DIY LED lighting?

GreenNeedle

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Wow what a thread this is. How did I miss this. Superb link to Mr Tester's thread too.

Back on track with the actual idea, is anyone planning to try this out? If so can they do a full journal like Mr Testers on that other forum but can they do some close ups of their fixing/soldering/wiring etc. plus power sources/extra items?

I quite like the idea of doing one of these after reading all the way through this and MrTester's thread. Looks cool to me and now I am a house husband I find myself quite bored at times!!! Something to getmy brains, concentration, fingers into.

Question to the electricians:

MrTester on that forum doesn't use a screen let alone a seal inbetween the LEDs and tank and has it only 60mm from the water surface. I notice that earlier in our thread it was said to be necessary so what is the truth there? Is it definately needed or not?

MrTester doesn't use heatsinks which were also suggested as necessary earlier in our thread. Was this just for the super high output LEDs and not apply to hundred of small 3mm/5mm ones?

In theory could you for example put 8 rows of lights front to back or left to right, each row wired into a seperate 12V transformer plug on timers, each timer into an 8 socket extension and then use this to do an 8 stage staggered sun effect from front to back or left to right?

I am seriously thinking about copying his efforts with the circa 500 LEDS but can't see the soldering or wiring clearly enough nor how he powers them.

Lastly if using those cheap 3mm / 5mm LEDS how many would be needed to replicate 45W T5HO. I know this would be an approximation but a guide would be good for me. lol

AC
 

Spider Pig

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I would have thought that using a few high output bulbs would be a better option that many low power ones as you would get better penetration through the water, although there is the problem with the heat.

Thought that these ones look promising:
http://www.luxeonstar.com/endor-rebel-c ... -p-183.php

especially if twinned with some of the different lenses available:
http://www.luxeonstar.com/polymer-optic ... -p-422.php

However they do seem a bit pricey- so not sure how much money would be saved in the end compared to current commercially available ones. Not even thinking about the waterproofing issue. Still- entertaining little project for anyone willing to take it on :D
 

GreenNeedle

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Thanks for that link James. I will have a read through that later tonight.

Does anyone have any idea of how many of those 3/5mm LEDs would equal 45W T5HO?

And about the water issue. As I see it hundreds of LEDs with the way they are 2 pins and soldered obviously leaves a lot of the 'circuit' exposed and therefore I would've though that with no screen/seal it could be mighty dangerous but MrTester seems not to be too worried.

I am prepared to take the project on but would need some links to how the wiring/powerage etc works. I have an old soldering iron lying in one of my many boxes that I can use and a small budget but I think I can stretch to similar to Mr Tester. I would however probs take a lot longer to do the project.

Any help would be great. No knowledge of electronics at all but then I have no knowledge of many things that I have done via research and trial 'n' error ;)

AC
 

GreenNeedle

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Great thread link there James. Not as bling as the first but definately much easier to build and much brighter. those LEDs are damned impressive and definately prove the people who say 1W=1W wrong. lol

With the condensation tray I have a problem. My tank is not standard dimensions being 80cm x 36xm and therefore not sure if I could get a condensation tray to fit it!! Question is would I need it as my unit would be 4 inches above the water line.

Other thing is I already have 3 x 40mm fans on this hood to use in the summer and where DaveTheTester says he can't hear his fan over the PC I think he must have a very loud PC. With mine I can't hear the PC over the fans even though the PC is in front of me while the tank is 7ft away. My PC is pretty quiet though.

If I were to fit the LEDs to square tubes rather than angle with the ends fitted into the hood so that the ends were open to the outside air would this airflow act as desired and keep the heat down? This would also mean that there would be no need for a frame as these square tubes would just slide into place with the tank holding them.

My plan if viable would be to run 4 strips of 4 seperately. Each on its own power supply. this could then mean I can stagger the lighting as simulated sunlight.

Would 12V variable transformer plugs like this one I currently have be OK?
trans12-1.jpg

I use this to power the moonlight and the 40mm fans. Not at the same time of course. I connect up the one I want to use at the time. If these would be OK and the square tube is viable also this project for a total of 16 3W LEDs could come in at less than £50. possible even less than that!!

