I would like to transmit 1 byte through an AC line from an arduino to another which is power by the AC line. This is something like what I want to do:
simulate this circuit – Schematic created using CircuitLab
So, let me explain what I have thought. The first arduino detects the zero crossing using the opto-isolator and after that for half a sine wave triggers the triac 8 times to form a byte inside the half wave. The second arduino, which is powered by the AC line also reads this wave and when it detects the encoded wave does something with that information. So there are some questions:
- Can that be done?
- Will there be problems?
- Are there any other ways to pass small info through the AC line without using off the shelf products?
- Can that be done for more bytes?
The specific example will be used to control a light bulb and an led strip both attached to the second arduino using a rotary encoder attached to the first.
Best Answer
Your circuit might work, but you probably can't mix data and power. Since you'll be dimming the power line for data bits. One bit per fundamental cycle because you can't turn the triac off until a zero crossing.
PLC works by injecting a high frequency carrier into the power line. It uses a capacitive coupling and a bandpass filter. Look at the example circuits in the TDA5051A datasheet of how they inject and receive the 132.5 Khz signal.