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

78 thoughts on “Mobile cellphone charger”

  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 🙂

    1. Ican not understand what the imprtant of thies project?
      Ican charge my mobile with battry 9v without thies circuit .Ihave just tried . please Ineed more information.

  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

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

    1. 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

      1. if we will put a rechargeable battery instead of AA cells and if we want to charge that rechargeable battery….what should be done??????

  3. 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….???

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

    1. 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.

  5. 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..:-@

  6. 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.

  7. 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

    1. 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.

  8. What happen to the circuit if the battery is fully charged? Does it stop charging the battery? If so, how does it happen?

  9. If i use connector at the output for a available handset. It can charge the cell? Without connecting positive,negative terminal to the battery instead i can use connectors. Yes or no.
    Please replay….

  10. Hi

    I want to remove the battery and ON button of the mobile and will connect the mobile with the USB power, and the mobile has to be ON when the USB is powered-on and it must be OFF when the USB is powered-off.

    Please let me know how to do this.


  11. i implemented the ckt on breadboard….the problem that i am facing is that when the mobile/load is not connected it gives constant output voltage….but when the load is connected the output changes constantly like 5v for one second n den 3v for one second….what it does is that it prevents the mobile from charging continuously…..can you plz tell me wat the problem is n how i can fix it….

  12. Hi nice work you have done, i want to use this circuit with Solar cell to charge mobile of Tab-late battery.
    Is their any modification required? and how much current is need by the circuit?

  13. i used 12v supply,iam getting output current as around 60uA ,for P1=P2=20K,plz say the values of P1,P2 for 100mA-200mA output current,i tested in TINA

  14. can you please send me a picture of layout of this circuit on a pcb….
    and a final pic of this project that how it looks…

  15. Can I use the same circuit to charge cellphone using my bikes battery 12V ???? or is thr will be any issue of higher current rating of the bikes battery…Pls reply asap.

  16. Gud a.m, hapi new year sir, about this cellphone charger circuit, i’ve construct it but wat hapen is dat i use 9v battery and when i test it , it display charging and after some secs it cut off and display battery not fully charger and after a secs it conect again and later disconect dats how d circuit does often and often, is it dat the 9v batery does’nt hv the capacity to boost it or wat? or is it compulsery i must use 12v batery?

  17. we have to improve this project like the speed of charge caring have to increase more i thought to efficient it more

  18. Hi Friends ,
    I just want to know about that any one is here to know about IEC : 60950 / IS : 13252 .If any than i want to discuss on this . Please contact .

  19. What if I am taking power input from USB, that outputs at 5V. Can I remove the zener diode from the circuit then?

  20. So from what I understand this circuit will charge lithium polymer based batteries and will not overcharge them once they reach their nominal voltage? Also, how would I change VR1 and VR2 if I wanted to output 8.4V at 350-370mA?

  21. is it working properly??????…….and if i want a to charge a iphone…. will it??????…is the potentiometer compulsory…..?????plzz reply

  22. hii instead of using ne555 timer we can use anyanother 555timer and i want working about this circuit plzzzz@@@@@

  23. hey.
    it isn’t working..:(
    i made it. the LED is glowing but it isn’t providing voltage at output..:(
    some one please email me it’s PCB or Connection on Bread Board.
    my Email is
    I shall be very thank full to him/her.

  24. Hi, I’m trying to use this circuit with a school project and I was wondering if you could explain the use of the capacitors in the circuit? Thank you 🙂

  25. Instead of 12 v battery my phine is charging at 5 v only with the use of this ckt . it is not give output & at 12 &9 v .the error is over charge occur.. So i can continue with 5v it is correct or not ?

  26. Sir is it safe for mobiles My superior says that it may harm ur mobiles after some days is it good and safe for mobiles

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