When I have time, I will try the driver at the link Martin gave ( http://www.nutsvolts.com/media-files/Forum-Articles/QA_201110.pdf), but without the transformer initially. As far as I can tell, the transformer is just to make the VFD drive isolated so you can pull it up above ground.
On Wednesday, August 25, 2021 at 4:37:56 PM UTC-4 Bill Notfaded wrote: > I'm kinda in the same boat Paul... VFD's hasn't really been my thing but > figuring out how to drive some weird ones is a new hobby. I love your > questions because it helps me figure out what I'm doing as well! > > Bill > > On Tuesday, August 24, 2021 at 12:57:53 AM UTC-7 Tomasz Kowalczyk wrote: > >> 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 <[email protected]> >>>>>> 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 [email protected] >>>>>>> > <mailto:[email protected]>. >>>>>>> > 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 [email protected]. >>>>>>> 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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