I think I already see blunders in my original post - the filament is the cathode (I think) at 5V, the segments (individual anodes) at 25V giving a 19V difference over the grid which is at 5V. I am unsure as to the correct value of the series resistor for the heaters- 10R has been used by others though I would prefer to know how that was calculated and indeed whether there are significant gains to be made by moving to an A/C drive for the filaments. - Richard
On Wednesday, 14 September 2022 at 09:02:24 UTC+1 Richard Scales 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/ca546e2b-dd94-4581-bc76-0c19105d4e1bn%40googlegroups.com.
