Battery Charger

Wireless Mobile Battery Charger Circuit

In today’s world, the continuous evolution of technology is significantly enhancing our daily lives. Ever since the inception of wireless mobile battery chargers, our lives have witnessed remarkable transformations. Mobile phones have revolutionized communication by merging traditional landline telephone systems. Moreover, recent innovations in mobile phones have introduced a plethora of services such as text messaging and internet access.

However, despite the multitude of technological advancements, we still find ourselves tethered to conventional wired battery chargers. Each phone necessitates its own unique battery charger with distinct designs. Consequently, we are compelled to carry these chargers with us at all times to ensure a reliable power supply. Imagine a scenario where your phone could effortlessly charge itself when you set it down on a table during a coffee break. This article illustrates the construction of a straightforward wireless battery charger capable of replenishing your phone’s battery when it is in proximity to the transmitter. This circuit serves various purposes, functioning as a wireless power transfer circuit, a wireless mobile charger circuit, and a wireless power distribution circuit.

Outline

  • Wireless Battery Charger Circuit Principle:
  • Wireless Power Transfer Circuit Diagram:
    • Wireless Mobile Charger Circuit Design: 
    • How to operate this Wireless Power Transfer Circuit?
    • Wireless Battery Charger Circuit Advantages:
    • Wireless Power Transfer Circuit Applications:
    • Limitations of the Circuit: 

Wireless Battery Charger Circuit Principle:

This circuit relies on the fundamental principle of mutual inductance. It harnesses the concept of “inductive coupling” to facilitate the wireless transmission of power from the transmitter to the receiver.

Inductance, in essence, is a property of conductors where the flow of electrical current through one conductor generates a voltage or electromotive force in that conductor or in another nearby conductor. Inductance can be categorized into two distinct types: self-inductance and mutual inductance.

The phenomenon of “mutual inductance” manifests when a current-carrying conductor is positioned in proximity to another conductor, leading to the induction of voltage in the latter conductor. This occurs because the flow of current through the former conductor induces a magnetic flux in it. This induced magnetic flux establishes a connection with the adjacent wire, consequently inducing voltage in the second conductor. The term “inductive coupling” accurately characterizes this interplay between two conductors.

Wireless Power Transfer Circuit Diagram:

Wireless Mobile Battery Charger

Wireless Mobile Charger Circuit Design:

This process is remarkably straightforward and uncomplicated. These circuits necessitate only basic components such as resistors, capacitors, diodes, voltage regulators, copper coils, and a transformer.

In our wireless battery charger setup, we employ two essential circuits. The first circuit functions as a wireless transmitter, generating the required voltage. It comprises a DC power supply, an oscillator circuit, and a transmitter coil. The oscillator circuit includes two N-channel MOSFETs (IRF 540), as well as 4148 diodes. When a DC power source is applied to the oscillator, current flows through both coils (L1 and L2) and the drain terminal of the transistor. Simultaneously, a voltage emerges at the gate terminals of the transistors. One transistor is in the “on” state, while the other is in the “off” state. Consequently, the voltage at the drain of the transistor in the “off” state oscillates through the tank circuit comprised of 6.8nF capacitors and the 0.674 transmitter coil. Consequently, the formula F=1/[2(LC)] is employed to determine the operating frequency.

The second circuit, which acts as the receiver, consists of the receiver coil, a rectifier circuit, and a regulator. When the receiver coil is positioned in proximity to the inductor, it induces AC power within the coil. This AC power is rectified by the rectifier circuit and then regulated to DC 5V by the 7805 regulator. The rectifier circuit involves a 1N4007 diode and a 6.8nF capacitor. The battery is connected to the output of the regulator.

How to operate this Wireless Power Transfer Circuit?

  • Initially, connect the circuit as shown in the circuit diagram.
  • Switch on the supply.
  • Connect the battery charger at the output of the circuit.
  • Place the receiver coil near the transmitter coil .
  • You can observe the charging of battery.

Wireless Battery Charger Circuit Advantages:

  • Usage of separate charger is eliminated.
  • Phone can be charged anywhere and anytime.
  • It does not require wire for charging.
  • Easier than plug into power cable. 

Wireless Power Transfer Circuit Application

  • Wireless chargers can be used to charge mobiles, camera batteries, Bluetooth headsets etc.
  • This can also be used in applications like car battery charger with little modification. Go to Simple Car Battery Charger Circuit post for more information.
  • This can also be used in medical devices.

Limitations of the Circuit: 

  • Power is somewhat wasted due to mutual induction.
  • It will work for very short distances only. If you want to use it for long distances, then the number of inductor turns should be high.
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