DIY LEDs - The write-up
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luther1200
Premium Member
<a href=showthread.php?s=&postid=15185732#post15185732 target=_blank>Originally posted</a> by qfrisco
I just last week switched from 2x250w MHs to T5s and LEDs (for shimmer) on my 90g (48"x18"x24"high), so not exactly what you're asking about, but I did the power consumption math. Maybe this will help.
When I was using MHs, I was using M80 Magnetic Ballasts which typically use more power than the bulbs they drive. For example, my ballasts were actually consuming 328w each. I was also supplementing my MHs with 2x54w actinic T5s. So total, my MH setup was consuming 764w. Note that an Electronic Ballast will usually pull closer to the rated wattage of the bulbs it's driving - they are much more efficient than Magnetic Ballasts.
For LEDs, just as a ballpark figure, you can estimate 3w per LED. And say you use 48 LEDs like Soundwave did in his 4-ft tank, that would total up to a whopping 144w. And just doing the math a different way, it would take ~255 LEDs to equal the amount of power consumed by 2x250w MHs on magnetic ballasts and 2x54w actinic T5s.
So 764w with MHs versus 144w with LEDs. A huge savings in power!
Thank you, So even if I used say 72 LED's it would only be 216w, correct? That would be nice.
How do you like it with the T5 supplements?
I had an idea to put 5 rows of 6 and then another row on the very end running from front to back. Then somehow angle them to light the side of the tank a bit better. So there would not be a shady spot on the side. Those heat sinks are aluminum right? So I could just cut and weld them on a 20-30 degree angle ( what ever it would take). This is still just a thought I had, but I think it would work. I am still just considering the LED fixture for my next tank, which I don't even have yet. But so many people seem to like them they have to be doing well with them. And the idea of not having to buy new bulbs every year sounds really good.
james3370
Premium Member
if i'm looking/interpreting it correctly, the LEDs are at the top of the 1st pic (bare emiiters w/ no starboards) & are what the copper wire is soldered to in the 2nd pic.....therby the heat transfers off the backside of the LED (it's "hotspot") which the copper tubing absorbs & is dissipated by air contact (& i'd assume convection cooling via fan(s) also)
Two royal blue LEDs without the starboards on the top of the panel. LEDs are mounted on the PC board I made, then PCB secured by nylon bolts. I am going put some more heatsink compound just to be sure between the LEDs and the copper wire joints.
And what james3370 said is right
And what james3370 said is right
NanoReefWanabe
Active member
just wondering guys...is it essential to use the arctic silver thermal paste on the star boards? will the JB metal weld work?
how do i fix the star boards to my heat sinks? will the paste bond them there or do i have to epoxy them? or mechanically fasten them with screws?
i see you guys connect more then one one led to a heat sink...is there anything special to do this or is there no electrical issues created by this? some of the reading i have done indicates that you have to electrically isolate the LED's from one and other if connected to the same heat sink...
lastly where is the cheapest place to buy dimmable 700mA buckpuck with the potentiometer?
how do i fix the star boards to my heat sinks? will the paste bond them there or do i have to epoxy them? or mechanically fasten them with screws?
i see you guys connect more then one one led to a heat sink...is there anything special to do this or is there no electrical issues created by this? some of the reading i have done indicates that you have to electrically isolate the LED's from one and other if connected to the same heat sink...
lastly where is the cheapest place to buy dimmable 700mA buckpuck with the potentiometer?
james3370
Premium Member
you can use arctic thermal paste (like between a computer cpu & heatsink/fan assembly) or the arctic silver themal epoxy....either one is suitable. either arctic silver is used as a "filler" between any irregularities in the surface of the star & the heatsink....this gives you the optimum heat transfer
the difference is that the epoxy will permanantly bond the star to the heatsink. if you use the paste, you will need to attach the star using a stainless screw w/ a nylon washer between the screw-head & the star. that is the method i chose since it makes it easier to remove the star if i need to replace them for some reason. see the clickable thumb below:
the stars are made of aluminum so there is no need to isolate them electrically since aluminum isn't conductive. now if you were to use "bare" emitters (as xenia2 did), then yes you would have to isolate them
i haven't seen a cheaper source for the buckpucks...whether dimable or not....from anywhere else than ledsupply.com
kcress
New member
Bare aluminum is VERY conductive..!
Anodized aluminum is not surface conductive. However a scratch changes that really quickly. You shouldn't depend on the anodizing to provide electrical isolation as it's pretty iffy. And completely busted if you have screws going into holes.
Anodized aluminum is not surface conductive. However a scratch changes that really quickly. You shouldn't depend on the anodizing to provide electrical isolation as it's pretty iffy. And completely busted if you have screws going into holes.
NanoReefWanabe
Active member
yeah a lot of residential main feed hydro lines are aluminum, what if i tap and use nylon screws? will they melt? is there anything else other then the arctic silver paste that could be used to thermally attach to the heat sink?
i am very excited to build this...already have the LED's ordered, and the power sources, and bought the heat sinks at a local metal supplier...
Just to clarify, I'm using T5s for my main lighting, and using LEDs for shimmer only. Used as such, I like them very much, and they are very effective for creating a nice MH-like shimmer.
I created the video below to show the shimmer that I'm getting.
http://www.youtube.com/watch?v=TVUfIatAXoE
One thing to note - in this video, the LEDs are not as bright as I was planning them to be. I had messed up my power budgeting and ended up driving the LEDs with only half the power (350mA) I had originally planned (700mA). So in this video, although the shimmer is already quite effective, it should be even more pronounced once I'm driving the LEDs with more power.
I have a bigger power supply on the way and I'll post a new video once I've wired it into my setup.
apt220
Member
Guys, I'm about ready to wire my LED fixture, but I have two questions about the fans and the power supply. I couldn't find data sheets for them.
For the fans (which are probably the same as soundwave's with the blue leds & 12V) what do these wires correspond to? I'm pretty sure the wires from the large plug are what I wire in series to the power supply, but I'm not sure what the third wire is that goes to the small plug. Is it just the ground?:
And for the power supply, I just want to make sure that I only need to use one of the voltage terminals (one V- and one V+).
Sorry if my electrical lingo is incorrect. Please correct me. Thanks.
For the fans (which are probably the same as soundwave's with the blue leds & 12V) what do these wires correspond to? I'm pretty sure the wires from the large plug are what I wire in series to the power supply, but I'm not sure what the third wire is that goes to the small plug. Is it just the ground?:
And for the power supply, I just want to make sure that I only need to use one of the voltage terminals (one V- and one V+).
Sorry if my electrical lingo is incorrect. Please correct me. Thanks.
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kcress
New member
Look on the fan body for some sign of polarity. If that doesn't work pull the case off of a PC and compare the big connector to the same style connector in the PC. The YELLOW is +12V and the BLACK is GND.
Depends... What is the supply's current rating? What current are you talking about drawing for your setup?
dtech
New member
Git a question for Soundwave or anybody that may remember, I thought it said somewhere that your light is on a 3x4 on end to get it approx. 4" off the top of the tank, and looking at the pic I think thats what I see(old thread0. am I right on that? I am doing a similar build and will neeed to mod my canopy to fit so I want to make sure the height off the water.
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