This circuit was obtained from a Radio Electronics from the 90's. The circuit limits the strength of an audio signal preventing saturation. Equivalent operational amplifiers can be tried.
Found in the 1965 Radio Shack documentation, this short-range AM circuit can be built with...
This circuit was found in a 1980s documentation. It is intended for remote vibration monitoring...
This circuit can be found on this website in similar versions. The power supply is given in...