Interested in the electricians opinions ;)

AC
 

SteveyG

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Yep, I'm almost ready to start.

aquariumLEDspic01.JPG


There's a few I may not use there, such as the superflux LEDs (at the top in the tube) and the Luxeon K2's (at the bottom). There's 5 royal blue LEDs for moonlighting, and 2 5W amber LEDs for sunrise. I also started prototyping a driver (proto board on the left). The 32x white Luxeon Star/O's will definitely be used, but I may use some 45 degree optics instead of the supplied ones:

aquariumLEDspic02.JPG


Also have a dimmable ballast for the fluroescents and some acrylic tube which will encase the LED assembly:

aquariumLEDspic03.JPG


The LEDs will be mounted on some aluminium strip and inserted into the tubes. The ends will have acrylic end-caps on.

aquariumLEDspic04.JPG
 

SteveyG

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SuperColey1 said:
I use this to power the moonlight and the 40mm fans. Not at the same time of course. I connect up the one I want to use at the time. If these would be OK and the square tube is viable also this project for a total of 16 3W LEDs could come in at less than £50. possible even less than that!!

The little power supply you have is 3.6W at 12V, so you won't be able to power many high powered LEDs.
 

GreenNeedle

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SO what is Dave The Tester meaning when he says he uses a 24V transformer for his 14 lights? He says the following:

To get the full 3W per LED they would need to run at 3.7V each

I am confused now. I thought my transformer if set at 12V would run a single strip of 4 x 3W LEDs

Is DTT wrong? Am I missing something?
 

SteveyG

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He's completely fudging it. These LEDs should be driven with constant current not direct off a 24V power supply with no current limiting :wideyed:

It looks like he's using a 10A 24V SMPSU , and you could indeed use a 12V power supply, but yours can only supply 300mA - it needs to be much more powerful. (I think the 3W LEDs draw 700mA at about 3.4V)

I wouldn't use the Luxeon III 3W versions though as they are toasty beasts and not as efficient as the 1W ones. The K2's and rebels are worth a look if you're after more than the 1W ones can offer. The 3W ones also have the disadvantage that the metal slug which is attached to the heatsink isn't electrically isolated from the LED die. If you mount them directly to a metal heatsink without electrical isolation the heatsink then cannot be used to mount any others if you have them in series. He's been lucky that by using double sided thermal tape that he hasn't damaged any of them from this.

Edit: I just read further into that thread and it seems they are having LED failures from not driving these from constant current supplies... ;)
 

GreenNeedle

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What does the constant current mean. Do you have any links to what sort of power supply is best.

Would it also be best to wire each LED direct to source rather than in line?

and do you think the idea of using open ended metal tube to mount the LEDs would work in helping remove the heat? What are you using to keep yours cool?

AC
 

SteveyG

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LEDs are diodes which have an IV characteristic like this:
Realidiode.jpg


So once the diode is forward biased and conducting, a very small increase in voltage causes a massive increase in current. Therefore you cannot accurately drive an LED from a constant voltage source as the forward voltage varies from LED to LED, so whatever voltage might happen to keep the current maintained at x for one LED could end up seriously overdriving or underdriving another LED. The temperature of the LED also affects the current at a particular voltage, which leads to thermal runaway - the LED starts getting warm, forward voltage drops so current increases, this heats the LED more causing the forward voltage to drop further until it destroys the LED.

By controlling the current into the LED we have a nice big area we can safely control the LED and no matter what manufacturing differences between LEDs you have it'll always be driving at your chosen current.

If you're into ebay, these kinds of things can be used:

http://cgi.ebay.co.uk/350MA-10W-Current ... 240%3A1318

http://cgi.ebay.co.uk/3W-Power-LED-Driv ... 240%3A1318

http://cgi.ebay.co.uk/1W-LED-Driver-for ... 240%3A1318

You should always have your LEDs connected in series, as this will guarantee each LED sees the same current and therefore close to equal brightness. If you have them in parallel you will not get even current distribution between LEDs so some may end up being overdriven.
 

GreenNeedle

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I think I'l wait till someone does one and then puts up a journal type thing. lol with clear explanantions for the unknowledgable. I guess MrTester made it look much easier than it actually is the way he did it.

