LED Array for a Pico

[neanderthalman]

Thanks kinktao. That makes it a lot easier for anybody to power a fairly large array. Sourcing an old power supply could be tough, fortunately I never threw away any of my old computer components. It should be cheaper to get your hands on an old power supply, but if you can't find one easily, for a few bucks you can just get a new one.

 

Keep us posted on your project CMS.

[bravocms]

Will do neanderthalman!! Thanks again............CMS

[il0vepez]

I'm trying my best to get together a little accent lighting using a luxeon flood cyan 18. I found this thread very informative.

 

PAR is all light between 400 and 700nm, with slight weighting of different colors. So, if you bought a UV or an IR LED, then it has no PAR. Otherwise, 100% of the LED's luminance is truly PAR (except IR from heat, which shouldn't be included in the rating). PAR is for ecologists determining the effects of greenhouse gases and other fun things, not for aquarium hobbyists. Although, many people here will tell you otherwise.

[noogie]

There was some controversy on this thread erlier about how an LED array can be set up without resistors.

 

I found this site doing a quick google for "LED array"

 

http://www.dansdata.com/caselight.htm

 

It bassicly reiterates everything neanderthalman has said. It uses vero board instead of acylic and comes up with a very dense pateren.

 

I'm going to do some searching to see if i can find any arrays premade that might work.

[noogie]

http://www.superbrightleds.com/specs/pcblamp.htm

 

Does this look like any thing usable?

[il0vepez]

I'm using a cyan flood 18 from future electronics. Here is a link to a comp. site.

 

http://www.lumileds.com/products/family.cfm?familyId=5

 

You should be able to find data sheets and see if any are right for you.

[neanderthalman]

noogie, those LEDs are only 5000mcd. I'd shoot for at least 10,000mcd white LEDs. You can get white LEDs up to 20,000mcd, but they're a little pricier. That article doesn't quite reiterate everything I've said....as he argues that you always need resistors. Not a single resistor in my array. Other than that, he does a decent job of walking people through building an array, and does a very nice job of soldering his connections.

 

As for the luxeons. You need heatsinks, and that takes up room inside the hood. When you factor in the space needed for those heatsinks, you wind up with very little gain from using luxeons, for substantially more cost.

 

They are sweet...and if space were not an issue, I'd have used them. Also, part of the idea of using LEDs on a pico is to reduce the issues of heat from lighting. LEDs don't run cold, but they don't generate the heat that MH or even PC lighting does. Luxeons produce quite a lot of heat, regular LEDs don't.

[neanderthalman]

Oh...noticed the fourth post. Pez....not all light in the visible spectrum can be used in photosynthesis, that's why leaves are green. Certain frequencies of green light would therefore not be Photosynthetically Active Radiation, and there are likely others.

[coralcrazy]

you should change your name to LED masta...jesus you are patient i would just start breaking stuff and cursing at my misfortunes .. Great job BTW

[fras]

Nearly a month since your last FTS, how are things going growth wise? Much different from your PC's? Have you noticed any ill effects?

 

Nice job btw.

[neanderthalman]

Thanks guys.

 

I've had some issues, actually, though they aren't related to the lighting. My water source dried up, so to speak. I was no longer able to purchase the distilled water that I had been using before, nor was the wal-mart purple cap distilled available. In desperate need of a water change, I grabbed a gallon of the only distilled water I could find.

 

Immediately after the water change, things went pretty bad pretty fast. I drove to nearly every grocery store in town before I found one with an RO machine, and did a couple of large water changes in short succession. Everything survived, and I am guessing that either the distilled water was contaminated, or that that particular company uses copper in their distillation process.

 

Whatever the exact trouble was, the RO water has been great. I didn't lose anything, though I did remove a portion of my GSP that seemed to have died. I don't really care if it might have come back, 'cause I was not about to give it the chance to rot and foul my tank. The rest is just starting to get a little green in the tips again.

 

I also moved a few hours to go back to school, and for whatever reason, my bumblebee snails didn't make it. I wasn't exactly crying, I think the little bastards were nipping at my zoos. I wasn't sure, and I wasn't going to kill them until I knew for sure. The dirty work was done for me I guess . By the time I had everything set up again, the shells were cleaned out by my crab. Good boy....

 

As far as growth, I haven't seen anything. I'm not surprised, as there's been a fair amount of stress. There's still likely some low levels of whatever contaminant got in there, who knows what trouble that might cause.

 

I'd post a FTS, but there's little point, it doesn't look any different right now. The light is still going great - I'm going to add a couple LEDs to it as moonlights, powered by the 12V power supply for the fan.

 

Now that I've got a good supply of water, I'm hoping the next month or two will show some growth.

[grandmaster fish]

hi guys, please allow me a very simple question:

 

How careful do you have to be (safety wise) when DIYing with 12V DC?

 

I would love to try something like this!!!

 

thanks!

[doncb]

Originally posted by grandmaster fish

hi guys, please allow me a very simple question:

 

How careful do you have to be (safety wise) when DIYing with 12V DC?  

 

I would love to try something like this!!!

 

thanks!

