This circuit is intended for detecting 3 levels power grid voltage, and it can be adapted to operate with the most diverse voltages. The circuit uses neon indicator lamps.
I found this circuit in a 1986 English magazine. It can still be easily assembled, exchanging Q1...
We found this circuit in an Argentine publication from the 70s. The coil can be made with 80 turns...
Found in General Electric documentation from 1967, this circuit makes use of an unusual...