I want to detect if there is a 40KHz frequerncy.So I create a 40KHz frequency with a NE555 and then I put the output of 555 in the input of the 567.The out of the 555 is 5 Volt peak to peak +2.5 offset.I use a ceramic capacitor in the input of 567 (100nF).I use the two formulas to find the capacitors and the resistors and the circuit doesn't works.The output doesn't goes up when i put the frequecy.I have to say that i use a ceramic capacitor for the bandwidth of the filter in the 2 pin of 567.Can someone suggest values for ceramic capacitors and resistors for 40KHz because it doesn't works.Thanks in advance.
https://www.electro-tech-online.com/custompdfs/2008/03/LM567.pdf
https://www.electro-tech-online.com/custompdfs/2008/03/LM567.pdf