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 circuit was found in a 1995 documentation. It drives a set of sequential LEDs from the sound...
This circuit was found in a 1968’s publication and uses germanium transistors. Equivalents can be...
The integrated circuit used is equivalent to the 555 and the transistor can be the BC558. R1 and...