How do I get a negative 5V and negative 12V from a car battery?

I built an mp3 player to go into my truck and I have to use an expensive powerinverter. what seems stupid is the truck already provides DC power and the motherboard requires DC power, so why use a power inverter and the power supply? I'll tell you why.....b/c I don't know what else to do. So if anyone could help would be appreciated!!!!




  • Yes, your truck has DC power - but, it is not just 12VDC it can sag much lower and peek much higher. In order to use it you will have to build a power supply that will take this 12VDC, filter it and convert it to the levels you need. A quick and dirty way is to use 3-terminal regulators (available at Radio Shack). The next step up from that would be to construct a system utilizing potted power moduals - these are actually miniature DC-DC converters.

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