Selectivity with LM567

[Pahom]

Originally Posted by omar

Hello Bahoum....

It seems that it is very difficult for amateurs and even advanced people. Dealing with radio frequencies and radio resonance circuits, adjusting, stabilizing and powering them, is not easy. The capacitive change, if any, will be slight, and sorting it out from all this noise seems impossible. I don't know, there may be a simpler solution.
What do you think? Give us an idea or theory .

I don't know! There seems to be a theory that the useful signal of the phenomenon is in the noise. By amplifying the signal, the noise is also amplified. It is necessary to somehow isolate the necessary signal without losses. In the Mineiro and PD Alonso circuits there is a passive filter, perhaps this is a ready-made solution.