Red is ground. Connect that to the power supply negative. The green circle is also ground. You can connect DIM- to that point if you like. One way or another it has to be connected to ground.

Ok, thanks!

I'll hold any other questions until I have the Meanwell in hand.

Hi Guy's
You talk about angles of the lenses. Can you confirm the angle you are talking about is the included angle of the beam per the sketch below?
Click to view attachment

Yup. On the LED datasheets it's refered to as viewing angle. On lenses it's known as the FWHM angle (Full Width Half Maximum).

Hello guys,

Just a couple questions concerning cooling fans. My heatsink will be 12"x7.28". Am I good with 2 fans ? What size should they be : 60mm, 80mm ? What is a good RPM ? And finally, under what DB level can we consider a fan as silent ?

Thank you!

One is fine. Fit as big as you can. Bigger fans move more air with less noise. Anything under 28db is pretty quiet. Under 20db is almost silent.

what gauge is everyone using for the wires between their leds and to the drivers? Also, do any of you guys have a wiring diagram to the MPJA power supplies?

I want to wire 2 buckpucks w/ pots and 2 40mm fans (in series) to a 24v 4.2A power supply

Thanx Evil ! I don't have any temp controller to check the heatsink temperature. How could I know if it runs too hot or too cool (is it even a problem for the leds if it's too cool ?) ? Would barely hot to touch is what we should be trying to reach or what ?

22-24awg stranded is what I like to use.

What do you need to know about hooking up to the MPJA power supply? All the DC outputs are labled. Wire the Buckpucks and the series wired fans in parallel together to the output.


As long as the heatsink isn't uncomfortable to hold your hand on, you should be fine. A cheap infrared thermometer might be a useful investment though.

oh if they're labeled then I can manage. I couldn't tell if they were labeled on the mjpa website.

Is it important for me to ground my fixture?

Here you go Supernip





Very easy, this is from cjerome i think...

thanks pal. why does it look like there are two sets of dc's?

Thanks for the confirmation. For your own thoughts I've been following this thread for a number of months now while researching LED instalation. This thread has more information on DIY LED advise than any other sites I've reviewed put together. It's amazing in this current time just how much effort you all put into helping each other both known and strangers alike. A VERY good job to all.

I'm now moving forward with my own project. Al the info I'll use will be decanted from this guide. I guess I'll owe all of you guy's many beers when I'm done.

There are, but they are common to each other. These power supplies don't have differen't output segements.

evil - hit up my pm when you can - i want to go ahead and get this ball rolling so I can make the lighting switch before the holidays hit and things get crazy. thanks man.

Yeah, sorry about that. I'll get you the pictures tonight. There is always something that pops up in the evenings, and I don't even have kids yet!

haha...totally understand. if you have to skip the pics, no worries. we can just make the switch. check my most recent PM - there were a few ?'s I had.

Hope you guy's can help me plan my tank lighting.

I'm trying to optimise the number of LED's considerate to the plan shape of the tank and seeing how the bracing bars cast a shadow with a halides omiting the areas where glazing bars lie. Also don't see much point in lighting up the wier.

Evil as the Guru in all things LED states 2 golden rules/ guidlines:-
1. It's not the number of LED's that give the penetration but the lense angle.
2. For 60 degree lenses spacing is around 2" between LED's and 2.5" between rows.

My tank has a rim around the outside which means the LED lenses will sit a little more than 4" above the bracing bars. Water level is a little over 1" below the bracing bars. I've put together a layout of the tank below. The solid circles represent the spread of light at glazing bar level. The dashed circles at water level.
Click to view attachment

My questions are as follows:-
1. On the layout shown the LED's are a little less than 4" apart in each direction. As you can see though they are overlapping at waterlevel and will considerably overlap when they get down to my living rock Around 5" below water level. At nearly twice the distance as that recomended will this still work?
2. Is 4" above the water level for the height of the LED's too high or should I be lowering them?
3. The tank has a water depth of around 19". Will 60 degree lenses be sufficient to grow LPS and soft corals at the sand level with the kind of LED pattern I'm showing in the above?

Thanks in advance

Dave

I'll get to it when I get home and can dedicate a little time to it. I haven't forgotten

I have another question about my BC29 LED retro. I'm using 2 non-dimming Meanwell drivers. Is it better to mount them onto the side of heat sink (inside hood) or in a project box?

same question but the main lighting will be a 10k 70w metal halide maybe even a 8k as I have both. I am also gonna add around 24 LED's on the sides (12 each side) on 7"x4" heatsinks(fan cooled). Should I go 8 RG and 4 CW or just go with a 1:1 ratio? And I was thinking 60 degree optics should be good to add a little par and lots of color ? Sorry Evil just I want to be sure befoer I buy becuase I only want to but things once as I don't have a lot of $$ to spare

What are your tank dimansions? Might help make things a little clearer. 4" on center is pushing it a little too far though.


