Some of the vfd driver chips are what I was looking at initially. Bill
On Wednesday, August 25, 2021 at 2:02:48 PM UTC-7 Paul Andrews wrote: > 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. 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/ea56bcbe-3574-4739-b2d3-7870e6984877n%40googlegroups.com.
