Wireless Power Transmission Mobile Charger Circuit Using Inductive Coupling

Project by
Mepits

Technology is one thing that keeps on changing to make life simpler. But, let’s take the case of charging a device, for decades, we still confine to the old traditional style of wire system. Think of a device or a system that can charge up multiple systems without all those snake-look-alike wires. The solution is to go with wireless power transfer using inductive coupling.

Wireless Power Transmission using inductive coupling, is one of the effective ways to transfer power between points without the use of conventional wire system. Wireless power transmission is effective in areas where wire system is unreachable or impossible. The power is transferred using inductive coupling, resonant induction or electromagnetic wave transmission depending on whether its short range, mid-range or high range.

The goal of this project Wireless power transmission mobile charger circuit using inductive coupling is to charge a low power device using wireless power transmission. This is done using charging a resonant coil from AC and then transmitting subsequent power to the resistive load. The project is meant to charge a low power device quickly and efficiently by inductive coupling without the help of wires.

Block Diagram Explanation of Wireless Power Transmission Mobile Charger Circuit using Inductive Coupling:

block diagram of wireless charger

Fig1 : Block Diagram of Wireless Power Transmission Mobile Charger Circuit using Inductive Coupling

 

In this project, the wireless charger works mainly on the principle of inductive coupling. With this inductive coupling idea, we are trying to transfer power wirelessly to charge low power devices, such as mobile phones, cameras, wireless mouse etc.

From the block diagram, it is clear that for the overall functioning of wireless charger circuit, it required a wireless power transmitter & a wireless power receiver sections.

The transmitter coil in this wireless power transmitter section converts the DC power from an oscillator to a high frequency AC power signal. This high frequency alternating current, which is linked with the wireless power transmitting coil, would create an alternating magnetic field in the coil due to induction, to transmit energy.

In the wireless power receiver section, the receiver coils receives that energy as an induced alternating voltage (due to induction) in its coil and a rectifier in the wireless power receiver section converts that AC voltage to a DC voltage. Finally this rectified DC voltage would be feed to the load through a voltage controller section. That is, the wireless power receiver section’s main function is to charge a low power battery through inductive coupling.

Working of Wireless Power Transmission Mobile Charger Circuit using Inductive Coupling:

This project has mainly two sections, wireless power transmitter & a wireless power receiver sections. The Transmitter section of wireless charger circuit consists of a DC power source, oscillator and a transmitter coil. A constant DC voltage is provided by a DC power source, and this DC signal is the input to the oscillator circuit. This oscillator converts this DC voltage to a high frequency AC power, and is supplied to the transmitting coil. Due to this high frequency AC current, the transmitter coil energizes, and generates an alternating magnetic field in the coil.

DC power Source: It consists of a step down transformer that step downs the supply voltage to a desired level, and a rectifier circuit to convert that AC voltage to DC signal.

Oscillator Circuit:  A modified Royer Oscillator circuit is used in our project. With this circuit we can easily achieve a high oscillating current for the transmitter coil.

The oscillator circuit used in the Wireless power transmitter section is given below.

Transmitter section circuit of wireless charger

Fig 2 : Transmitter section circuit 

 

Wireless power transmitter section :Here in the transmitter circuit section, we uses two N channel enhancement power MOSFET (IRF540 – Q1,Q2 ),Two chokes (L1 & L2) , capacitor C (works as a resonating capacitors), diode D1 & D2( provide cross coupled feedback) , the transmitter coil L(inductor), resistors R1,R2,R3 and R4 (works as a biasing network for Q1&Q2)  etc. are used.

When power is given to the oscillator circuit, the DC current starts flowing through the two sides of the coil (L1&L2) and also to the Drain terminals of the MOSFET. During the same instant, voltage appears on gate terminal of both the transistors and tries to turn ON the transistors. Any one of the transistor will be faster than the other and it will turn ON first.

Assume that Q1 will be turning on first, and then Q1’s drain voltage will be clamped to near ground. At the same time, Q2 will be in less conductive state or in off state, then Q2’s drain voltage will rise to peak and starts to fall due to the tank circuit formed by the capacitor C and the primary coil of oscillator through one half cycle. The operating frequency of the oscillator is determined by the resonance formula given below

F = ½ × π × √ (LC)

Note: A Heat sink is provided with each of the MOSFET to protect them from overheating and make them cool.

