X10 Modulation Theory

In pursuit of my remote control G-job I've been looking at X10.

I can find schematics, but nowhere can I find a discussion of how the modulation is to be accomplished... how are you supposed to introduce the signal onto the AC line? (*)

Any pointers, URL's?

Thanks!

(*) I tend to always think wa-a-a-ay outside the box and devise my own circuitry ;-) (I just need the theory.) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson
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Bye Jack

Reply to
jack4747

Maybe this will help...

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Or maybe not since you have me blocked. Good luck.

Reply to
John S

Years ago I snagged some pages off of x10's website which I believe has the info you are looking for. check your email. Art

Reply to
Artemus

[snip]

I e-mailed back the e-mailing info, but no hurry, going out for a burger ;-) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

I believe it is similar to Caller ID. Form a link on the wiki..

Cheers

Reply to
Martin Riddle

Schematics

Cheers

Reply to
Martin Riddle

IIRC, it's a transformer (for signal gain) driving through a cap.

You might want to *try* a couple of X10 modules in the two locations desired as the wiring characteristics of your home can play a big part in how well (*if*!) it works.

[The X10 modules themselves are pretty crappy; they don't reliably turn on and often spriously activate or deactivate. Also tend not to fare well with lightning strikes, etc.]

You can probably avoid much of this by using a *static* approach: turn remote relay on WHILE carrier is detected (instead of using carrier to *command* relay on)

OTOH, the modules are "pre-packaged" and pretty inexpensive.

Reply to
Don Y

...

I wouldn't recommend using the X10 protocol - it is not robust and I found it very unreliable, it does not have any error detection nor retry mechanis m.

Many years ago I did build an X10 transceiver - the analog portion used the output from the microcontroller driving a tuned circuit at 125kHz then thr ough a capacitor onto the AC line (suitably transformed to match the few oh ms impedance of the AC line at that frequency. I used a LM567 as a tone de coder on the receive side.

There are more modern versions of Power Line Communications that are much b etter. You may be able to find some easy to use modules - Qualcomm makes a set of chips for the purpose.

I used to use it for lighting control but its reliability gradually became worse until it was unusable. I think the main reason for the deterioration seemed to be that as I installed more electronic equipment the capacitors at the power entry at each piece was shunting the 125kHz signal that it use s. I made it last a few more years by putting small inductors in series w ith the ones that were causing more attenuation such as the TV and the ster eo amplifier. I eventually gave up.

An additional problem that any PLC system will have is that a typical US ho use is split into two with each half being fed from one of the phases with the 220v items between the two live lines. A capacitor across the two phas es can help (~0.5uF or so).

I am now using a wireless system that works well, ZWave - it uses mesh netw orking to propagate the signal throughout the house and has error detection and retry mechanisms. Even then as with any wireless system operation cann ot be guaranteed.

Most of the modules are for controlling lamps or appliances but they do hav e dry contact input and relay output modules available for custom applicati ons.

kevin

Reply to
kevin93

Everyone is still thinking protocol rather than the nuts and bolts of the modulation CIRCUIT. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson

Don't use the protocol. Just use (a variation of) the technology. I.e., couple a carrier to the power line to indicate the current state of the *one* switch. Remotely detect this carrier and drive the relay accordingly (i.e., "Carrier Detect").

Falls down if you want to have multiple such circuits (use different carriers?). But, cheap and dirty and reasonably robust (put some "memory" on the carrier detect signal so momentary dropouts -- or sporadic "false detects" don't manifest on the relay drive). Biggest hassle is ensuring power line distrubances don't eat the circuitry.

NatSemi had an FM device that was contemporary with early X10. But, still relatively low data rates (you could use it for audio, too!).

Nowadays, you can move ~500Kbps over PLC reasonably reliably (and inexpensively)

Though there are only a few "select" places where that can easily be done.

Reply to
Don Y

Sent. Sufficient? Art

Reply to
Artemus

The X10 inventors showed their full circuit in their 1977 / 1980 patent, US4200862.

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 Thanks, 
    - Win
Reply to
Winfield Hill

Yes. Thanks! ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Thanks, Win, I am looking for "goose" information... how hefty a pulse. I'll read thru the patent and see if I can glean more info.

Musing I think I see a way to avoid having to use a transformer. And my own simple modulation scheme... I only need on/off for one device, I don't need any complex addressing schemes. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

On Tuesday, August 30, 2016 at 8:52:52 PM UTC-7, Jim Thompson wrote: ...

...

The circuitry is pretty trivial - it is normally done with a step-down tran sformer. This is useful since you need to drive about 1V RMS into the line impedance of only a few ohms. Without a transformer you would need an Amp or so pk-pk in the output stage.

The transformer is also useful in isolating the low frequency transients fr om the drive/receive circuitry. Most of the X10 modules use a capacitative non-isolating power supply to pr ovide the few mA they need so the line isolation is not really needed.

Here are a few schematics I found on the web - the Lamp module is the most basic one - receive only and it is based on a primitive of the shelf micro.

The Wall switch module is a transmit only but uses the same injection circu itry as the receive only.

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good luck

Kevin

Reply to
kevin93

So, you're gonna make a hot chassis... two of 'em, one for send and one for receive.

And "it only takes two tin cans and a string" ... but it turned into the POTS network

Reply to
whit3rd

So? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Then you are not really following the standard, which is perfectly OK, as l ong as you don't have other X10 devices around. Once you are breaking away from the standard, nothing wrong with doing anyway you want. For example, injecting/retrieving Ethernet frames during AC zero crossing.

But this is going to be heavily digital, not analog, in respond to another post of this thread.

Reply to
edward.ming.lee

If you're just interested in power-line carrier stuff you might want to look at Lonworks' schematics, if you can find them.

X10 was never all that reliable but it was cheap.

--sp

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Spehro Pefhany 
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Spehro Pefhany

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