DIY LEDs - The write-up

[tahiriqbal]

I want to add some LEDS to supplement my metal halides. What do you guys recommend? Cree? Lumileds? Osram? Give me some advice please, thank you!

These............ and they could straight from 230V.... Now this will get rid of all LED drivers and stuff.... Anyone dare to try them??????


http://www.leds.de/en/High-Power-LE.../Seoul-Acriche-3-Watt-Emitter-white-230V.html

Ordered 10 and hopefully should be with me next week or so....

 

[Neogenocide]

extra; Welcome to RC. Normally square tube is no way near as good as U or angle iron for heat sinking. The reason is because a large part of heat sink function is radiation. This is where the temperature of the sink is higher than the surrounding materials. When this happens heat leaves the sink as light on it's way to these cooler surfaces.

If you have an L section none of the surfaces see each other and so everything in sight is cooler and radiation cooling occurs.

With something like square tubing think about what any of the inner surfaces see... More of the same heatsink. This essentially prevents all radiation from the inside surfaces. Only the outside surfaces can participate and only if they aren't 'seeing' adjacent surfaces that are about the same temperature. To have any external radiation cooling happening on the top side the heat has to conduct across the face up the sides and around the corners to the back.

What this all means is if you need that shape for aesthetics or some other reason then go ahead. Make sure you force air somewhere. If the full tube isn't needed for structure or some other reason then use sheet, or angle, or U channel, and NOT tubing.

I actually thought about using rectangle tube on my next build. I'm having trouble sourcing the exact size I want though. The heat that we are dealing with here isn't a huge amount and should be easily dispersed by some means of active cooling. As someone stated above, mount fans in the end of the tube, force the air through it, I believe it will be plenty of cooling. The best part is the fans will be hidden from sight, it should provide a nice clean install for a LOT less money than the high dollar heatsinks some others have based their projects around. I'm all about building it as cheap as possible. My ONLY worry at this point is the fan noise blowing through a "tube" and how it will sound in the end.

Scott

 

[davidchmaus]

I have the Meanwell LED kit from Rapidled. If I am running 12 LEDS with the Meanwell, will it also power a small fan? I am mounting the 12 leds on a 10x8.5 heatsink from heatsinkusa.

If it wont what would be the simplest way to power the fan?

Thanks!

 

[der_wille_zur_macht]

I want to add some LEDS to supplement my metal halides. What do you guys recommend? Cree? Lumileds? Osram? Give me some advice please, thank you!

How much supplementation do you want?

 

[tahiriqbal]

I have the Meanwell LED kit from Rapidled. If I am running 12 LEDS with the Meanwell, will it also power a small fan? I am mounting the 12 leds on a 10x8.5 heatsink from heatsinkusa.

If it wont what would be the simplest way to power the fan?

Thanks!

Yes...You can....

 

[g8gxp]

It seems you are using Meanwell ELN-60-48 (P or D) version of the LED driver. If that is the case then you need to open up the driver with great care, you will see a screw which you could turn to adjust the voltage. With this option your driver could be fully turned up to just over 1.2Amp and lowest is just under 987mA (I think). These drivers could handle load up to 52volt or just over but it is not advisable, what I would say reduce the number of LEDs to 12 per string and turn your Meanwell's internal POT to full and Walla........Y

Go

Yeah but I should still be ok with a 13 light string shouldn't I? at the max load of the cree which is 3.7V (i Think) this only comes out to 48.1V. Even with the voltage pot turned all the way up which is about 54.4 or so, my max current is still only .76. I would think that it should be at least close to 1A at that setting.

 

[der_wille_zur_macht]

I have the Meanwell LED kit from Rapidled. If I am running 12 LEDS with the Meanwell, will it also power a small fan? I am mounting the 12 leds on a 10x8.5 heatsink from heatsinkusa.

If it wont what would be the simplest way to power the fan?

Thanks!

NO you CANNOT use the output side of the meanwell to drive a fan! If you wanted them to turn on and off at the same time and have a single "power cord" then you could get a DC power supply for the fan and splice it into the supply side of the meanwell, but you're still going to need something to power the fan - a 12v wall wart will work fine, as long as it's not really wimpy - find out the current draw of the fan, and make sure you get a wall wart with at least 20 - 30% more capacity.

Yeah but I should still be ok with a 13 light string shouldn't I? at the max load of the cree which is 3.7V (i Think) this only comes out to 48.1V. Even with the voltage pot turned all the way up which is about 54.4 or so, my max current is still only .76. I would think that it should be at least close to 1A at that setting.

I'm losing track of your troubleshooting through the thread, so forgive me if this is repetitive, but I'd check the following:

1) Can you verify the multimeter is reading correct - voltage and current?
2) What do you have on the dim circuit? Are you SURE it's telling the driver to run at 100%?
3) Have you measured voltage drop across individual LEDs in your string?

Your numbers really aren't adding up - at ~760mA, the LEDs you're using should be dropping about 3.5v each. That's only 45.5v, but you said you're seeing ~54v across the output of the driver? Either your multimeter is wrong, or you've got two or three invisible LEDs in your string that you don't know about, causing the additional voltage drop. :lol: Or maybe a few really bad solder joints causing a ton of resistance? Though I'd suspect that would be obvious. . .

