Found in an old publication about neon lamps this circuit works directly connected to the power grid, serving as an indicator for various situations. Ordinary neon lamps can be used.
Found in an Electronics World of 1968, this circuit is indicated for applications in photography...
We found this circuit in documentation from the 1980s. It is an input stage for a digital...
This circuit of various uses on the bench was found in Radio Electronics magazine from January 1960....