sure what do u recommend transformer or some other way
Thanks
regards
I second the opinion that others have given you.
The first time one builds an electronic circuit, one must build and troubleshoot a far simpler version. To learn how buck converters work, you could build yourself something that would regulate 12 to 24 volts down to 5 volts at 1 amp. This is a very useful little supply that will allow to power your digital projects from a vehicle.
Then you can tackle more challenging projects.....and you'll very soon find the limitations of simple topologies.
For instance, at the current and voltage levels that you are looking to regulate, a simple buck will not cut it. For those higher power units, one must use either a push-pull or full bridge topology. If one must use a buck, then an interleaved multi-phase buck is required.
And indeed, using an isolation transformer while you are troubleshooting is a must. Power supply engineers use them all the time in conjunction with a Variac. Of course, if one has got the money, an AC source is the way to go.
I like designing power supplies, and can help if you are serious about them. For starters, I would STRONGLY RECOMMEND getting yourself a good power supply design book. Abraham Pressman's book is a classic, and you can find them used both at ebay and amazon.
EDIT: you can also read the many app notes that IC companies provide on the web. I've found the app notes from OnSemi and TI (Their older ones) to be the most enlightening.