This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are common neon and the circuit indicates whether the voltage is 110 V or 220 V.
This circuit was found in a Radio Electronics magazine from November 1992. The components are from...
This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent...
This simple expandable circuit was obtained from a Popular Electronics from the 80's. The supply...