LED project... input appreciated

[utahsaltreefer]

Yes, the rough cost is about $1 per led. I have no idea what the high lux ones are. They do save a lot of power, but it would depend on where you are as to if they are cost effective based on outlay. A 100 LED array running at 3.4 volts and 20 mA per led is 6.8 watts not including loss in the transformer and resistors. Any way you slice it, its very low. In fact you can run the array on normal batteries (but that's another topic ). So running them 12 hours a day is less than .1 kWh per day.

What adds up is the time to make a 100 LED array. Its very tedious unless you just use breadboards. They is very easy to use, but add immensely to the cost.

Like I said, they were fun to play around with and I may try them again on a nano, but for now I'll stick with the new MH unit I got from hellolights.com. 400 watt for $150

 

[Anonymous]

I totally understand that you could not beat a 400 watt MH, but for small Nano's they seem ideal

Now, the question everyone has been waiting for...


Is it possible to put them underwater?

Like if you were using small arrays of them or even a string of them up each corner of your tank for some focused lighting

 

[Anonymous]

their light intensity and focus sucks-led's still have quite a ways to go before they'll really be usefull for corals-even in a nano, imo

 

[Anonymous]

their light intensity and focus sucks-led's still have quite a ways to go before they'll really be usefull for corals-even in a nano, imo

Even in a specialized Finger Leather .5 gallon bowl type nano???


:wink:

 

[Anonymous]

I agree that using them in nano is still pushing it, but there are some pros and cons that make the decision a bit more subjective.

There are specialized resistors package that you can use to save space and fabrication time. For example, resistor banks come in SIP and DIP format, and that would save you a lot of soldering time. In addition, it maybe worth while to make etched circuit board if they are not available commerically. Did not check, but if there is a high enough demand, and nonexistence of ready-made circuit board, maybe I can ask RDO or someone else to make a bunch of them (12+) so that you just need to add the LEDs. Maybe even a IMAC class? :?

 

[utahsaltreefer]

Vitz I normally appreciate the posts you make. I've taken your advice on topics and like to hear your knowledge on many topics. That said, it is clear that you don't like LEDs and feel they are not viable. Thats a fair statement and one you have made several times in this post now. I think they are fun to toy around with and some day will be a viable main light replacement. For now they are too weak for a big tank, but MAY work for a nano. They do have advantages over MH and PC bulbs. Mainly they take very little electricity and produce almost no heat. Both of those are issues that many of us encounter. True you can't duplicate the light intensity yet, but for lower/moderate light items they should work.

Back on topic. If you are asking if the leds can accidentally fall in the water and survice, the answer is yes (experience here unfortunately). The transformer could blow if they stay submerged though as well as the metal leaching into the water. If they are completely sealed in acrylic they should be ok, but I personally wouldn't risk it.

As for their long term effectiveness with corals, I can't say. They are the right wavelength (Blue is mostly 420-460 nm and white is a mix of mostly blue and other colors). 50 focused in a 2 foot by 2 foot area is brighter( to the naked eye, I don't own lighting meters ) than a NO and very close to a PC. The cost is pretty high as is the time to assemble, but they may be viable for a nano. The angle of them is HELPFUL for a nano type setup. You spend no effort to make the light shine down into the tank. They do have to be spaced out so that they cover well though.

One last comment is that I have a 20 blue led array as a moonlight in my main tank that spans 4 feet. It gives off beautiful color and makes viewing the tank at night very fun. I don't have then on a timer, I just leave them on 24x7. They've been running for 1.5 years now and look as good as the day they were first used. I tested with new ones and they have not lost visual intensity. The corraline grows much better where they shine directly also ( I know corraline is a low light thing unlike corals ).

 

[Anonymous]

I was more asking if I could use them underwater

For instance if I drilled a hole in the bottom of an acrylic tank and ran a group of wires up into the tank and then split them out in all directions around the proposed center piece of coral. Then epoxy coat the whole mess so that there is no chance of the wires coming in contact with the water.

