This 4-tube amplifier with 6W of output was found in an American manual from 1947. The sound quality is excellent.
This circuit was obtained in an old documentation, receiving the medium wave range. L1 has 20 + 60...
This circuit is from an old documentation from the 70s, so the transistors used are not common....
We found this circuit in a publication for radio amateurs of 1976. The operational amplifier is a...