This circuit is from Motorola's Linear Interface ICs of 1993. The circuit can be powered by symmetrical 6 to 12 V voltages and for a stereo version, two channels must be built.
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...