This circuit, with output of 1.5 A, was found in a magazine 73 of the 90s. The integrated circuit is from the time and must be mounted in a heat sink.
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...