Dynamic compressor (CB21762E)

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

Who’s the Fastest (CB14987E)
This speed or priority switch set uses two LED indicators and two SCRs in a common configuration. The...
Capacitive discharge ignition (CB9522E)
Found in a 90s American documentation, this circuit is used in vehicles with contact breaker. The...
Pulse Amplitude Comparator (CB23834E)
This circuit for activating a relay was found in a Radio Electronics magazine from August 1962. The...