Found in July 1975, Radio Electronics magazine this circuit can use any operating circuit, including the 741. The circuit must use a symmetrical power source.
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...