Tavel

Why LED's

1. Low heat dissipation; perfect replacement for halogen bulbs in small aquariums or for planted aquariums with very bright lights.

2. "Ambiance": Ripples on the water surface cause dancing shadows on the bottom of aquarium.

3. Improved fish appearance: Undiffused light gives fish a brighter, more iridescent color. (my glo-lights look AWESOME under LED light!)

4. Potentially brighter...depending on how many LED's you use.

5. Lower energy consumption; always good!

PRIMER

We're using high power LED's because they have a greater choice in light color, have higher output per dollar, and are simpler to work with and wire.

High power LED's come in a variety of colors, just like fluorescent bulbs. However, they do not emit any light beyond the visible spectrum. Be aware of that.

You can pick any color you want for your project. I like 6500k because it's the color of sunlight on an overcast day, what I imagine as "perfect white". 6500k LED's will also nicely match my 6500k CFL house lights.

LED supply is probably the best place to purchase high power LED's. You can also pick up an awesome power supply from the "accessories" section.

I chose the "Luxeon Endor Star" 6500k 1-up. The endor star series offers the best price/performance ratio and the widest selection of colors. If you choose the "3-up" variety, remember that's THREE LED's and should be wired as such.

WIRING

Now, as you recall, LED's are semi-conductors. No two are identical so you should never run LED's in parallel. Some will take more than their fair share of the current and burn out, starting a cascade that will quickly burn the rest out.

Run LED's in series. My LED drops 3.4 volts at 700ma, so I can put 3 in series on a 12V line, dropping 10.2 volts across all 3 (still drawing only 700ma from the source). You can run 6 in series on a 24V line. If you want more than 3, you can run multiple series in parallel, each with their own driver. These are called "channels". We can do this because each channel has it's own current limiter, so no single LED will hog more than it's share.

Each channel draws 700ma, so if your power supply can provide 3 amps, you can run 4 channels.

THE VERY EASY VERSION

If you don't feel confident in soldering the following circuit, you can purchase an LED driver from the same site. It could potentially be cheaper than the DIY method if you use an AC compatible driver (careful though, some of them use 24VAC, not 120VAC mains)...

EASY VERSION

You can run it on any power supply you an find, up to 40VDC. I recommend running it on the 24VDC power supply from LED supply, you can power up to 18 LED's this way. You can alternatively repurpose a laptop charger, in which case you're kind of on your own when doing the calculations. but hopefully you can figure out how run the numbers from my examples.

While people typically use resistors to regulate current, we'll be using something a bit more elegant with our hi-power LED's...the LM317 voltage regulator. It actively adjusts current based on input (unlike resistors). It's also readily scalable; you can put 1, 2, or 3 LED's on one of these drivers without any changes. But most importantly, the LM317 has reverse current protection so you won't see $50 of LED's go up in smoke because you switched polarity on your power plug.

A resistor circuit would require a different resistor for a different number of LED's, and would dump the difference as heat (unlike the Transistor). But it also offers NO protection to reverse current, not good!

We set the current on the LM317 with a resistor on a feedback loop. the 317 continually checks the output against the feedback and adjusts accordingly. Here's a handy calculator. Take note of the estimated resistor wattage and buy a resistor with at least double that.

We want to run our LED's at full power (700ma) so we put a 1.8ohm resistor in the feedback loop. Now the LED's will be supplied with 700ma no matter what.

The LM317 should generally be heat sinked. I didn't use one in my photo because my setup dissipates very little heat. You should use a heat sink just to be safe!

Parts List:
1. LM317
2. 1.8 Ohm Resistor
3. Heat sink for LM317
4. Thermal Paste. Any thermal paste will be fine, I just link to this one out of convenience.
5. Wire: speaker wire will work fine because it's very flexible.
6. Aluminum foil
7. Small machine screws with nuts...I honestly don't know what size I used, but they should be small enough to fit the heatsink. You can should use the same size screws to mount the LED's too. You can get these at your local hardware store.

1. Wiring:

1a. Choosing a power supply:

First figure out how many LED's you want. 3 LED's replaces a 15watt fluorescent tube (so that's 5 watts per LED, if you can't do math). if you want 30 watts equivalent, try 6 LED's, or even 9 if you like it brighter.

