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 Linear Technology documentation from the 1980s, this generator uses integrated circuits...
We found this circuit in a Radio Electronics from December 1963. The circuit combines valves and...
This oscillator, from an old Argentine publication from 1973, uses the inductance of the 500 ohms...