What might be happening in your clock is the PNP driver is damaged, and only allowing a tiny amount of current through. That can still result in ~170V across the tube with no visible glow. I wonder if the PNP's Vceo rating is less than 170V, and it suffered from long-term exposure. -------- I've observed erratic behavior on 7971 nixies when the current is limited to a few uA. I was attempting to measure the ionization voltage, but the behavior was so erratic I cant get consistent readings. But I did notice the voltage was significantly higher in this pre-ionization phase, versus normal operation. For example, I would measure around 140V across the nixie at 100uA (dim segment); during pre-ionization I'd see 160-180V and faint erratic glowing.
I'm sure other nixies show similar behavior. BTW, I used my nixie bench supply to plot I-V data in Excel for my 7971 nixies (7tubes * 15 segments * 7 currents = lots of data) and came across this behavior. -- 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 neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/ae2b1ea2-660c-495d-b1e5-2f77925dad87%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