These drivers are "moisture proof", but I'd mount them outside the hood where they can't get water on them.


I typically prefer a 1:1 mix. It blends so much better, and is easier to lay out on the heatsink and not get any odd color spots. Let the drivers take care of the color temp.

I started drilling and tapping my heat sink. What a pain in the arse. My kit came with thermal epoxy which is looking pretty attractive right now.

[quote name='evilc66' date='Nov 13 2009, 07:21 PM' post='2523551']
What are your tank dimansions? Might help make things a little clearer. 4" on center is pushing it a little too far though.


Nominal tank dims are 4' long by 15" wide with a water depth of around 19"

I personally wonder if tapping is really all that necessary. If you are shooting pilot holes (which can be done very easily with a hand drill that has 1500RPM or higher) you could easily go to Lowe's and buy some self-tapping screws that will bite the aluminum quite fine. Get 3/4" long self tappers, get the appropriate hex-head bit, and go to town.


You might not need the pilot holes, but aluminum that is 5/8" thick might be asking a bit much for self tappers to chew through without over-torqueing the LED's PCB star (if that can be done).



Any thoughts?


I have a heatsink from HeatsinkUSA.com that I can experiment on, but I do not have any LED's.

Try a layout with the LEDs about 4" off the glass, and on 2" centers. That will give you a lot better result in terms of overall intensity, and color blending. When pushing the spacing out to 4", you get a lot of spotlighting in the upper areas of the tank. It's much more noticable when you start to put optics on the LEDs, which you might need to do depending on what your stocking lit is going to look like.


I'm not a big fan of self tappers that small. Pilot hole size is critical. Too small and you will never drive the screw all the way in and can twist off the screw head. Too big and you can strip the hole very easily. Hex head self tappers also have very large heads compared to button or pan head machine screws.

[quote name='evilc66' date='Nov 13 2009, 09:40 PM' post='2523764']
Nominal tank dims are 4' long by 15" wide with a water depth of around 19"

Try a layout with the LEDs about 4" off the glass, and on 2" centers. That will give you a lot better result in terms of overall intensity, and color blending. When pushing the spacing out to 4", you get a lot of spotlighting in the upper areas of the tank. It's much more noticable when you start to put optics on the LEDs, which you might need to do depending on what your stocking lit is going to look like.


OK - So that will result in around 60 LED's in 3 banks of 20 -40 -20 per the below - That seems an awful amount of LED's. Did I understand you correctly?
Click to view attachment


I'm going to use an aluminium sheet for the whole of the lid. that's nominaly 4'long x 15" wide. For structural strength I was looking at 1/8" or 1/4" thick. With this many LED's will this suffice as a heat sink? I can epoxy 1"x1"x18"angle locally if that makes any sense.

I intend to use a 50/50 mix of CREE XRE-RB & CREE XRE-WG-Q5 with 60 degree lenses from Nanotuners.com.

Again from Nanotuners I'm looking at the Meanwell ELN-60-48D drivers. Just spoken to a really nice guy - Nick. He suggested that 1 driver will handle 15 LED's - meaning 4 drivers in total for 60 LED's. Each driver needs a dimming control. Presumably I can take this off the power supply for the fans. Would this be a correct assumption?

Thanks in advance Evil for your advice.

Dave

I guess through 5/8" aluminum, that would be the case. When I shoot self tapping screws it's usually through a medium to heavy gauge steel sheetmetal anyhow, which they hold quite nicely.


I am hoping the adhesive thermal pads from Nanotuners will be plenty strong enough to hold the LED's. I will likely be ordering them Sunday. I'm not planning on screwing anything down unless I have to.

I got all my holes drilled and tapped. Leds are screwed onto the heat sink okay. Now I just spent 2 hours soldering wires and nothing. No light. Going to unsolder tomorrow and try it again. My soldering technique definitely could be improved.

No, that's about what you are going to need for good coverage. I never said getting into LEDs was going to be cheap The 2" spacing is going to be far more important with the 60 degree lenses.

The Meanwell drivers are actually only good for 13 LEDs. I'll have to update Nick and Chris on that one. For dimming, please take a read through the Meanwell thread in this lighting forum. It goes through a lot of the details on how to get dimming working.

For 60 LEDs, you are going to need something more substantial than an aluminum plate. There just isn't enough surface area. Adding L-channel "fins" will help, but I strongly suggest bolting them to the plate, not epoxying them. Even with L-channels, you will be relying heavily on fans to keep everything cool.

Hey, maybe a dumb question but here goes... Why if we build our own array of CREES is good to have a 2" spacing between LEDs and this modules like the ones nanotuners have they're so tight? Isn't heat a problem in those? In the retros the LEDs goes directly to the heatskink, not to a board which I don't really know how well it transfers the heat.

