I took apart a car charger today

[lebevti]

...and all it was was a simple buck converter, with a IC chip used as the switch and control circuit

it steps down the DC voltage in your cigarette lighter to 5 V

i had to break open the black case with a hammer

boy they squeeze a lot of components onto a small PCB...probably not more than 2 square inches of area

there was also a 1.5 A fuse in there that would connect to the cigarette lighter end

 

[Diver300]

On many of those the output voltage is set by a potential divider, and it is quite easy to alter the ratio if you want a different voltage.

 

[Blueteeth]

MC34063A by any chance? those things get everywhere

 

[lebevti]

yes exactly, that was it