Transmitter Coil:  For this Wireless power transmission mobile charger circuit using inductive coupling project, we can use 6mm enameled wire (Magnet wire) for constructing the transmitter coils. Actually this enameled wire is a copper wire, which has a thin layer of insulation coatings on it. Here the transmitter coil is constructed with a diameter of 16.5cm or 6.5 inches and 8.5 cm of length.

The equation for finding the inductance of a single layer air core coil is given below.

L = 0.001 N2 (a/2)2 / (114a + 254l) H

Now we are applying the desired values for the coil,

 L = 0.001×22× (0.165/2)2 / ((114×0.165) + (254×0.085)) H

L = 0.674 μH

Wireless power receiver section: The receiver section consists of receiver coil, rectifier circuit and a voltage regulator IC. The AC current flowing through the transmitter coil creates a magnetic field. When we place the receiver coil with in a specific distance from this transmitter coil, the magnetic field in the transmitter coil extends to this receiver coil, and it induces an AC voltage and generates a current flow in the receiver coil of the wireless charger. The rectifier circuit in the receiver section converts this AC voltage in to DC and the voltage regulator IC helps to provide a constant limited regulated output voltage to the load for charging the low power devices. Here we are using LM 7805 voltage regulator IC. It is used because the IC gives a regulated 5V as its output and it don’t allow more than 5V to the output.

The circuit diagram for Receiver section is given below.

 Receiver section circuit of wireless charger

Fig 3 : Receiver section circuit 

The receiver coil in the wireless power receiver section is constructed using 18 AWG copper wire having  diameter of 8cm.The equation for finding the inductance of a single layer air core coil is given below. 

L = 0.001 N2 (a/2)2 / (114a + 254l) H

 Now we are applying the desired values for the coil,

 L = 0.001×32× (0.08/2)2 / ((114×0.08) + (254×0.01)) H

L = 1.235 μH

The whole circuit section of our project is shown below.

wireless charger

 

Fig 4 : Wireless Power Transmission Mobile Charger Circuit using Inductive Coupling

 

 

Electronic Components:

Transmitter Section

  • Voltage Source, Vdc: 30V
  • Capacitors, C :  6.8 nF
  • Radio Frequency Choke,L1:  8.6 μH
  • Radio Frequency Choke, L2: 8.6 μH
  • Transmitter coil, L:  0.674 μH

Resistors:                                                           

  • R1: 1K
  • R2: 10 K
  • R3: 94 ohm
  • R4: 94 ohm
  • R5: 10 K

Diodes:

  • D1: D4148
  • D2: D4148

Transistors:

  • MOSFET, Q1: IRF540
  • MOSFET, Q2:  IRF540

 

Receiver Section:

  • Diode, D1, D2, D3, D4:  D4007
  • Resistor, R 1k ohm
  • Voltage Regulator IC:  IC LM 7805
  • Receiver coil, L:  1 .235 μH

Capacitors:

  • C1:  6.8 nF
  • C2:   220 μF=

From this Wireless power transmission mobile charger circuit using inductive coupling experiment, we conclude that wireless charging through inductive coupling is a better way for future energy transmission systems,that is witricity (wireless electricity) because with this technology we can transfer power wirelessly to charge electronic equipment, vehicles, etc.

Find the video related to wireless mobile charger,

Advantages of Wireless Power Transmission Mobile Charger:

  • We can charge our mobile phone anywhere with this wireless mobile charger circuit.
  • No need of separate mobile phone charger.
  • Easy to operate and it is environmentally friendly.
  • Does not need any wired charger.

Disadvantages of Wireless Power Transmission Mobile Charger:

  • Low efficiency compared to the wired charging method.
  • Extra heating.
  • The wireless mobile charging circuit is more complicated than the traditional charger.
  • The cost is comparatively higher than the wired charger.

Applications of Wireless Power Transmission Circuits:

  • Wireless Power Transmission Circuits can be used to charge camera batteries, mobile phones, wireless mouse, bluetooth headset etc.
  • Future development in this Wireless Power Transmission technology like witricity (wireless electricity) will allow charging of car batteries, household equipments, medical devices and other devices to charge wireless instead of wires.

