This circuit shows how to simulate a high-performance diode with two diodes. The circuit is from a 1960s RCA documentation. Modern general-purpose transistors can be used.
This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time....
This old oscillator using germanium transistors has a high impedance headphone as inductor to...
This preamp with several inputs using germanium transistors from the time was found in Japanese...