in order to make ir rays travel longer distances from an ir led which circuit is appropriate

either a multivibrator or an oscillator circuit input which will be to an ir led

Look at boosting your AMPLIFICATION of the return signal, rather than concentrating on the transmittter.

Think about it, a TV remote can trigger a TV at least 10 metres away.
rickharris2 years ago
The light will travel Vast distances - In a straight line.

However it will weaken by the inverse square law.

You can focus the light with a lens OR improve he sensitivity of the receiver.

sandiri (author)  rickharris2 years ago
sir but i don't have an idea regarding how should we mount a lens system

As I know nothing about your set up

Your problem

Your capability I can't answer your question - You put a lens in front of the transmitter IR LED and or the receiving device How you do this depends on a lot but shouldn't be that hard.

Practice with a LED you can see so you know what is happening and search focusing light beams.
Re-design2 years ago
Neither will. Use a lens to focus the ir beam and a lens at the receiver to collect more of the beam.