AC
 

GreenNeedle

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I have decided to 'probably' waste some money now. lol. Don't ever let the housewife tell you that she is overworked. My house is incredibly clean. The washing basket is empty, the cupboards are full of food. the oven is clean etc. etc. and I am soooo bored with nothing to do so this project is a must for me now I'm house husband. lol

I want however to do this the cheap, easy way for me if possible and was thinking of this idea;

Each individual 3W 700ma 3.67V LED to be mounted individual screwed to the wooden hood like the diagram below:
LED.jpg

blue is a bent strip of aluminium, red is a heatsink, green is the LED, black are screws/bolts

Then 16 of these individual units wired in groups of 4 to seperate 12V 700Ma plugs(DC/AC adpator plug) using a 12V current controller making 3V into each LED:
full-1.jpg

blue are the individual units, red and black are the+/- wires, green is the current controller and pink is the wire to the DC adaptor.

Also in this diagram there are 2 in fans and 2 out fans. All the heatsink fins would have be lined up with their fin ends facing the fans. There would then be a simple piece of clear perspex or glass 2 inches below the LEDs that would seperate the water from the airflow to avoid too much evaporation.

Question. Have I got this right. I know its not perfect but will it work. Should I use thermal tape/grease in between the LED/aluminium/heatsink of each unit etc. Is it a good idea to keep it as individual from a replacement point of view?

AC
 

SteveyG

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That power supply is just a tad under 40W, so you could drive 13 LEDs from it.

As I said before, there is a line in the Luxeon III datasheet that says "3.Electrical insulation between neighboring Stars is required —aluminum board is not electrically neutral.". You will need an insulating material between the LEDs and your aluminium if it is going to be one complete section holding more than one LED. Luxeon I's do not suffer from this problem, but you would need twice as many to get the same light output (the light output from the 3W'ers is not the same as three 1W'ers hence the reason they get so hot!!)

You also want to connect your LEDs in series, so you have one wire from the driver to one to the anode on the first star, the cathode on the first star to the anode on the 2nd star etc then loop back from the final one back to the driver. Obviously polarity matters.

Yes, use thermal grease (if you can keep the aluminium separate between LEDs) or an electrically insulative but thermally conductive tape/film if you cannot. The screws must be insulated too! I'm using plastic nuts/bolts

http://cgi.ebay.co.uk/90W-15-24V-Laptop ... 240%3A1318

Or if you can prevent contact with the mains terminals:
http://cgi.ebay.co.uk/60W-Single-Output ... 240%3A1318

http://cgi.ebay.co.uk/MEAN-WELL-S-60-24 ... 240%3A1318
 

GreenNeedle

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Is this what you mean by series?
full-2.jpg


So if I were to use the tape on each unit between the LED and the bent aluminum strip I could then fit the individual units to another aluminum sheet the size of my hood and fix that in as one full unit?

And am I right in thinking that a single 12V - 700Ma adaptor plug could run each series of 4 at 3V each? (or 12 x 1W @ 1V each)

EDIT : Just got a reply back from a vendor of the drivers/controls and he says each one needs 1.5V leaving 10.5V left over so that would mean if I put 4 x 3W on each they would only be able to get 2.625V each if I am thinking correctly?

AC
 

SteveyG

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The drawing is now correct, but you won't be able to drive 4 in series from a 12V supply. In reality you will need at least at 16V supply for four white LEDs in series and the driver. 24V would be recommended though and 4 in series will still be fine because the driver controls the current. Voltage is irrelevant so long as it's higher than the maximum forward voltage of 4 LEDs and the driver voltage drop.

The LEDs won't conduct below their threshold voltage which will be about 3V. This is the point on the IV graph in my earlier post where the current suddenly starts to rise.

Your drawing is also correct now.
 

GreenNeedle

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I think I am starting to understand now, Problem is I have loads of 12V 700ma-1000ma lying around the house and therefore with me reducing costs it makes sense to use them. lol Saves some money and also provides a cheap way of being able to sequence the lights too as I also have plenty of timers.

Would you say I should run 5 series of 3 with 5 adaptors of these and settle at 15 LEDs? Not after huge amount of light. Am I right in assuming that 15 x 3W even slightly underpowered will better 48W of fluorescent even if 30W of that is T5HO??

I was thinking of using this sort of heatsink that are used on memory chips:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=022

each unit would then be a dedicated strip of aluminium fixed into the hood or perspex with the heatsink one side and the LED the other.

Thanks for your help matey. I suppose others are reading with interest too. I can see a surge of DIY LED lighting coming ;)

AC
 

SteveyG

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Yeah strings of 3 LEDs from 12V supplies would work fine, and those heatsinks look ideal. It may be worth you getting some optics/collimators for your LEDs depending on your aquarium size and the distance between the LEDs and the water source, but these can be added later of course.

What size is your aquarium?
 
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