Just interested to know if any of you have ever tried to use a break-beam type of triggering device instead of a PIR. Years ago in collage, I designed a IR beam transmitter and receiver that would work over 200 feet away. For the tranmsitter, I used a small maglite, replaced the bulb with an IR diode and added a simple 555 timer based pulse width oscillator to pulse the output to save power and eliminate false alarms such as birds and falling leaves. The receiver had an LED that would turn off when the receiver detected the IR pulse from the emitter. The IR receiver was also 555 timer based and was tuned to the same 44kHz pulse frequency of the emitter. I had a pot. which adjusted how long the beam had to be broken to trigger the counter. To set it up, you simply place the emitter box on a strudy tree and aimed the maglite at a parabolic dish on the reciever in which the IR transistor was located. It worked great, the only problem was that it went through the 9 volt batteries to quickly. I am going to build another trail cam for using this same circuit and higher amp/hour batteries and will let you all know how it goes. The benifit of the break-beam design is that you can set it to whatever height you want to detect such as deer eliminate the smaller animals like rabbits, squirrels, etc... . It also can have much longer range.