USB power socket using the car battery

Nowadays, many portable electrical appliances generally use USB ports as their power plugs. For example, portable reading lights use USB ports to charge their internal batteries. However, it is not appropriate for such small electrical appliances with large power consumption to use the USB port on a computer. In this regard, a USB power socket is provided here, which can use the 12V battery inside the car to power or charge portable devices that use a 5V USB port as a power source.

The attached figure shows a universal USB power socket circuit, which can safely convert the 12V battery voltage in the car into a stable 5V DC voltage. This circuit can power or charge any device powered by a USB power supply. The 12V power supply in the car is taken from the cigarette lighter socket on the dashboard.

The DC voltage from the cigarette lighter socket is connected to the three-terminal adjustable voltage regulator chip LM317L (IC1). C1 eliminates the noise in the input power supply. R1/R2 adjusts the output of the regulator to a stable 5V. This 5V is sent to the A-type USB female socket. The red LED indicates the output status. The voltage regulator diode ZD1 is used to protect the output from high voltage.