The Build: Chassis fabrication to power-on

[SoulFetish]

What limits the current through the neons?

Load resistors in the driving stage.
Normally, you see a value of around 100K current limiters for coditions where they will stay on for extended periods. I didn't add any additional resistance to the driver load resistors, because that Won't be conditions here.

[SoulFetish]

I should add that, in it's current configuration, the grid stoppers in addition to the load resistors will limit the current. But, those are subject to change if I decide to drive the grids into positive voltage.

[Mick Bailey]

Can the grid circuit p[rovide enough current to threaten the neon lamp?

Probably not under normal conditions. I originally had neons in an 807 hi-fi amp I built and on first turn on they would sometimes permanently glow brightly unless the amp was turned off and on again. The glass soon had the shadow you get with a tired neon. I never really investigated it - could have been some kind of oscillation. I originally debated whether to use them, but I clipped them out and the amp has worked fine for years.