Found in a Maxim publication from the 90s, this circuit generates signals from 10 to 25 kHz with a THD better than -80 dB. The circuit makes use components of the time.
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...