Here is circuit 8V 1A Switching power supply, Use IC LM2575.
Input Volt 10V-40V DC only.
This Citcuit to become for Car or motorcycle,Use Volt 12V-14.4V 2A.
And Volt Output 2.3V-37V change by R1,R2
Detail see in image circuit and PCB.
Source:
http://www.ngc.pe.kr/bbs/zboard.php?id=data_others&no=28