# DIY LED Fixture for 7 Gal (w/ pics)



## Temuchin (Jun 9, 2008)

Though not done yet I think I have taken a different enough plan from the others listed before that I have some thing to add here. 

Hoppy was discussing PAR comparisons in an earlier thread. I don't have a PAR meter but I do have a nice digital SLR camera. This allows for somewhat of a qualitative comparison. The following images are all taken with the same shutter speed and aperture setting. The difference in light intensities between images accuratly portrays the difference in lighting conditions.

First in my 14 Gal bio cube. This tank is being set up this week. It is not the final destination for this LED fixture. It has a 24 W 6700K PC bulb that is brand new and a 24 W 10000K PC bulb that is about a year old.

Both bulbs









6700 bulb









10,000K bulb









Led Fixture












Now on to the tank this light will be used on. This standard light here is a 6700K 14 W florescent tube light, but it is over 2 years old.

Old light









Led Fixture









Just White









Just Blue


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## CL (Mar 13, 2008)

Very nice build. It seems that leds are really becoming popular!


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## kev82 (Feb 6, 2009)

I'm looking forward to see some growth results from this... I like how you put your leds together nice and tight


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## malaybiswas (Nov 2, 2008)

Nice job. Good to see other fellow diy led enthusiasts.

10 1w is more than enough although the visible difference does necessarily equate to PAR differences.

I was about to say that 3 blue moonlight is not necessary for 7 gals but you already done it and it looks nice.


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## Regloh (Jan 17, 2009)

This is very nice.. you guys are slowly convincing me that I need to put an LED light fixture onto my todo list  

I also would like to see how plants react to LED's in general.


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## Wicket_lfe (Aug 21, 2008)

That is awesome. If you did buy the parts do you have a guesstimate of the approximate cost? I want to do this with a 2.5 gallon, so i would only need a few leds.


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## purplecity (Jul 28, 2008)

can u please tell us how much all the materials cost you roughly and where you got them from?

i am very intrested in making two light fixtures for my 10 gal's
how many watts/leds would you recommend for a 10 gal


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## Cactus Bastard (Jun 5, 2007)

Good job here, I'll be watching this one.
You added some blue LEDs, originally intending on using them as night lights but mentioned you were re-considering that? I'm assuming you noticed how much of their energy plants derive from the blue spectrum. Have you looked into imbalances that may occur from the lack of equally heavy 650 - 700nm lighting?


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## Temuchin (Jun 9, 2008)

Parts List (Yeah for Google Doc's)
http://spreadsheets.google.com/pub?key=pWfI2ynwNHl7hrT8zoxAXVw

Total cost was ~$230. This is way more expensive then what it would take to build an equivalent PC fluorescent lamp



> I'm assuming you noticed how much of their energy plants derive from the blue spectrum. Have you looked into imbalances that may occur from the lack of equally heavy 650 - 700nm lighting?


I'm not a plant biologist, but yes plants are typically efficient at converting blue light, with an average peak at about 420 nm. (The blue I used is at 460 nm.)

In researching my plan for the light I came across message boards for people growing hydroponic plants (tomatoes). While it is might be more efficient to use a spectrum of light, these people showed that plants can be grown with just Blue and/or Red LED's. That said, it will be very interesting to see what plants do well and if others do even better as all plants have a different spectral response. When I plant this tank I will have to focus on as many different colors as I can pack into such a small tank.



> I was about to say that 3 blue moonlight is not necessary for 7 gals but you already done it and it looks nice.


My plan was not well thought out regarding these blue lights. The second I powered them up I realized that even dimmed down, they would be too bright for a moon light. I am now thinking I will just use them as part of the normal day time light. I would love access to a PAR meter to measure their impact directly. Thats the problem with lumens though. An 11 lumen blue LED has a lot more photons available for photosynthesis then an 11 lumen green or even an 11 lumen white LED.


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## Hoppy (Dec 24, 2005)

I keep forgetting to ask this: what kind of heatsink is that? It looks like a surplus electronic device sink of some kind. And, of course, what does it cost?


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## purplecity (Jul 28, 2008)

lol, wow i always thought DIY's were for people on low budget guess not lol
anyway i dont think i can do it myself with that kind of prices lol


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## Hoppy (Dec 24, 2005)

purplecity said:


> lol, wow i always thought DIY's were for people on low budget guess not lol
> anyway i don't think i can do it myself with that kind of prices lol


It doesn't have to cost that much. You can do fine with a standard DC power supply, and current limiting resistors. That can save a big bundle. My local surplus electronic equipment store has DC supplies, wall warts, and others, by the hundreds, in many voltage ratings, and most for about $7 max. Resistors aren't expensive either, also being available at the surplus store. Cooling fans, in all sizes, are about $5 each at that store. (If I had found that store earlier my cost for a light for my 45 gallon tank would be around $125 total.)


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## purplecity (Jul 28, 2008)

I have two 10 gal's that are in dire need of lighting I was guna go down to homedepot and pickup a light fixture or something i dont know what to do,

hoppy how much do you think it would cost to make 2 of them? 
i like these leds because theyr so sleek and small and i heard its possible to attach a dimmer to the leds, that will be so amazng omg:thumbsup:






Hoppy said:


> It doesn't have to cost that much. You can do fine with a standard DC power supply, and current limiting resistors. That can save a big bundle. My local surplus electronic equipment store has DC supplies, wall warts, and others, by the hundreds, in many voltage ratings, and most for about $7 max. Resistors aren't expensive either, also being available at the surplus store. Cooling fans, in all sizes, are about $5 each at that store. (If I had found that store earlier my cost for a light for my 45 gallon tank would be around $125 total.)


