X10 Transmit Buffer

The X10 Transmit Buffer prototype has been working 100%. I have tweaked a few component values, but that had no significant effect on overall operation. While our X10 operation was virtually 100% before installing the buffer, signal levels on some circuits were marginal. With the buffer replacing the Leviton 6201 repeater, signal levels are now much stronger throughout the house.

The Word document referenced here earlier has been revised down to 200K, and will download much faster:

Please read it if interested. I would also appreciate any questions you may have.

My goal was to develop a device that would increase X10 signal levels, and significantly increase the reliability of your X10 systems.

Jeff

So this would be a good thing to make a CM11A usable in a large house without requiring an in-panel repeater? The CM11A was not mentioned as a compatible controller but I am assuming it is. Is it? (-;

The XTB would not be practical if you used a lot of mini/maxi controllers or TM751s, correct? I assume they'd all require their own XTB.

What, if any, are the issues with increasing the transmit voltage? Will it overload any components in receivers that are close to the XTB?

Can you tell me more about part that says "The XTB also includes an amplifier to boost low-level X10 return signals" and whether that means it might be modified to act as Boosterlinc does, hearing the first X-10 "frame" and retransmitting it in sync with the second command "frame."

Are you going to take deposits via Ebay or Paypal? I'm definitely interested in one.

-- Bobby G.

Hi Bobby,

I'll answer below:

I didn't include the CM11A because I had not specifically tested with it. I did test with the RR501 and a maxi-controller. But, I don't see why it wouldn't work with the CM11A. The only limitation is that the plugged-in module consume less than about 20 watts, which is 10 times what a typical X10 module draws.

Not really. Where reliability is most important for us is from the Ocellot that pretty much runs everything. And manual controllers are frequently used locally, so the signal may not have to propagate reliably throughtout the house. But, that is certainly something to consider for someone who uses a bunch of manual controllers.

I can't answer that other than from my testing. The XTB output 20Vpp into the circuit at my workbench. I didn't measure it with a scope at the breaker panel. The ESM1 pegs on circuts near the panel, but those levels drop off as a function of distance from the panel. Most of the house is in the 2.5V to 5V area, which is well above what I had with the Leviton 6201. I suspect the "normal" level is limited because most X10 transmitters use a step-down output transformer to increase their drive current capability. Higher current means reduced voltage.

The first prototype passively coupled incomming signals back to the TW523/PSC05. There was some attenuation in that path, and a signal that had been marginal was no longer recognized by the Ocelot. I added an amplifier in that path to actually boost low level incomming signals in the present version. Strong signals are still limited to prevent kicking on the power amplifier and setting up a feedback loop.

I had thought about including a microcontroller to recognize and also boost incomming signals, but I was concerned about running afoul of any Boosterlink patents. Anyway, that market is already covered. I don't think the Boosterlink has the drive capability that the XTB has. I believe they recommend one per each 1000 square feet. Unless there are several bad signal suckers, one XTB can easily cover more than 5000 square feet.

I just need names at this time to make sure I order enough printed circuit boards. Those that don't follow through will be available to others. I'll add your name to that list.

Thanks for your interest,

Jeff

Fair enough. Is the amplification proportional? Since the CM11A's output is among the most anemic of all X-10 controllers would the amplfied signal be as strong as with the more powerful controllers like the Maxi (sort of an AGC) or would it be proportionally weaker?

So you couldn't use the pass-through port or the switched outlet on any of the modules. It is an easily replaceable fuse or catastrophic failure if there's error and someone plugs something into the module? I suppose I could always just craxy glue an outlet cover on the amplfied device, just to make sure.

controllers

It seems the best use would be for a centralized house controller like the CM11A that usually can't reach the outer edges of even a small home without help.

What do the output pulses look like on a scope compared to something like a Maxicontroller?

I never had much luck with my Boosterlincs. Oddly enough, a remote branch circuit that used to be beyond the range of my Maxicontroller is now working again without the Boosterlinc. I believe that one of the new switching power supplies for an external drive has somehow boosted the signal or, more likely, has neutralized some signal sucker on the line. I test all new equipment with my Monterey but apparently devices affect the signal depending on what's plugged in nearby.

Thanks!

-- Bobby G.

Hi Again,

See answers below:

Any X10 input above about 3.5Vpp produces a full-amplitude output. Below about 2.5Vpp, it doesn't output any signal at all. Those thresholds seem to work well, but they can be adjusted slightly through value changes if necessary. The low level cutoff prevents a feedback loop caused by the buffer from coming on in response to an incomming signal being passed back to the X10 controller.

It was intended as a booster for the TW523/PSC05, so pass through was not an issue. Inductors capable of passing several amps of 60Hz back to the source device while totally blocking the high power X10 signal are prohibitively large for this small package.

My target was the TW523/PSC05 used with high end automation controllers, but boosting the CM11A output would be an excellent application.

