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    For the cell phone to charge, charger output must be above 4V and can deliver a maximum current of 500mA. This charger circuit will step up the voltage from 1.5V to 5V DC to reach the cell phone charging requirement. The circuit uses only an AA or AAA 1.5v battery (1V to 2.4V). The charger is composed of simple oscillator, a rectifier, and voltage regulator. This is similar to the Joule Thief circuit.

    The feedback winding F is composed 5 turns of #30 AWG magnetic wire and main winding P is composed of 6 turns of #24 AWG wire. The 5.1V zener diode and 2200uF capacitor regulates the output voltage to ensure proper charging.

    The windings are not critical, you can experiment using different number of turns. If ever the charger doesn’t have any output, try to reverse the winding connection.

    Cellphone charger circuit schematic

    circuit schematic of the cellphone charger using 1.5V battery

    My opinion is that this can charge the cellphone battery only for short period of time because the 1.5 volt battery power capacity is much lower than the phone’s battery.

    This article was received from Subham Chatterjee. Thank you!

    ask a question

    51 Responses to "Cell Phone Charger Using 1.5V Battery"

    1. I believe that this is useful for experimentation only. Another major drawback is the that voltage regulator (zener) will continue to soak up power when the battery is fully charged thus fully killing 1.5V source battery.

      Perhaps useful for emergency mode charging when no AC/DC/USB power is available.


    3. I believe that this circuit will work, the problem lies on the source, the 2.4 Vdc battery, as the source battery is depleted, the voltage will drop according to the load demand, and eventually the oscillator will fail to oscillate. when the potential between the source battery and the lithium battery being charged equalizes,(not considering the internal charging circuit for the mobile phone), then charging will cease.

    4. ENGR. AGU ELIAS OKWUDILI says: on July 4, 2012 at 10:32 am

      Cesar is correct, the voltage value of the source battery and the zenar diode need to be changed.

    5. Did I miss it or was there a material specified for the transformer.
      Is it air-cored or on a ferrite?
      If on a ferrite, what profile and what grade?

    6. terns are too less it will just short the battry try more turns to improve the life

    7. Yes of course the Dry cell from which you would charge the cell is used in emergency where these cells would be easily available and power not available to use chargers.

      This is similar to a joule Thief.
      The Biflar Torriod will provide the boost voltage.

      I agree that the 2222 would be a better choice of Transistor,

      For similar projects and Voltage doublers do write to us we provide kits. with PCB’s and components.

      • karsang dorji says: on July 10, 2012 at 11:31 am

        i am interested to buy the kids, PCB and components of above project, so please give me price list and the mode of purchasing the item form you.


    8. GERHARDUS JOHANNES STROEBEL says: on July 5, 2012 at 1:52 pm

      Rather make this for a D size battery otherwise excellent idea

    9. It will work somehow for sure.. transistor is enough good and zener too but 4001 diode is too slow, affecting efficiency… better a 4148 or even a schottky one

    10. sir can u please explain the design of it?
      why the circuit design has to be like that only

      I needed the complete information.

    11. hi,
      i am going to do this as a mini project. so please could you explain it?

      • Ivor Cadiramen says: on July 12, 2012 at 3:04 pm

        Hi Gayathri,
        Going through the comments, I find that you are very much like me – a new student to the subject. I have just started building such projects and would love to correspond with you on this.
        Could we share circuits that we have tried and tested.
        best Regards

      • GAYATHRI says: on July 16, 2012 at 4:26 pm

        thanks alot i hope u will help me

    12. I built the circuit, it seems that at 1.4 volts the circuit stops oscillating, and starts to load the supply battery thus depleting it further, and stabilizes at .75 volt. The mobile phone never achieved the 15% charge, however with a 4.2 volt single cell lithium polymer, as the supply battery the phone achieved a good over 50% charge, and continue to oscillate with a load current of 8 mA. , however I terminated the process, for fear of damage to the lithium cell below 3.2 volts.
      In this exercise, the internal charging circuit for the Nokia N71 was not taken into account.

    13. my circuit use 12VDC,,, 500mA,, how many cell battery should i use??

    14. where to connect +ve and -ve terminal power supply

    15. i cant produce 3v.. only 2.7V.. used 3v battery, 2222 transistor and 8v zener.. how does the coil or metal wire works?

    16. is it okay if the zener becomes hot?

      • Yes, this means that the circuit is generating more voltage than necessary. This will discharge the battery quickly. Try removing 1 or 2 turns from the P winding and see if the zener runs cooler.

        Circuit efficiency may be improved by winding the turns on a ferrite rod. That way the saturation characteristics of the ferrite will reduce the current at which it switches.

        With an air core, the switching does not occur until the transistor is “maxed out” at a high current where its gain is significantly reduced.

    17. thanks.. its working now.. the cellular phone starts indicating that its charging..

