How I can choose kFrequency?

[mrdsn3]

38khz doesn't work for me in SmartIRRepeater Can you suggest kFrequencies that might work?

[NiKiZe]

Moved to discussion since not really an issue with the library.
You can find a great deal of information on the net, here is some: https://en.wikipedia.org/wiki/Consumer_IR#Technical_information

Some times you might be lucky and get it to work with your demodulator even if the frequency is different, but you might also be not.
Either find documentation for your device (or provide more information about the device here)
Or check the existing components in remote or receiver. - That is unless you are able to check with an oscilloscope on the transmitter.

[crankyoldgit]

@mrdsn3 Please see/read:

IRremoteESP8266/examples/SmartIRRepeater/SmartIRRepeater.ino

Lines 18 to 22 in 0b19d94

	* W A R N I N G
	* This code is just for educational/example use only. No help will be given
	* to you to make it do something else, or to make it work with some
	* weird device or circuit, or to make it more usable or practical.
	* If it works for you. Great. If not, Congratulations on changing/fixing it.

The most common IR modulation frequencies I've experienced in rough order of most popular to least are:

• 38kHz
• 36kHz
• 57.6kHz
• 40kHz