This 6-transistor circuit had excellent sensitivity using germanium transistors. The push-pull stage used two transformers, one drive and one output as we usually find at the time.
This circuit has two response curves that depend on the position of the tone control switch. The...
This circuit is from a 1977 Signetics manual. BC107 transistors can be replaced with BC547 and...
This circuit is from a Popular Electronics from 1992. The circuit employs an equivalent transistor and...