This circuit, suggested by an Electronics World of 1969, keeps a blinking LED for a while when a power outage occurs. Time depends on capacitor C1.
This configuration can be found in several articles on this site. The one shown in the diagram is from...
The integrated circuit used in this configuration of old documentation is not very common today. The...
This circuit mimics the trill of a bird. We found it in an American documentation from the 90s. It is...