For the longer tubes where the brightness gradient is problematic, the usual DC-DC converter to get the voltage followed by an H-bridge to generate an alternating polarity square wave is another option.
David On Sat, 17 Jun 2023 at 04:29, Richard Scales <rich...@scalesweb.co.uk> wrote: > Many thanks for all your replies and advice. > DC seems t be the way then, with some series resistance on the filament > supply. > I'll start in that direction and get something working on the bench. > - Richard > > > > On Friday, 16 June 2023 at 20:32:01 UTC+1 Moses wrote: > >> Richard, >> >> Same here! I started to experiment with the IV-21 tube and how to drive >> it recently. I have some drivers on the way. I don't have much experience >> with VFDs at the moment.. but I did light one up on the bench recently. >> >> I used the datasheet recommended filament voltage/current on the IV-21 of >> about 2.7v at 35ma, and I lit up all the segments/girds manually without a >> driver IC. With everything on, I was able to perceive a difference in the >> brightness but I had to be looking for it, it was not obvious. Now in >> operation as a clock, as opposed to a static display with all segments on, >> I would expect it to be less noticeable. >> >> The IV-21 is one of those 8 digit small calculator type tubes, the >> filament is about 40cm long or so. I believe the IV-22 single digit tube >> would have a shorter filament, and hence less of an effect? Maybe. >> >> Keep us updated on your progress. >> >> Regards, >> -Moses >> >> On Thursday, June 15, 2023 at 10:45:02 PM UTC-7 Richard Scales wrote: >> >>> Greetings all, >>> >>> I am starting to look at VFD displays and am reading all I can about >>> them. >>> >>> I am trying to get a better understanding of the pros and cons of using >>> a AC filament drive rather than an DC one. >>> >>> I am aware that on larger displays (like those monster ones from Russia) >>> it is necessary in order to create a more even glow across segments. I >>> wonder however how important this is for smaller segments like those in >>> IV-22 for example. >>> >>> Making the filament drive AC adds a small degree of complexity but if >>> the difference is visible and beneficial then I'd like to go that way. >>> >>> My project would be direct drive, no multiplexing required. >>> >>> Any advice would be greatly appreciated. >>> >>> - Richard >>> >>> >>> -- > 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 view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/20b78aec-a35e-4d5f-a677-921eaa14ca0fn%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/20b78aec-a35e-4d5f-a677-921eaa14ca0fn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAOQ6x0FdbgpcDagd7gkqLqzG-dNh7tff0u5Cgk46qnjZwMp4VA%40mail.gmail.com.
