Power bank now becomes the necessity of every person who is using smartphones, but in our market, if we are going to buy a power bank, then at least it will cost Rs.1000.So if you're a geek hobbies and you and to have a power bank then this tutorial is for you... so let's start. 

Parts Required:-
  • 5 * lithium ion battery(2000 mAh)
            To Buy Some of these Battery go to this link:-
  •     DC-DC Voltage Automatic Booster Module:
              To buy this Product Go to this Link:-
  • Lm 317
  • Led * 2(For Indicator), Mutka White Led For Flash Light
  • 5k Potentiometer
  • 1 * 240 Ohm, 1 * 480 Ohm Resister
  • Dc Switch * 2
  • 1n4007 Diode:
  • Dc Female Socket, Or you can use Micro USB Female
  • Wire, Tools, Vero Board, Etc..
Final Schematic:-

  1. First Of all, we will make theCharging circuit So lets Start:-
  2. At first insert, the lm371 in the Vero board then connect a wire to the V input pin of the Lm317.
  4. Now Connect the IN4007 Diode to the Volt Pin of the Lm317
  5. Now connect 240 Ohm resister in between adj pin and Vout pin of the Lm317. 
  6. Now insert the 5k potentiometer in the Vero board and connect Adj pin of lm317 to the potentiometer as displayed in the Schematic below 
  8. Now connect a wire to the 5k potentiometer( like the schematic )below ) which will act as the   GND input for the Circuit
  9. Now Solder a 480 Ohm Resister to the -ve pin of an led, the connect the +ve pin of the led to the Vout Of the Lm317 before the IN4007 and -ve pin to the GND of the circuit as Connected in the below Schematic.
  10. Now Connect a switch after the In4007 diode which will on /off the charging...
  11. Now connect 5 2000 mAh Lithium Ion Battery parallel, then make a common Vcc and Common GND pin.
  12. Now Connect the Vcc, After the In4007 and before the Switch, And connect the GND of the battery pack to the GND of the Circuit.
  13. Now Connect the DC-DC Voltage booster to the Circuit As connected in the Schematic below...
  14. Now check the Voltage Output of the Booster using a multimeter, it may Show you 36V.So it is your job to reduce the voltage by using the Potentiometer Mounted on the Booster module.
  15. Now Connect the USB Female's Vcc , GND to the Vcc out and GND out of the Booster module .then connect +ve strand of mutka led to a dc switch, then connect the other end of the switch to the Vcc of the Battery, GND Pin of the Mutka led to the GND of the Battery Pack.
  16. Now make a box for the Power bank, And insert all the thing in their according to your conveniency, One check the Final Output voltage from the power bank before connecting to the mobile phone because high voltage may destroy your phone.And test and enjoy the Power Bank...
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