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USB Cellphone Charger Circuit

Now you can charge your Mobile Phone from the USB outlet of PC. This simple usb cellphone charger circuit can give regulated 4.7 volts for charging the mobile phone. USB outlet can give 5 volts DC and 100 mA current which is sufficient for the slow charging of mobile phones.

USB Cell Phone Charger Circuit Schematic

usb mobile charger circuit diagram

Most of the Mobile Phone battery is rated 3.6 volts at 1000 to 1300 mAh. These battery packs have 3 NiMh or Lithium cells having 1.2 volt rating. Usually the battery pack requires 4.5 volts and 300-500 mA current for fast charging. But low current charging is better to increase the efficiency of the battery. The circuit described here provides 4.7 regulated voltage and sufficient current for the slow charging of the mobile phone.

Transistor T1 is used to give the regulated output. Any medium power NPN transistor like CL100, BD139, TIP122 can be used. Zener diode ZD controls the output voltage and D1 protects the polarity of the output supply. Front end of the circuit should be connected to a A type USB plug. Connect a red wire to pin1 and black wire to pin 4 of the plug for easy polarity identification. Connect the output to a suitable charger pin to connect it with the mobile phone. After assembling the circuit, insert the USB plug into the socket and measure the output from the circuit. If the output is OK and polarity is correct, connect it with the mobile phone.

Note: If the polarity is incorrect, it will destroy the cellphone battery. So take extreme care.

51 Comments

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  • Swapnil

    Dear Sir,

    I want to create a compact cellphone charger that will be able to charge multiple cellphones at once. I want this charger to be able to charge mobiles with different types of chargers.

    This charger aims at charging the cellphones while on long distance journeys(typically more than 5 hours), especially in trains. Can you please help me?

  • Soumen Mal

    (i)What is the function of capacitor in this circuit?
    (ii)Can I replace the USB port by a 6V solar cell?
    Please sir answer me immediately because this is my college’s project.

  • nas

    pls i am writing a project on mobile cell phone solar charger i dont know if you help me with some write up use it in chapter 2,3 and 4
    Thanks.

    Nasir

  • maria

    hi i am maria plz help me i am the student of 2nd year electronics i want to make a unnique electronic project pls guied me what should i do

  • Soumyajit

    Sir can you say that,the short circuiting in the circuit needed or not(which is shown in the diagram)between the resister r1 and t1?

  • ayat

    hi
    i was trying to test this circuit using cicuit maker but i didnt find the same transistor type , what can be replaced instead of this transistor.
    thanks

  • atique

    can this circuit be used with 6 volt dc supply and if not than what changes are needed.i want to design the mobile charger circuit with 6 volt dc INPUT supply and 4.7V output AND current around 200-300mA.PLZ PROVIDE THE CHANGES NEED TO BE DONE.

  • atique

    can this circuit be used with 6 volt dc supply and if not than what changes are needed.i want to design the mobile charger circuit with 6 volt dc INPUT supply and 4.7V output AND current around 200-300mA.PLZ PROVIDE THE CHANGES NEED TO BE DONE.

  • bhushan

    dear sir i am intrested to start manu of mobile charger unit so u can send same helfull informashion regarding how to manu… of mobile charger

  • vijaya lakshmi

    sir,

    shall we use a solarpanel in place of USB?

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