Wireless Mobile Battery Charging

With the advancements in the mobile phones with many services such as internet and various apps, the usage of mobile phones have increased a lot with increased internet usage with often leads to drain of battery power. we have to carry mobile charger and search for power socket. imagine if u carry a charger which does not require any power socket. 

The project aims at providing a very inexpensive charger, solution for all type of mobile phone battery. 


The circuit works on the principle of mutual inductance. Power is transferred from transmitter to the receiver wirelessly based on the principle of “inductive coupling”. Inductance is the property of the conductor, in which the current flowing in a conductor induces a voltage or electromotive force in it or in another nearby conductor. There are two types inductance. 

1) Self inductance

2) Mutual Inductance

“Mutual inductance” is the phenomena in which, when a current carrying conductor is placed near another conductor voltage is induced in that conductor. This is because, as the current is flowing in the conductor, a magnetic flux is induced in it. This induced magnetic flux links with another conductor and this flux induces voltage in the second conductor. Thus two conductors are said to be inductively coupled.




  • Voltage Source, Vdc: 30V
  • Capacitors, C :  6.8 nF, R1: 1K, R2: 10 K, R3: 94 ohm, R4: 94 ohm, R5: 10K, Diodes D1: D4148, D2: D4148
  • Radio Frequency Choke,L1:  8.6 μH
  • Radio Frequency Choke, L2: 8.6 μH
  • Transmitter coil, L:  0.674 μH 
  • MOSFET, Q1: IRF540 
  • MOSFET, Q2:  IRF540

For Receiver 

  • Diode, D1, D2, D3, D4:  D4007
  • Resistor, R 1k ohm, Capacitors: C1:6.8nF, C2: 220microF

  • Voltage Regulator IC:  IC LM 7805

  • Receiver coil, L:  1 .235 μH


The circuit consist of  a transmitter circuit and a receiver circuit.

The transmitter circuit consists of step down transformer of 230/12V. This transformer steps down 230V AC from main supply to 12V AC. Then that 12V AC is converted into 12V DC with the help of bridge rectifier. After that a 2200/25V capacitor is used to filter the ripples and pure DC is supplied. The transmitter circuit consists of DC source, oscillator circuit and a transmitter coil. Oscillator circuit consists of two n channel MOSFETS  IRF 540 , 4148 diodes. When the DC power is given to the oscillator, current starts flowing through the two coils L1, L2 and drain terminal of the transistor. At the same time some voltage is appeared at the gate terminals of the transistors. One of the transistors is in on state while the other is in off state. Thus voltage at drain of transistor which is in off state raises and it fall through the tank circuit made of 6.8nf capacitors and transmitter coil of 0.674. Thus operating frequency is determined by using formula F=1/[2π√(LC)].

Receiver circuit consists of receiver coil, rectifier circuit and regulator. AC power is induced in the coil when the receiver coil is placed at a distance near the inductor. This is rectified by the rectifier circuit and is regulated to DC 5v using 7805 regulator. The rectifier circuit consists of IN4007 diode and capacitor of 6.8nf. The output of regulator is connected to the battery.

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





please tell me the current rating applied to the transmitting coil and to the receiving coil..

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