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.
August 2017 - Bourns Multifuse AEC-Q200 PTC resettable fuses can be obtained from Mouser...
This circuit can be used as a buzzer from 3 different locations, allowing you to identify where it went...
This reducer was found in documentation from the 1980s, using transistors of the time. The higher...