This circuit was found in General Electric documentation from the 1980s. The circuit is intended to receive 50 kHz modulated optical signals. The components support modern equivalents.
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...