LM2596
Slapped together this board using nothing but junk parts and some nice 3A Step-Down Voltage Regulator chips from TI. Blew the arse out of one feedback pin with a short and a CC supply on only 500mW.
You can get 10 modules from China for £6! "WTFlaygen hoy with the switching and the bloooyg'n zabble" - Prof. Frink.
Bet they don't have Coilcraft inductors