yeah, good old TL494
![Tongue :P](https://www.eevblog.com/forum/Smileys/default/xtongue.gif.pagespeed.ic.J5mTe0A2NA.png)
Assuming you want mains input you could probably source the high frequency transformers from a junked modern ATX psu.
Modern ones have dual 12V rails, so repurposing the transformer with the windings in series for 24V should be possible.
I don't really recommend using the ATX psu, or modding it, but rather recycling some of its parts.
Transformers, fets, mains input section etc. and building a new powersupply.
(A midrange ATX supply isn't really designed for 24A at 12V continuously and the noise maybe too much depending on your intended application)
But in terms of effort/time yeah, as you have posted, a 50hz transformer + bridge rectifier for 24V unregulated DC would be much easier to build.