So, I got an arduino uno and a RGB shield from velleman for christmas because I mentioned I might want to do a project with high power LEDs - a neat surprise, but now I have to use it (: The shield can do PWM on an external power supply and this can be wired through to the high power LEDs itself. I aim to power about 10W of LED light in total, with different colors in order to make good use of the board. Can I go for Option 1? If not, what would you advise?
Update: I talked to an electrician and a constant current supply typically works on a PWM basis; putting this in series with the PWM of the shield is not smart.
Alternatively I could connect a standard constant voltage supply and make sure that the current is within limits:
- One option would be to use resistors; but, with 12V DC and 350mA I would need like 33 Ohm resistance dissipating 4 Watts of power, which is inefficient.
- Alternatively there are DC voltage to constant current LED drivers which will take care of the constant current for me; I could put those at the exits of the shield for the LEDs. They supposedly have a better conversion efficiency than the resistors, but I do have any knowledge about their performance with PWM as input; but I have serious doubts they would like that type of input. Furthermore, these drivers also often have PWM capabilities. This kind of module would render the shield functionality largely useless.