Welcome to DIY electronic dot com,Im pleased to present simple circuit for your device or gadget in car . Including it is charger for those device . USB Power Supply and Charger We take IC regulator MAX603″ for reduce voltage from between +2.7 V and +11.5 V DC of battary to 5 VDC for USB standard devices. MAX603 (5 V output) and MAX604 (3.3 V output) First of all , Look at the picture below which show circuit diagram for this project. USB Power Supply and Charger Circuit How to this circuit work ,Voltage source 12VDC from car battary into circuit with diode for protect current direction and filter noise signal with capacitor before MAX603 in signal after that IC regulation process completely will send voltage signal (5VDC) to out pin and filter with capacitor .Output current 500mA maximum load. You should all be connected to ground, as they act as a small heatsink for the device. When laying out the PCB, place a ground fill under the regulator and connect these five pins directly to it. Picture below is show USB pinout diagram for you referent. USB Pinout Diagram We are looking for electronic parts. Part list 1.PCB 2.Wire cable 3.Diode 1N4044 4.Capacitor 10 uF , 2 pcs. 5.IC MAX603 6.USB connector .