Assume our LED's draw 700ma (or .7A), and drop 3.4 volts.

If you choose the 3A @ 12V power supply, you can run up to 4 channels (4 x .7A = 2.8A), with 3 LED's in each channel (12 3(3.4) = 1.8V). That's a total of 12 LED's.

You can run up to 18 LED's on the 2.2A @ 24V power supply. 3 channels (3 x .7 = 2.1A), with SIX LED's in each channel (24 - 6(3.4) = 3.6V). While it appears you can run a seventh LED, realize that the transistor drops about 1.5V by itself, and that the LED's typically come in groups of 3. So it makes good sense to plan for powers of 3.

NOTICE: the "3-up" LED's are in fact 3 distinct LED's on a single board. Treat each LED individually.



1b. Driver:




Each channel will have it's own LM317 and resistor. order parts accordingly!

( You can't get a 1.8 ohm resistor at radio shack, so you may as well order both items online).

Wire it like the diagram. You'll be using "surface mount soldering" for this. It's easy though. Melt some solder onto the pins, put the wire onto the pin, then press the soldering iron against the wire until the solder melts. Remove the iron and hold it until the solder cools (1-2 seconds).

If it takes more than 5 seconds, stop! You may damage the transistor. Let it cool, apply flux to the solder, clean the iron and try again.

Do the same for the LED's. Melt some solder onto the pads, and go from there. Connect the negative of one LED to the positive of the next, this is series wiring.

1c; Assembly

Remove the old wiring from the hood, but leave the switch and the accompanying wire leads (we'll use them).

(Here's where you get to see one of the great mysteries of the universe...black means "hot" in house wiring, while black means "ground" in electronics. I don't get it. )

Stick a 2.5mm barrel plug adapter from radio shack into the hole from the AC cable. Not essential, but it makes it look nice. The barrel plug adapter has 3 leads, but you only need two. The center pin is "hot", while either adjacent pin is "ground". Get it right, switching polarity is a good way to break things.

Now, run the "hot" wire to the switch, and from the switch to the "+DC" in the diagram. Then connect "to GND" directly to the plug (not the switch.).

Test it before moving on. It will be harder to fix once you put it together. The LED's should light up...and blind you. if the LED's do not turn on immediately, TURN IT OFF! check polarity of all the connections and make sure everything is connected correctly.

Once it's working, use electrical tape or heat shrink tubing to insulate all the connections. Also insulate the transistor's pins individually, you don't want those touching by accident.



2. Thermal management:

LED's don't produce a lot of heat, but they are very small (low surface are for dissipation) and are very sensitive to heat (because they're semiconductors). So it is imperative to provide them with an adequate heat sink.

You're in luck if you have an aluminum reflector in you hood, just bolt the LED's to the hood with a dab of thermal paste between the two surfaces. It's tight enough when you see the thermal paste just squeezing out from the edge.

If you have a plastic reflector (like me), it's still not very difficult. Just apply some aluminum foil to the reflector using spray adhesive. Then bolt the LED's to the reflector, again with thermal paste between the two surfaces.




Foiled again! keen observers will notice the circuit board and potentiometer. This is for the hard version with a dimmer knob...which i fried.

The bolts may be touching the solder pads so you'll need to isolate them with electrical tape. Cut a small square with a hole in the middle, then slide it onto the bolt (sticky side up works best) like a very thin washer. That's it.




3. Final assembly

Put everything together...that's about it.



If you don't like the rippling light on the bottom you can make a light diffuser by roughing a piece of plexiglass with sandpaper, then stick it under the LED's.

I personally like the rippling light, it's peaceful and natural looking.

The hard version will come later...I have to get it working again, I fried the IC and a capacitor by reversing the polarity. Don't be like me kids, check polarity!

Wyphy

Looks like a nice little project, with lots of nifty pictures.

