Now the charging of your mobiles has been made easy with the help of USB outlets present in the Laptop and PC. For the charging of your mobile phone, this circuit provides you a regulated voltage of 4.7 volts. 5 volts of DC voltage and 100mA of current is being provided by the USB outlet which is well enough for the mobile phone charging slowly. We can use this circuit to charge the mobile while we are in journey also. So, we may treat it as Mobile Phone Travel Charger Circuit.
The USB port of the mobile is used for the charging, as the USB port is the very helpful voltage source that can charge the mobile. Nowadays, there are two to four USB ports on the laptops that are available in the market. USB actually refers to Universal Serial Bus. It is one of the newest incarnations of method which is used to get information in as well as out from your computer. We are concerned at the fact that ±5 volts of power is being provided by the USB port to the external devices and can avail at the pin number1 while on pin number 4, it is 0V. Till 100 mA of current can get from the USB port which is more than sufficient that we required for this small application.