Serial data over mains (110V) ??

Discussion in 'Homebrew and Kit Projects' started by W4INF, Oct 7, 2008.

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  1. W4INF

    W4INF Ham Member QRZ Page

    I am looking for information on how I can do serial data over mains power, 110v specifically. (No, this post is not a parody!)

    I am using PICAXE chips (think: PIC) to send and receive serial data. Works FB over wire... but I want to control AC devices (think: X10) by way of sending my serial data over mains lines.

    Something silly simple and dirt cheap, thats my goal! Yes, I did a google on this, you do one too and see if there is a lack of data, thats why Im looking for help! If you are someone smarter than you knows, ask them what there feedback is!

  2. KC0ZJZ

    KC0ZJZ Ham Member QRZ Page

    While not strictly what you are asking for, this should give you some pointers on how info is sent over the powerlines. And I supose you could use it by FM enconding the data bits.

    FM remote speaker system:

    Should give you some ideas, anyways. The main key is DON'T directly connect anything to the mains wires.

    edit: On second thought, it may be easier to on/off key the 200 KHz carrier being placed on the power line. Then the sending device is very simple, and the receiver only need to detect the presence of the carrier. Hint: run the baud rate very low, say 300 bps. After all, for your application, you only need a few bytes.
    Last edited: Oct 7, 2008
  3. AB1GA

    AB1GA Ham Member QRZ Page

    At what level do you want to do this? Do you want to build the circuit from components yourself, or are you willing to buy a module?

    there's a company called HTH that makes power line modems. You connect a source of serial data at one end, connect the mains to the other end, and you're done. Cost is about $35 for the kit.

    ST Microelectronics makes a power line modem chip which I think takes serial input and produces modulated output. I'd be amazed if their application notes didn't show how to connect to the mains.
  4. AB1GA

    AB1GA Ham Member QRZ Page

    Additional info: ST7538/7540 chip, data sheet includes host interface and power line interface schematics. Can't find cost and availability info right now, but this is a cost-sensitive market, so it shouldn't break the bank.
  5. W4INF

    W4INF Ham Member QRZ Page

  6. ZL3GSL

    ZL3GSL Ham Member QRZ Page

    BPL by an amateur. :) Shame. ;)

    If you use capacitors for isolation from the mains voltage (even your wimpy 110V; real men use 230V) be sure to use proper mains rated capacitors. Even "600 VDC" rating might not be really safe. The ones I'm thinkig of are intended for use in noise suppression circuits.
  7. W4INF

    W4INF Ham Member QRZ Page

    4800 baud aint exactly BPL! HA HA! I just want to control some switches, maybe fetch the outdoor temp via power line. Would be a big step forward in home automation!

  8. KC4YLV

    KC4YLV Ham Member QRZ Page

    Be aware that control via mains can get flaky when you have to hop breakers or get to a different leg of the circuit. X10 kind of died because of that, it would perform erratically if sender + receiver wasn't on the same leg.

    My suggestion would be to look into the 433 MHz data radio equipment. It's getting pretty ubiquitous and it appears easy to work with.
  9. W4INF

    W4INF Ham Member QRZ Page

    Thanks, Ill do that! has them too!

  10. KD7HB

    KD7HB Ham Member QRZ Page

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