That said, anecdotal evidence from others has suggested that it's best to run the ELN60-48's with 12 LEDs, even though the spec sheet suggests 13 is possible. Might be worth taking one LED out to see how it behaves.

 

[DFason]

I have the chance to pick up a few XR-E's and XP-G for a good price. The only problem is the star are not pre-tinned at all. Will this be hard to solder?

-Dave

 

[der_wille_zur_macht]

Depends - how great is the price? :lol:

If you have a good iron and tin them on the sprues (i.e. before mounting to the heatsinks), it's not that hard. Or just solder them off the heatsinks, though that would make mounting tricky.

Oh and I hope you share this discounted source with the rest of us.

 

[Santoki]

DFason,
yes, please do share...
As for your pre-tinned question, I did not have any troubles soldering on those bare stars. I did use a lead rosin core solder though.
-R

 

[extra]

thank you scott and kcress. So from your comments i could conclude it is most probably possible to use a u-channel without active cooling and common led-specs & -spacing?

This would simplify things for me... Though, for the certain look i want to achieve i thought about using a tube to hide most of the stuff away... cabling, buckpucks, arduino and fan. i was heavily inspired by the project i mentioned in my first post.*Scott i share your concerns about the sound. Thinking 6 trompets above my tank :lol2: there are some smallish ultra-silent (<10db) fans but i can't find prices nor retailers. It's probably cheaper to use a dimmed down 12V fan. I need to figure how to drive the 12V fan with the ardiuno pwm... adding a temp sensor and programming the controller wouldn't be such a problem (i feel confortable as soon as it comes to software )

krcress your light metaphor makes it very clear. I (wrongly?) assumed a bare channel, no matter what shape, would need forced airflow anyway. I made some tests over my nano with 3 crees mounted on a 8inch square AL plate. Its thickness is 0.04inch (1mm). It got so hot i could barely touch it; needed to add a fan. To avoid noisy resonances from the fan its probably also better to use something about 4 times as thick?

this brings me to the question, what material thickness is needed to ensure good conductivity away from the leds? (assuming a u-channel or force-cooled tube).

tahiriqbal:
I have tried the 230V Seoul Acriche and i really didn't like them. I could clearly see the Acriche flicker in 50hz... Also, i would not feel confortable to have 230V diy-wiring over my tank. i guess earlier in this thread someone also showed that their efficacy isn't that great (well, imo you don't have to care if great efficacy isn't one of your goals. e.g. i'm also trading efficacy for CRI in my project...).

 

[TheFishMan65]

I realize this is a little off subject. BUT how does dealextreme do there BULKRATE. I selected it, but it does not show the low price in checkout. Can't find any reference on the site to the fact that they might correct it later.

Thanks in advance

And now back to the regularly scheduled thread

 

[stugray]

DWZM,

"NO you CANNOT use the output side of the meanwell to drive a fan! "

Well..... not completely accurate.

If you can find a DC fan that runs at your target current ( say 700mA ), it would work as long as you feel like giving up 4 LEDs on that string as it will use up 12V of the voltage in that string ;-)

http://ezhuoma.en.ec21.com/10.5_Inch_DC_Fan_speaker--3924917_3924939.html

And the fishies can listen to the radio with that one ;-)

It just isnt practical though, not would I risk my $40 meanwell when a $5 wall wart does the trick.

AND it is easy to control a fan speed with the PWM such as the Arduino.
You just might need an external FET since the pins on the Arduino probably cant handle much current.



extra,

Have a look at my post on page 13 of this thread for how I did my LEDs with the aluminum channels.

Stu

 

[der_wille_zur_macht]

DWZM,

"NO you CANNOT use the output side of the meanwell to drive a fan! "

Well..... not completely accurate.

Oh fine, be that way. :lol: At least we can agree that it is officially a Very Bad Idea.

AND it is easy to control a fan speed with the PWM such as the Arduino.
You just might need an external FET since the pins on the Arduino probably cant handle much current.

Will definitely need something external, Arduino pins are good for only 40mA and I doubt a fan pulling that would be much use. Plus, it would only be 5v. Here's a schematic that shows fan control with temperature compensation:

http://www.uchobby.com/index.php/2007/09/23/arduino-temperature-controlled-pc-fan/

 

[g8gxp]

Kcress,

I saw your schematic in one of the other threads regarding the proper way to provide air circulation over a heatsink. Do you think that enclosing the top of a heatsink and blowing air through the channels provides superior cooling as opposed to an open top heatsink with the fans oriented face down?

I was contemplating putting a piece of sheetmetal over my heatsink fins to hide all the wires/nuts/bolts etc. and putting a fan at one end and blowing air through...

 

[customcolor]

ill ask and say it again

what if you put a laptop fan on the end of each square tube to force air through the entire square tubing??

now i have a question for ya....would cat5 wire or telephone wire be able to connect a meanwell to a led array with no lose of power? or is it to thin of a wire..... just thinking of a quick disconnect....

