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 neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b7180d16-a87c-437b-9926-7d6361f49bb6n%40googlegroups.com.
