H@rry
Troll
About a year or so ago I became interested in LEDs due to all the threads popping up on the forums. In particular the DIY part of it appealed to me since I had just build some controllers. I read a lot on this forum as well as RC about building LED system, which diode to use, things to avoid, as well as the "right" way to do things. The problem was that several people had different ideas about the right way. It was pretty confusing. Buckpuck, Meanwell, Cree, Bridgelux, Heat Sinks, parallel strings, etc.
Then I ran across a tread about DIY drivers created by some of the same guys that started the DIY controllers that I built. This went on for quite a while with people changing their minds about which chip to use.
I finally settled down to the LM3409HV chip to be used in an I2C dimming arrangement with the controllers I have so I ordered the components to build a prototype. I had heard about the absolute need for real heatsinks so I ordered a 12 inch heatsink and built a test string with half on it and the other half on a piece of U channel from Lowe's. I finally got a driver board built and fired the string. It lit like it was supposed to and I was elated. I did notice that the part of the string on the U channel was only very slightly warmer than the heatsink. They don't really get that hot.
What I didn't like about the I2C dimming driver was the fact that the dimming was not linear (I guess that is the term). They would come on dim but before I increased the voltage just a little bit they got real bright before I thought they should. I made a couple more drivers and they all did the same thing. Besides that, the chip got so hot you couldn't hold your finger on it. I didn't think it would last very long like that.
Some more reading revealed that the guy who designed the circuit also had a design using the same chip and almost the same board that uses PWM dimming. After looking at the board I realized that I could make a few minor modifications to the boards I already had to use PWM dimming. It worked! Now I could do dawn to midday in 255 steps and the same way back down at dusk. I was happy.
I decided that the frag tank would be the first LED "guinea pig" since it was the smallest. I built the "racks" out of U channel and ordered 36 Royal Blue Cree XT-Es and 36 Cool White Cree XT-Es. I arranged them in 3 strings per rack; Blue, White, and half and half. I programmed the blue to come on and begin ramping up to full power over a 2 hour period. After the blue came on the mixed string came on an hour later, and an hour later the whites came on. They all had a 2 hour ramp up period and them in the evening the whites began to ramp down for 2 hours with the other strings following in reverse order to the way they started. That looked good, again I was happy.
That was August 20th. I had read that you need to be carefull about switching to LEDs because they can easily bleach corals at full intensity so I started them all out at 40% of full intensity. I planned to increase them 2% a week until I noticed a problem and them back down. In a couple of weeks I noticed that most of the acros had browned out, the algae quit growing, and the xenia quit pumping and started receding. This is not good. I then noticed a few small bare spots on some of the acros. I freaked and pulled them out and dipped them. Nothing came off except a few asterina starfish. I have a lot of asterinas. My theory was that the asterinas had been eating algae but when it quit growing they switched over to the corals.
While I was trying to plan my next move I had occasion to talk with another reefer who had been doing LEDs for quite some time. He told me to turn the blues up to 100% and the whites to 50%. That seemed to cure the problem. I'm increasing the white by 2% per week and now am at 70%. The corals have colored up very nicely and are growing. The algae has come back (but not to the extent as when I had the MH), the starfish have left the coral alone, and the xenia is starting to pump again. On the advice of others I added a couple of red, green, and violet LEDs to the mix. I'm not sure I can tell much difference but it does not seem to have done any harm.
I'm confident that I'll be satisfied with LEDs and started working toward a build for a 180. The rest of this thread will deal with that and show pics of my progress.
Then I ran across a tread about DIY drivers created by some of the same guys that started the DIY controllers that I built. This went on for quite a while with people changing their minds about which chip to use.
I finally settled down to the LM3409HV chip to be used in an I2C dimming arrangement with the controllers I have so I ordered the components to build a prototype. I had heard about the absolute need for real heatsinks so I ordered a 12 inch heatsink and built a test string with half on it and the other half on a piece of U channel from Lowe's. I finally got a driver board built and fired the string. It lit like it was supposed to and I was elated. I did notice that the part of the string on the U channel was only very slightly warmer than the heatsink. They don't really get that hot.
What I didn't like about the I2C dimming driver was the fact that the dimming was not linear (I guess that is the term). They would come on dim but before I increased the voltage just a little bit they got real bright before I thought they should. I made a couple more drivers and they all did the same thing. Besides that, the chip got so hot you couldn't hold your finger on it. I didn't think it would last very long like that.
Some more reading revealed that the guy who designed the circuit also had a design using the same chip and almost the same board that uses PWM dimming. After looking at the board I realized that I could make a few minor modifications to the boards I already had to use PWM dimming. It worked! Now I could do dawn to midday in 255 steps and the same way back down at dusk. I was happy.
I decided that the frag tank would be the first LED "guinea pig" since it was the smallest. I built the "racks" out of U channel and ordered 36 Royal Blue Cree XT-Es and 36 Cool White Cree XT-Es. I arranged them in 3 strings per rack; Blue, White, and half and half. I programmed the blue to come on and begin ramping up to full power over a 2 hour period. After the blue came on the mixed string came on an hour later, and an hour later the whites came on. They all had a 2 hour ramp up period and them in the evening the whites began to ramp down for 2 hours with the other strings following in reverse order to the way they started. That looked good, again I was happy.
That was August 20th. I had read that you need to be carefull about switching to LEDs because they can easily bleach corals at full intensity so I started them all out at 40% of full intensity. I planned to increase them 2% a week until I noticed a problem and them back down. In a couple of weeks I noticed that most of the acros had browned out, the algae quit growing, and the xenia quit pumping and started receding. This is not good. I then noticed a few small bare spots on some of the acros. I freaked and pulled them out and dipped them. Nothing came off except a few asterina starfish. I have a lot of asterinas. My theory was that the asterinas had been eating algae but when it quit growing they switched over to the corals.
While I was trying to plan my next move I had occasion to talk with another reefer who had been doing LEDs for quite some time. He told me to turn the blues up to 100% and the whites to 50%. That seemed to cure the problem. I'm increasing the white by 2% per week and now am at 70%. The corals have colored up very nicely and are growing. The algae has come back (but not to the extent as when I had the MH), the starfish have left the coral alone, and the xenia is starting to pump again. On the advice of others I added a couple of red, green, and violet LEDs to the mix. I'm not sure I can tell much difference but it does not seem to have done any harm.
I'm confident that I'll be satisfied with LEDs and started working toward a build for a 180. The rest of this thread will deal with that and show pics of my progress.
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