Instant on. A fun topic.
First the B+ already has inrush covered by the usual 5.6 ohm
fusable.
As far as filaments go you could add a thermistor thats 0 ohms
hot & maybe 120 ohms cold. Needs to carry a few amps also.
I bet it will fail faster than a filament so why bother. Just leave the
set unplugged & wait 30 secs to use it.
Instant on was sold on the fact that tube life will be better
due to less shock to the filaments, maybe some truth in that.
Here's the catch. Most sets with instant on were all tube PCB based
sets & the cheap brands. Basically the sets cooked themself to death.
I had even pull a hoz out / damper tube & the socked came with it !
Early all solid state sets used it also. The Zenith Chromacolor & CC2
sets had it ( D-F line). They are considered the longest lasting CRT's
ever by most here. So on a 100% solid state set there may very well
be a good argument for instant on.
enuf fer now
73 Zeno
LFOD !