The integrated circuit used in this application is uncommon today. The circuit is from American documentation from the 1980s. It can be changed to use more modern equivalent components.
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...