That way you could stunningly light a single coral in a bowl with no light from above.


That is my idea, of course its top secret :wink:

 

[Anonymous]

IT would work as long as you seal the whole thing in epoxy/poly resin. but after that you couldn't focus or move them, or you'll break the coating.

So as long as you seal them well, I'd say it's viable bry.

B

 

[Anonymous]

That is what I was thinking

 

[Anonymous]

How obout putting the string in clear tubing. Seal both ends with silicone then rubber caps. You could then place them in water. Just be sure to renforce the soder joints so they will not bind in those locations. You would need to take care and not over bend but should work. IMO

 

[Anonymous]

Good idea, OES12

 

[Anonymous]

How bout this one, when making a tank out of glass with silicone you could embed the lights in the corners.

Might be a bit of a mess to accomplish, but I think it would be possible.

 

[Anonymous]

Fiber optic, How about that?

 

[Anonymous]

Fiber optic, How about that?

That is something else I am considering playing with.

Doesn't almost all the light come out of the end of the cable?

But, it always leaves me with the question of how do I get the light into the cable...

 

[Anonymous]

Typically, you can add a diffuser/lens at the end of the fib. opt. cable to spread out the light if you are concern about it. Take a look at those fiber optic decoration. They just shine the light directly into one end of the cable. Obviously, they don't care much about efficieny there. Just run the fib. cable down the side of the tank, along the bottom, and come back up. You can burried it in the sand if you want.

 

[Anonymous]

How about this here idea I just had

Any possible way to focus all of the light from a MH bulb into some of that there cable? Then you can keep the actual light mounted some where where heat is not an issue, like outside and run the cable inside and point it at the tank.

Is that a totally nuts way to do something or what?

I know, I know, a chiller would be cheaper....

 

[Anonymous]

there are two options. Fiber optic cable or liquid light guide.

things that you need to keep in mind is that cable/guide may not be able to carry all the light that MH/sun generates.

There is nothing nutty about your idea, since it was looked at in various time. It usually make use of collimating lense, as well as filter to give the desire optical property. Issue is $$$$

 

[simico]

Hi, I read with interest the post about the potential for using LEDs for lighting up a tank with minimal heat.

Part 1…

My big problem now is how to wire up an array. :?

I have purchased:

100 White 130,000mcd 10mm
(Forward voltage 3v Min /3.8 Max /3.4v Typ. 20mA) 12 degree angle

100 blue 60,000mcd 10mm 465-475nm colour range
(Forward voltage 3v Min /3.6 Max /3.2v Typ. 20mA) 12 degree angle

50 near UV 10,000mcd 10mm 625nm colour range
(Forward voltage 3v Min /3.6 Max /3.2v Typ. 20mA) 12 degree angle

In all cases a 330 ohm resistor was included for each LED with instructions to supply 12V to each LED and resistor combo.

Only problem is that the array wizard I used on the net, (http://led.linear1.org/led.wiz) only recommends a 330 ohm resistor with these figures for a supply of 9v (not 12v). :?

(I input, Source Volts to 9, Forward voltage to 3.4 (good for all 3 LEDs), 20mA diode current, and for illustration, 1 LED.)

So assuming the wizard is right, and the 330ohm supplied resistors only need 9v, I guess I can just wire all 250 LEDs in parallel, and then my only issue is what spec I need for the mains powered transformer...

The wizard says, :arrow:

each 330 ohm resistor dissipates 132 mW
the wizard says the color code for 330 is orange orange brown
the wizard thinks 1/4W resistors are fine for your application
together, all resistors dissipate 132 mW
together, the diodes dissipate 68 mW
total power dissipated by the array is 200 mW
the array draws current of 20 mA from the source.

So is the following right?

each 330 ohm resistor dissipates 132 mW
together, all 250 resistors dissipate 50235 mW
together, the diodes dissipate 17000 mW
total power dissipated by the array is 67235 mW
the array draws current of 5000mA from the source. (????) :?

