Infrared LEDs Problem

[MetaCipher]

I am using a USB cable as a power supply, and some High Infrared LEDs from Radio Shack. I was messing around with it yesterday, and now it seems that they don't work. I read somewhere that sometimes you can't see the light on them and try a camera (which I will when I can). Is it possible that the USB 5V would have fried the LEDs? I am new to all of this, and I am not really sure. I was using resistors at first and nothing was happening, and with my normal Green LEDs. I eventually got the Green ones working, but I think I may have fried those too! If there is no current going through the LEDs does that mean there is not enough power, or are they bad?

Thanks for any help.

 

[Siniša]

You really need some beginers book on electronics.
There are two ways you could fry your LEDs, by connecting them in reverse or by running too high current through them. Ø5mm LEDs are usually driven with maximum 20mA current.
How you can calculate resistor to limit current is explained here:
h**p://en.wikipedia.org/wiki/LED_circuit

 

[mengghee]

if there was light coming out before and not anymore, then i think you damaged it, otherwise, might not be anything wrong with it as sometimes infra red led shows nothing. You do need to connect a resistor in series to limit the current before it blows it up.

 

[sonal]

A light-emitting diode (LED) is a semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction. This effect is a form of electroluminescence. LEDs are small extended sources with extra optics added to the chip, which emit a complex intensity spatial distribution [1]. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible or near-ultraviolet. Rubin Braunstein of the Radio Corporation of America first reported on infrared emission from gallium arsenide (GaAs) and other semiconductor alloys in 1955. Experimenters at Texas Instruments, Bob Biard [2] and Gary Pittman, found in 1961 that gallium arsenide gave off infrared (invisible) light when electric current was applied. Biard and Pittman were able to establish the priority of their work and received the patent for the infrared light-emitting diode. Nick Holonyak Jr. of the General Electric Company developed the first practical visible-spectrum LED in