NOTE: If you want to know more simple and interesting mobile battery charging circuits and techniques just go through,

User Review (77)

Abrar Butt  

sir i am from pakistan , your work is very helpfull. I have problem in making coil . You have not mention the radius of a coil. can you plz explain. thnx waiting for your reply

Reply  Report Abuse   25 November,2018 05:11

IBRAHIM MUBARAQ  

pls am in nigeria, i'm undertaking wireless mobile charging as my project and i will be glad if someone can aid me with both the write up and the device. ibrahimmubaraq5@gmail.com. its very urgent. Thank you

Reply  Report Abuse   02 May,2017 03:05

didar habib  

do i need to install receiver in mobile .

Reply  Report Abuse   27 November,2016 08:11

ainaade01  

pls where can I get the transmitter and receiver coils

Reply  Report Abuse   16 October,2016 06:10

ainaade01  

pls where can I get the transmitter and receiver coil

Reply  Report Abuse   16 October,2016 06:10

Ronnel Gonzales  

Can I know if it is working? Please reply ASAP, thanks!

Reply  Report Abuse   30 September,2016 07:09

fbauth1   Addis Abeba

plz sir can you send me the proteus simulation file in ahurry plz my mail engmido251@gmail.com. i will be very happy if you decide to send this filr

Reply  Report Abuse   28 June,2016 08:06

fbauth1

plz any one sent to you the simulation file

Reply   Report Abuse   28 June,2016 08:06

BIBIN ALIAS cochin,Kerala

I dont think u can fully simulate this project, u can do section wise in matlab simulink; but this will work in hardware that i m sure

Reply   Report Abuse   02 August,2016 02:08

BIBIN ALIAS cochin,Kerala

I dont think u can fully simulate this project, u can do section wise in matlab simulink; but this will work in hardware that i m sure

Reply   Report Abuse   02 August,2016 02:08

wariskhan335  

sir can you send me the proteus simulation file on my mail id wariskhan335@gmail.com. i will be highly obliged if u will help me

Reply  Report Abuse   29 April,2016 05:04

fbauth1

plz any one sent to you the simulation file

Reply   Report Abuse   28 June,2016 08:06

EMMMANUEL DONTOH   TARKWA,Western

pls am in the western part of Ghana and a student of Takoradi polytechnic pursuing HND electrical/ electronics engineering, i'm undertaking wireless mobile charging as my project and i will be glad if someone aid me with both the write up and the device. dontohemmanuel@gmail.com Thank you.

Reply  Report Abuse   15 March,2016 11:03

fbauth1

plz any one sent to you the simulation file

Reply   Report Abuse   28 June,2016 08:06

adiey  

hai sir, what software you use to simulated circuit?...can you help me to give simulate copy? hope you will help me sir..thanks you

Reply  Report Abuse   08 March,2016 08:03

fbauth1

plz any one sent to you the simulation file

Reply   Report Abuse   28 June,2016 08:06

adiey  

hai sir, what software you use to simulated circuit?...can you help me to give simulate copy? hope you will help me sir..thanks you

Reply  Report Abuse   08 March,2016 08:03

fbauth1

plz any one sent to you the simulation file can any one send to me this file

Reply   Report Abuse   28 June,2016 08:06

niti.tumble  

sir, i am going to do this project, but i am unable to find any base paper or research paper related to this hardware circuit so can u please send me the link or the base paper which you have used in this project? Its urgent

Reply  Report Abuse   16 February,2016 12:02

weijiedylan  

i tried it in multiSim , it seems like doesn't work neither... (see image below) https://scontent-ams3-1.xx.fbcdn.net/hphotos-xpf1/v/t35.0-12/12333010_173759989644374_953950250_o.jpg?oh=1811c6e2aaebd95db79d64132280acb5&oe=5663C13E

Reply  Report Abuse   04 December,2015 03:12

weijiedylan  

i could only find a wireless coil of 6.3 uH... if i use 2 of wireless coil 6.3uH how can i change my other components value? http://nl.rs-online.com/web/p/leaded-inductors/8631236/(this was the wireless charging coil i found) couldnt find the 0.674 ?H... pls help. i'm doing this for my school project...

Reply  Report Abuse   04 December,2015 02:12

ashutosh das   dhenkanal,Orissa

how can i make rf choke ?

