This circuit was found in a 90s Silicon Chip documentation. The current of the transformer is 1 A maximum, a value given by the integrated circuits used.
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...