This noise limiter for low intensity signals was found in a 73 magazine for radio amateurs from the 90's. The circuit is for signals from 10 mV to 1 V amplitude.
Two operational amplifiers are used in this source obtained in an American documentation...
This circuit is suggested by the Linear Applications Handbook of National Semiconductor, being used...
This simple circuit for headphones or small speakers was found in documentation from the 90s. The...