This is the most easy and simple way to make a power bank.
There's only One major component. Without further delay lets begin.
Step 1: Parts
1. IC 7805 Voltage regulator IC .
2. 9v battery.
3. 9v battery connector.
4. Usb cable
And that's it.
It will be rechargeable if the battery is rechargeable. Both the rechargeable and non rechargeable batteries are available on market.
Step 2: The Circuit Diagram
This part is too easy too. I've cut the long legs but that's not mandatory. Then soldered the wires as the circuit diagram . Then hot glued them to secure the connection.
This IC supplies 5v 0.5 Amp of current which is slow in some cases but if you want to make it faster just coonnect another IC in parallel then the output voltage will be 1Amp.
Step 3: DONE !!
Congratulations, you are done making this. just connect a 9v battery and then connect the usb cable to your phone. Thats it. VOILA ! It's working.