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Admit I am just a hobbyist and new to Sparkfun. Trying to construct Halloween pumpkins that send IR signal between them (about 12 feet for my porch) so triggered by kids ascending porch and triggering scary sound effect. Bought pair of Sparkfun IR emitter/detector SEN-00241 but they cannot transmit/receive 12 feet (actually only effective 6 inch with full 5v at 50ma on emitter)and bothered by stray infrared. Would like advice on IR emitter and detector that would be useful at 12 feet .. Sparkfun sell any ir sensors that effective using 5v for 12 feet ??? .. Thanks for any help
This type of IR detectors usually works better in stray IR light.. When lighting it up with pulsed IR light it is better able to ignore ambient conditions. It outputs a low signal if it detects IR pulses at 38 kHz. :

At the same time you might want to use a proper led housing that is beter able to focus the light. The ones you bought are usually used for short distances (centimeters) like encoders. Pulse it via a transistor, as pins of a microcontroler/arduino board usually cannot supply as much as 50 mA.

Also note that 50mA is it's absolute maximum forward current continous, with short peaks upto 80mA . There are no doubt other leds that have a higher current rating. Wether or not you can reach the full 12 feet/4 meters I don't know. But it should do better.
Look around for infrared burglar alarms and the like. This was a very common project years ago in the electronics magazines. Most added optics (even a lens and a black-painted paper towel tube helps) and the better ones, as Valen mentioned, modulated the beam.