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You are here: Home / Battery Chargers / Timer Based Cell Phone Charger Circuit

Timer Based Cell Phone Charger Circuit

Last Updated on July 6, 2019 by Swagatam 44 Comments

A simple cell phone charger with timer circuit is presented in the following article, which could be used for charging a given Mobile phone for a specified predetermined length of time. The idea was requested by Mr. Saad.

Circuit Objectives and Requirements

  1. Could you design me this charger circuit ? Input 230V 60 Hz, and the output 3 USB port for charging Smartphones.
  2. What I need in this circuit is a Timer (Three sets of time), 30 mins, 60 mins and 120 mins.
  3. So I connect my phone to any of the three usb port and press (on/off) switch then the time start for example 60 mins then the power cut off.
  4. Hope you understand my request.

Circuit Diagram

Timer Based Cell Phone Charger Circuit

Circuit Operation

The proposed cellphone charger circuit with timer can be seen in the above figure, the design primarily comprises of an IC 4060 timer stage and a DC to DC multi cell phone charger stage.

The cell phone charger section is a standard LM338 based charger circuit, wherein the output is bifurcated into 5 individual charging outputs facilitating charging 5nos individual cellphones. From these outputs 3 channels could be utilized for the intended 3 cell phone charging, at a rate of 1500mAH each. The series resistors may be accordingly calculated using Ohms law, as given below

R = V/I = 5/1.5 =  3.33 ohms, 10 watts each

R2 in the LM338 circuit must be appropriately adjusted to achieve around 5V across the output terminals or across C2 terminals.

The timer stage is made up of the IC 4060 whose pinouts are also configured in its standard timer/counter mode.

P1 may be adjusted to get a delay time of around 120 minutes on pin#3, which would allow pin#2 to produce a delay of 60 minutes, and pin#1 a delay of 30 minutes.

Initially when power is applied across the indicated  mains input terminals, the cellphone charger circuit with timer does not respond and stays deactivated.

However, the moment the given push button is pressed, causes the N/O side of the relay to get connected with the other unconnected mains wire.

This momentarily connects the AC  mains with the transformer leads, which in turn powers the rectifier stage enabling a momentary DC supply input for the IC 4060 timer stage. 

This momentary supply to the IC 4060 stage activates the counting of the timer, and simultaneously produces an initial zero potential at the base of the relay driver BC557 transistor, switching ON the relay from N/C to N./O points.

As soon as this happens, the relay contacts now take-over the push-to-ON switch connections and allows the AC to flow through these contacts into the transformer primary.

This ensures that, now even if the push button is released, the circuit is able to get latched into the powered position enabling the LM338 to begin charging the attached cell phones and the timer IC 4060 to count the stipulated amount of time via the pot P1.

As soon as the counting of the IC 4060 gets elapsed, pin#3 (pin#1/2 whichever is selected) turns high, switching of the BC557 and the reverting relay contacts from N/O to N/C.

This action instantly switches OFF and disconnects the mains AC from the transformer, deactivating the whole process and bringing the whole system into its original standby position.

This cellphone charger timer circuit could be yet again initiated simply by pressing the push button for the next charging cycle.

Time Delay for the IC 4060 can be calculated using the formula:

f(osc) = 1 / 2.3 x Rt x Ct

where Rt = R2 +P1 (in Ohms)

Ct = C1 (in Farads)

Parts List

Resistors, All 1/4 watt 5%

2M2 = 1
22K - 1
10K = 1
1M = 1
120 ohms = 1
1M pot= 1
5K pot = 1

Capacitors
1uF/50V non-polar = 4
0.33uF = 1
470uF/25V = 1
1uF/25V electrolytic = 1

Diodes, 1N4007 = 5
Transistor, BC557 = 1
IC, LM338 = 1

Relay,12V/400 ohm = 1
Push button = 1

Transformer = 0-12V/5 amp

Output resistors as per the given formula

SHARING IS CARING!



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Next: 3 Smart Laser Alarm Protection Circuits

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

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  1. Search Related Posts for Commenting

  2. Hooman says

    Hi, thanks for your amazing website and all the effort you put into articles. Would you be kind and explore the QuickCharge or other similar protocols enabling chargers and powerbanks to deliver 9 or 12 volts? I’ve found only one person (embedblog.eu/?p=504) who has made the circuit himself and yet he did it with a special IC and considering I’m in iran and there’s little to no chance I can get my hands on a special IC or order it from china without spending a fortune on it I wanted to ask you to figure out if theres a way to implement the QC 2.0 or 3.0 with an arduino or an attiny85. thanks again and have nice day

    Reply
    • Swagatam says

      Hi, fast charging concept is not so difficult and can be implemented using ordinary ICs. It is just about applying high current at the initial stages until the battery voltage reaches a specific value, and then gradually reduce the current until the battery fully charged.

