Thanks for the response. I wasn't thinking of multiplexing anyway exactly for the reason of excess currents, I only implement direct drive in my designs :)
But what I wanted to ask is, I only saw these constant current regulators operating as for example, LM317 (http://diyaudioprojects.com/Technical/Current-Regulator/Precision-Current-Limiter-Schematic-Circuit-LM317-LM338-LM350.png)..so would this have to be implemented in series of each cathode? Dana srijeda, 22. veljače 2017. u 21:08:04 UTC+1, korisnik gregebert napisao je: > > Given the high cost + rarity of b7971 tubes, I would only recommend a > current-regulated driver for each segment. Using individual cathode > resistors will limit the current, but it's not well-regulated and will vary > tube-to-tube and with age. Yes, the HV5530 will *work*, but I would be > concerned about reduced tube life. > > Also, I would not multiplex these tubes because the brightness will be > reduced. Boosting the current to compensate for this will likely exceed the > datasheet limits and shorten tube life. In fact, driving all segments of a > b7971 tube at their rated current *at the same time* will exceed the spec > limit for maximum anode current. So, along with limiting the current on > each segment, you should also have a current-limit for each anode. > > I spent a lot of time gathering & analyzing data on my 7971 tubes to get a > tradeoff between segment-current, max-current, and brightness. > > I know it sounds like overkill, but a few extra $ for components to > protect a $100 tube is well worth it. Besides, I had a lot of fun designing > and simulating the driver circuitry. > > The HV series drivers aren't necessary for current-regulators; you can use > TTL or LVTTL shift-registers (74HC595) to control the driver transistors > (PMBTA42DS). > > I haven't had the time to fab the PCB for my 7971 tubes yet; once I get > the board running I'll post schematics. Just too doggone busy with my day > job..... > > -- 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/253bee53-8aff-46d5-a9d6-44bca55f5131%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
