I think that you should try to lower the value of the 100k resistor across the base-emitter of every MPSA92 to say some 10k-22k, they will not be fully turned off in some instances with the 100k resistor.
Did you use the correct anode pin for the IN-4? Have look here: http://www.tube-tester.com/sites/nixie/data/in-4/in-4-sh2.htm , they can be driven in bi-quinary or normal mode and the anode pins are not in the same place depending on what mode is used. What resistance do you use for the anodes, maybe you need to change that for the IN-4 to work properly compared to the IN-17? /Martin -- 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/0558bbfa-3d3d-4f33-8189-2866260af7df%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