      3 Step Automatic Battery Charger/Controller Circuit

      Make this Fast Battery Charger Circuit

      Reply
  3. Stephen Hansen says

    I am tasked to oversee an electric motor-propelled feed pellet disperser that is powered by a 6V rechargeable battery (solar panel power source). The device performs well and delivers feed at intervals dictated by an existing timer. This timer is limited however, in that it can only actuate the feed dispenser for 1,2, … , or 6 whole seconds at a time; no fractions of a second allowed. I want to refine the feed intervals by programming to tenths of a second.
    I purchased a DROK timer relay. I programmed it to turn OFF for time “CL” (0.5 seconds) after getting a trigger signal, and then turn ON for 2.0 seconds time “OP”. Relay turns OFF after finishing timing.
    I checked all this out at home on a breadboard and the circuit (less the timer, of course) worked flawlessly using an LED load.
    I couldn’t get the circuit to work in the field! I am connecting the (+)BATT to the timer (default), but now interposing the preconfigured DROK between positive terminal and timer. I figure something is either amiss with my design, or I need to go into the newly fashioned wire connections/splices and replace solder for the wire nuts.
    I’d like to use the DROK and not home build a timer relay myself.
    >Could you diagram a circuit for me that I can use on this project?

    Reply
    • Swagatam says

      If you can replace the external timers with a single IC 4060 based timer, then probably you can achieve the desired results. A IC 4060 can provide 10 selectable outputs with each output having a delay 50% less than the preceding one, or vice versa. You can either get this in repeatable form or a one-shot latching manner.

      https://www.homemade-circuits.com/how-to-understand-ic-4060-pin-outs/

      Reply
  4. Farrel says

    Hi Mr. Swagatam, great circuit !
    Please help me to making timer and autocut off phone charger circuit (specialy with super tiny components as single 4060&0.1uf,thats awesome).
    Iam using fast charging (5-9V 1-3A) with indicator cable but im NOT SURE ITS SAVE after batterys full at overnight charging (i think thats bad for phone battery).
    What should i make to have 2 hour charging but can auto cut off even before time out if batterys full? Also please part list if theres any changes of existing components (for 2 hour timer)
    Thank you for your big help
    Regards.

    Reply
    • Swagatam says

      Thanks Farrel, All phones have built in state-of-the-art battery protection system with auto cut off so need of adding any external cut off circuit…but if you still want it then I can add it in the above article

      Reply
      • Farrel says

        Thank you Mr Swagatam.
        As we know is yes new phones are have built in auto cut off (I) feature..i just want to add that feature to next circuit that i make from both your design. Please contact me if you made it but i already sub your youtube channel&fb.
        Once again thank you a lot..

        Reply
        • Swagatam says

          Hi Farrel, you can try the second circuit from this article, the charger adapter’s mains 2-pin will go the points indicated as “load”:

          https://www.homemade-circuits.com/simple-triac-timer-circuit/

          Reply
  5. Jindro says

    Sir Good Morning!! could i ask you a image or schematics on what to do with unconnected pin of any IC?
    thank you very much Sir, im sorry to ask because i cant understand when you say it has to be connected to a logic level.

    Reply
    • Swag says

      jindro, the inputs of a CMOS IC such as which start with 74XX or, 40XX or 4XXX consist of logic gates in them, for example nand gate, NOT gates etc. When one of these gates are not used or are unconnected, their input pins should be terminated either to the positive line or to the negative supply line…in order to keep them stable.

      Reply
  6. Saad says

    One more thing, could you edit the design to be UK pluge type which contains 3 pins!

    Hope you help me.

    Thanks.

    Reply
    • Swag says

      the indicated transformer/switch wires will become the inputs for the 220V AC, and a 3rd earthing pin could be included which could be connected with the chassis or the enclosure if a metal enclosure is used, or simply with the body of the transformer.

      Reply
  7. Saad says

    Hello mr. Swagatam,
    Hope you are doing well.
    Would you kindly provide me with a software that I could use to design this circuit.

    Regards.

    Reply
    • Swag says

      Hello Saad,

      Do you mean PCB? Sorry I am not practically familiar with any PCB designing software that I can recommend, although you could find plenty if you search online

      Reply
      • Saad says

        I mean simulation software.

        Thanks for your response.

        Reply
        • Swag says

          sorry I do not use simulators, I simulate my circuits in my mind, and according to me the above designis perfect… just needs to be built and tested practically

          Reply
  8. dennis rollo says

    thanx.i will.

    Reply
  9. dennis rollo says

    how to calculate capacitor and resistor in transformerless power supply.thnx

    Reply
    • Swag says

      you can read this

      https://homemade-circuits.com/calculating-capacitor-current-in/

      Reply
  10. dennis rollo says

    hi swag.i have a rechargeable flahlight with capacitor of 584J 400V .it always puff up.it has no resistor across it.what value should i use.

