It can indeed..... For single digit tubes the brightness gradient isn't usually noticeable but for the multidigit ones eg the one from the adafruit iceclock, it certainly is.
David On Wed, 14 Sept 2022, 10:42 Adrian Godwin, <[email protected]> wrote: > Using DC for the filament means there is more accelerating voltage at one > end than the other and results in a noticeable difference in brightness. > > I have wondered if it could be solved without a transformer by driving the > filament with a h-bridge. > > On Wed, Sep 14, 2022 at 9:02 AM Richard Scales <[email protected]> > wrote: > >> Hello everyone, >> I have just managed to acquire a set of these and would ideally like to >> drive them the best possible way. >> I had initially though about a 5V for the filament and then 24V for the >> cathodes and grid. >> The clock would only have segments activated when someone is nearby - the >> segments will not be left on all of the time. >> Now I read about A/C supply to the filaments and wonder if I should be >> going that way. >> Would anyone be able to post their findings and/or suggest the right way >> forward? >> [image: VFDsnip.JPG] >> >> I just noted that the picture above shows the connection for the grid >> (pin 9 on H1) connected to 5V and not the 24V as used on the cathodes. >> The more I think about it - the less clear this all becomes! >> I need to get it right in my head before I go breaking something and then >> I would like to get the best possible result via reasonably straight >> forward means. >> Would anyone be able to point me in the right direction and/or share >> proven drive methods? >> - Richard >> >> >> On Monday, 16 September 2019 at 22:23:47 UTC+1 gregebert wrote: >> >>> Yes! That's exactly what happens. The current through the center-tap is >>> the sum of the anode (segment) current and the grid current. And the peak >>> current through the filament wires is actually *greater* than just the >>> current to heat the filaments. >>> >>> >>> *Tomasz* - As you found out, those VFDs draw a lot of current. I have a >>> future design for a 6-tube ILC1-1/8 (smaller tubes than the ILC1-1/7) and >>> I'm just going to use a high-current filament transformer with the >>> center-tap at GND. Grids will NOT be pure DC; closer to full-wave rectified >>> around 15-16V. Segment anodes will be pure DC around 36-40V with >>> current-regulators and non-multiplexed. >>> >>> I actually have an Op-amp summer+ADC+Software to monitor the current >>> thru the center-rap on my NIMO clock to determine the tube health, though >>> it's orders of magnitude smaller (30uA per tube). >>> >>>> -- >> 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 view this discussion on the web, visit >> https://groups.google.com/d/msgid/neonixie-l/88406a7a-3854-4dc2-bf24-8a33f769811en%40googlegroups.com >> <https://groups.google.com/d/msgid/neonixie-l/88406a7a-3854-4dc2-bf24-8a33f769811en%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 [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/CALiMYruQ0Qbm741UYeurekUGAPWVPU_GnTYCHurMpfO1odi0_g%40mail.gmail.com > <https://groups.google.com/d/msgid/neonixie-l/CALiMYruQ0Qbm741UYeurekUGAPWVPU_GnTYCHurMpfO1odi0_g%40mail.gmail.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 [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAOQ6x0EO1CMNvsXVpgX8MyMcvn2ryQfYysT_4quiX-O0M2z%2BAQ%40mail.gmail.com.
