Switch ON/OFF any Appliance Remotely using Mains Wiring

Using the explained transmitter and receiver circuits, you can quickly exploit the existing mains home AC wiring to send signals across different rooms, for remotely switching ON/OFF any desired appliance such as lights, fans ACs, heaters, between rooms of your house.

This home power line remote controller circuit combines the transmitter and receiver protocols based on your home’s mains power network for remote control of the single-phase household appliances.

Transmitter Circuit

In the first figure below, a transmitter is represented. This device overlaps a 36 kHz signal on the 50 Hz AC voltage of your home when switch S₁ is actuated.

Then, IC₁ is supplied the voltage from the mains through rectifier circuits that comprise D₁, D₂, Zener diodes D₃ and D₄, and a filtering capacitor C₄. We recommend to set up the circuit with +20V supply concerning the mains network-neutral (0V) line.

The opamp generates the 36 kHz signal and it is channeled to the mains using a coupling capacitor, C₃. A bleeder resistor, R₃, is used to discharge C₁ and C₂ when you uncouple the circuit from the AC voltage.

Receiver Circuit

In the next receiver circuit diagram below, it is supplied with a cost-effective doorbell transformer but any other power supply that can give out 6 to 8 V AC at around 0.3 A works just fine.

Besides driving Tr₁, the AC voltage with the 36 kHz carrier is filtered by a circuit of L₁-C₆ which is connected in parallel.

This small section of the entire network functions to sense the existence of the overlapped 36 kHz carrier which is directed to amplifier IC₁ through resistor R₇.

After effective rectification by D₉, the relay driver circuit which consists of T₁ and T₂ becomes enabled to energize Re₁.

D9 should be preferably a germanium diode such a OA79 or similar. If you don't get this, a simple 1N4148 might do the job as well.

Afterwards, preset P₁ is regulated to determine the correct cooperation between the sensitivity of the receiver and the noise resistance. When choosing the value for R₁₄, make sure to consider first the relay coil current.

How to Install

Fundamentally, the implementation of this Power line AC remote controller circuits an entirely secure con-ABS case is utilized to avoid accidental contact with the AC voltage wires.

This step is always obligatory when working with any mains voltage circuits.

After this is verified, the transmitter can be mounted on a spare adaptor case with a small opening for attaching switch S₁.

The ABS case of the receiver is expected to bigger if the mains socket is included for simpler connectivity with the household appliance to be controlled.

Be mindful of the rating of relay Re₁ if you plan to switch heavy loads, like the coffee machine which houses a current of 4A.