This circuit is from a 1975 RCA tube manual. It appears elsewhere on the site. R5 depends on the voltage of the amplifier with which it is used and can be changed.
The configuration shown is suggested by National Semiconductor in its 1994 Linear Applications Handbook....
This simple receiver, which requires a good antenna and grounding, was found in an Argentine...
This circuit was found in an Electronic Design from the 90s. Operational amplifiers admit modern...