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High Power RGB Led Project Answered

I will be doing my first high power RGB Led project soon based on these leds:

I will be using it in my boat utilizing this RGB controller:

I will be using the project in my boat and thus tied to 12v dc battery power bus.  The RGB specs call for:
DC Forward Voltage (VF):Red 7.5V;Green 10V ~ 12V;Blue 10V ~ 12V @ 350ma per channel.

My question is 'What is the best way to get the voltage down to the 7.5v required for Red'?  As I am in a boat with a single 12v battery, I would like to be as efficient as possible.  I plan to use 4-6 of these leds.  Since each requires 12vish on the highest channel, I am planning to put them in parallel.

Thanks in advance!


That board is probably going to struggle with 350mA LEDs - I suspect you'll burn the transistors out very quickly. Your limiting resistor for the red LED will need to be at least 1.5W rated - and that won't go on the board.

I also suggest you take the transistors off and mount them, insulated, on a heatsink.


I will be using 50N06 Fets so the current should be good to go. I think heat should be okay but I will definitely put them on a 220 HS if necessary. I guess since 1.8 is pushing the 2w limit I could use a small concrete resistor available at my local shop (Tanner's Dallas). I think they are 5W. Is there a more efficient way? Thanks!

Well there are much more efficient ways, but not with what you are proposing to use. Its the subject of an 'ible I really, really must write, but mine would be >>80% efficiency.

I'm not convinced the 50N06s will turn on that well on a 5V gate drive. Prepare to heatsink them ;-)