The Nanotuners kits have premade strips. Redesigning the strips to 2" spacing would work just as well. The extra density somewhat makes up for the lack of optics. Heat isn't an issue. Chris went through a lot of thermal testing to make sure that the LEDs stayed nice and cool.

http://www.nano-reef.com/forums/index.php?...st&id=56406
http://www.nano-reef.com/forums/index.php?...st&id=56365

Can I use these to connect a 12 LED string to the non-dimming Meanwell?

Sure.

No, that's about what you are going to need for good coverage. I never said getting into LEDs was going to be cheap The 2" spacing is going to be far more important with the 60 degree lenses.

The Meanwell drivers are actually only good for 13 LEDs. I'll have to update Nick and Chris on that one. For dimming, please take a read through the Meanwell thread in this lighting forum. It goes through a lot of the details on how to get dimming working.

For 60 LEDs, you are going to need something more substantial than an aluminum plate. There just isn't enough surface area. Adding L-channel "fins" will help, but I strongly suggest bolting them to the plate, not epoxying them. Even with L-channels, you will be relying heavily on fans to keep everything cool.
[/quote]

OK Evil - I've rationalised the pattern to
Click to view attachment
Per your concerns re cooling I've re-designed the project so that the LED's will be mounted on 8.5" wide heatsink from Heatsink USA. I'll enclose the heatsink in a shroud with a couple of large fans to blow air along the length. Hope that will work

I have a couple of questions re. Meanwell's that I will place in the Meanwell discussion. I'll be ordering the LED's and drivers tomorrow from Nanotuners. In addition - I have a couple of more questions on the general build if you would be patient enough answering:-

1. For testing purposes can you put a 9V battery accross +/- of the dimmer circut of the meanwell's without damaging the circut?

2. I want to rig a simple testing rig to test the LED's during the build. Would a couple of wires fixed to the +/-of a 1.5 V battery such as a AA series be sufficient - or do I risk damaging the LED's in this way?

Looks good. Still keeping to the 2" spacing?

1. Yes, that will work fine.

2.You will need two AA/AAA batteries. 1.5v isn't going to be enough to light the LED up. 3v will. You won't damage anything doing this for short periods.

evil,
How do you feel about overdriving? I was specifically looking at some graphs of the xp-g on another forum(cpf? not sure) where they did show numbers beyond stock and they looked pretty impressive.

I dont see getting the junction temperature down to be to big of an issue with a mild overdrive. Seems like this could cut the cost of the setup by a significant amount, at the expense of LED life no doubt.

hey evil,

i have been getting Q's from my LFS on the par my fixture puts out, have an estimate for me of the par at the sandbed? no one i know has a par meter in my area, so i would appreciate that.

the fixture is 24 cree xre leds, 50/50 white blue, no optics, on top of an AP24.

Thanks,

MG

Spacing a smidge over 2". Spacing between rows around 2 1/4" to even out the width over the heatsink.

Dave

If you got the info from CPF, then they are looking at it from a flashlight perspective. They aren't as worried about overall life as they are raw lumens. We need to take LED life into account here. I still don't see where people are getting the idea that they can save a bunch of money from these new LEDs. You still need about the same number of LEDs for coverage. The only advantage is that you can run on deeper tanks with wider optics, or without optics all together, so you only save on the price of the lens.


I'd estimate that with everything turned up, you are in the 200-210 range on the sand.


Cool. That works.

This is what I'm reading on my build. This was taken as close as possible to the die where it meets the star using a Tektronix DMM916. I don't think I can measure the true temperature, and I don't know how much variance there is between the measured vs. true.

These were taken after running for 6 hours.

25.7C Ambient
51.0C Heatsink
59.2C LED Die for Cree XR-Es

Assuming that the temperatures are not too far off, my whites are operating at ~94% efficiency and my blues at ~99% efficiency assuming I've interpreted the datasheet correct.

Comments? Cooling seem sufficient?

Sounds good.

ok, thanks. fairly high output, like avg. t5 setup, correct?

Just picked this up for my new PAR38 - 4 different height level options. I'll do without the glass shade.




http://www.lowes.com/lowes/lkn?action=prod...&lpage=none

My goal is to build two spotlights, each having both white and blue LEDs that will be separately controllable. I will wire them in series (blue series / white series). will be used over a biocube 29 (19l x 15.5w x 15.5h)

Setup:
2x Spotlight: 6x White Cree XPG (80 degree optics) + 4x Royal Blue Cree XRE (60/80 degree optics)
(total of 20 LEDs)
2x Meanwell ELN 60-48D, one for 12 white LEDs and the other for 8 blue LEDs (understanding it will be underutilized)
Meanwells will plug into the wall and the 1-10V dimming will be controlled by Profilux Plus II Ex.

