This circuit was found in an Electronic Engineering of the 80s. The circuit indicates when a telephone line is being used, being useful in case of extensions.
I found this circuit in a 1992 Electronics Experimenter Handbook. The circuit can be easily...
This egg timer has been found in an English magazine that no longer exists in 1982. The...
This comparator application circuit was obtained from the June 1986 Radio Electronics magazine. The...