 

[davidchmaus]

I'm getting ready to mount my 12 leds to a 10x10 heatsink. I was looking at a wiring diagram earlier in this thread and have a question.

I am using the meanwell driver. (D) The diagram I saw shows the - from the meanwell wired to the + of the first led. Then they are wired in series - to +

Then the - on the last led is connected to the + on the meanwell.

Is this correct? It seems like the + and - are backwards?

Thanks

 

[sammy113]

I'm getting ready to mount my 12 leds to a 10x10 heatsink. I was looking at a wiring diagram earlier in this thread and have a question.

I am using the meanwell driver. (D) The diagram I saw shows the - from the meanwell wired to the + of the first led. Then they are wired in series - to +

Then the - on the last led is connected to the + on the meanwell.

Is this correct? It seems like the + and - are backwards?

Thanks

No is not correct. The (-) from the meanwell goes to the (-) on the first LED and the (+) from the last LED in the series goes to the (+) in the meanwell (in case you are using just one meanwell for your 12 LEDs.

Anyway if you have 2 drivers the same apply.

 

[kcress]

thank you scott and kcress. So from your comments i could conclude it is most probably possible to use a u-channel without active cooling and common led-specs & -spacing?

Yes, depending on just how many LEDs, how close, and the drive levels.

krcress your light metaphor makes it very clear. I (wrongly?) assumed a bare channel, no matter what shape, would need forced airflow anyway. I made some tests over my nano with 3 crees mounted on a 8inch square AL plate. Its thickness is 0.04inch (1mm). It got so hot i could barely touch it; needed to add a fan. To avoid noisy resonances from the fan its probably also better to use something about 4 times as thick?

The metaphor is NOT a metaphor. It is reality. You just, cannot see that color light with only your eyes.

this brings me to the question, what material thickness is needed to ensure good conductivity away from the leds? (assuming a u-channel or force-cooled tube).

I will be doing my lights on 0.080" aluminum. 40mil is probably a bit thin. And just a flat sheet of it blocks huge amounts of convection. With a flat sheet you end up with most the convection cooling just around the edges. If you put a bunch of holes in that flat plate - in strategic locations - you would see the temperature drop.

Kcress,

I saw your schematic in one of the other threads regarding the proper way to provide air circulation over a heatsink. Do you think that enclosing the top of a heatsink and blowing air through the channels provides superior cooling as opposed to an open top heatsink with the fans oriented face down?

Absolutely! Ducted air across the heat sinks is much more effective that blowing air down on a heatsink and hoping it runs down all the channels. But if the heatsink is massive and multifinned then lousy air flow verses very effective airflow is still more than adequate.

I was contemplating putting a piece of sheetmetal over my heatsink fins to hide all the wires/nuts/bolts etc. and putting a fan at one end and blowing air through...

That would be a more effective use of the fan's output.

ill ask and say it again
what if you put a laptop fan on the end of each square tube to force air through the entire square tubing??

I already answered your questions in gross detail Yesterday! Too bad RC somehow lost my responses.

The fans would work. You realize that the air will get hotter and hotter as it moves down the tube. So one end may not get much cooling. Also pancake fans really rather have their air shoot out in a very steep cone. It almost comes out perpendicularly. If you stick them in a tight tube you can reduce their air moving capability by amounts like half. Then you turn the voltage down for noise and you may have no air moving. You need to experiment.

now i have a question for ya....would cat5 wire or telephone wire be able to connect a meanwell to a led array with no lose of power? or is it to thin of a wire..... just thinking of a quick disconnect....

Yes you could use CAT5 because it's 22 and 24AWG. But.. Have you priced it lately? It's now ridiculously expensive. A two dollar cable three years ago now costs about 12 dollars. Also it has 8 wires. You only need two. Plus you will need various lengths which are hard to come by.

 

[customcolor]

I already answered your questions in gross detail Yesterday! Too bad RC somehow lost my responses.

The fans would work. You realize that the air will get hotter and hotter as it moves down the tube. So one end may not get much cooling. Also pancake fans really rather have their air shoot out in a very steep cone. It almost comes out perpendicularly. If you stick them in a tight tube you can reduce their air moving capability by amounts like half. Then you turn the voltage down for noise and you may have no air moving. You need to experiment.





Yes you could use CAT5 because it's 22 and 24AWG. But.. Have you priced it lately? It's now ridiculously expensive. A two dollar cable three years ago now costs about 12 dollars. Also it has 8 wires. You only need two. Plus you will need various lengths which are hard to come by.

darn rc!!

a laptop fan is like a squirrel cage fan and to what it looks like can be bolted to a cut out of a square channel of alum...then its ducted...you say it will get hotter...i thought so. but if it only ran 2' it may work...ill have to get a ir temp meter again like the ones i use for nitro r/c's to find out for shure.

i was thinking about using the cat5 to connect the driver and 12v supply for fans (thats in a separate box) to the led array that will have 24 leds and a pc fan ...total of 6 wires i would just need to female connections also....it will look nice and clean