Mobile cellphone charger

While travelling charging of mobile battery is great problem because power supply source is not generally accessible. Here is a simple project using very common electronics components for charging mobile battery using AA cells.

Circuit descriptions of mobile cellphone charger

The main part of the circuit mobile cellphone charger is timer IC NE555, used to charge and monitor the voltage level. IC1 get control voltage to pin 5 by zener diode ZD1­. Threshold pin 6 and trigger pin 2 is supplied with a voltage set by VR1 and VR2 respectively. The trigger pin 2 of IC1 is below 1/3VCC when discharge battery is connected to the circuit as a result flip-flop of IC1 is switched on to take output pin 3 high. The process is reversed when battery is fully charged of charged battery is connected. Here transistor T1 used to enhance the charging current from output pin 3 of IC1. Adjust potentiometer VR1 and VR2 as per require.


LED status for different charging conditions

Load across the output

Output frequency (at pin 3)


No battery connected

765 kHz


Charging battery

4.5 Hz


Fully charged battery




Resistors (all ¼-watt, ± 5% Carbon)

R1 = 390 Ω

R2 = 680 Ω

R3 = 39 Ω/1W

R4 = 27 KΩ

R5 = 47 KΩ

R6 = 3.3 KΩ

R7 = 100 Ω/1W

VR1, VR2 = 20 KΩ


C1 = 0.001 µF (ceramic disc)

C2 = 0.01 µF (ceramic disc)

C3 = 4.7 µF/25V (Electrolytic )


IC1 = NE555 timer IC

T1 = SL100 or any Medium power general purpose NPN transistor like: 2N4922 , 2N4921,2N4238, FCX1053A

ZD1 = 5.6 V/1W



SW1 = On/off switch

1.5V*8 AA cells

Mobile connector

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  1. hii ur projects are good vr tryin mobile cellphone charger in tat mobile connectors is been specified wat kind of mobile connectors to b used can u clear please :) thank you :)

  2. @agasthya
    it is a universal mobile charger so u can connect any mobile connector..for example..if u want to build a charger for nokia then u have to install a nokia pin or if u want to connect a sony ericsson mobile u can install sony charger pins at the output

  3. ajay durgude says:

    can we make a wireless phone charger ,if yes then tell me the processor

  4. to which type of mobile ,this circuit can be used for charging

    • you can charge any type of mobile battery! And you have to change the value of zener diode according to battery voltage.

  5. plese explain me how values of zenar diodes can be varied according to battery voltages

    • I mean if your battery volt is less then 3.5V then you have to replace zener diode ZD1 with appropriate value i.e. 4.2Volt

  6. hi i am doing my first project can u help me to judge a title

  7. please explain the working of this circuit

  8. hi..just want to ask..the voltage supply in your circuit is only 12v, how long that will last?

  9. can i get the abstract and introduction about the same above…

  10. dastan triphon says:

    am trying to make universal one but for laptop , an u help me

  11. I just want to ask u dat the switch that is mentioned in the circuit diagram so want kind of switches can we use for this circuit and r these easily available if yes then wat do we have to say fr the same….???

  12. can u please xplain the working of this circuit

  13. please tell me total cost of this charger..nd if we connect it with a electricity then what type of change needed?


  15. i want a full report on this mobile charger. (pdf)
    where can i get it?????

    • I am not sure about that!
      You cannot find a pdf report in our site ; And I also doubt that you can find it anywhere online.
      But with some simple online research and this article you can for sure create your own PDF report.

  16. Any Hussain says:

    It came @ the right time

  17. Any Hussain says:

    If we dont get a SL100 transistor than is there an equivalent trnasistor that can be used…??

  18. aditya kumar says:

    hey hi….,
    cn u explain me…
    if the battery is discharge which v connect in this circuit…..
    then how cn i charge this battery…
    do reply a.s.a.p..:-@

  19. Anisha Rajput says:

    Can we use a battery of 9V instead of 12V without changing any other values? And can we keep C1=0.1uF??? Will it work?????????
    Please reply as soon as possible.
    Thank you.

  20. I tried to make this project but led is not blinking when battery is connected.I used 9 V battery.Battery is 3.7 lithium ion battery. I took VR1=VR2=20k and Zener diode of 5.6V.Plz help asap

    • The factors that determines the working of the circuit are:
      > Setting VR1 and VR2 by rotating it to limit output current.
      > Many of the cellphone batteries contains three terminals , one for common or ground , one for charging and discharging and one for sensing , So making sure the output is connected to correct terminals.

  21. Where is the connection for
    the 7th pin of the ic ????
    Its not marked in the fig….

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