With your 'easy version', you still need to worry about heat with the regulator.
The LM317 should always have a heat sink and it must be isolated from circuit ground. You should be able to get a sink from wherever you got the regulator; some RadioShack's aren't as well stocked anymore. so a specialty shop or online ordering may be needed.
The regulator will have to dissipate whatever isn't used by the output.
For example, if your source voltage is 24VDC and your drop is 10VDC at 700mA, it has to dissipate 14VDC at 700mA, that comes to 9.8W
Dissipated Power = (Source V - Drop V) * Current in Amps; so (24V-10V) * 0.7A = 9.8W, a substantial amount.
Less of a difference between input V and output V results in less dissipation in the regulator. Ideally, you want an input V as close as possible to the output V; 12V with 10V drop comes to around 1.4W, much more reasonable, but you still need to use a heat sink.
Those resistors also need to be fairly beefy, something in the 1W or greater range, don't just go buy those small ones at RadioShack that are rated 1/4W, as you'll let the smoke out of them very quickly.

Watts do not directly translate to lumens, and you need a light meter to accurately measure Lumens.
If you just want to replace a 1 tube fixture for a fish only aquarium, that '5W per LED' rule is probably fine (for those LEDs you used, each brand is different), but if you have planted tanks you really need to do the lumen calculations. Though if you're into that, you should already know how to do so.
The site you linked has data sheet links that show the parameters for various conditions.
Based on my rough calculations, those LEDs are estimated to still have 70% of their initial light output after 50,000 hours, which if you run a 12hr light cycle should be in the neighborhood of 11 years.
Not too shabby, and certainly cheaper than replacing tubes 1-2 times per year.

mjordan

cool but could u do a planted tank with led...

if not than it would be good for african chiclids..

ps: i dont have african chiclids haha no help there to me

Tavel

Thanks for the feedback, I much appreciate it.

you're right with heat sinking the lm317. It only drops about .5 volts in my setup, so it doesn't need a heat sink (I checked it, only 80F after 8 hours). People running on 24 volts, or only 1 or 2 LED's should throw a heat sink on there. I'll edit it accordingly.


You're very correct about the resistors too. they will dissipate about 1 watt of heat...so the resistors I linked to are 2 watt power resistors, for the outrageous price of 14 cents each!. I'm pretty sure you can't even get 1.8 ohm resistors at radioshack, so no one's going to accidentally get 1/4 watt resistors.

Good point on the light output. Anyone who needs a precise light level will already know how to calculate said light level, lol.

Tavel

yes you can do a planted tank, it's actually more efficient than fluorescent lights because plants only use the visible spectrum...which is exactly what LED's emit!

You'll save money on electricity and eliminate those bright lights heating the tank. Plus, I think the pricing between T5's and LED's is pretty comparable.

Many people are even doing hydroponic gardening with only LED's, cool stuff out there.

Wyphy

I'd been thinking about doing a project like this even before this thread / conversion demo.
I previously had an Eclipse hood that was a 2 lamp fixture (lamps were near front glass and not center-ish like standard fixtures), but also gives a very sleek look to the top and goes well with my high(ish) gloss black stand.

I'm planning to make a top to fit similar to the Eclipse, and also build a lighting fixture using (most likely) the same Endor Star units you chose.
6700K is a nice temp, though I like 5500-5800K too.

You did this project as a fairly quick-n-dirty looking conversion and DIY circuit design (not that this one is too hard), but for those that want a slightly cleaner look, there is an option.
On the LEDSupply site, you can go to the Drivers page and choose a driver that allows 110VAC input instead of the power supply and regulator you used.
They are a bit more expensive, but give a more professional look. In a fixture like yours, you could most likely hide it where the ballast was, as the drivers are fairly small at around 5"x1.5"x.75".

Something else to consider is that they also have 4100K LEDs which can be used for moon lights, though you would need a separate driver, and one driver (the MicroDriver 9) actually has both 350mA and 700mA outputs so you can choose to have a 'full' moon look or something less, like a 1/2-1/4 moon look.

Tavel

Id have to argue that it's kind of pointless to spend more money for something you'll never see. I went for biggest "bang for buck" with my design. You can run a lot of lights off those power supplies, and they're still quite a bit cheaper than the cheapest of pre-built drivers. They'll look neat and clean if you use a barrel plug, like I suggest.

And if you felt so inclined, you could just pick up a $3 project box from radio shack and stuff all the bits into that...but again, why?

I'll concede that my aluminum foil is pretty cheap looking, but it is really an elegant solution to heat management. why machine a new reflector from aluminum stock? no point really, except that it looks nicer...but who looks at your reflectors?

