Electronics Projects, USB Power Boost Circuit article
"power electronic projects, simple circuit projects, " tagged with
Designed for high power consumption USB devices though USB Power Injector circuit draws high power devices designed accordingly happens adapter for different projects, but you may need this type of circuit. Computer to the USB port on the main board … 500mA from the 5V output is limited to 100mA (500mA in a new generation main board) for operation of the circuit necessary to use an external adapter or computer power supply +12 v output can be used
A bit complicated, is not used for 500 IRF9540 MOSFET switching relays and L7805 (5Volt regulator) on the PCB board layout and scheme and there.
USB Power Injector
Source: http://siliconchip.com.au/cms/A_102685/article.html USB Power Boost Circuit pcb alternative link: usb-power-boost-circuit.RAR alternative link2