I have tryed look at other topics on here, but i cant understand what all they are talking about need something simple and to the point please.
So i got thease 3 watt LED chips, Forward V 2.2 And Forward Amps (Current) 700MA
I want to hook this up to a car battery. I tryed a resistor of 15ohm 1/2watt and i dint think about the wattage power coming in effect so it got hot in a hurry.
So a calculator reccomends 7.6 watt capable resistors. There expensive and hard to find and big. Is there any other way to get the voltage and current were i need it? Please use simple terms. Country Boy Here.
Electrical – Run A 3 watt LED chip off a 12v Source
integrated-circuitled
Best Answer
Typically, you want to use a switching or buck based led driver for this. Or you can use multiple 5W resistors in series/parallel. These will be cheaper. Especially if you want to use a 12V supply. A linear or resistive solution would be dissipating 9.8V at 0.7 Amps = 6.86 Watts.
A better solution is a 5V or USB supply. In this case, a cheap car usb charger would work best. It does the 12V to 5V with a switching regulator, and the rest can be done with a smaller resistor. 5 - 2.2 = 2.8V * 0.7 = 1.96W. A 2 or 2.5 Watt 4 Ohm resistor will work.
As mentioned 2.2V * 0.7A = 1.54W, half of the supposed 3 watts btw.