This crowbar circuit for alternating current causes a quick fuse to blow when the load current exceeds a certain value. The circuit is from an American 80's documentation.
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...