I just bought a IR emmiter and it looks like a LED, it has two pins, Longer and Shortest ( + , - )
My question is do i have to use a resistor or not. I have just one so i dont want to burn it...
Thanks,
do i have to use a resistor or not
Yes you do, with an LED you always have to have a current limiting device and a resistor is the easiest.
It looks like a led because it is a led. It just emits longer wavelength than visible light leds. Use the same rules as for the normal leds to calculate the resistors size. If you are not sure how to do it, google "led resistor calculator".
(Vsource - Vforward_LED)/current = Resistor needed. (Ohms law: Voltage/current = resistance)
Ex:
(5V - 2V)/.02 = 150
A webcam or other CCD camera can see IR LED light as white. You can use one to know when you've got it cranked and....
they make a funny smell when they burn up.