Today I designed and made step-down converter with pins like the 78xx stabilizers have. So it's perfect for breadboard design or replacement for 78xx stabilizer. Unfortunatelly it's using small SMD inductor so it cannot give you more than about 350mA. But it can handle the input voltage to 40V and don't get too hot like linear stabilizers. So no need for cooling :) You can use online calculator to change output voltage or change values of parts so you can get higher current.