eln-60-24 outputs 24v @ 2.5a, 6 crees per string is ~21v and 2.5a / 3 strings = ~833ma per string. I was pming kcress a couple weeks ago about this and he started to mention the fuses but after that I decided not to do parallel, and now have changed my mind again. I swear my project plans have changed almost weekly for the past few months! anyways, I could use an inline fuse holder like this along with a fuse like this and that should work... I think.........