For mine I used one of those cheap eBay buck converters. 5v in, 1.x v out (adjustable). 8 iv11 tubes, running for a few years without a blip.
If you needed AC, you could always just use an H bridge and a microcontroller pin to flip it at a suitable frequency with a smoothing cap. I found I couldn't have ordered the components cheaper than the finished eBay module... David On Wed, 1 Sep 2021, 14:57 Dekatron42, <[email protected]> wrote: > You can use airgaps in transformers in some cases but this design should > be without one according to Ed. > > I am using ferrite pot cores in some other designs where they are wound as > a transformer but where the Q-value is of importance and there I use an > airgap and also a trimmer through the center to adjust them for a minimum > Q-value at a certain frequency. > > Q-value according to TDK: > https://product.tdk.com/en/contact/faq/inductors-0003.html and also at > Wikipedia: https://en.wikipedia.org/wiki/Q_factor > > This article explains airgap in inductors/transformers somewhat: > https://www.linkedin.com/pulse/why-do-we-provide-air-gap-usually-inductor-designs-transformer-p > > So sometimes it is a choice depending on design criteria like Q-value and > material used in the transformer. There are normal laminated transformers > that use an airgap too, but most mains transformers do not. > > /Martin > > > > On Wednesday, 1 September 2021 at 15:11:31 UTC+2 Paul Andrews wrote: > >> Martin, >> >> I wonder why there should be no air gap? >> >> - Paul >> >> On Wednesday, September 1, 2021 at 1:55:30 AM UTC-4 Dekatron42 wrote: >> >>> Paul, >>> >>> I'll ask him, but a quick search at Digikey showed both some RM10 and >>> ETD29 cores, but only a few. Finding Ferrite cores today is not easy, I >>> have searched some for other projects and they aren't usually stocked in >>> the ranges that the manufacturers make them, and if you want something >>> outside what is available in stock it becomes very expensive as you'll have >>> to by thousands if not more. I usually try the ones they have and have to >>> live with that since I can't buy the thousands needed to get the perfect >>> one. I'll ask Ed to have a look and see if any of the ones that are stocked >>> will do - just remember that they will have to be the transformer type >>> without an airgap between the center pieces to work in this application. >>> >>> /Martin >>> >>> On Wednesday, 1 September 2021 at 04:26:30 UTC+2 Paul Andrews wrote: >>> >>>> >>>> Hi Martin >>>> >>>> I tried to find a suitable core at digikey, but their parameters don’t >>>> map very well to the equation that Ed gives. Could he take a look at what >>>> they have and perhaps recommend something. For simplicity’s sake I just >>>> looked at toroids >>>> https://www.digikey.com/en/products/filter/ferrite-cores/936?s=N4IgTCBcDaICoHsBOCCWATAhgGwAQGNkBTAZxAF0BfIA >>>> >>>> Thanks - Paul >>>> On Friday, August 27, 2021 at 8:45:56 AM UTC-4 Dekatron42 wrote: >>>> >>>>> Since transformers isn't my best area, I only have basic understanding >>>>> of the intricacies but I have experimented some with different >>>>> transformers >>>>> in different cases like when driving Trochotrons and Dekatrons I decided >>>>> to >>>>> ask an acquaintance who has worked with transformers. His name is Ed >>>>> Dinning, I got to know him over at the UKVRRR forum (UK Vintage Radio >>>>> Repair and Restoration forum: https://www.vintage-radio.net/forum/), >>>>> he told me you are welcome to contact him via me so that his email is >>>>> somewhat protected - if you ask him anything related to the >>>>> VFD-drivers it would be kind if you could post something here in this >>>>> forum >>>>> so we all can learn from it. >>>>> >>>>> This is his answer to my question on what transformer to chose for the >>>>> driver in the article, it sure helped me and I hope it helps anyone who >>>>> wants to experiment with this driver: >>>>> >>>>> "Hi Martin, as it operates about 50/100KHz virtually any ferrite >>>>> should do. It should be a transformer type with no air gap. >>>>> The turns are normally based on the transformer equation for square >>>>> waves >>>>> >>>>> N= V/ 4 * F * B* Ae >>>>> >>>>> N=turns, V=volts F=frequency,B= flux density, typically 200/250mT for >>>>> a ferrite, Ae the centre pole area in M^2 >>>>> >>>>> The actual losses come out later on in the design process and are not >>>>> part of the initial criteria >>>>> >>>>> Copper sizing is normally based on 3A per mm^2 of cross sectional area >>>>> >>>>> The turns figure he gives looks about right for something like an RM10 >>>>> core, or you could try an EE25 or an ETD29 core in sat F44 materials >>>>> ETD's are the core of choice for this type of application and should >>>>> be readily available. >>>>> >>>>> The more turns that are used the lower the iron losses and the cooler >>>>> the core runs, but the copper losses increase unless fatter copper is >>>>> used. >>>>> Skin effect will be of minor importance at your frequency >>>>> >>>>> It would also work on a normal laminated core at 50Hz which should not >>>>> be too big as you can run that at up to 1.5T flux density. >>>>> Regulation could be a normal type of regulator set for constant >>>>> current. >>>>> >>>>> Always many choices in Engineering >>>>> >>>>> Cheers, Ed >>>>> >>>>> Ed Dinning Retired Engineer" >>>>> >>>>> /Martin >>>>> >>>>> On Wednesday, 25 August 2021 at 23:02:48 UTC+2 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. >>>>>> >>>>> -- > 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/8943cc8d-1219-44d0-9f19-62357cdf4951n%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/8943cc8d-1219-44d0-9f19-62357cdf4951n%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/CAOQ6x0HXJ3DSW962Ox50y6mBSxN4COouWubmuqZ7evFxF%3DMT8g%40mail.gmail.com.