Also a quick note on moonlighting:

First: 4500k lights will look like incandescent lamps, maybe you're confused on color scales? i think it would look fine anyway. But it'd probably be cheaper to use standard LED's for moonlighting, why buy all that lighting power and never use it?

Second, as a point of general reference...moonlight is actually the color of daylight (5500-6500k). It's just too dim for our eyes to sense the colors so we see everything in gray scale. If you use blue lights (as typical "moonlights" do), then blue things will look white, and anything else will look black. A dim WHITE light will yield the correct gray scale and look like moonlight.

mjordan

so wat would you estimate for a 29 g tanks which is a total of 30 inches acrost.
how many leds and individual price would be nice




thanks

Tavel

two or three of these I would think. 2 will be on the dim side, 3 will be on the brighter side.

mjordan

any ideas on prices

Wyphy

I'm not confused on color scales, I frequently reference color temperature in my professional work; concert and theatrical, and occasionally video, lighting.
Incandescent lighting is in the 2800K-3500K range, depending on the specific lamp.
4000K-4500K is a 'neutral' white, and what moonlight is, which is why I suggested those LEDs for a moonlight lamp.

I suggested those drivers because there are many reasons that someone may wish to use them.
Perhaps someone doesn't know how to solder; doesn't like to solder; doesn't have steady enough hands to solder; doesn't have the confidence to build their own; has money but no time to build their own; and others that I haven't thought of.
As to cost, the drivers are more expensive than the basic power supply; Those power supplies are basically the same as a laptop supply, which can frequently be had for very cheap, say $5-$10, yet you didn't mention that as an option.
You are already ordering the LEDs, and by buying the other parts from a different vendor your shipping costs are increased. I've used Mouser many times, and they have no minimum order, but even 'cheap' shipping is $5 or so. If you want to know the true costs, you also have to include your labor time. How much is your time worth?
True, this is a hobby and we do it for fun, but one should analyze their own situation and decide what things are worth.

And when I said 'quick-n-dirty', that was not meant in any derogatory way, just that it was not 'professional made' looking.
Not that it doesn't work or wouldn't reflect light properly. Not that much of any light would be reflected with those LEDs anyway.
Why put things in project boxes? Who sees your reflector? Well, why do people tie up the plugs for their filter, heater, etc.; why tie up their computer cables; why put their coats in the closet? Some people like to have things neat. It's just a personal preference.

As for thermal management, aluminum foil isn't a very good heatsink.
I cook things in my oven on sheets of foil and remove them with no gloves or pads. Try it, heat an oven to 400 degrees and put a piece of foil in there for 10 minutes then take it out bare-handed; it will be warm, but not too hot to remove.
The foil doesn't have enough mass to hold any heat. If you put several layers together, then you begin to get the mass required to absorb some heat.

I didn't post here to offend or tear down anyone.
I posted to offer a different point of view.
This is a worthwhile project and I'll be doing one very similar sometime this year.
I could design and build a 120VAC-xVDC power supply, I plan to build an RF power amplifier (600-800W range) in the next 5 or so years. Not everyone can do that.
Perhaps you could do those also.
Not everyone has the ability to do what we can do, or may have other reasons for wanting to do something the 'easy' way, and not caring that the 'easy' way frequently costs more money.

Tavel

All good points...I actually never thought of using a laptop power supply! I probably should have made some accommodation for people who don't want to solder. I just figured anyone confident enough to tear apart their hood was also confident enough to solder up a transistor. (I did all that with my 30w Radioshack fire-starter, fun times).

I updated the write up, check it out and let me know if I missed anything.

aluminum foil is an excellent heat sink, that's precisely why it cools off very quickly when removed from the oven. Thermal mass is good to buffer heat spikes in components that have rapid temperature fluctuations. (CPU's and such). But LED's don't do that, so aluminum foil works great.

Wyphy

How did you measure the temp of the 317?

Tavel

I taped a kitchen thermometer to the backside, I don't have an IR thermometer.

Fla_Larry

very nice job there Tavel, how is the light output?

