VXX200 is the +200V supply; the PDRV signal varies from roughly +200V to +188V. I used an isolated 12V DC-DC converter to generate "negative 12 volts with respect to VXX200". There's a potentiometer across the 12V DC-DC converter's output, and the wiper connects to PDRV. That way, I can adjust PDRV between 0v and -12v with respect to VXX200. Changing PDRV changes the anode current.
R8 limits the potential for over-current in the nixie tube in case something goes wrong with the current limiter, such as a power-up transient. Also, I can infer the anode current by measuring R8's voltage drop. The way the PCB is laid-out, I can't access R7. C3 provides filtering of any noise that might get coupled onto PDRV. The 'unlabeled' anode resistors (2 per IN-18 tube) were put on the PCB in case only one of the anode pins should be used. At the tme I sent my PCB to fab, I wasn't sure. As far as my research went, I could find no problems using both anode pins. -- 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/cd60176b-cb19-4a9e-899d-3fcd1c565f02%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
