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In my home/office/business I have a 4 incoming electricity lines, (Government line, private subscription generator 1, private subscription generator 2, home gasoline generator)

I want to send through my wiring a signal indicating which source is 'on' at the moment. I would put a receiver near high consuming devices to work only when the government source is on.

I thought about a wireless solution, but I believe power-line solution is much more robust and better to the environment, and obviously cheaper.

Is there any simple circuit that allows me to send such small amount of data, without the use of a micro controller and serial data transfer? As far as I can tell, all I need is 8 bit parallel data transfer to send this data.

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  • \$\begingroup\$ Your constraints make this impossible to answer. I've never heard of any form of powerline communication that doesn't use at least a small microprocessor. And if you have more than one bit to transfer and only one pair of wires, you must serialize somehow. Or use FDM, but then you're back to the microprocessor question. \$\endgroup\$ – Dave Tweed Feb 17 '13 at 12:08
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    \$\begingroup\$ related question electronics.stackexchange.com/questions/29492/… \$\endgroup\$ – kenny Feb 17 '13 at 12:32
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    \$\begingroup\$ If all you want is to know who's power is coming in, you could put a different tone on each. Say, 60Khz for Govt line, 65Khz for private line1, 75Khz for line2. Or, just a tone on the Govt. line, since that is what you want to switch on. See atmel.com/products/other/power_line_communications/default.aspx \$\endgroup\$ – Bobbi Bennett Feb 17 '13 at 16:50
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    \$\begingroup\$ I find it a bit sad that several experienced EEs here have become so blinkered that they find it ridiculous or impossible to think back to the analog ways of doing things. The new tools make things easier, better, safer, more reliable, ... Perhaps. But they evidently also stunt our memory or our ability to think out of the microcontroller box. \$\endgroup\$ – Anindo Ghosh Feb 18 '13 at 2:04
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    \$\begingroup\$ @Anindo: It's not that this can't be done with discrete parts or analog electronics, but that a microcontroller is easier and a digital solution will yield a more reliable overall result. Saying you don't want to use the obvious and clearly effective tool for this job without any justification means it's being done for some silly religious reason, which has no place here. \$\endgroup\$ – Olin Lathrop Feb 18 '13 at 12:57
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What you are looking was very common practice in power distribution networks upto and for some time after radio communications, SCADA and other systems started to come into play in the distribution control, and communication with generating sites.

The difference being that you are looking for the low voltage side of things where as the old systems were on the 8KV and up type of systems. And it was very clever with signal routing being determined by frequency and at tie points they had special electrical networks that would shunt the signals to specific branches. I know some of these systems were still in operation in North America well into the '80's (but certainly not mainline systems)

I mention this because this might be the best place for you to look for either old eqt. or even to find papers and techniques of doing this.

Most modern solutions will have many more layers and levels of sophistication than what you need. So looking to these earlier sources of information will help you the most if you want to build something similar.

That fact that these were robust systems also should be reassurance that you can make your own if you are sufficiently experienced /careful when dealing with mains voltages. A modulation scheme and absence/presence detection with robust filtering should work.

There were attempts a setting signalling standards for power-lines, and you might find some of the older modules for transmitting and receiving (even if you are doing just carrier detect) which was made by Echelon systems. They still exist and sell modules. But this might be a too pricey solution.

On-semi and Cypress both sell Cenelec Band-A and Band-B module solutions as semi-conductors. So the app notes there will certainly be useful. However, these solutions may very well be way too much. But you might be able to find demo kits at low cost.

TI has an integrated PLC front end PLC = Powerline Communication which you could use by itself without using all the protocol stack.

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