Finally I've decided to buy an Android phone... Well, after all, it's like a pocket computer, very useful and lots of fun! Then I started to install tons of apps, and came to this one:
I was excited to try it out and built the ir transmitter described on the site, very simple, and it actually works, but on my Samsung Galaxy I5500 the audio output is really too low to give a good signal to drive the ir leds. So I've decided to build an active driver using a single transistor. Ok, to make it short, it worked and here is the circuit for everyone to try it out. Hope you'll enjoy it!
R1, R2 - 56ohms 1/8W
Q1 - 2n3904
battery - 3,7V (cellphone battery)