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.
We found this circuit in recent English documentation. It can provide an output current between 9 and...
This amplifier circuit for listening was found in a book by Hugo Gernsback from 1960. The...
This circuit was found in an old GE manual. It uses a thermocouple as a sensor. The SCR must be in...