DIY LEDs - The write-up
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Reef_Matrix29
Water Lover
What's height are people keeping their lights suspended over the water level at with or without optics? Is 6 inches too low or high?
Reef_Matrix29
Water Lover
Okay, sounds good....6" from water level or just the top of the tank frame? I'm using 40 degree optics, so I might increase to around 8" above water level.
Reef_Matrix29
Water Lover
Okay, thanks and once I figure out how to crop and downsize these pictures, I will post pics of my light.
stugray
Premium Member
I'm not going to go back & search the whole thread to see if someone has already suggested it, but...
I found a single chip LED driver that is capable of driving 20X 3W CREE LEDs with dimming capability for $3.57 each :-0
It is the Nat Semi LM3406(HVMH).
http://www.newark.com/national-semiconductor/lm3406hvmh-nopb/led-driver-ic/dp/08P3934
You still need an external 75 Volt DC power supply, but this is still the cheapest option I have seen.
Stu
I found a single chip LED driver that is capable of driving 20X 3W CREE LEDs with dimming capability for $3.57 each :-0
It is the Nat Semi LM3406(HVMH).
http://www.newark.com/national-semiconductor/lm3406hvmh-nopb/led-driver-ic/dp/08P3934
You still need an external 75 Volt DC power supply, but this is still the cheapest option I have seen.
Stu
TheFishMan65
New member
Cheap Drivers
Cheap Drivers
Someone also posted one on page 9 (it is a different one). But in my opinion has the same problem - please tell me you have a solution. They are surface mount chips - OK you could probably solder a wire to them. BUT they also have (from what I understand) an exposed bottom pad that must be soldered to a board to act a heat sink. Is there a work around for this?
Yes, you could design a board, but the cost goes up. Especially in small quantity. Any ideas?
Cheap Drivers
Someone also posted one on page 9 (it is a different one). But in my opinion has the same problem - please tell me you have a solution. They are surface mount chips - OK you could probably solder a wire to them. BUT they also have (from what I understand) an exposed bottom pad that must be soldered to a board to act a heat sink. Is there a work around for this?
Yes, you could design a board, but the cost goes up. Especially in small quantity. Any ideas?
stugray
Premium Member
TheFishMan65,
"please tell me you have a solution"
Well, you have a good point, it is challenging.
However I have done surface mount soldering on my very first attempt after watching how to videos on youtube. Its not as hard as you might think.
Now the thermal pad underneath, that poses another problem.
That means that we pretty much have no other options than solder paste & a toaster oven ( also on Youtube ).
Stu
"please tell me you have a solution"
Well, you have a good point, it is challenging.
However I have done surface mount soldering on my very first attempt after watching how to videos on youtube. Its not as hard as you might think.
Now the thermal pad underneath, that poses another problem.
That means that we pretty much have no other options than solder paste & a toaster oven ( also on Youtube ).
Stu
bottom pad
bottom pad
You can use a little thermal epoxy unless this is also an electric contact point. In that case you need electrically conductive thermal epoxy. It exists but is hard to get in small batches.
The other method is low temperature solder. You will spend more on tools and special items than you will save. Unless you make a bunch and plan to sell them, look at something else.
bottom pad
You can use a little thermal epoxy unless this is also an electric contact point. In that case you need electrically conductive thermal epoxy. It exists but is hard to get in small batches.
The other method is low temperature solder. You will spend more on tools and special items than you will save. Unless you make a bunch and plan to sell them, look at something else.
marspeed
Member
sammy113
New member
Hi guys, I was doing a small array of 6 "El Cheapo" LEDs from ebay just to try them and see how they compare to the CREE. If they are worth anything could be lighting my 3G Pico. I did everything on the soldering and all but I'm having a WEIRD problem. 5 out of 6 LEDs are turning on. The one that doesn't turns on does not affect anything in the series BUT if I test it individually with two AA batteries it does turns on. Tried switching the cables to the other two available polarity slots and still does the same. If I test it while all the array is On it will turn on but the rest will turn off.
Any idea to solve this?
Any idea to solve this?
Blue_Ribbon
New member
I've thought about this a few times and the best i can think of is to have your emitters (Led's) away from the tank. Not so hard when you consider the price of fiber optic light cable/paths are pretty cheap. I saw 2mm for under 2 bucks a foot I believe on ebay. 5mm is what most would be usin, I bet on a rollit could be pretty cheap, prob 250 bucks?
This way, you could put the optics on the end of the light cable and place it very close to the surface of the water. Submersion would even be possible
Not to mention the ability to direct the light as needed. Heck you could evn mount the lights on a basemnt walll or ac duct away from the tank. leds could be mountd closer and more compactly. it'd also remove electricity from above your tank.
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