Did you try simple PWM? I once tried it, but didn't leave it on for long time, so I can't tell if it shortens the tube life or not, but by simple logic it shouldn't. For most of the time the cathode will be at the same potential. Also it's a nice method of elevating the cathode potential above negative segment/grid voltage to get rid of faint glow of off segments.
poniedziałek, 23 sierpnia 2021 o 20:19:58 UTC+2 gregebert napisał(a): > Transformers are not ideal, so even with zero load, they consume > inductive current. Most of the energy gets returned to the AC line, but > some of it gets dissipated as heat (winding resistance, and hysteresis). > This is why unloaded wall transformers still get slightly warm. > > You can measure the magnetizing current with multimeter. > > > --------------------------------------------------------------------------------------------------------------------------------------- > Be warned that large transformers will have a startup surge current; I > have an isolation transformer in my workshop that can supply 20A/120VAC. It > has dual primaries, so I can run it from 120V or 240V. If I try to run it > from 120V, even with no load, it almost always pops the 20A breaker for my > workbench. So, I use 240V and even then I can hear the wires in the conduit > vibrate for an instant when it's energized. > > If you are worried about blowing the fuse in your multimeter when > measuring the magnetizing current, it's good practice to use a variac to > increase the line voltage starting from 0 volts into your transformer. > > On Monday, August 23, 2021 at 8:49:01 AM UTC-7 Paul Andrews wrote: > >> Thanks Martin, >> >> I'm OK with using a transformer. I would prefer something off the shelf, >> but perhaps I should just wind my own anyway. Seems like a useful skill to >> have. >> >> As with a lot of these things, I find that I have a lot of questions. For >> example, this statement: >> >> "The transformer is 1:1, center-tapped. Since the output is to be 300 mA >> max, the magnetizing current at the input should be no more than 30 mA. I >> will try 10 mA" >> >> First of all, how does he get a 10:1 ratio of output current to 'maximum >> magnetizing current'. Second, what is 'magnetizing current', does he just >> mean current through the primary? >> >> Then he introduces terms in equations without defining them - they are >> probably obvious to the initiated (which I am not unfortunately). For >> example, Xl in L = Xl/2/PI/F and Al in N = (L*1e6/Al)^.5. Then having >> calculated the required number of turns, he just ignores that and goes with >> something much larger. >> >> On Friday, August 20, 2021 at 5:51:17 PM UTC-4 Dekatron42 wrote: >> >>> There is a nice article in NutsVolts magazine: >>> http://www.nutsvolts.com/media-files/Forum-Articles/QA_201110.pdf where >>> a powerful driver is shown, needs a small transformer but seems to be well >>> designed with equations for calculations of the transformer. >>> >>> /Martin >>> >>> On Friday, 20 August 2021 at 21:37:46 UTC+2 Hannah Mishin wrote: >>> >>>> Theres a section on filament driving in my blog here: >>>> >>>> https://hannahmishin.com/blog/2017/4/30/russian-tri-color-vfd-indicator-clock >>>> >>>> *Hannah Mishin* >>>> * She/her/hers* >>>> <http://hannahmishin.com/> >>>> >>>> *hannahmishin.com* <http://hannahmishin.com/> >>>> >>>> >>>> >>>> On Fri, Aug 20, 2021 at 1:48 PM Toby Thain <to...@telegraphics.com.au> >>>> wrote: >>>> >>>>> On 2021-08-20 12:58 p.m., Paul Andrews wrote: >>>>> > I'm designing a clock for DT-1704 tubes and am stumbling at the >>>>> filament >>>>> > drive stage. They want 1.6V. I want to power it from 5VDC. ... >>>>> > >>>>> >>>>> FWIW I've used LM2575 1A adjustable step down for DC filament voltages >>>>> in that range. >>>>> >>>>> --Toby >>>>> >>>>> >>>>> > ... >>>>> > >>>>> > So I would appreciate any suggestions for what direction I should >>>>> take >>>>> > here. I have too many options and no clear criteria. >>>>> > >>>>> > -- >>>>> > 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+...@googlegroups.com >>>>> > <mailto:neonixie-l+...@googlegroups.com>. >>>>> > To view this discussion on the web, visit >>>>> > >>>>> https://groups.google.com/d/msgid/neonixie-l/860d4d78-c807-415e-a740-b576a4b5d18cn%40googlegroups.com >>>>> > < >>>>> https://groups.google.com/d/msgid/neonixie-l/860d4d78-c807-415e-a740-b576a4b5d18cn%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+...@googlegroups.com. >>>>> To view this discussion on the web, visit >>>>> https://groups.google.com/d/msgid/neonixie-l/ce44816f-120e-abae-060f-fe062d24f836%40telegraphics.com.au >>>>> . >>>>> >>>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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