Transisor questions

I figure this is the best place to ask this. I want to use a 5v pwm signal to control a 12v power output. I want to be able to control the output voltage with the pwm from 0 to 12. From my old days when I learned dc fundamentals I can 't remember how to put together this circuit. Do any of you know where I could find a diagram or know how to build what I need?

Google: circuit to control 12v with 5v.

You'll get lots of links including some commercial products

Thanks, that gives me some ideas. I was also thinking of using a mosfet. my output is very low I, driving a gauge so I don't need anything very fancy.