Reply  Report Abuse   24 September,2015 06:09

nishant251093  

Sir the switches used,i.e, the IRF 540, don't the require any gate pulse? how will it operate without an external pulse. do reply, its urgent.

Reply  Report Abuse   21 July,2015 12:07

harika d  

Hi, gate of both IRF will never off.How the irf WILL TURN OFF

Reply  Report Abuse   08 June,2015 03:06

Chamodi Randika  

Hello sir I want to that is it possible to supply DC power using batteries ,and if so is it enough to transfer the power? Please reply me because I'm going to do this as my final year mini project.And I want your ideas about new project that suits with real world applications.

Reply  Report Abuse   05 June,2015 12:06

abbyat8

Can it be done by using DC batteries .. is it possible ?

Reply   Report Abuse   07 September,2015 05:09

adhajohn  

Respected Sir I am fascinated by the project so I decide to implement it in simulink to see whats the output. I have send the attached simulink copy to the mail id provided over here. In the simulink the output that i am getting is very low can you rectify me where i am gone wrong in the simulink model Thanks

Reply  Report Abuse   19 May,2015 04:05

abbyat8

Sir can u plzz send me the rectified Simulink File .. even iam getting very low output .. plzzz could u help

Reply   Report Abuse   07 September,2015 05:09

fbauth1

my mai engmido251@gmail.com

Reply   Report Abuse   28 June,2016 08:06

fbauth1

plz any one sent to you the simulation file can yo send to me the simulation file

Reply   Report Abuse   28 June,2016 08:06

Abrar Butt

@adhajohn kindly send me your simulation.. I am making the same project for final year .. replyme soon thanks

Reply   Report Abuse   07 December,2018 09:12

afonky02  

Hello, I'm to build this wireless charger as my project. Please I want know if it is possible to simulate this circuit with Proteus and can anybody guide in the cause of the project as I've not built anything like this before. Thank you

Reply  Report Abuse   08 May,2015 06:05

ecomcp6918  

What is the output voltage and current from the transmitter side before fed into inductor?

Reply  Report Abuse   25 April,2015 12:04

harshadpate  

Sir,plz send me this project ...conconclusion..

Reply  Report Abuse   22 April,2015 10:04

Sukhad Sadawarte  

also i want an how to connect an output of recever circuit

Reply  Report Abuse   23 March,2015 12:03

Sukhad Sadawarte  

will you please tell the size (Distance,Diammeter,) of the transmitter and receiver coil...please send a actual image of mounted component circuit diagram

Reply  Report Abuse   23 March,2015 12:03

nokunato  

pls i need help simulating this circuit on proteus, it keeps giving errors and especially how to get a Air coil on proteus...... needed direction with urgency asap...as am all most out of time.... thanks

Reply  Report Abuse   08 February,2015 01:02

Richard Gueli   Accra,Greater Accra

Hi pleas am not getting the R 94 ohms to buy online can you help me whit that and am doing this as my final year project diploma in telecom engineering and pleas I don’t have much time left so pleas if I can get a personal assistant`s email or anything to contact the person to help me in my project...... thank you.

Reply  Report Abuse   28 January,2015 09:01

Mepits

Hi Richard..., Just replace the resistor with a 1K pot ..and try..

Reply   Report Abuse   29 January,2015 09:01

Richard Gueli Accra,Greater Accra

pleas I don't get you... ok what if you get me all the components via DHL ... ?? I will pay any how you want do it... pleas

Reply   Report Abuse   06 February,2015 08:02

Romeo F

There is no such " 94 ohms" standard resistor. Please use 470 ohms/ 3 watts resistor instead.

Reply   Report Abuse   21 February,2015 04:02

fbauth1

plz can you send me the proteus simulation file my mail engmido251@gmail.com because i make this circuit and it not works

Reply   Report Abuse   28 June,2016 08:06

Brown  

Hey I need urgent help! When I try to simulate the above circuit, What I got from the output of Royer Circuit is some strange waveform I want to ask what is the waveform expected to be? Ripple sine? OR else?

Reply  Report Abuse   27 January,2015 09:01

Brown

and I also want to ask what is the kind of input to be powered in to the Royer circuit? 30V DC? OR 30 V sine wave?

Reply   Report Abuse   27 January,2015 09:01

Alaa Younes

30 volt DC

Reply   Report Abuse   06 December,2016 10:12

Shreyas Shinde  

Hello I want to know can i use inductor instead of rfc chokes?

