DIY LED Hood: Prebuild Thoughts...

[Lampshade]

I think the cheato should do fine, the cree white's are a 6500 - 10K bulb, that's what i use on mine and they grow great. I think the reason people have problems is the intensity of the light, most algee gets nuked in VERY bright lights, and LED's have the same intensity(lumens) per watt as some of the best MH bulb available. Just keep them up a bit and don't use optics and they'll do fine.

[GMGQ]

Thanks. Plus I'll tweak the intensity with the pot.

Now do you know how I would calculate the AC power requirements?

Originally Posted by Lampshade

I think the cheato should do fine, the cree white's are a 6500 - 10K bulb, that's what i use on mine and they grow great. I think the reason people have problems is the intensity of the light, most algee gets nuked in VERY bright lights, and LED's have the same intensity(lumens) per watt as some of the best MH bulb available. Just keep them up a bit and don't use optics and they'll do fine.

[StirCrazy]

Originally Posted by Lampshade

As for heatsinks, there's lots of choices, but generally people WAY over build heatsinks. Cree's give off a lot of heat, no doubt, but you can calculate the heat gain vs loss pretty easy to see what you actually need.(i posted links on some other recent DIY thread).

I don't see a problem with this at all, I would rather have an overbuilt heat sink anyday than one that is a perfect match. so many people try to skimp on some things for a matter of 20 bucks, this isn't one area that should be done IMHO. for example.. if you fan dies on a exact sized heat sink and you don't know about it then you run the risk of burnning out several LEDs, if you have a over sized heat sink it reduces the chance of losing LEDs as you are not as dependent on the fan.

Originally Posted by Lampshade

As for cheap controllers. Depends on how fancy you want to get... but look at arduino boards. There's LOTS and i mean LOTS of LED builds using these. Uses C programming, but i've found many chucks of code online that people have posted that got their LED's working and controlable. Arduino's start at $20 for something that will control 2 drivers with PWM outputs and $35 for something that'll do 6(Arduino Mega). If you get into it the arduino can do pretty much everything, i'm building a tank controller based off one right now.

on this topic, have you seen any dimming programs for Arduino using a varable voltage output instead of PWMs?

Steve

[Lampshade]

on this topic, have you seen any dimming programs for Arduino using a varable voltage output instead of PWMs?

Arduino's can't output a variable voltage, but you can buy filters that will change PWM outputs to a 0-5v or 0-10V. check out:http://www.nano-reef.com/forums/inde...owtopic=230743 - different values work for different pulse widths, there's online calculators to see what you need.

As for heatsinks you are right, overbuilt is no problem at all with me either. I'm not going to go buy 60" of 10" pure aluminum heat sink with 1.5": fins now though, after calculating it a bare piece of aluminum with a fan on it would work "in theory". I'm going to probably run aluminum channel, and also I'm going to have an arduino running my LED's, so for $2.50 i can get a thermometer on the heatsink to shutoff for overheating, i'll proably put 4-5 of them on just to be sure.

[Lampshade]

Now do you know how I would calculate the AC power requirements?

Your AC should be pretty much Watts in = Watts out/efficiency

Drivers vary efficiency depending on how well they're used(they like to be run near max all the time). usually >70% though. so 48LED's, driven at 3v per LED, at 750mA(3/4 load) would be about 86.4W at 80%, so 0.72A at 120V. Not bad at all...

[GMGQ]

How did you calculate that?

And what is that in terms of a power supply's AC_out and Amps? So in your example, would this one suffice?
http://ledsupply.com/04004-p96.php

Originally Posted by Lampshade

Your AC should be pretty much Watts in = Watts out/efficiency

Drivers vary efficiency depending on how well they're used(they like to be run near max all the time). usually >70% though. so 48LED's, driven at 3v per LED, at 750mA(3/4 load) would be about 86.4W at 80%, so 0.72A at 120V. Not bad at all...

[Lampshade]

Watts is just P = EI, or watts = voltage * current

[GMGQ]

For guys that have DIY LED setups, do you just run the royal blue array at the lowest voltage for moonlights? Or would that be overkill (i.e. if you had say 24/48 in blue LEDs)?

Or did you install a separate set of blues for moonlights? And if so, how many do you run? My tank is 48" wide, will 5-6 LEDs evenly spaced be sufficient?

[GMGQ]

Just an update on my mini LED build. I'm going down to point roberts on saturday to pick up a bunch of stuff that I ordered:

- Weller 40W Soldering Station (figure it's time to upgrade from my old 25W Radio Shack soldering iron)
- 7"x6" heatsink from HeatsinkUSA.com
- Meanwell LPC-35-700W driver from RapidLED.com

And I already have the LEDs from Milad (4 x XP-E CW, 4 x XP-G RB).

I'm going to pick up some Artic Silver Thermal Adhesive from NCIX (I get a discount there), and I should have enough misc electrical supplies in my toolbox. Oh I want to get some ballast quick disconnects from Home Depot.

I should also pick up a sheet of Acrylic from IP&P to make a splash guard.

[TheMikey]

I can't find the thread, but when I was considering doing a DIY, I came across a thread on RC about LED optics.

The poster looked at the PAR range between 40, 60, and 80 degree (I think) optics and found that the 60 degree optics were the most efficient and gave the best PAR.

I'll dig around a bit longer and see if I can find it...