After months of plotting and scheming I finally was able to build my LED retro for my Nano Cube 28CF.
My mission was to keep it as simple and quite honestly as cheap as possible.
The parts:
12 Blue 3W 90 degree SemiLED 200lm
12 Cool 3W 90 degree Cool White SemiLED 200lm
4 Sure Electric 3W Drivers http://www.sureelectronics.net/goods.php?id=1035
1 Old Dell laptop power supply
556 based PWM for dimming
2 potentiometers for dimming
Thermal tape
3/8 inch aluminum plate / heat spreader
I miscalcualted when specing this all out and didn't realize that I need a couple more drivers or a bigger power supply to drive the LED’s at the full 700ma. So at the moment the best I can do is 350ma. So I'm currently running 4 drivers with 6 LED's each. I'll be adding a couple more drivers soon.
I wanted to see how this would do heat wise with just mounting to a plate and no external fins. I am still running a couple of quiet fans in the hood so there is good air flow across the plate. At full power after a couple of hours its around 115f in the hottest spots right on the heatsink and quite a bit less everywhere else. I’ll probably add some U channel to the back to get some more surface area when I add more power later. BTW - that plate looks filthy in the pics. It was actually quite smooth and clean.
The Sure Electric drivers are nice little units. Built nice and work well. I ended up stuffing them in the compartments in the back of the hood, that's not shown in the pics below.
So running at 350ma, I am getting about 130 PAR on the sand. Not bad I think as I can push a lot more to them if I want. Compared that to the old CF bulb that was way hotter and only gave me about 30PAR on the sand. Intereting also is that I have the LED’s mounted high in the light box from the old CF light, so there are sides all around. That and the directional properties of the LED’s make far less spilled ligaht in the room.
Not bad for $150 bucks, eh? Should be even nicer when I add the extra drivers and push the LED's to 700ma.
***EDIT*** My orginal PAR numbers were based on a quick measurement in one spot at the end of a long night. Tonight I had to pull the lid to move around some of my wiring as I ran out of time when I originally put it together and things were a bit sloppy. So I took the opportunity to remeasure my PAR numbers.
Tonight after spending some time cleaning the glass on the splash shield under the LED's and taking measurements all over the bottom I averaged 130 PAR across the sand.
Then I added some 60 degree optics and I got a 287 PAR average across the bottom.
See if you can spot the mistake(s) in my wiring