Simple Wireless Power Transmission Circuit

The idea of wireless power is not new Nikola tesla even experimented with it way back when!

Today, we use wireless charging for all sorts of things, like phones, electric toothbrushes and even some medical devices.

But there is always room for improvement.

This article will show you how to build a basic wireless power transmitter and receiver circuit using easy to find parts.

This will help you understand how wireless charging works.

What is a Wireless Power Transmission Circuit:

A Wireless Power Transmission Circuit is an electronic circuit designed to transfer electrical energy from a power source to a target device without the need for physical connections like wires.

Wireless power transmission is based on technologies that use electromagnetic fields to transmit power over short or long distances.

One common example of wireless power transmission is through inductive coupling.

Transmitter Circuit Working:

Parts List:

Below mentioned is the transmitter circuit working:

The output of the LM386 is a 1KHz Square pulse signal.

This signal is then fed to the copper coil initiating an oscillation in the coils magnetic field at 1KHz.

As the coils magnetic field starts to oscillate, it produces a strong fluctuating magnetic field around it.

Receiver Circuit Working:

Parts List:

Below mentioned is the receiver circuit working:

The induced electromagnetic flux in the receiver coil results in an electromotive force (emf) with an amplitude depending on the number of windings and the distance between the coils.

The potential difference produced in the receiver coil is rectified by the bridge rectifier converting the alternating current AC into direct current DC.

The rectified DC voltage is then regulated by the positive voltage regulator 7805 ensuring a stable and controlled output voltage.

Experimentation with the values of the timing resistor R1 and timing capacitor C1 allows for adjustments to the output frequency range.

Customizing the transmitter and receiver coils enables the adaptation of the circuit to specific power transfer requirements.

Formulas:

1. The below mentioned formula is used to calculate the frequency of an RC oscillator circuit:

f = 1 / (2 * π * R1 * C1)

where,

• f: This represents the output frequency of the oscillator circuit in units of hertz Hz.
• Frequency refers to the number of cycles that occur per second.
• π (pi): This is a mathematical constant with a value of approximately 3.14159.
• R1: This represents the resistance of resistor R1 in the circuit, measured in ohms Ω.
• C1: This represents the capacitance of capacitor C1 in the circuit, measured in Farads F.

How the formula works:

A resistor R1 and a capacitor C1 are linked in an RC oscillator circuit to form a feedback loop that produces a voltage that oscillates continuously.

The formula connects the oscillation frequency to the resistor and capacitor values:

2. Below mentioned formula is represents a simplified relationship between the factors affecting the induced electromotive force EMF in a transformer or an arrangement of coils.

Induced EMF ∝ Number of Windings, Distance between Coils

The symbol ∝ stands for “proportional to.”

This means that there is not always a linear relationship between the induced EMF and the product of the number of windings and the distance between the coils.

Induced EMF:

It is the voltage induced in a conductor as a result of a changing magnetic field and is represented by the symbol ε (epsilon).

It is the voltage produced in the secondary coil of transformers as a result of the primary coils current modifying the magnetic field.

Number of Windings N:

• This is a reference to the quantity of wire turns in a coil.
• It is applicable to both the main and secondary coils in transformers.

Distance between Coils (d):

• The distance between the primary and secondary coil centers is meant by this.
• A larger magnetic field coupling between the coils is possible at a smaller distance.

How the formula works:

The electromagnetic induction concept underlies the operation of a transformer.

A fluctuating magnetic field is produced when the main coils current changes.

The secondary coil is then cut by this magnetic field, which causes Faradays Law of Induction to be activated.

Construction Steps:

Transmitter Circuit:

• Configure the IC LM386 as a Square wave oscillator.
• Connect the Timing Resistor R1 and timing capacitor C1 to control the output frequency range.
• Apply a power supply of 5V to 12V to initiate the LM386 oscillator.
• The LM386 produces a 1KHz Square pulse signal, which is then transmitted to the coil.
• The coil starts oscillating at 1KHz, generating a strong fluctuating magnetic field.

Receiver Circuit:

• Connect the receiver coil to a bridge rectifier and a positive voltage regulator 7805.
• The receiver coil when placed near the transmitter coil induces electromagnetic flux.
• The amplitude of induced electromotive force (emf) depends on the number of windings and the distance between the transmitter and receiver coils.
• The potential difference produced in the receiver coil is rectified by the bridge rectifier and regulated by the positive voltage regulator.

Conclusion:

Building a wireless power transmission circuit is an exciting DIY project that enables you to understand the principles behind wireless energy transfer.

With a basic understanding of components, formulas and construction details, you can explore further innovations in this field and contribute to the development of wireless power technology.

References

Wireless Power Transmission System Design

Wireless power transfer