The circuit produces a series of flashes in the IR range.
Most TV remotes blink an led on and off at 38-40 thousand flashes per second.
This high speed flashing is then switched on and off (Modulated) to send the actual data.
The problem may be that the detector on your devices is very sensitive and is able to pick out the data even though you are sending a different IR signal. Think of it like radio.
If the transmitter and receiver are both tuned, outside signals will have very little influence over them. The only way to JAM a signal is to overpower it so that the receiver can not detect the original signal, or to match the signal carrier and send a interfering series of pulses.
I'd suggest you try a 556 chip, it has 2 555's in it.
Set one up to create a 39khz signal and set the other one up to produce a 1khz signal.
Use the output of the 1khz signal to (Modulate) the 39khz signal.
Imagine you are in a loud stadium during an exciting game.
If your friend beside you tries to talk while the crowd is yelling loudly you may not be able to hear him at all. This is the method of simply overpowering the receiver with blanket noise. Later during a quiet moment you have 2 friends who both try to say something at the same time. You can’t understand them because their voices blend and make no sense. This is similar to what I am explaining.
What your current circuit is doing is similar to you and your friend talking while a trumpet player holds a very long steady note. The note is easy to ignore because it sounds nothing like your friends voice and it is not loud enough to overpower his voice.
In fact a single note would have to be a very powerful signal to interfere because the modulation helps the receiver pick out the most subtle signals from a sea of IR noise.
Some equipment will even work in direct sunlight, now THAT is a noisy IR source.
I am sure someone will post the Circuit Diagram.
-Mike
