This circuit was found in a 1970's Radio Electronics. The pulse transformer has a 1: 1 turn ratio. The triac must be in accordance with the controlled load.
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...