Given the forward Vf curve of the LED when the LED is at 12v it will only be using a fraction of the current compared to the 1A at 15v. At 12v the LED might be at 200mA. So having the fan running at 80% speed then should be fine.I'd originally thought of doing that and almost didn't post this thread because of it, but using a resistor would leave the fan underpowered if/when the driver dropped to 12V.
A 300 Ohm resistor will give me 50mA @ 15V but at 12V it's only 40mA.
Is this significant? no, not likely, but ideally I don't want the fan slowing down at all, so I may just stick with AK's circuit for the regulation.
Given the forward Vf curve of the LED when the LED is at 12v it will only be using a fraction of the current compared to the 1A at 15v. At 12v the LED might be at 200mA. So having the fan running at 80% speed then should be fine.
But anyway, a voltage regulator will perform better if you want to do it that way.
by Jake Hertz
by Duane Benson
by Jake Hertz
by Aaron Carman