This circuit is from a 1968 documentation. It generates a non-symmetrical signal with the waveform shown next to the diagram. Transistors are of the time, but modern equivalents can be used.
May 6, 2015 - Mouser Electronics, Inc., the global authorized distributor with the newest...
This TTL module can be used in counter and many of them can be cascaded to counts up to 99, 999,...
Placed inside the refrigerator, this circuit triggers an oscillator when the part is opened...