    18. what should i do,i have put this on the pcb then the transistor is releasing heat and no output can be obtain please help me asap.

    19. This is another circuit which I think has not been tried out.
      Consider this:-
      1.One Transistor
      2.One Resistor
      3.One Rectifier diode
      4.One Zener Diode
      5.One Transformer
      6.One 470uF Capacitor
      7.One 2200uF Capacitor
      8.One PCB
      These eight components are used in this circuit to charge a mobile phone battery.
      I would like to present here an amazing circuit, a miracle of electronics, which shall charge a mobile battery much faster, more efficiently ie.without any losses and fully utilize the reserve power of the charging source!
      Here it is:
      Take three cells, any size, but bigger the better. Connect them in series. Take out the positive and negative wires and feed them to your mobile phone charging port and watch your mobile battery get charged! All the 8 components in the above circuit becomes redundant. If you find that the mobile battery is not charging, you may even add another cell. The main charging functions are all controlled by the internal charging circuitry of the mobile phone, you only need to supply a DC power ranging between 4.5V to 6.0V, that’s all. Please do not waste your time in building this circuit for charging you mobile batteries, but you can use this circuit to light white LED’s, since this is simply a “Joule Thief” circuit, of which you will find plenty of variations in the internet.
      Now I shall discuss why this circuit is not optimum in design:-
      1. The 1.5V after boosting to 5V will not be able to supply enough POWER to the cellphone battery, the current will be in milliamperes, which is peanuts for a 800-1200mAh li-On Battery.
      2. Secondly, the charge content of a single AA battery is so less that even if you are able to transfer all the power of the battery to your cellphone battery, the cell phone will be able to operate maybe 5-10 minutes at the most.
      3. This circuit basically produces short, high voltage spikes (which may go up to 20V), and most of the power will be absorbed by the 5.1V Zener diode, and whatever is left behind will be available to the cellphone battery, what a wastage of power!
      4. The 2200uF capacitor on the output is overkill. This type of circuits produce high frequency AC output, and even a 10uF cap is more than enough to filter this high frequency ripple.
      Now here are my suggestions for improving this circuit for lighting white LED’s.
      1. Remove the 470uF and 2200uF capacitors, they are not needed.
      2. Add a small polyester capacitor of value between 0.001uF to 0.01uF between the base of the transistor and ground (emitter). This will immediately increase the brightness of the LED and also reduce the current consumption of the circuit at the same time. Please experiment with the value since the optimum value depends on the inductance of the transformer windings.
      3. And lastly, if possible try to use a Schottky diode in place of the 1N4001 diode, this will further improve the efficiency of the circuit.
      I hope my suggestions will be helpful for all the experimenters.

    20. i am new to this…what is feedback winding..how to prepare…i cant get it in shops sir..

    21. hello sir

      ya curkit kaam to kar raha hai. par mobile charg nahi kar raha. karant ruk ruk ka jata hai. 1020mah 3.7v 3.8wh nokia

    22. Can you tell what change to make for 9v battery ? 9 v will give more power for charging than 1.5 v smaller version

    23. Also want to add LED on until fully charged, after that should be off

      • Hi Heena, the normally available 9V battery will not give you enough POWER to run your mobile for any length of time. You need a really BIG battery to use with this circuit. Nowadays batteries for charging cell phones for emergency purposes are available, these are called Power Banks, you can check in any online shopping website. They are huge batteries. So I think you should forget about using this circuit for charging your cell phone. Please read my detailed explanation of September 28, 2012 above.

    24. can this circuit funtion if i put a solar cell. the solar cell is transistor 2n3055 (12pieces)

    25. Sir Mitra, can this circuit funtion if i put a solar cell. the solar cell is transistor 2n3055 (12pieces)in series connection ?

      • Sir Jayson, were you able to work on your project which uses a 2n3055 transistor as solar panel to charge a cellphone??? I’m working on the same project. Your help will be very much appreciated. Thanks.

    26. can any one help me .. what is the voltage of the 2200uf and 470uf .. tnx in advance for the answers ..

    27. what is the diameter or size of the tube where to wind the magnetic wire ?

    28. where is the negative input point?

    29. what value if PF in this circuit

    30. Pls I bought a battery bank,but it no longer charges my phone,,,,but it lights an led what do I do?

    31. Salutare la toata lumea . Acest articol este ideal .mai bine de asa cred ca nu se poate . Oare daca se pune un Darlington (EX. BD678a ) se va mari tensiunea de iesire ? (evident ar creste si curentul ).iuliu19

    32. Subham Chatterjee says: on August 20, 2015 at 7:35 pm

      hello, i designed this ckt.I made it at my home. if we change the zener from 5.1v to 8.1v the output will not come & the source battery will drain out with in few minutes.
      the 5.1v zener is suitable to charge mobile phone. I agree with Mr. SAGAR SEN that the transistor may be changed into 2222.
      battery supply you may give 1.5v to 3v.

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