Thanks. I put 5v into the filament and got a orange glow from one of the holes the lead goes into the cylinder. The cylinder started glowing a deep cherry red after a while. No mercury glow at all. Even on 12v. The cylinder just glowed a deep orange. I put my flyback lamp tester lead on the top contact. Nothing on either 5v or 12v.
You can put 15 Watts, 120 volts incandescent light bulb in series between the filament and the anode (top of the tube) while the filament in 5 volts burning. That should have rectifier going
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