220V Power Line Communication Remote Control Circuit

Our houses already use electricity to carry signals besides just power.

This post shows you how to build a remote control that uses the electricity in your walls 220V to send signals.

It works for short distances inside your house or apartment because the signal is at a much higher frequency 5 kHz than the regular electricity 50 Hz.

This makes it easy to separate the signal from the regular electricity.

WARNING: Building circuits that connect to the mains electricity can be dangerous.

Only do this with adult supervision.

What is a Power Line Communication Remote Control Circuit:

Communication and control signals are carried over by existing power lines using an electronic circuit called Power Line Communication PLC Remote Control Circuit.

With the help of this innovation, equipment are controlled directly by a building electrical wire infrastructure or power distribution network.

Transmitter Circuit Working:

Parts list for transmitter circuit:

By selecting a frequency of 5 kHz the transmitter effectively separates itself from the 50 Hz power line frequency.

The required frequency is generated by the oscillator which is the IC 555 integrated circuit.

For transmission, the signal is increased by the power amplifier which consists of two transistors.

The output is linked to the phase voltage through a capacitor which allows the high frequency signal to pass while blocking the lower frequency mains.

The transmitter is powered by a battery AC/DC adapter or a simple supply using capacitor reactance to reduce voltage.

Control is achieved by either switching the power supply or applying a logical 1 to the 4th pin of the IC 555 determining when the transmitter is active.

Formulas:

Following formulas are mentioned below for 220V Power Line Communication Remote Control Circuit:

Transmitter circuit for the 555 IC astable circuit are calculated below::

R1 = 4.7k

R2 = 56k

C1 = 2.2nF

We can calculate the following:

Time Constant 1 (Charge Time):

T₁ = R₁ * C₁

T₁ = 4700Ω * 2.2nF

T₁ = 10.34 ns (nanoseconds)

Time Constant 2 (Discharge Time):

T₂ = R₂ * C₁

T₂ = 56000Ω * 2.2nF

T₂ = 123.2 ns (nanoseconds)

Oscillation Frequency:

Frequency (f) is calculated using the following formula:

f = 1 / (ln(2) * (T₁ + T₂))

where,

• ln(2) is the natural logarithm of 2 which is around 0.693
• f = 1 / (0.693 * (10.34 ns + 123.2 ns))
• f = 1 / (0.693 * 133.54 ns)
• f = 7.49 kHz (kilohertz)

Duty Cycle D:

D = (T₁ / (T₁ + T₂)) * 100%

D = (10.34 ns / (10.34 ns + 123.2 ns)) * 100%

D = 7.7% (Due to the control of R2 the charge time is mostly smaller than the discharge time resulting in a low duty cycle)

Summary:

• Oscillation Frequency (f) = 7.49 kHz
• Duty Cycle (D) = 7.7%

Receiver Circuit Working:

Parts list for receiver circuit:

The high pass filter at the receivers input separates the transmitted signal from the mains voltage ensuring only the desired signal enters the circuit.

The transistor with a base resistance of 220k regulates the current to the triac gate.

When open triac is closed when and when closed frequently the triac opens.

The triac operates in the II. and III. quadrants enabling it to control loads with a maximum current of 4A.

Signal reception triggers the triac to open allowing power to flow to the connected load.

The receiver is directly powered from the mains through a 330n capacitor.

The 330k discharging resistor and the 470 ohm limiting resistor manage the current during power on preventing spike.

Transmitter Construction:

For short distance transmission a frequency range of 1 to 25kHz is suitable.

In this design a transmitter frequency of 5kHz is chosen providing a 100x difference from the power line frequency for effective separation.

f_transmitter = 5 kHz

The oscillator is constructed using an integrated circuit 555 combined with a power amplifier featuring two transistors.

Diodes are employed to protect the transistors from voltage surges.

The output is connected to the phase voltage through a capacitor with a capacity ranging from 220nF to 470nF rated for 250V AC and Class X2.

C_capacitor = 220n to 470n

V_rated = 250V

The transmitter is powered by a battery AC/DC adapter or a simple supply using capacitor reactance to reduce voltage.

The transmitter is controlled by either switching its power supply or applying logical 1 to the 4th pin of the 555.

Receiver Construction:

The power line receiver incorporates a high pass filter at the input to separate the signal from the mains voltage.

This ensures effective signal detection.

A transistor maintained in an open state by a base resistance of 220k regulates the current flow to the triac gate.

The triac is closed when the transistor is open.

Signal reception causes the transistor to close intermittently charging the capacitor through two resistors (820 ohm) and subsequently opening the triac.

R_base = 220k

R_resistor = 820R

The triac operates in the II. and III. quadrants allowing connection to loads with a maximum current of 4A.

I_max = 4A

The receiver is powered directly from the mains through a 330nF capacitor.

It includes a 330k discharging resistor and a 470 ohm resistor to limit the current peak at power on.

C_power = 330n

R_discharging = 330k

R_limiting = 470R

Signal Range Considerations:

No additional filters are required in an apartment or home because the electricity meters coil naturally lowers higher frequencies.

Older fluorescent bulbs could be troublesome because of power factor capacitors.

Some options include disconnecting or adding serial RF chokes.

Safety Precautions:

• Both the transmitter and receiver are electrically connected to the network.
• Use suitable fuses in power inputs to ensure safety.
• The construction and use of the 220V power line communication remote control circuit is at the individuals own risk.
• The author does not assume responsibility for any injuries or harm incurred.

Conclusion:

Power Line Communication is commonly used in situations where the existing power lines offer a practical way of communication between tools such as smart grid systems, industrial control and home automation.

The implementation of PLC remote control circuits is made simpler by commercially available PLC modules and integrated circuits.

References

Design of Power-Line Communication System (PLC) Using a PIC Micro-controller

Power-line communication