This sensitive motion sensor with inductive sensor was found in a 90s Elektor. The circuit uses only transistors to activate a buzzer.
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...