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.
In this source, suggested by National Semiconductor in its Linear Applications Handbook, D1 must...
The diodes in this circuit are used for waveform correction. The circuit is from Electronics Now...
This is a conventional alarm that uses NO and NC type sensors for doors and windows. The circuit is...