My curiosity comes about from just how wide is the spectrum spread from those led's?

have you made any measurents as far as lumen yet? and again i do understand most photomoters are more green weighed, it should still give some sort of baseline value depending on the spectrum spread answer.

Tavel

the only photometer I have is in my camera...but that certainly doesn't have a scale. It did allow me to confirm that the output of the LED's was comparable to the output of the 15W fluorescent tube. again, I don't know the values of the output, only that they're (close to) equal.

I was thinking though, and my florescent tube was pretty old (9 months) so it probably wasn't a good measure for typical luminosity. I recommend bumping up my original estimate, maybe 4 LED's for a 15watt fluorescent.

The spectrum output is complete, as far as I can tell. These are produced for lighting purposes, so their color output is far superior to standard LED's (like in flashlights). I did several color rendering tests (with my camera, again not absolute, but good for comparison) and everything looked good. It has a little more blue than a 6500k fluorescent light, but is otherwise balanced.

Also, the beam spread is very wide, I think it is officially 130* or so, and I believe it. They produce a very even light, no spotlights on the bottom.

FYI: my camera is a Nikon D50, and I was shooting in raw.

Wyphy

Go to the LEDSupply site and look at the page of the specific LEDs you are interested in.
Almost every item page has a data sheet.
Some sheets are better than others, and for some models you need to go to the manufacturer's site, but there are spectrum graphs available for all of the K2, Endor Star, Luxeon Star, and whatever other models are made by that company (I think it's LuxDrive.com, it's part of the Philips company).

I do remember that the Endors have a pretty big blue spike in them and kind of a big hump in the green area too while sloping off towards the red end.
Not a bad spectrum, but more green and probably a bit less red than a fluorescent lamp.

Tavel

http://www.ledsupply.com/docs/Rebel.pdf

page 12.

I tend to feel these charts aren't very useful if you're just trying to get an idea of how it looks. I guess they would be if you had a lot of experience with lights and reading the charts...but I don't, lol.

Wyphy

True, they aren't very good for seeing how a light will actually look unless you have a lot of experience, and while I do have experience, it's not so extensive that I can visualize a light by a spectrum plot.
It's also not helpful that there isn't a color reference in the chart.

Go to DFS's site and look at the fluorescent lamp pages, most of the lamps have a spectrum chart on the 'More Info' button that shows the colors to go with the numbers in the chart so you will have a much better idea what you're comparing. Try this link to see what I mean.
You can see that there are some spikes at certain colors and what those colors are as well as the overall output.
The red end of the spectrum is called 'cool' and has a lower Kelvin rating and is similar to regular incandescent lamps, while the blue end is the 'warm' side and has a higher K rating.

So now that we have a color comparison, we can see that the LEDs have a big blue spike which is the main color component, and a general mix of most of the rest of the visible spectrum, but with more green and probably a bit less red than a typical aquarium fluorescent lamp.

mjordan

ok i talked to my dad boutt this and thinks this will be a ton cheper and safer than a diy with floresent bulbs.

just to refrence this these are the tiny bulbs that are the size of a wood nail.

() <----- see that right there the prentises like that size..


if so my dad doesnt think 4 bulbs/leds will be sufficent for my planted tank.
i have a small flash light that has 9 leds in it.(super powerful) but i dont even think that could light it.

whats the output on and individual led.
reason being i would like to no that 5 leds would = 20 wats of florencent so i can put in 15 to the eqivalent of 60 wats florencent.

thanks

Wyphy

The proper way to get the light output you need is to find out how many lumens you need then get the number of LED units to match.
Off hand, I don't know what the lumen output of the fluorescent tubes that we generally use, nor do they seem to be listed on DFS site.
I have a few 60W equivalent (14W I think) compact fluorescent lamps, for incandescent replacement, and they are about 600 lumens each.
If you have a friend that is a photographer, you may be able to borrow a light meter from them, or have them help you use it, to get a better idea of the light you need.

As to size, the units are about .75" in diameter, and the lamps are fairly small, but have a very high output of 145 lumens for each LED
15 of the 1-up Endor Star units would be 2175 lumens, and the 3-up units would be 6525 lumens.
15 3-up units would be way too much light.

