I'm making a light barrier and working on a "sender" part right now.
The main thing I want to achieve is the maximum distance. I'm using Vishay TSSP4038 for receiving signal. In the datasheet it's stated that it can work on distances about 30m. I can't get even close. With 350mA (1W) LED it's about 3m max (outdoors).
T1 is NPN transistor. Q2 is N-channel mosfet. LED power schematic is taken from this instructable.
ATTINY25 turns the LED on/off 38000 times per second (kHz). So effectively I can double max current through LED (change R3 to 2.5).
I also have some 1W chinese LEDs from ebay, which do work better (distance-wise), but I'm not sure how much more current I can give them without burning.If you think that the transmitter is good then should I provide receiver details ?
I would be very thankful if someone better than me in electronics would check the schematic and maybe give me some advice or tell if something is really wrong.
Best Answer
As others have suggested, beam spread is likely to be your problem. Most digital cameras will detect IR to some extent. (Try pointing your TV remote into the lens of your camera and press a button.) You can try using this technique to see what's going on.
Have fun.