555 timer 40khz IR:


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.