Question on driving a nixie tube with two anodes

[Planetariophage]

Hello. I'm very new to nixie tubes in general but I want to be able to drive a few B5025 tubes that I have lying about.

I'm using this site as a reference:

http://www.dos4ever.com/nixie1/nixie1.html

Figure 2 shows the recommended driving voltages, and Figure 3 shows a simplified version that has a small amount of glow on adjacent numbers. I want to try using the simplified circuit, but I have a few questions:

1) The simplified circuit does not show any voltage on the screen. Was this assumed to be just at 50V or did the author leave this pin unconnected?

2) Why are the resistor values on the odd and even anodes asymmetrical?

3) Being new to nixies, I want to make sure I have the fundamentals here correct: If I apply 180V through a 27K resistor to the odd anode of the nixie tube, and connecting a single cathode to ground with everything else unconnected, should the single corresponding digit light up? Figure 2 shows all the cathodes being pulled up to 40-110V when not enabled, so I was unsure if I can leave them unconnected.

4) What is the wattage recommended for the 27K or 15K resistors? I guess a better question is how much voltage does the nixie tube consume?

5) I read about cathode poisoning. To clarify, if I drive only a single digit on the nixie tube and never drive the other digits, would the other digits eventually be unable to function? And am I correct in that I should "refresh" the tube periodically by turning on the other digits for a bit of time?

Thanks for the help!

[threeneurons]

Even though the B5025 has the same pinout as the ZM1030, the electrical characteristics are bit different. The ZM1030 has the same levels as normal (non-biquinary) nixies. Strike at ~170V, and maintain ~130V. The B5025 strikes ~130 to 150V, and maintains ~100V. Also the ZM1030 is a mercury enhanced, and therefore "long life". The B5025 has no mercury.

1- the screen should be attached to some mid level. 40 to 50V is a good start point

2- the even stack is behind the odd stack. I think Ronald used different anode currents, to even out the brightness. The even stack has higher current. With the B5025, you'll either need a lower supply voltage, or higher resistor values.

3-Ideally, you can omit the cathode "mid-pull" resistors. In reality, however, mid-pulls divert leakage currents, which is more important with biquinaries, since the "off" cathode of the selected pair, has a tendency to also glow. For a B5025 go to the lower portion of that range. Between 40 to 80V.

4-1/2W is safe.

5-Cathodes that are never energized, will eventually develop cathode poisoning. Should you have a utility that exercises them ? That's really up to you. If these tubes are to stay in this item for the rest of their lives, it shouldn't matter. 

[Planetariophage]

That was really informative, thanks for the help!