need 12v dc down to 5v 2 amp,

I've looked and looked to find something to power a portable usb drive in my vehicle. My stereo powers a flash drive but wont a portable drive.
I bought a lighter style adapter--it worked for a couple months an the output changed just enough it creats a power error. The drives AC adapter takes it down to 5v 2 amps DC.
While it was working-- it was pretty awesome, 160 gigs of music.
I hooked up a power inverter to power the AC adapter but thats a pain in the neck,, really bad when you forget to unplug it(the battery is dead)

Anyone know of a device or a way to make a little curcuit board to do what I need?
Cant believe its something I couldnt find on the web. Seems like it should be easy OR Im not asking the correct thing.

You should be able to simply use a 5V regulator such as the NTE1934 which regulates up to a 30 DcV input to a 4.9-5.1 DcV output with a current up to 2A.

You might consider a 1N4734 5.6V zener after the regulator to protect your devices from overvoltage and be sure to add a fuse.

Many cellphone 'cigarette lighter' chargers put out 5vdc.

Avoid Motorola they are not. Samsung are 5 vdc. Two amps might be a challenge. Go for 3G phone charger which is more likely to put out up to 2 amps.

Probably cheapest and fastest solution.

Thanks All

I give these a try and post results]Thanks.

for 5v from 12v you can go for voltage regulator(7805 ic) & then using buffers you can achieve desired current magnitude.