Author Topic: Simple (cheap) power line communication circuit  (Read 1811 times)

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Offline xtv

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Simple (cheap) power line communication circuit
« on: August 03, 2015, 11:11:00 pm »

I'm no electronic engineering, but I'm willing to build a simple (and cheap) circuit for sending data over the power line in my house (220v ac).
As it's possible having data modulated in different frequencies travelling over the same wire pair, like in coaxial cables (obviously, I'm aware they're designed for carrying a wide range of frequencies, and just for that), I'm wondering what would take to do a very simple circuit for power line communication.
For that I have some doubts, which I will list below. I'm not lazy, so if you can't give a straight answer, but point a direction on where to head for getting these data, I will dig for them. Some of them are:

1. Is it possible for doing it (the modulation and signal injecting) with simple transistor(s)?
2. How am I suppose to "isolate" my transmitter from the high voltages running in the line?
3. What are the output peak voltage I will need for the transmitter signal output?
4. For the receiver, I'm wondering if I can use passive RC and/or LC filters for recovering the signal ?
5. Any other useful considerations.

This is all for the sake of curiosity, save the safety warnings. I wont burn my house down!  :)
Thank you all!

Online T3sl4co1l

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Re: Simple (cheap) power line communication circuit
« Reply #1 on: August 04, 2015, 12:02:38 am »
There have been, from time to time, these household intercom devices, which use low frequency AM radio waves carried on the power lines.  Such a circuit could be built in just a few transistors if you're desperate (such as a keyed oscillator and regenerative receiver), a good one in perhaps 10 transistors (if you're keen).

Representative circuits should be available online.

Isolation is easily obtained with an isolation transformer, or using Y1 type (line to earth) capacitors.

What kind of communication are you expecting?  Morse code, voice, digital?

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Offline Richard Crowley

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Re: Simple (cheap) power line communication circuit
« Reply #2 on: August 04, 2015, 12:22:59 am »
There are schematic diagrams of various power-line communication circuits out there for the Googling.
But the state of the technology for wireless transmission has gone way beyond what is practical to do over the power lines.
There have been power-line communication schemes for over 50 years but it has never become very popular because it was never the best way of doing anything.

As @T3sl4co1l said, is rather difficult to discuss this topic without a better idea of WHAT KIND of "communication" you are talking about.

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