This circuit is from a Radio Electronics from March 1970. The crystal depends on the frequency at which the signal is to be captured and the resonant circuit determines the tuned band.
This circuit allows the division of the frequency generated by an oscillator with the 4069 by two,...
Found in ancient documentation, this circuit uses a high voltage transistor of the time. Observe...
This circuit with TTL compatible output was found in a 1968 US documentation. The circuit is...