That is somewhat a function of line characteristics. A tuned LC filter couples the 120KHz to the AC line. The waveform is near sinesoidal. I don't have a spectrum analyzer to determine its harmonic content.

When this house was wired, I tried to have all "unfriendly" electronic loads on one circuit fed through a big 20A filter. And I placed all X10 devices on one phase. These two factors are probably the main reason we have had such good X10 reliability.

Since then, unplanned loads have been creeping in here and there. What got me started on this project was that even though we still had virtually 100% reliability, some of our X10 signal levels were barely acceptable. I wanted some safety margin. The XTB has done that, and it should certainly help in cases where reliability is a problem.

Jeff

Sorry. I was unclear. A while back I looked at a lot of screen shots done by Dave H. and others that indicated some unusual characteristics for the CM11A when compared to a TW523 or a Maxicontroller.

AFAIK (and that ain't much!) the CM11A, besides having lower output voltage than most controllers, also suffers from a peculiar output voltage decay during the signal transmission itself. I would assume since you're able to boost the signal to a uniform output level despite varying input voltages that the XTB X-10 signal will not contain the original transmitter's waveform flaws. I just wanted to be sure a CM11A plugged into the XTB device would NOT show the same voltage drop during its output burst.

I'm sorry if I am being a pest about the CM11A but I think your device will have appeal to those who like that controller but do not like repeaters. If you don't own a CM11A, I'd be happy to loan you one for testing.

It's probably better that you discover any unusual device interactions before anyone else does! IIRC, (but probably not) the CM11A very occasionally self-immolates in the presence of certain sorts of dimmers, or at least I vaguely remember reading reports of serious CM11A overheats for one reason or another a few years ago.

Great job, BTW. Why didn't someone do this 20 years ago? Were the components or the brainpower not available back then?

-- Bobby G.

Hi Bobby,

Thanks for the discussion. Again, see my replies below:

Ah, now I understand. I sent you a snippet of my simulation by e-mail so you can see the waveform itself. What doesn't show in that snippet is that there is about 5% voltage decay over each 1mS burst as energy is pulled from the primary storage capacitor. It has an unregulated full-wave bridge supply, and recharges on each half cycle. The normal X10 capacitor supplies recharges once a cycle, and their practical limit is around a watt. Also, a capacitor supply must dissipate that power continually. An unregulated transformer supply such as used in the XTB has minimal dissipation except when actually driving a load.

I'm glad you brought up the CM11A, and it is an excellent application for the XTB. I had used one at the old house before beta testing the CM14A. I'll locate it and do some testing in the next couple of days.

Yes, I remember all those too. It was fairly reliable for me, but I did have to do the cold reset every couple of months.

Signal suckers have gradually become more and more of a problem as they proliferate through the average household. And X10 must do everything as cheaply as possible to hit their target market. Others have taken a different approach, requiring a significant expense in new equipment. Of course, it is to their benefit have homeowners rip out all their X10 equipment so they can sell them new stuff. My goal is to improve the reliability of existing X10 systems by addressing the signal level issue with minimum effort and expense.

Jeff

The CM11A fade problem is easily cured by changing one resistor. If you search CHA for "CM11A schematic John Galvin" and read the entire thread you'll find where John recommended two possible fixes. I've changed the resistor on one of my CM11As and can confirm that it now has a steady output. It's still just over half of that from other X-10 PLC transmitters but the fade is gone.

Doing that and then using Jeff's booster should really help with the CM11A.

The specific thread is...

Changing R12, per John's recommendation, is a fix.

I'm surprised that there haven't been more people asking questions.

Hasn't arrived. My email is munged - it might have bounced back.

A high-powered "master" transmitter will go a long way towards addressing the problems the people experience with X-10. I'm hoping it's going to solve some gnarly problems that I've never been quite able to cope with. Thanks again for all your effort in creating the XTB.

-- Bobby G.

That's nice to know. I doubt I'd be making any mods to the CM11A that involved soldering. I just reconfirmed my awful soldering skills by trying to solder a replacement XLR connector for Dad's scooter that got lost. The shrink tubing shrunk too soon, the wire insulation got nicked by the alligator clips I was using to hold it and the joint broke after a few test tugs. Soldering and I were not meant for each other.

I was worried that the fall-off in voltage might cause the XTB to reject the trailing edge of the CM11A signal, since its max voltage seems to be close to his cutoff for weak signals. If I see any evidence of that happening, I'll advertise here for a contract solderer. :-)

Thanks again, Dave!

-- Bobby G.

For those of you that want further information on the XTB, I have added a preliminary parts list, layout diagram, and assembly instructions:

It is possible that some values may change in the coming weeks. I would appreciate feedback to help me answer any questions you may have.

Printed circuit boards are being ordered this week. Parts kits and assembled boards should be available in about a month.

Thank you to all who have contacted me.

Jeff