modern flyback cross reference?

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I linked to.

There is a correlation between quality and price.

There a rather stronger correlation between production volume and price - i f you can find a part that is being used in large volume for a different ap plication you can almost always get it cheaper than you would if you had it made just for your application.

John Larkin is convinced that you ought to use off-the-shelf transformers w herever you can, rather than designing something for your particular job an d having it made.

Transformers have a lot of parameters you can adjust during the design proc ess (if you understand what you are doing, which John Larkin may not be abl e to manage for transformers) so the purpose built part tends to be a lot m ore cost effective than the nearest off-the-shelf part. You can get lucky, but I mostly ended up designing the (few) transformers that I needed.

I have designed dozens, if not hundreds, of custom transformers, most of which were laboriously made by my technician, R.I.P. And many were made for me by local transformer companies, also R.I.P. And I've amassed a huge inventory of cores and bobbins of all types, along with their relevant data. But, like John, I'm a huge fan of repurposing off-the-shelf parts, if possible. So I also have a huge collection of candidate parts, ready to be evaluated. I won't be criticizing anyone who wants to go down that path.

You can wind your own prototypes - you do need a coil winding machine with a turns counter, but they aren't big or expensive.

It's a good ten years since I had a transformer made, when I was still in Nijmegen , and it took me a bit of hunting to find a coil winding shop, about forty minutes drive away, in Venlo. They still seem to exist.

These days, there's probably a Chinese supplier, and Sphero Pefany could probably tell us if they were any good.

Me too. But it often isn't possible, even if you are prepared to live with a decidedly sub-optimal transformer.

My feeling is that you always need to look at what a purpose-wound transformer would look like. You won't get a feel for what's attainable, or important, until you've done it.

That may be a counsel of perfection, but this is sci.electronics.design not sci.electronics.slap-together-something-that-sort-of-works.

Sometimes, slap-together-something-from-parts-at-hand, that-works-just fine, is not a bad approach. Engineers can do the calculations, to get a clear understanding of whatever tradeoffs are being made, and the margins, then we needn't be ashamed of making a few tradeoffs.

I would go further than that. Design *is* tradeoff. Finding the right compromises is absolutely central to the work of designers in any field.

But it's an informed trade-off. You need to know what a purpose built transformer could do for you before can work out how much that trade-off is costing you.