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 a documentation from the 70s, this source allows to obtain continuous voltages from a...
This simple test circuit was found in the April 1983 issue of Radio Electronics magazine. The...
This amplifier was found in a Radio Electronics of the 90s. The circuit uses unusual operational...