This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even adapted to act as a shield. The circuit has the frequency given by C1 and adjusted in R1.
This circuit, obtained from the component manual used, has an ultra narrow 1 kHz range given by...
Mouser Electronics is providing the MGA-622P8 low noise amplifier for frequencies from 1.5 to 2.7...
This circuit of the 1970s uses Germanium transistors. Changes can be made to use silicon...