I will buy a switch-able power supply that can supply the 9v (If that's the right voltage?) but how many amps do I need? It looks like 5 amps, ( :?: )but I only got that by multiplying 20mA by 250, and I really don't understand what I am doing, although the wizard is a great help, it tries to put all the LEDs in series changing the resistors that are required.

Any help gratefully recieved...


Part 2… :idea: :?: 8O

http://led.linear1.org/lumen.wiz says that a 130,000mcd LED with a 12 degree angle will yield about 4.475 lumens. So 100 will give only 447.5 lumens.

However, at 10mm (or 1cm), each in a grid of 100 LEDs (10 x 10) will fit within a 10cm x 10cm grid, - that’s not too bad! (…and hopefully without adding difficult heat for my tank.)

I have read that “natural reef light” peaks at 100,000 lumens for a 1m square area. On a larger tank, a 1m by 1m square area will (theoretically) yield 44, 750 lumens (100 x 100, 10mm LEDs = 10,000 LEDs) just less than half full strength peak natural reef midday sun.

Now… the brightest LEDs I have found on eBay currently are power LEDs at 150,000mcd with a 30 degree power angle. So each one of these would yield; 32.114 lumens. So 100 will add 3211.4 lumens on a 10cm by 10cm grid! (?)…

…so now I start to worry because, if this is right, - on a 1m square or grid, - that would give 321,1140 lumens! - 3.21(ish) times the suns natural “concentration” of light!?! 8O :?

I admit:

a) 10,000 LEDs would take me a fair while to solder.
b) The power would be (assuming part 1 is right, and for the first example in part 2), - 50 amps.
c) This is based on “white” 130,000mcd LEDs possibly not the perfect colour temperature for reefs, (and e.g. “blue” equivalent LEDs yield only 60,000 mcd each.)

But, (unless I have made a miscalculation/mistake ), are LEDs not at least promising because of their efficiency and “cool/heatless” properties? :?:

Since I bought the LEDs 2 months ago they have drops 50-60% in price, so (ignoring price) and just looking at the technology: :arrow:

• What is the future/potential of LEDs?

• Is there a quality to the nature of this light that’s either beneficial in the depth it penetrates the water and/or tissues of reef organisms?

• What water depth penetration qualities do LEDs have over other technologies?

Any comments welcome…

Cheers, Si.

 

[Anonymous]

Welcome to RDO, Si!

With the LED and resistors, 250 of them will draw 5A. The calculation is correct.

LED price is still on the decline, particular due to recent development, production in China, and R&D money going into it from automotive and photonic sectors.

Currently, LED does not beat MH in lumen/watt. There are various issues that it needs to cope with before high intensity application can become widespread and economical. Issues like heat dissipation, lower light intensity are the drawback. The advantage such as low degradation, long life, and ease of control are the main reason it is such a promising technology.

LED typically have very narrow spectral distribution. It does not give any additional benefit compare to any other light source that emits in the same spectral region.

For most of the reef aquarium applicaiton, where the tank depth is less than a meter (! 3 feet), this "depth penetration" is usually can be ignored due to the relatively shallow depth. The color of the LED is usually matched in such a way to give a pleasant appearance to the viewer, not specially made to go to the bottom of the tank with minimium lose. As long as there is sufficient power in the region where the photosynthesis is needed (PAR), there is no great concern.

 

[simico]

Hi, many thanks for that. I didn’t think I would get a response that quick!

Really good news about the 5A question, I will give it a go this week once I have the right power adaptor…

So, to be absolutely sure I have got this right… :?

… contrary to the manufacturer’s recommendations, am I right in running a 9v supply (not 12v) to optimally power each LED with 3.4v in series with the 330 ohm resistor? :?:

…and am I right in thinking that the 330ohm resistor is in effect blocking out 5.6v of the initial 9v of power, and that is the thing that ensures the LED gets a steady 3.4v of power? :?:

…and, assuming that is right, 12v would effectively “cook” the LED and resistor burning out the array? :?: (and therefore I really don't want to give it 12v)...

Many thanks in advance… Si.