[MrFixr55]

Hi Marion,

I don't know; I never researched it. I would think that function would be really annoying, but it would be desirable for it to work to be historically accurate. You can probably test the lamp by charging up a capacitor to about 150V and discharging it through the lamp with a 1K resistor in series with it. (I have not tried this; this is just what the voices in my head are telling me. I suspect that the lamp may have outgassed, ingassed or have "inactivated". The link below is to a good article in Wikipedia on gas discharge tubes.
https://en.wikipedia.org/wiki/Gas-filled_tube

Looking at the circuit, this is a simple "time constant" circuit where the rate of charge of the cap is determined by the capacity of the cap, the resistance of the resistor and the supply voltage. The voltage required to flash the lamp must be rather well below 90V.

Ne-2 and Ne-51bulbs are still available. The problem is that these bulbs fire at approximately 105V. I remember as a kid, putting 120VAC directly across the bulb and it shattered.

I guess that one possible solution is to get an "orange" 5V indicator LED and put that in the circuit. You may have to increase the resistance and the capacitance to increase the time constant. I have to assume (possibly incorrectly) that the LED will flash when the charge voltage on the cap exceeds the conduction voltage of the diode. If this does not work, then a transistor switching circuit must be devised. For a "raw" LED, I do not know whet the voltage required to light the LED is. It may be as low as 0.6V, but may be much higher. Most LED flashlights use 3 batteries in series, but some cheap Eveready flashlights use a single cell. Having this type of bulb will cause you to put this circuit on the 1.5V "A" bettery as opposed to the 90V "B" battery.

Hope that this all helps!