CarPowerSupply

intro

in high school (~1997) i got a cheapo CRAIG cdplayer that had a car adapter and one of those tape adapter things for about $20 (that wasn't a lot even in those days). the tape adapter crapped out years ago, the cd player still works (yeah i still use it) but since my car has a cd player in it, i've had little use for the power supply. of course i hung on to it on the off chance that i would need it eight years later...

the hack

turns out there was little more than a huge heat sink inside. this shouldn't be too tough...
	what the f? absolutely no filter, not even a small cap...
after examining the circuit i've decided to modify the circuit board to take a LM1086 3.3V, 1.5A regulator. while i'm at it i'll through in some filtering caps for good measure.

always read the spec sheet first! i made an incorrect assumption about the pinout of the lm1086 - now i've got the legs all bent up and have to reinstall the heat sink upside down...

luckily the now upside-down heat sink shorted 12V to Gnd when the case was screwed back together... a bit of electrical tape later i have a nice power supply for my gp2x. now i can watch movies or play games while i'm driving home from work...

outro

This is really all there is to it. This is a very simple power supply and is by no means the best. Since I am dropping 12V down to 3.3V and drawing over 500mA the heat sink gets pretty warm and without a heat sink I could cook an egg on the LM1086 (no really). Just be sure that your input voltage can source enough current for the GP2X and you should be good.

-- ChristopherPepe - 29 Mar 2006