Found in Popular Electronics from the 90s, this circuit aims to drive a solar panel, constantly changing its position to follow the movement of the sun.
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...