Parts:

U1----------------555 Timer IC

R1----------------47 ohm resistor

R2----------------470 ohm resistor

R3----------------5k variable resistor

C1-----------------0.0047uf ceramic capacitor

LED1,LED2--------Infrared LED's


This circuit oscillates two infrared LED's at 40 khz. To make sure it is transmitting IR light, you can get a little tool from radio shack for about $5. It is a small sheet of plastic about 1" by 3" with a special strip of material, that when exposed to IR light glows (it's actually kinda cool..) A way to check for 40khz IR light is to build a circuit that lights an led when 40khz light is detected. You can get the schematic by clicking here.


Source:http://www.reconnsworld.com