    Reply
    • Swag says

      Hi Dennis, It is happening simply because the capacitor is a bad quality capacitor, change it with a good quality one, preferably from some reputed brand. because if it is rated at 400V it can never puff up. the resistor is not compulsory, it may be included to discharge the cap while it is unplugged from mians, to avoid a discharge shock to the user in case he touches the plug pins accidentally.

      Reply
  11. Dennis Rollo says

    thanx .hope u don’t mind me asking for electronic circuits because you are such a BIG HELP . i’m just starting to hook in electronics.till next request.god bless.

    Reply
    • Swag says

      you are most welcome Dennis, keep up the good work!

      Reply
  12. Dennis Rollo says

    hi swag,thanx for reply,what i mean was simple wifi signal booster antenna for cellphone or laptop using usb cable.

    Reply
    • Swag says

      Hi Dennis, it may be any related item but still it will require a lot of accuracy and calculations to build it…
      by the way I have seen that whenever I sit beside my wifi 4G device it becomes faster…it seems my body acts a like an antenna.

      Reply
  13. dennis rollo says

    and can you help me design a signal booster circuit for laptop and cellphone to boost internet and wifi.thanx

    Reply
    • Swag says

      sorry, I do not have this kind of circuit with me at the moment, and moreover designing such circuits can be really complex…

      Reply
  14. dennis rollo says

    hi swag.thanx for fast response.i just opened my email now since my last message to you. can you help me decide what is the best soldering iron wattage and soldering lead diameter to use
    in pcb’s.thanx

    Reply
    • Swag says

      Hi Dennis, I prefer the following type of soldering iron, It is a 25 watt soldering iron which is normally recommended for most sensitive and normal PCB soldering work

      http://www.dnatechindia.com/image/cache/catalog/Soldron_25Watt_1-500×500.jpg

      Reply
  15. Dennis Rollo says

    gud day swagatam.can u help me provide:
    1. a circuit for rechargeable battery operated soldering iron like ISOTIP with adjustable current to vary wattage from 30w to 60w with digital wattage display using 4.2v lithiun or 3.7v 18650 if possible.
    2.circuit for adjustable current to vary wattage soldering iron with digital watts display directly on 220 v. thanx

    Reply
    • Swag says

      Good day Dennis, you can accomplish it with a simple IC 555 PW circuit as shown below:

      https://homemade-circuits.com/2012/05/make-this-pwm-based-dc-motor-speed.html

      you can replace the motor with your soldering.

      I do not have a digital watt meter circuit at the moment, however you can use a digital ammeter which will allow you to get reading equivalent to watts…you can calibrate the meter range into watts…so basically it will show amps but the modified calibration will enable it to convert the readings into watts…as per my assumption.

      Reply
  16. shubham ingle says

    how to calculate the resistor and capacitor values for 4hours
    please provide me the formula

    Reply
    • Swagatam says

      what is your battery AH rating??

      Reply
  17. Sowpath das says

    Nice post

    Reply
  18. Saad Alghamdi says

    Great! Thank You.

    Reply
  19. Saad Alghamdi says

    Thank you Sir. Would you please provide me with the part list!

    Reply
    • Swagatam says

      Hi Saad, I'll try to update the info soon…

      Reply
    • Aindra says

      Hi mr swag..great timer circuit..i’ve few question.
      1. What should i do If i want to use it for timing my dc fan or my dc motor from 4.5v to 12v and using adaptor or charger (transformless, no relay) coz i want to make smallest circuit timer. maybe cut the transformer and give the (+) (-)voltage to the 470uf caps?
      2. If i need that voltage range, are there any component to be replace?
      3. I still dont understand at the output. What you mean are few usb output arrange by pararel right?.

      Thank you mr swag, you are my big help

      Reply
      • Swagatam says

        Hi Aindra, the above circuit is intended for charging cellphone, if you want to control only a motor in that case you wouldn’t this complex design, rather you can use the last circuit from the following article:

        https://www.homemade-circuits.com/how-to-make-simple-timer-circuit-using/

        You can replace the relay with a power transistor such as TIP31, depending on the motor rating. use a 470 ohm for the base of the transistor, and make sure to connect a freewheeling diode across the motor.

        Reply
  20. Saad Alghamdi says

    Ok. Thanks for the help.

    Reply
  21. Saad Alghamdi says

    Would you please add it for me.
    Sorry for bothering you.

    Reply
    • Swagatam says

      Saad, you will have to practically check and identify which pinout of IC 4060 gives the required pulses equivalent to seconds or minutes…but before that you will need to build the 4033 counter circuit successfully….

      Reply
  22. Saad Alghamdi says

    Sir, Thank you for the design.
    Can you add LCD screen showing a Digital countdown of a certain time!

    Reply
    • Swagatam says

      You are welcome Saad,

      You can add the following design for counting the pulses from one of the outputs of the IC 4060 which may be corresponding to seconds or minutes

      https://homemade-circuits.com/2013/11/cascading-ic-4033-in-multiple-digit.html

      Reply



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