MYRRA 74000/1 both are 120V primaries. What exact specs are you looking for? Might be able to help you choose one.

If you are designing around a particular SMPS chip then the place to start looking at transformers and inductors is in the manufacturer's apps notes and recommendations. Würth (Wuerth) have a reasonable range of parts and selection guides: [https://www.we-online.com/catalog/en/pbs/power_magnetics](https://www.we-online.com/catalog/en/pbs/power_magnetics)<br> <br> Their REDEXPERT tools are pretty good too. If you want to try simulating the design then have a look at: [https://easyeda\.com/andyfierman/Simple\_Open\_Loop\_Flyback\_Converter\-ywqkCTb5n](https://easyeda.com/andyfierman/Simple_Open_Loop_Flyback_Converter-ywqkCTb5n)<br> <br> though for a better experience with long simulations and with results analysis and display, I recommend installing a local copy of LTspice and doing simulations from there. BTW: LTspice schematics can now be imported into EasyEDA Pro as non-simulation schematics to save having to redraw lots of it in preparation for PCB layout.

@cjohnson The datasheet i was refering to, suggesting a transformer, was this one : [https://docs.rs-online.com/99d9/0900766b813f2bac.pdf](https://docs.rs-online.com/99d9/0900766b813f2bac.pdf) which states 85 - 265V mains as far as i can see, so good for the country i live in. @andyfierman thanks for the great pointers to start the crusade about building SMPS on board, i already fiddle quite a while with power supplies (mainly non-isolated ones, capacitive droppers, zener based, and so forth) and though i'm no expert (but i know my safety rules, and am comfortable around mains curcuit and power equipement) My reasons : i want to go beyond simply using [https://www\.lcsc\.com/product\-detail/Power\-Module\-AC\-DC\_HI\-LINK\-HLK\-PM01\_C209903\.html](https://www.lcsc.com/product-detail/Power-Module-AC-DC_HI-LINK-HLK-PM01_C209903.html) and similar items power modules. My first thought was that the price of transformers itself often costs around or more than a power module, so there is no economical incentive (AFAIK) to design/include your own SMPS design if the power module satisfy my requirements, sadly.

There are less obvious costs to SMPS design mainly in terms of the compliance testing and filtering components that are required to pass it that goes into a commercial module. For hobbyist and embedded designs (part of a bigger design where the SMPS does not directly interface to external mains supply power outside if the enclosure) then maybe those costs can be ignored but if it's remotely near being a commercial product then, unless the quantities are high, buying a commercial module is usually much cheaper. An exception to this is if you want something a bit out of the ordinary.

But the starting point for any design has to be your Design Requirements Specification and from there the choice of regulator or controller devices to implement the basic design. From there your inductor or transformer requirements are derived. You can't really expect to design an SMPS around choosing the inductor or transformer first. Unless you're restricted to what you already have in the junk box and you're not fussy about the end performance. .. :)