I'm trying to work with some IV-3A VFD Tubes from Russia. In the datasheet, the filament is specified to be driven with 0.85V (?). So I just google around for a solution to use this with a 12V power supply, and come accross those ideas:
1. Drive it with DC since it's a short tube: 0.85V regulation with 6 filaments as load, it's a scary thing to do. I'm thinking about a LM317, set the output to its minimum, and drop the output voltage using a few diodes. I might get close if the temperature of the diode does not fluctuate too much.
2. Drive it with AC voltage: I don't quite understand it right here, so I might need some help to clear my head. Anything will be of use. I'll be refer to the Noritake VFD guide:
The output of this "DC-AC Converter" is a square wave? If that's true, can I drive the filament using a micro and a few opamps? (with an output BJT).
3. What's the filament bias voltage? On the Noritake website, it's said to be applied to the center-tap of the transformer. So how can I do it using the forementioned method (MCU and opamps).