 

Well, it's not the volts, it's the amps. 12vdc is pretty safe to work with. If you wear a pacemaker or have heart problems, I wouldn't go touching the wires to your tongue or anything.

 

Once I got hammered by 2000vac @ 4.5amps. Blue flash and found myself 4 feet from where I started! Took the rest of the day for my right hand to work again. Lucky? You bet. Learn something? Oh, yeah!

[neanderthalman]

The chances of you getting a shock from anything below 30V or so is pretty minimal - that's why most electrical codes get pretty lax below 30V.

 

My best shock story). The 25kV lead on a CRT while building a biefield-brown effect lifter. Limited current, but it sucked.

[grandmaster fish]

yeah i took a hit once from a sandwich iron that when it closed pinched the cord and melted it. Found myself laying on the floor amongst the remains of my kitchen table. Never wish to do that again.

 

I guess what i am asking is that if i start to muck around with a project like the one outlined in this thread, there is not risk of disaster occuring? eg fire etc etc etc

 

thanks again

[neanderthalman]

The chance of disaster when dealing with a 12V system is minimal. I wouldn't recommend working on it in...say...a room filled with natural gas. I did have to do a little work on the 120V side of the power supply, but the great thing about this setup is that the 120V power supply is nowhere near the saltwater.

[allen00se]

what do you guys think about the 12v power source off of a laptop, the ones that have the black box built into the cord (i believe thats the inverter). Seems like if these would work it might simplify things....

[neanderthalman]

That should be a high quality power supply, and would be good. I don't know what the power output or wiring configuration is, but you should be able to get it to work. To be honest, I don't have enough experience with laptops to know if it's even 12V, though it likely is.

 

At any rate, the power supply HAS to be labeled with it's voltage, and either a current output or a power output. From there, it's a matter of cutting the end off of the cord and finding out what wire is +12V, and what wire is common.

[allen00se]

The cord on my laptop actuall says 19v -- 3.42a. What is your opinion on those numbers?

[neanderthalman]

19V? That's a very strange number.

 

You CAN use that, but you're either going to need to use resistors, or wire the LEDs in clusters of five, whereas I wired mine in clusters of three.

 

The only problem I could see is that if that power supply craps out on your, finding a replacement could be difficult. I dunno if all laptops use a 19V power supply.

 

Old computers and old computer power supplies are easy to find for a few bucks. Using power supply with a common voltage makes finding a replacement power supply really easy, should you ever need to. The power supply voltages that I see most often are 9V and 12V, if that helps at all.

[Undertheradar]

have you guys seen this one? Nice use for an icecap heatsink!

 

Scroll down to the third pic or so...

http://www.sparklingfloorservice.com/melev...cool_stuff.html

[neanderthalman]

That's pretty cool. I'd like to know what LEDs he used, 'cause he's ony got six of them lighting the whole tank. No way to find out tho. Must be luxeons or something.

[techdef]

Hey, this looks very promising!

 

Looking around found this seller, got 420nm 5mm LEDs

https://www.ledreps.com/store/products/uoe2.htm

 

about 1/2 way down the page. Still learning these mcd units - but it looks like these may be significantly less bright than what ya'll are finding? They sure ain't cheap, but the wavelength is dead-on.

 

Anybody got a rule of thumb for how many watts/mcd/lux whatever you're advocating in LEDese for how many suckers to put over a 6g tank?

 

I've got a laser cutter here in the office so putting an array together is a breeze, looking at a mix of whites ~ 7000K or 10000K and some of these lower 400nm range (more actinic)

 

[edit] found these too - another option for 1,3,5 watters with wide dispersion http://www.led-bulbs.com/eShop/10Browsepro...tegory=Prolight

 

THanks for all the wiring tips!

[neanderthalman]

Those will be quite a bit dimmer than the LEDs that I used for my array. Those whites are listed as about 2400mcd, with some that go up to 9200, but they're also listed that the typical output is only 5600mcd. That's less than half of the output of the white LEDs that I used, 12000mcd.

 

I wouldn't use anything less than 10000mcd, because of the effort involved. Those LEDs are also more expensive than the ones I got on ebay. Look for a seller called professorled, I have nothing but good things to say about my dealings with him, and the LEDs are impressive. They'll be cheaper and brighter than the LEDs you were looking at.

 

As far as a rule of thumb....I don't know...6g is kinda big for LEDs...you'd have to have a lot of them, or spread them out. Spreading them out reduces the overall intensity, so to keep the same intensity, you'd need to keep them closely spaced.

 

I would estimate my array as being roughly 25 sq. in. and I used 267 LEDs. That'd be about 10 LEDs per sq. in. Calculate the footprint of your tank, and mulitply by ten. That's how many LEDs you need to approximate what I've done. It's gonna be a lot....

[noogie]

Those will be quite a bit dimmer than the LEDs that I used for my array. Those whites are listed as about 2400mcd, with some that go up to 9200, but they're also listed that the typical output is only 5600mcd. That's less than half of the output of the white LEDs that I used, 12000mcd.

 

 

What exactly is 'mcd'? I mean what does it stand for, and how is it used?