Friday, June 14, 2024

Wireless Electricity Charger

ashwiniSmartphone batteries don’t last for long, and charging cables, which can break after a few months of use, can be annoying.

Wireless Chargers can be a convenient alternative – you simply set it and forget it. But how does it work, exactly?

While wireless charging may seem like a recent invention, its origins date back more than 100 years to the famous Serbian-American inventor, Nikola Tesla.

Working Principle

In the late 1800s, Nikola Tesla successfully transmitted electricity through the air. He used a process called resonant-inductive coupling, which works by creating a magnetic field between a transmitter (which sends electricity) and a  receiver (which receives the electricity) to power light bulbs in his New York City laboratory. 

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A few years later, he patented the Tesla coil – a tower with a coil at the top that shot bolts of electricity. Tesla had much grander visions of a wireless power grid, but these dreams were never realized. 

The same basic principle of inductive charging applies to smartphone wireless charging.

Bill of Material:



0.3 – 0.4mm Enamelled Copper  wire  5 Metres  For Transmitter & Receiver Coils  250
Resistor 1K  1 No  For current limiting  1
Transistor BC-547  1 No  For Switching  10
LED  1 No  For Half Rectifier  3
USB Cable  1 No  For Charging mobile  50
9V battery with connector  1 No  For Transmitter power supply  20


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You can use Stepdown Transformer (230/5V-1A) with DC rectifier also.

Designing Process:

Step 1: Designing Transmitter & Receiving coil

Here, I have taken one plastic bottle (8CM dia) for making a coil. You can use PVC pipe or any other material for making coil like shapes. Wound 15Turns  Enamelled copper wire over the material. After 15 Turns need to terminate and again wound 15 Turns of copper wire (like Centre Tapped Transformer).

For Receiving coil, Similarly Wound 15 Turns of enamelled copper wire and make it.

Step 2: Connections

Now ready for connections, in my circuit I used BC547 NPN transistor for  oscillator. You can use TTC5200 Transistor for better results. 

Connect Transistor base through 1K resistor for current limitation. The center tapped coil is connected to Positive terminal of battery and Negative terminal  connected to Transistor Emitter terminal. The other two end of transmitter coil are connected to Transistor collector terminal and base terminal through current limiting resistor. 

Receiving coil ends are connected to USB cable through LED (Here LED is  used for indication and half wave rectifier purpose).

Circuit Diagram:

Circuit Diagram for Wireless Electricity Charger
Circuit Diagram for Wireless Electricity Charger


Step 3: Principle of Working

 The Transmitter coil is connected to battery through Transistor an DC current  is converted into frequency (Oscillating circuit). The oscillating current inside the  transmitting coil causes the coil to emit 1Mhz magnetic field. This oscillating  magnetic field induces an electrical current in the receiving coil. The induced 

current is alternating current so it need convert into DC for mobile charging  applications so I used LED for indication and rectification purpose. 

Author Prototype for Wireless Electricity Charger
Author Prototype for Wireless Electricity Charger
Ashwini Sinha
Ashwini Sinha
A tech journalist at EFY, with hands-on expertise in electronics DIY. He has an extraordinary passion for AI, IoT, and electronics. Holder of two design records and two times winner of US-China Makers Award.

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