High power 5V for sparkfun gap igniter

I've created an fire-spitting dinosaur.
Works cool but I need a higher power 5 v supply.
It runs on a 12V battery, but for the spark i'm using a 230V supply reduced to 5V by a transformer. (sparkfun gap igniter == cool!!!)
How can I reduce the 12V to 5V 3Amps!
I've tried an 78T05 but that one fried after a couple of seconds.

You need a switching regulator or DC to DC converter.
There are lots to chose from either chip

or as a built module

These are just the first examples I found through google.