zachtheterrible said:I'm working on an IR beam break system right now.
I have modulated an IR led with a 25/26kHz square wave from a 555 timer. I'm not sure how to make a filter for the receiver though. I would like to make a passive RC filter. The square wave turns the LED on during negative pulses.
Use 38KHz, and not 25KHz, you can then use a common IR receiver IC, as used in TV's etc. These are a simple three pin device, the output pin goes LOW when it receives IR modulation of around the correct frequency.
This cures ALL your receiver problems, why reinvent the wheel?.