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.
Found in the September 1984 issue of Radio Electronics magazine, this circuit uses common...
Found in the July 1968 Supertena Bulletin of a Popular Electronics, this receiver makes use of the...
This intercom for the 27 MHz band was found in a recent English documentation, working with a...