Hi all, this is my first topic. I need to obtain the following: I have to drive an IR barrier with the "classic" 38kHz. I'm easily able to do so using this tutorial:
From pin 9 and 10 a constant 38kHz is generated, this signal drives a power transistor that drives my IR LEDs. The problem is that the generated waveform is 50% duty cycle and I'm not able to understand how to change the duty cycle to 10% acting on timers parameters. The reason to go to 10% is that my IR LEDs are rated to 60mA with square wave and 120mA with 10% duty cycle. Working at this reduced d.c. allow me to use higher current resulting in higher barrier range.
Apart from above, I have another question: the TSOP1838 IR receiver works only with 50% or also with 10% modulated signal? I ask this because I'm not able to find this information on the data sheet and if the IR receiver does not recognize the 10% duty cycle modulated signal the problem is solved :-)
Thank you very much.