You don't say how big the tank is, so guessing it would be for the 29G listed in your aquarium info, it should have a 24" T8 tube, or multiples of that.
Tavel can better tell you the brightness of the LEDs, since I haven't seen them, but I would guess that you'd want somewhere around 6-8 of the 1-up units evenly spaced across the tank, maybe even in a small zig-zag pattern to try for an evenly lit tank.
That would give you 870-1160 lumens, and unless you have some plants that need a ton of light, it should probably be ok, but again, this is just my guess.

As to being safer, I don't think there's really much difference.
Standard safety rules apply, unplug from the wall before working on things, check polarity and for short circuits before plugging in, etc.
You have to wire something no matter the route, a ballast and to each end of the caps for fluorescent or the power supply and to each unit in series/parallel for LEDs.

Cost?
Well, 8 of the 1-up units is $52 plus a driver unit or power supply and the other parts Tavel mentioned for LEDs ($10-$40 depending on your choice), if you get those specific LED units.
A complete 2 lamp 15-40W ballast/end cap kit at DFS (Link) is $55, then you need lamps (2x $6-$15 depending on lamp choice), which will need to be replaced at least once per year, possibly more.

Overall, the LEDs are probably cheaper in the long term, but are less flexible. If you decide to change from fresh to salt, the LEDs may not be the optimum choice, and definitely not if you want corals.
That ballast kit is pre-wired, so you just need to mount the ballast and clips to the hood, plug the caps into the lamps, and plug it into the wall and you're done; you really can't get any simpler than that.

Hope that helps ya some.

Tavel

Wyphy: why are LED's unsuitable for corals? I thought they thrived off the symbiotic algae, which only use the visible spectrum. Perhaps they need UV light for shell development?

the LED emitters are absolutely tiny (half the diameter of my machine screws!). but these come on heat sink wafers which are about the size of a quarter, making them much easier to work with.

You are right, 5 LED's will be equal to 20-25 watts fluorescent. there's no easy way to compare brightness which makes things difficult. You'll just have to trust me.

these LED's are far brighter than your dad thinks. Your flashlight has standard LED's, and these are 20x brighter than those. I can't emphasize enough that they are literally blinding and will blind you for 10-15 seconds if you look at them. (it's mostly because it's like a 5 watt light bulb, but all the light is coming from a pin-***** of light)

I would recommend 4x 3-up units (so, 12 LED's total).

You can actually get any brand of LED you want, I just chose the Endor star because I feel it's the most cost effective. Just tell me if you choose a different lamp because it will change the layout and specification of your circuit.

Then you would get the 2.2A @24v power supply. You should use two channels, each with 6 LED's in series. You can always add up to 6 more LED's if it's not suitably bright. (Any more will overload the power supply, but you can try to find a different power supply -- like a laptop power supply)

then of course, you should order 3 each of the LM317 regulators, resistors, and heat sinks to save shipping just in case you DO decide to spring for the extra LED's.



COST: The initial cost is high. $70 for the LED's and $20 for the power supply plus shipping, then maybe $10 for the other electrical components.

Don't let that discourage you though, these LED's will last for 12 years (at 12hrs a day operation) and still have 70% of their initial output. Fluorescent bulbs are down to 50% after just 6 months! you WILL save money in the long run and will break even after a year or two.

Safety: I tend to think this is safer than fluorescent lights, if only because it's low voltage and on a low current supply. So it probably won't start a fire if it falls into the aquarium (don't sue me!).

I can only imagine how bright 18 of these LED's would be...you could blind airplanes! hahaha

Wyphy

Go to the DFS site and look at the spectrum graphs for reef lamps and compare with the LED graphs; these LEDs don't have the needed spectrum output.

There are some full LED systems designed for reef use but they are very expensive. Partly for the enclosure (requires fans and good heatsinks) and partly for the features
One of the systems at DFS uses Luxen Rebel LEDs, which is the same type as these, but has several different varieties, is computer controlled to have calendar correct sun rise/set, moon rise/set and phase, and cloud cover.

If you're going for a fish only salt tank, then these LEDs should be just fine.
You could do a combo DIY setup with these LEDs and a couple of actinic lamps and be ok for corals and such.
Or you could get ambitious and do it all with LEDs, but it'd be pretty expensive, needing 3-5 power supplies/drivers, LED types, and generic timers if you want a semi-realistic look. Computerized control optional, but certainly adds to the wow-ain't-that-cool-ness of the thing.
It'd be cheaper than the commercial units, but still pretty pricey.