Reply  Report Abuse   13 January,2015 08:01

Romeo F

In electronics, a choke is an inductor used to block higher-frequency alternating current (AC) in an electrical circuit, while passing lower-frequency or direct current (DC). A choke usually consists of a coil of insulated wire often wound on a magnetic core. It is a functional name; the name “choke” is used if an inductor is used for blocking or decoupling higher frequencies, but is simply called an “inductor” if used in electronic equipment. So the answer is YES, you may use inductors. :)

Reply   Report Abuse   21 February,2015 04:02

Brown  

hello, i wound like to ask is the modified Royer Oscillator built by yourself? its seem a complicated circuit as i dont have expereince in building such large circuit Or can I buy such circuit online? Moreover, what is the size of coil and the number of turns you used?

Reply  Report Abuse   27 December,2014 09:12

Brown

Thanks for your comments. I would like to first simulate the above circuit to find the optimum value for the parameter what software do you suggest? PSIM? SABER? or Simulink?

Reply   Report Abuse   27 December,2014 07:12

Mepits

Hi Brown, Actually this is not a complicated circuit. It is designed like this for obtaining high oscillating current. High current is necessary for increasing the magnetic fields strength. You can get the components listed in the project through our on line shop. But the online shopping is done across India only. Here the transmitter coil is constructed with a diameter of 16.5cm and 8.5 cm of length. The receiver coil is constructed using 18 AWG copper wire having diameter of 8cm. But you should adjust the coil diameter and length for proper power transmission. For better power transfer, the transmitter and receiver coils must be in similar size and shape also it should be tuned to the same inductance. The no of turns and diameter of the coils depends up on the inductance value. Plz go through the previous comments for detailed explanations.

Reply   Report Abuse   27 December,2014 10:12

gurudeepchandu  

Do we need to give power supply at both transmitter and receiver section?

Reply  Report Abuse   24 December,2014 06:12

Romeo F

No, you need to supply power only to the transmitter circuit. :)

Reply   Report Abuse   21 February,2015 04:02

harika d  

Hi can you please tell me how to decide the number of turns and diameter of a coil

Reply  Report Abuse   15 December,2014 07:12

Mepits

For better power transfer, the transmitter and receiver coils must be in similar size and shape also it should be tuned to the same inductance value. For additional tuning you need to consider about the impedance matching of the primary and secondary coils. The no of turns and diameter depends up on the inductance value. You can use this handy inductor calculator ( www.pronine.ca/multind.htm) to find out the diameter and no. of turns of the coils. But it will not provide the actual reading and consider this as your start point reading. You should check out the equations given in the project.

Reply   Report Abuse   16 December,2014 11:12

Rafaella Bernadette Bautista  

Hi Sir, Can I Ask if what can I do to make the distance of the CP longer? what should I do if I used this circuit. Thank you for the Reply.

Reply  Report Abuse   12 December,2014 09:12

Meng Wang  

Also, did you find out what is your actual power efficiency on the receiver side?

Reply  Report Abuse   01 December,2014 09:12

Meng Wang

Thank you for the quick reply. Great work! We also doing this for our final course project and this is really helpful. Thanks!

Reply   Report Abuse   01 December,2014 09:12

Mepits

Here in this circuit, 30 Volt is applied as the input. Then the voltage across the transmitter coil is measured as 6.6V. When the distance between transmitter and receiver coil is 0 inches, the voltage across the receiver coil is measured as 4.1V. From this we get the efficiency,i.e energy transfer efficiency as 62.12%. The energy transfer efficiency can be decreased by increasing the distance between the transmitter and receiver coils. So the effeciency mainly depends up on the distance between the transmitter and receiver coils.

Reply   Report Abuse   01 December,2014 11:12

Meng Wang  

Hi, Just wondering what frequency did you use? Also did you adjust the receiver coil to tune to this frequency? w = 1/sqrt(LC)? It seems like that the value you used are not at the exact resonant frequency.

Reply  Report Abuse   01 December,2014 08:12

Mepits

It is desirable to tune the receiver and the transmitter coils in the same resonating frequency for better performance. i.e, F = ½ × pi × sqrt (LC)

Reply   Report Abuse   01 December,2014 11:12

ba bo  

hello, i want to simulate this circuit. how can i it? which programme ? how can i add the inductive coupling in simulation ?