Each Meanwell tuned down to run at min current of approx. 0.975A
Heatsinks & fans for each spotlight


it'll look a little different, but here's the idea:



Each of those wires represents 2 wires (+ and -). I'm trying to use the fancy RCA plugs so that the spotlights and cables can easily be moved / hooked up.

I'm planning to make a project box either containing or directly in front of the drivers to facilitate the series wiring.



I am HOPING that i will be able to use these cables to achieve series wiring. I need to learn a bit more about that but my thinking is i can use these to attach the + and - from the led to the + and - from the driver:


http://www.radioshack.com/product/index.js...oductId=2102693


then I'm hoping that i can connect two of these in series:



http://www.radioshack.com/product/index.js...oductId=2102540

such that if i plug in the second RCA jack from the other spotlight it will be in series with the first spotlight. If this works...i'll do this for both the blue and white drivers and therefore use only 2 drivers to drive the 2 spotlights which will both be dimmable by color.

I'm particularly interested in what you think about the concept of wiring in series via the RCA jack. My plan would be:

Positive lead from Driver -> Positive end of RCA socket 1> Positive end of RCA plug 1> first white LED ....series of LEDs (pos > neg >pos).... sixth white LED > negative end of RCA plug 1> negative end of RCA socket 1 > positve end of RCA socket 2 > positive end of RCA plug 2 > second spotlight, seventh white LED > ...series of LEDs > negative end of RCA plug 2 > negative end of RCA socket 2 > negative end of driver

Lastly, if this does work ...what would happen if i had everything running and tripped over the wire for RCA plug 2 and yanked it... danger? or does it just open the circuit and shut off... or does it continue to run just now it's not feeding the second spotlight?

Can anyone with electrical experience weigh in on whether or not this will work (wiring in series via RCA jack)? Any other thoughts are appreciated. I also want to add that I spent Thursday - tonight reading this entire thread post for post and have learned a lot. THANK YOU.

One thing I've noticed about LED builds. Because you have a point source of white and a point source of blue, you can get this banding of blue/yellowish on rocks and the substrate. This comes from the different point sources casting shadows at different angles. The nice 14kish blended color is when the point sources both merge in a given area, the blue bands from places where no white can reach due to obstructions, and the yellowish from the lack of blue.

Wider optics doesn't solve the problem, though it can help reduce it since you have more blue and white LEDs casting light toward the same area.

why is it that you dont see any mention of grounding wires in the wiring for the DIY LEDs? Aren't they a good thing to have in case faulty soldering / wear causes a positive lead to touch something like the heatsink -- if you then touched the heatsink wouldnt that be very bad?

that's what this scary video made me question.

http://www.youtube.com/watch?v=ndH0JNEaP7g

I intend to build a 12 Cree RB-12 Cree Q5 Led system and will get an Arduino to control 2 drivers. That means i'll have 2 separate led strings, one for the white and another for the blue.

I'm wondering if the lighting from the blue leds, when dimming it down to the minimum, would be low enough for moon light ?

Or should I get another single blue Led driven separately ?

Not really. The optic angle won't change the effect that much. Like you said, it comes from having two different color point sources. The only way to remove this effect is to have an LED with the perfect spectral output we need to elliminate the need for seperate colors. Even on LEDs with multiple dies in the same package that are less than 1mm apart, the effect is still there.



If you have a short, grounding the heatsink will be catastrophic for the drivers, and possibly the LEDs. Grounding the output of a buck driver is basically creating a dead short, that will kill the driver. At least right now, if there is a short to the heatsink, it just creates faults in the string and really doesn't do much harm. If we were dealing with AC at the heatsink, yes, we would ground. With low voltage DC, it's not a concern.

Leave the connectors out of the picture for the time being. Figure out all of your wiring first, then add in the connectors where you need service breaks. I think you are over analyzing the use of the connectors and making it too complicated for your self. Keep it simple and start with your wiring layout first, then add the connectors.

Thanks for input. Understand value of not overcomplicating, it's just with my current plan the connector is integral to making a series connection between the two lamps so that I can use 2 drivers instead of 4. The alternative would be to solder the series between spotlights directly (I.e. without the connector) but avoiding wire clutter is the challenge. Anyways doesn't sound like you approve of the design? Don't want to ask you about it if you have given a 'no' vote.

Re: grounding - still all new to me so I may not understand it properly but as it stands now, in the scenario where a hot lead touched the heatsink, isn't the heatsink now charged? If someone touched the ungrounded heatsink and they are grounded won't they get a massive current flowing through their body like in the video? Depending on how the heatsink is connected to the frame also the frame could shock the person. That's my question really.

If you can elaborate on how grounding the heatsink or frame is a bad idea (kills driver or LEDs) that might be useful knowledge for a lot of people as well. I'm researching on my own but if you have any good resources for learning electrical please post!

Thanks for any input!