Fla_Larry

looked at the charts you referenced, are these lights going to be used on a marine Tank? if so i would think they will work quite nicely at replacing the actinic. visually i think the neutral white will look good, but all that aside, they are seriously lacking on the red end of the spectrum, and FW plants need that also i noticed some deep Vally's in the green range, remembering of course that a plants needs across the spectrum is fairly consistent, do you have plans for compensating?

Still all that aside, i think this will be an interesting experiment, very anxious to see how it all plays out.

Oh BTW Fluorescents only loose < 10% lumen output over 10000 hours at least according to the manufacturer, and they would not exagerate.... would they, color on the other hand.... no guesses there

mjordan

my dad can get the little ones and there power supplys for FREE at his work. they have tons that they were/are going to toss out and he grabed a few bags that are still brand new that have a couple 100 in each.


he says he has bout 500 prob.
could i get 20 of these as u said would equal 1 of the other led and mult by 12 to get 240 of the little ones to equal 12 big ones.

do they last the same time with the same output without fading to much. like u said bout the 70% for led and the 50% of the florecent.

my dads and electrical engineer for a radio sation so he can help me do this

Tavel

I think you would need more like 30 standard LED's to make up for one of these high power LED's. Of course, I can't find any lumen ratings on these, so I just did 700ma (high power) / 25ma (standard) = 28. That's pure power draw, I'm not sure if they have differing efficiency or not...you'll have to check that out.

I honestly wouldn't recommend using standard LED's because they're not meant for general lighting, so they just don't have a nice output. I'm sure you could find a few graphs, but they have a HUGE blue spike, and then a little green and even less red. It'll look like your flashlight, basically. the high power LED's won't be discernible from a fluorescent. But I guess the price is right...lol.

Also...soldering 250 LED's? Yikes. that will take days, hahaha.

You could, if your dad helped you, run the LED's off the mains and save money. Just put them in series of 47 (5x47= 235) with a bridge rectifier and some other goodies (like a fuse!). check out this Instructable on the topic. It could be fun and save some cash if you're going in that direction anyway.

mjordan

so the leds are not as good from your understanding of big to small and wouldnt be good for a heavely planted tank

Tavel

they'll still be fine, especially if they're free. But they won't look as good as the high power LED's (poor spectrum), and it is seriously going to be a huge project just to solder all those LED's. 250 LED's means 250 mounting holes and more than 250 solder joints...i definitely wouldn't do it.

As a side note, I just realized the LM317 has reverse current protection. I kept trying to figure out why I didn't fry my LED's when I applied reverse current to my PWM circuit and cooked just about everything else...and the LM317 is that "why". Another good reason to choose the LM317 over a resistor.

Wyphy

I'm definitely no expert of aquarium lighting, fresh or salt, but I don't believe that these particular LEDs have enough of the blue output for some (many?) of the corals, which is why, I believe, that the commercial units have several LED units that emit a blue spectrum along with the white lights.

The low red spectrum is also a concern for plants, but...
As many have proven before, you don't need optimum conditions for plants to survive.
They may not do as well as in optimum conditions, grow as fast for instance (but maximum growth isn't always desired for aquariums), and many species will live long lives in our small, contained environments despite our somewhat limited resources. Obviously some will do better than others, but it's up to us to choose plants that have the best chance for survival in our individual circumstances.
Likewise, there are some corals and invets that will do fine in just these 6500K LEDs, but some that won't, too.

As to the the output of fluorescent lights, they may not lose much in total lumen output over time (I can't say as I've not researched this), but they do lose spectrum output faster than overall output.
Basically, they put a certain amount of specific elements into the lamp and they burn off at a specific rate. Once they are gone, the lamps lose that spectrum of light. I can explain how this works, or you can try to find info on how fluorescent lamps work at places like wikipedia or howstuffworks.com
This is fine for standard 'shop lights', and in general, fine for fish only tanks, but for plants and corals, they need those specific wavelengths for growth, at least, an maybe even survival (again, not an expert on plants or corals).

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