Reply  Report Abuse   27 October,2014 08:10

praful badami  

Hey, I am doing this project.I have a doubt in transmitter coil. What do u exactly mean by the length 8.5"Cm" and dia 16.5cm and why isnt length mentioned in receiver coil.

Reply  Report Abuse   24 October,2014 08:10

Romeo F

It is important to note that the transmitting and the receiving coil are similar in order to provide the best power transfer. Typically, for an inductive coupled system the two coils have the same inductance value. For this project you need to do additional tuning of the primary and secondary along with impedance matching capacitance or inductance to achieve a matched magnetic resonance. This tuning and the use of well-engineered low-loss coils in turn allow distances to be extended up to four times the diameter of the transmitter.

Reply   Report Abuse   27 October,2014 02:10

ba bo  

and where should i start from ?

Reply  Report Abuse   23 October,2014 03:10

ba bo  

hi, i want to do this project as design homework. i need to help you. firstly, what is the required equipment as detailed ? my english is some bad. i hope, i can tell you my problem.

Reply  Report Abuse   23 October,2014 03:10

rahul garg  

without connecting the mobile charger how mobile is charged, is mobile is also needed a reciever circuit into it to charge

Reply  Report Abuse   18 October,2014 09:10

Romeo F

Yes, you need to install a “receiver” into the mobile phone. See all the details about such device here: http://www.youtube.com/watch?v=j44osF7l7ds

Reply   Report Abuse   19 October,2014 05:10

Romeo F  

Hi there, First of all, thank you for promoting my video clips. The mobile phone wireless charging was just a demo about practical applications for the already built Royer oscillator. For a usable wireless charger in practice we need to have a different approach. There was too much wasted energy in the above project implementation, due to high frequency oscillator in use and limited access for the space needed in order to integrate the receiver into a normal mobile phone case. mister_rf

Reply  Report Abuse   13 September,2014 04:09

lesllie joseph  

innovative one....

Reply  Report Abuse   08 July,2014 01:07

Mepits

Thanks Leslie..

Reply   Report Abuse   18 July,2014 03:07

shahid Nawaz

Good after noon Hi Shahid here. Sir I have created the same circuit in proteus(labcentre) software and when I run the simulation it show the error (Real time simulation failed to start). kindly guide me that how i dubug it or any other solution. Thanks

Reply   Report Abuse   21 October,2014 03:10

SUJITH MATHEW   Kochi,Kerala

what is the range of this??

Reply  Report Abuse   07 July,2014 02:07

Mepits

The range depends up on the number of turns and diameter of the coils

Reply   Report Abuse   19 July,2014 11:07

Umair Chaudhary

how it depends on turns and diameter ? is there any formula of spacing which varifies that by increasing diameter and turns, spacing (range) can be increased ...? waiting for ur reply thanx

Reply   Report Abuse   17 November,2014 09:11

Romeo F

The efficiency of the power transfer depends on the coupling between the inductors ”k” and their quality factor “Q”. (“Q” = the ratio of the inductance ”L” to the resistance “R” of a coil) The quality factor Q is mainly dependent on the shape and size of the coil as well as the materials used, usually you may expect values around 100.The coupling “k” is determined by the distance between the inductors (we mark the distance by “z”) and the ratio of two coils diameters D2 / D1. The coupling is further determined by the shape of the coils and the angle between them. The coupling factor is a value between 0 and 1. The value of 1 expresses perfect coupling, so all flux generated in the transmitter penetrates the receiver coil. By the other hand, a 0 value expresses a system where transmitter and receiver coils are independent of each other. Poor coupling can be linearly compensated by a better quality factor and vice versa. So the efficiency drops dramatically at larger distance (z/D > 1) or at a large size difference of the coil (D2/D1 < 0.3). A very high efficiency (>90%) can be achieved at close distance (the ratio z/D < 0.1) and for coils of similar size (D2/D1 = 0.5 ~ 1).

Reply   Report Abuse   19 November,2014 02:11

jiss joseph   cochin,Kerala

Nice project

Reply  Report Abuse   04 July,2014 05:07

Mepits

Thanks Jiss.....

Reply   Report Abuse   18 July,2014 03:07
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