Originally Posted by Tankhobby

Use an infrared detector with a 38Khz modulation frequency (40Khz will work also) if you can't get this RadioShack part. Pay attention to pin out if you use a different part, they differ between manufacturers. The 1M and 1uF will give you the flash time when hit. The 180 ohm is current limit for the LED. The 22uF is a filter, a .01uF in parallel next to the IC and detector wouldn't hurt. Shield the detector from ambient light, sunlight, camera flashes and other infrared emitters otherwise it will always flash. I recommend testing indoors in a dark room first.