circuit problem??

cool said:

I have a circuit about a IR modulation. Any around 40kHz IR signals will will be detected and decoded. However, I want to detect 20kHz IR signal instead of 40kHz~ :cry:
How can I change the circuit?? which components' values have to change??
THANKS~~ :lol:

The circuit in https://www.electro-tech-online.com/custompdfs/2004/02/k58-1.pdf

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cool said:

Oh, actually, I don't want my IR receiver is affected by some common TV remote control easily~ since most of the IR signals used in the market is around 40kHz~ :?
So I want to change the circuit no matter it is 20kHz or not~ I just want my IR receiver can only detect my transmitted signal. :wink:

then what can i do??? :?: :?:

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