I used the resistor values listed here <https://tayloredge.com/reference/Circuits/1386SmartSocket/B7971%20assembly%20instructions.pdf>. Estimate a maintenance voltage of, say 140V. Then the total current used, if all segments are lit using those values is < 21mA. The brightness of the segments when using these values seems to match those of other displays I have seen.
In other words, pick some total current < max and then distribute that current between all cathodes such that the ratios between them stay the same as the maximum values in the datasheet. On Friday, August 9, 2019 at 1:29:37 PM UTC-4, newxito wrote: > > In 2016 I bought some B7971 to build a clock, not the best tubes for a > beginner with no skills in electronics. Until now I have not even tested > these tubes. But now, after building some clocks with numeric nixies I > think I'm ready to design a board for a 6-digit clock. > > I know that these tubes are hard to find a very expensive these days, so I > don't want to mess it up. > > The design will have a fuse for the 12V, another fuse for the 170V, > reverse, over and under voltage protection and a temperature sensor for the > HV PSU. Just to be on the safe side :-) > > I found the datasheet and a lot of information on the internet. I know > now, that I should use different cathode resistors for the different > segment lengths, but I still have questions about the max. current limit > (21mA): > > - I don't want to go to the limit, 18mA max. Is it ok to choose the > resistors to be able to light up all 15 segments at the same time? (average > 1.2 mA/seg). Or is it better to drive the segments with a bit more current > (2mA) and limit in the software the number of concurrent segments to 9? (0 > has 8 segments + underscore according to the font in the datasheet) > > - Do I need some kind of anode current limiter? > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/a77fb312-ff8c-4408-b556-ab9e2d87edf1%40googlegroups.com.
