Infrared LED

I have been trying to get online the working principle of the infrared LED.. please I would like any one with a link to a site with good tutorials on how to use this to please post it... I am trying to use it with a multivibrator in a counting circuit

THANKS

the transmitting infrared diode is very similiar to a regular LED except that it give off a certain wave length of light. On the other had the receiver diode react to a certain wave length of light ( infrared ). I basically treat them light photo diodes - which they are - somewhat.

Here is a link for a infrared detector circuit.

http://hackedgadgets.com/2007/11/10/ir-detector-circuit/

If you are talking about a simple IR LED, then it works the same as a regular LED (i.e. in terms of biasing it). The forward voltage can be anywhere from about 1.1 to around 1.7 volts. Like all diodes, it's a current device, so best to run it with a constant current, but a resistor will do for simple, low current (~20ma) cases, but use a high enough supply voltage to swamp out forward voltage variance. The higher the drive current, the more important is using current regulation. And for high power LEDs, use PWM into a lo-pass filter, with peak current sensing at the LED.

So, bottom line, any article on driving a visible LED will apply to an IR LED. Just take into consideration the lower forward voltage.