>From the datasheet, collector leakage current is about 100nA. Assuming all of the NPN leakage current is amplified in the PNP, you would get 4-5uA of actual leakage to the anode from the PNP. That doesn't seem like enough current to me to cause a visible glow in a nixie.
Your scope probe (10meg) will "pull" 5uA of leakage current down to 50V. You can do a quick leakage test on the PNP by disconnecting the nixie anode, and any bleeder resistors, and measure the voltage at the PNP's collector when it's off (but while your power supply is on, of course). You should measure substantially less then 40v; anything near or more than that, confirms a leaky PNP or NPN. Be aware that if the NPN is leaky, it can cause a good PNP to appear leaky, because your driver is basically a 2-stage amplifier. Based on the scope pictures so far, I'm not convinced it's leakage. But we need to know if we can rule it out. The last set of scope photos show good turn-on, turn-off, blanking, and control signal behavior. So I think that can be ruled out. There's definitely a clue with the 'ugly' shaped signals; I just havn't figured it out yet. Can I assume your probes are properly compensated ? The leading-edge 'spike' at the anode when it turns on is hopefully the effect of the tube ionizing. But on the falling-edge I noticed some undershoot which goes significantly below 0 volts. That could be a clue. -- 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 post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/8aac8a90-6197-4d1e-8963-f8b673a12842%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
