This circuit was found in the April 1971 Radio Electronics magazine. It uses common transistors and can be adapted to use an LED or audible indicator instead of a light bulb.
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...