We found this circuit in the 1992 special edition of the Electronics Experimenter Handbook. The components used are still current, many admitting equivalents.
This polarity test or indicator indicates the polarity of a power line by LEDs. The circuit is...
This is the circuit of a digital clock published in the January 1975 issue of Radio Electronics magazine....
Found in an Elektor from the 90s, this circuit can be powered directly by the power grid. The...