Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It can be replaced with LED with appropriate series resistor. Transistors may be modern equivalents.
I found this circuit on a December 1976 Radio Elettronica. The Italian magazine no longer exists, but...
This circuit for the power grid was found in the June 1969 Radio Electronics magazine. The load is...
This circuit with common CMOS components was found in the November 1984 issue of Radio Electronics...