I hope this post isn't too remedial for this forum. I am trying to make a Wii sensor bar that will run on both batteries and USB. I have two IR LEDs:
Maximum ratings
Forward V: 1.6V
Reverse V: 5V
Rreverse C: 10uA
Wavelength: 940nm
Electronic characteristics
Radiant power: 16mW mjn
Forward V: 1.2V
Forward V: 100mA
I have seen similar circuits but I am baffled by what kind of resistor I should use. I assume the resistor is to limit the current to the LEDs. So would it be easier to have 5V from batteries to match the USB voltage so that the current limiting resistor would work for both? Also, Is there a formula to find out what resistor I should use? Any help would be appreciated.
Maximum ratings
Forward V: 1.6V
Reverse V: 5V
Rreverse C: 10uA
Wavelength: 940nm
Electronic characteristics
Radiant power: 16mW mjn
Forward V: 1.2V
Forward V: 100mA
I have seen similar circuits but I am baffled by what kind of resistor I should use. I assume the resistor is to limit the current to the LEDs. So would it be easier to have 5V from batteries to match the USB voltage so that the current limiting resistor would work for both? Also, Is there a formula to find out what resistor I should use? Any help would be appreciated.