Hello,I have a IR emitter/detector pair, the package pair from Radio Shack (http://www.radioshack.com/product/index.jsp?productId=2049723) working on a breadboard wired up in "beam cut" manner pointing at each other. When the beam between the two is blocked an led will light. This works good and the response is very fast; quickly swinging a pencil between them will flash the led as fast as I can swing it. I purchased the side-looking IR pair from Sparkfun (https://www.sparkfun.com/products/241) ... should I expect that pair to be a drop-in replacement for the radio shack pair? So far it is not; in fact I cannot get them to operate as a pair at all using the same circuit that works for the radio shack pair.I'm completely new to electronics and admittedly, my interest lies more in programming the arduino rather than building the circuits, so I just hobble together any examples circuits I can find on the internet that meet my needs.