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## Regloh (Jan 17, 2009)

Hoppy said:


> It doesn't have to cost that much. You can do fine with a standard DC power supply, and current limiting resistors. That can save a big bundle. My local surplus electronic equipment store has DC supplies, wall warts, and others, by the hundreds, in many voltage ratings, and most for about $7 max. Resistors aren't expensive either, also being available at the surplus store. Cooling fans, in all sizes, are about $5 each at that store. (If I had found that store earlier my cost for a light for my 45 gallon tank would be around $125 total.)


Another resource for cheap electronic equipment is this:
http://www.mpja.com


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## Hoppy (Dec 24, 2005)

I have been thinking about how much a LED light for a 10 gallon tank would cost. So, I think I will make that a project for today - not making one, but trying to design a minimalist one. I do have an empty 10 gallon tank, but, please, please, I hope this doesn't get me back to two operating tanks again!

EDIT: It looks like I could make a 10 gallon LED fixture, giving moderate lighting intensity, using 16 Cree LEDs, for about $125 total, making good use of surplus materials. Not cheap for a 10 gallon tank, but the need for DC power, a heat sink, cooling fans, etc. makes it almost impossible to build one cheaper than $100, no matter how ingenious you are. You have to look at this as half entertainment and education, and half getting a nice light fixture.


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## Temuchin (Jun 9, 2008)

As Hoppy says, this type of project is not about saving money. Its more of a "craft" project. This is what happens when you get rid of your TV. 
I also had a need for a custom solution to upgrade my lighting for a non-standard fixture length.


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## purplecity (Jul 28, 2008)

ok let me see if i have the right idea, in my diy light fixture i would use a very thin plate of aluminum, attach the leds, the dc power, and fans

so my parts list would consist of
- 22" aluminum plate
- 16 Leds
- one computer fan
- dc power supply

what other parts would i possibly need? the led driver or something?

i really really love this led fixture made byKev82!










i know i can get my hands on a aluminum plate from homedepot or some place cant be that expensive , i think i may have a dc powersupply if i look through my stuff, a pc cooling fan is easy to get 

so all these items stated above will be cheap the main important and expensive stuff would be the led's itself

what if all the people intrested in making Led fixture got together and we order over 150 LEds im sure we could get it for cheap, 

Also there is a led store on ebay can anybody check to see for the cheapest led bulbs we can use that would output enough light for 10 gal?


i think if we all work together we can find the best cheapest and most effective way to create led fixtures


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## Hoppy (Dec 24, 2005)

Actually the LEDs are not even half of the cost! http://www.dealextreme.com/details.dx/sku.2395 is the cheapest source I have found for high power LEDs suitable for our use. Note that this particular batch is a "bin" of lower lumen output high power Cree LEDs.

Just a flat aluminum plate might work ok, but keeping the LEDs cool is a major requirement for long life and most output, and they do get very hot if not actively cooled. A finned aluminum heat sink extrusion is obviously the best idea, but my local surplus metals dealer sells aluminum extrusions, not heat sink extrusions, that include all sizes of channels. They are sold in 8 foot lengths. So, for a 20 inch long heat sink, that gives you 5 lengths. A 10 gallon tank is about 10 inches in depth, so 2 inch channel would give you an almost perfect fit with the top. But, you don't need that, so a 1.5 inch channel gives you a 7.5 inch wide heatsink, which is perfect. And, 1.5 inch channel is only about $15 per length - very cheap. But, you have to use a heat conducting grease between the channels, and rivet or screw them together, side by side. So, $15 plus about $5-$10 worth of grease, and another $5 worth of nuts and bolts will give you a heat sink.

The DC power supply has to provide enough amperes to drive all of the LEDs, and at a voltage that lets you put the LEDs all in series, or in parallel groups of equal numbers of LEDs in series. Each LED will use about 3.1 to 3.6 volts. If 16 are put in series, the DC voltage required is 16 x 3.6 volts, or 57.6 volts, but you need a bit more in order to limit the current, so a 60 volt source is needed. The LEDs, for maximum output, will need .7 amps, so that 60 volt supply has to be capable of 700 mAmps output, preferably up to 1000 mAmps (1 amp). It is hard to find such a AC to DC converter with those parameters.

To control the current you need 1% resistors, maybe at worst 5% resistors, able to handle the power you will drop on the resistors.

For best cooling you need two fans, 12 VDC and a power supply for them, or 110VAC, which are more expensive.

To mount the LEDs you need a heat transmitting grease or adhesive between each LED and the heat sink, and that stuff can cost from $3 to $20.

Even hookup wire isn't free, and nuts and bolts, switches, etc. all add up too. And, you still don't have a nice looking housing for the light fixture.

The important thing is to really enjoy the adventure of learning about LEDs, electric circuits, designing the fixture, and making it.


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## kev82 (Feb 6, 2009)

Well there is one factor that *might* save you a little cash in the long run. You don't have to replace the LEDs anywhere close as often as fluorescent bulbs. F.e. the cree LEDs I used for my build are rated that after 50,000 hours of usage they will emit 80% of the light they originally emitted.

I did this mainly for the fun and learning factor tho. Doing stuff like this yourself is fun stuff


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