This high input impedance circuit is suggested by Motorola's 1993 Linear Interface ICs. The power supply must be symmetrical. The circuit has a differential input.
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...