Nixie Tube Question: B5866 vs B5856.

[Paceguy]

A question for those who know their Nixie tubes: Can a B5866 be used to replace a B5856? These are the simple +/- indicators used in Nixie tube voltmeters. From what I could find online, the only difference I can see is one in used for pulsed DC and the other isn't. It looks like the one for pulsed DC can be used to replace the non-pulsed DC, but the DC one cannot be used to replace the one made for a pulsed DC circuit.

[Roehrenonkel]

Hi peaceguy,
 
yeah, i guess you're right.

Best regards

[CaptDon]

The 'Long Life' series of Nixies are the only ones recommended for Mux/pulse duty. I think the long life versions have a bit more mercury content than the regular service versions. Cathode material migration from ion bombardment is the killer. The life of a Nixie is very dependent on average cathode current. You can download the catalogs including data and operating curves and guidelines for both Burroughs and National Nixies. I have observed three distinct Nixie glows, normal neon orange, neon orange with the blue mercury halo (long life) and the strange neon orange leaning a bit toward a pinkish tint. I am not sure what other gas causes the pinkish tint. I remember that some Nixies were doped with a radioactive isotope to insure ionization in pulse duty and dark environments. It is a well known fact that old Nixies and non-doped Nixies will either fail to ionize, or certain cathodes will fail to ionize in dark environments or in pulse duty. I have some 'lazy' Nixies in a rack mount device. When the unit is first energized the Nixies will flicker and carry on for about a minute and then settle down and work correctly. They are in a 1-of-6 multiplex scheme with about 9ma of peak current and 1.5ma of average current which is well within spec for the large long life tubes in the unit.