Found in a RE Experimenter Handbook from the 90s, this circuit is intended for the use of LEDs in a flashing system for Christmas trees. The circuit can be expanded
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...