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.
The LM195 is a fast power transistor from National Semiconductor not very easy to find today. C1...
This circuit was found in a 1977 documentation. The gain is 3 dB and instead of the original...
This useful instrument has dual function, operating both as signal injector and continuity tester. The...