Simple Wireless LED Light Circuit

These days wireless charging is present in everything from your phone to advanced medical equipment.

This article demonstrates how to use a common chip known as the IC 555 to construct a simple wireless LED light circuit.

Without using any wiring it will illuminate an LED to demonstrate how wireless charging operates!

What is a Wireless LED Light Circuit:

An electrical circuit that allows control over LED light operation without the need for cables or other physical connections is known as a wireless LED light circuit.

Several technologies including as Bluetooth, Wi-Fi, infrared and radio frequency (RF) are used in this wireless control.

LED lights are suitable for lighting systems with remote controls because of these circuits which make operating them simple and adaptable.

Circuit Diagram:

Parts List:

Transmitter Circuit Working:

The 555 IC is configured as an astable multivibrator to generate a continuous 20KHz square pulse.

Resistor R1 and R2 along with capacitor C1 calculate the timing of charging and discharging cycles.

As capacitor C1 charges through resistor R1 and discharges through resistor R2 it creates a continuous cycle of oscillation.

The internal flip-flop of the 555 IC changes states when the voltage across capacitor C1 reaches two thirds of the power supply VCC.

Capacitor C1 releases power through resistor R2 and the discharge pin when this results in the discharge pin 7 become low.

When the voltage across the capacitor drops to one-third of VCC the flip-flop switches states once more allowing the discharge pin to rise.

By repeating this cycle of charging and discharging the 555 ICs output pin 3 generates a continuous square pulse.

The gate terminal of the IRF540 N Channel MOSFET receives the square pulse produced at the output pin.

On positive pulses the MOSFET works as a switch on negative pulses, it turns off.

When the MOSFET is switched coil L1 which is connected to the drain terminal experiences different ON and OFF states.

As a result the electromagnetic field surrounding Coil L1 starts oscillating strongly.

Receiver Circuit Working:

To keep track of the fluctuating electromagnetic field the receiver coil L2 is placed close to the transmitter coil L1.

By using Faradays law of electromagnetic induction the receiver coil L2 generates a current in response to the fluctuating electromagnetic field.

When linked to one end of the receiver coil diode D1 functions as a rectifier.

It produces a unidirectional DC signal from the pulsing AC that is created in the coil.

After being rectified the signal is run via a voltage doubler circuit which increases the potential difference sufficiently to power twelve LEDs.

To light up the connected LEDs in the circuit, a potential difference is created.

Formulas and Calculations:

We can calculate the following formulas for astable 555 IC for wireless LED light circuit:

Flashing Frequency Formula:

Frequency = 1 / (1.1 * R1 * C1)

where,

• Frequency (f) is in hertz Hz
• R1 is the resistance of resistor R1 in ohms Ω 1k
• C1 is the capacitance of capacitor C1 in farads F (3.3nF = 3.3 x ^10-9 F)

Calculation:

f = 1 / (1.1 * 1000Ω * 3.3 x ^10-9 F)

f = 294.1 Hz

As a result the circuits flashing frequency is roughly 294.1 Hz.

This indicates that there will be around 294.1 flashes of the LEDs every second.

Duty Cycle:

The duty cycle is the percentage of the whole cycle time (on and off time) when 555 IC output is high (LEDs on).

The following formula can be used:

Duty Cycle = R2 / (R1 + R2) * 100%

where,

• Duty Cycle is a percentage (%)
• R1 is the resistance of resistor R1 in ohms Ω 1k
• R2 is the resistance of resistor R2 in ohms Ω 10k

Calculation:

Duty Cycle = 10kΩ / (1kΩ + 10kΩ) * 100%

Duty Cycle = 90.9%

Approximately 90.9% of the cycle is used with the LEDs on and the remaining 9.1% is used as off.

Summary:

With the given component values the circuit will produce a duty cycle of roughly 90.9% and a flashing frequency of roughly 294.1 Hz.

This means that when the LEDs are on they will flash for a greater duration than when they are off.

Remember:

These calculations are based on the 555 IC operating perfectly and having exact component values.

Actually there might be small differences because of component limits and other issues.

How to Build:

To build a Simple Wireless LED Light Circuit following steps should be followed:

• Place the IC 555 on the PCB.
• Connect the VCC and reset pins to the positive supply on the PCB.
• Connect resistor R1 between the discharge pin 7 and the positive supply.
• Connect resistor R2 between the discharge pin and the shorted threshold and trigger pins.
• Connect capacitor C1 between the threshold and ground pins.
• Connect the trigger and threshold pins together.
• Connect resistor R2 between the shorted trigger and threshold pins and the discharge pin.
• Connect the gate terminal of the IRF540 MOSFET to the output pin of the IC 555 pin 3.
• Connect the drain terminal to the Transmitter Coil L1.
• Connect the source terminal to the ground supply on the PCB.
• Connect the positive terminal of the power supply to the VCC pin.
• Connect the negative terminal to the ground.

Transmitter Coil L1 Winding Details:

• Use Insulated copper wire 18 SWG
• Ferrite Core optional
• Use 18 SWG insulated copper wire for winding.
• Wind 25 turns of the insulated copper wire.
• Wind the wire around a suitable form such as a cylindrical object to maintain consistency.
• Connect one end of the coil to the drain terminal of the IRF540 MOSFET in the transmitter circuit.
• If required you can use a ferrite core to enhance the performance of the coil.
• Wind the copper wire around the ferrite core for better coupling.

Receiver Coil L2 Winding Details:

• Use Insulated copper wire 22 SWG
• Use 22 SWG insulated copper wire for winding.
• Wind 100 turns of the insulated copper wire.
• Construct the coil by winding the wire carefully to avoid overlapping turns.
• Connect one end of the coil to the anode of diode D1 in the receiver circuit.
• The other end of the coil is generally connected to the ground or reference point in the circuit.

Additional Note:

• Ferrite core for receiver coil is an optional
• Similar to the transmitter one can optionally use a ferrite core for the receiver coil to improve performance.
• Wind the copper wire around the ferrite core.

Safety:

• Avoid short circuits between turns and keep the winding intact.
• The coils capacity to transfer power wirelessly is influenced by the number of turns and the core material selection.
• Depending on the results of experiments and the particular needs of the project this simple wireless LED light circuit if required should be modified.

Conclusion:

With both the Transmitter and Receiver circuits constructed you can observe the wireless power transmission causing the LEDs to glow.

Ensure safety precautions while working with power supplies and electronic components.

References:

Wireless power transfer