/diy/ - Do It Yourself

>>2539601
>I'd like to design a switch mode power supply to convert 120/240V AC to 5V dc.

why?
every home has 10 unused phone (etc) chargers that already do that.
if not, you can buy an arm-full at the thrift store for $5.
if you're gonna expend some effort, make it unique and fun, like an orgasmatron or an upskirt camera.