By using this circuit we can charge nickel – cadmium battery through USB port available in computer. Here the DC supply voltage (5volt) taken from USB port (Red wire +5V and Black wire GND), the green LED connected with R1 resistor is to indicate the supply. Diode D1 protects reverse polarity supply, take extra care on battery polarity while connect with this circuit.
[stextbox id=”warning”]Do not connect single battery, don’t connect battery in wrong polarity.[/stextbox]