Dynamic compressor (CB21762E)

This circuit was found in a 1977 publication for radio amateurs. Transistors are common general-purpose types of the time.

Decade Counter with Nixie Tube (CB20141E)
This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time....
Two-Transistor Oscillator (CB1387E )
This old oscillator using germanium transistors has a high impedance headphone as inductor to...
Tone Control Preamplifier (CB18561E)
This preamp with several inputs using germanium transistors from the time was found in Japanese...