Line Noise Interference Question

I use X-10 controllers all over my house. Please no X-10 tirades here. I bought a new computer. I am having interference with the signals now to my X-10 devices. I have installed a line filter from "smarthome" that is supposed to filter out interference from power supplies. However, it does not seem to be working. In fact, I must not only shut down the new computer, but unplug it also in order for it to not interfere. Any one have any suggestions her. Thanks in advance!

Reply to
Dimbo Spams
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What you have described is a perfect example of an X-10 sink. The power supply in your new computer has some large and effective capacitors across the AC line which are shorting out the X-10 signal. This is a common problem with switching power supplies as used in computers, televisions, and an increasing amount of consumer equipment.

As a partial fix you can try plugging the computer in a different outlet, hopefully a different circuit. It may improve performance a bit. The 100% fix (for this specific sink) Is to separate it from the outlet and your house wiring with an X-10 "filter". For example:

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These filters have inductors inside which are limited in the amount of current that they can handle. The smaller ones like this are good for 5A which is plenty for your computer, a TV, a stereo receiver, etc. For bigger jobs there is a 15A version that is quite a bit bulkier and correspondingly more expensive.

Geo.

Reply to
George Pontis

Reply to
Dimbo Spams

Reply to
Dave Houston

well, i just got a filter to address my ws12 switch problems, and somehow I managed to get a bum unit myself, so it does happen apparently...I got the smarthome branded 10amp filter, and when I plug a module into either the filtered or unfiltered outlet, i can still control the module. Needless to say i'm pretty irritated at getting a unit that never should have made it out of quality control. Have not contacted smarthome yet to see what they're going to do about it (after business hours) but they better have a free shipping label for me.

Reply to
random735

Yours is the opposite of a noise problem. The power supply has a capacitor across the mains that acts as a near-short to the 120kHz X-10 signal. It's intended to block noise from the power supply from reaching the powerline but it's also eating your X-10 signals.

I'm surprised that the filter isn't helping. It should block the 120kHz signals from reaching the capacitor. Which model filter are you using? The filter should be plugged into the wall outlet and the computer plugged into the filter.

Reply to
Dave Houston

Two things to try: Double up the filters, thatis plug one filter into another and see if that helps. If not, an isolation transformer should do the trick or you can try a different power supply in the PC.

From:Dimbo Spams cuervojose(remove)@jps.net

Reply to
BruceR

Reply to
Dave Houston

Reply to
Dave Houston

It may be the powerstrip that is the signal eater. How do you have the filter, powerstrip and PC connected?

If it's wall plug -> powerstrip -> filter -> PC and you have to unplug the powerstrip to eliminate the problem, the powerstrip is the likely evil doer.

Try wall plug -> filter -> powerstrip -> PC.

If that doesn't fix things then you may have a defective filter but I think the chances of that are very low. You can test it using wall plug -> filter

-> lamp (or appliance) module. If you can control the module, the filter is defective.

If it is the powerstrip, you can open it up and remove the capacitor.

Reply to
Dave Houston

That one is fine but the power strip is likely part of the problem. The power strip should be plugged into the filter and the filter to the wall. Sometimes two filters will solve a particularly bad problem. You can use the 5 amp filters instead as it's unlikely that your PC and associated equipment will draw more than that.

From:Dimbo Spams cuervojose(remove)@jps.net

Reply to
BruceR

You may be right. Doesn't hurt to try though. I've heard it sometimes works but have never needed to try it. Sorry my last post was redundant to what you had already said. Should have read through the thread first.

From:Dave Houston snipped-for-privacy@whocares.com

Reply to
BruceR

The ACT filter he's using is a 30:1 bandstop filter. It blocks the passage of 29/30 of the signal, preventing it from getting sucked down the drain. Since only 1/30 of the signal gets through the filter, adding another filter will only help ACT's bottom line.

OTOH, when the problem is noise, adding a second filter may sometimes be necessary. It depends on the efficiency of the filter.

It's unfortunate that ACT uses the term "attenuate" >You may be right. Doesn't hurt to try though. I've heard it sometimes

Reply to
Dave Houston

It depends on the filter. None are 100% efficient so one might allow enough signal through to operate a module. Are there any published specs for the filter you have?

Reply to
Dave Houston

I was a little too quick with that suggestion. I can't find a spec on the X-10 web site but, from memory, the older units need 100mV signal and newer ones only 50mV. I'm not sure whether that is peak-to-peak or just peak.

With a 5V signal level even the 30:1 filter will allow 167mV through and many transmitters have a 10Vpp signal level.

Reply to
Dave Houston

this is the filter i got:

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specs claim:

2 stage modified pie filter centered around 120khz 49.4 db attenuation at 120khz

anyway I got an RMA on it (no questions asked), so hopefully it is indeed non-functional. (before trying it with a module, I was trying to use it to filter the PC that i had established as the source of my problems, and was noticing no effect whatsoever). Otherwise I guess i get to start trying to relocate my PC or something.

Reply to
random735

I noticed that when I put an ACT 5A filter between a signal sucker and the line that a maxicontroller could still reach and control an appliance module located very closer to the other side of the filter. I also noticed very odd results combining a surge protector with a Leviton filter.

I confess to not having read up as much as I would like on filter design, but perhaps you can give me some guidance. Is it possible for two "signal suckers" to interact in unexpected ways? I plugged two surge strips that gave me X-10 troubles and used the ESM-1 to measure a signal at the end of both of the units. It was higher at the end then it was in the middle. Is that even possible?

[outlet] (2v)---------->[strip1] (.5v)---------->[strip2](1.5v)

Since I can't get the level of precision I want from the ESM-1, I decided to bite the bullet and buy the Monterey unit. The Lynx wasn't very useful to me in making detailed analyses of the "power picture" at my house. The ACT unit was just too damn big. From what I read, aside from the BSC problem, it's going to give me a signal and noise readout that promises to be useful in both bug hunting and testing.

What I want to do is design a test bench that can not only get some sort of "device profile" for all my 110VAC equipment. I was going to set up the meters (I want to make sure the ESM-1 and the Monterey agree) on a plain vanilla power strip plugged into an ACT 15A filter. Is that a good idea? I'm worried that devices might react differently in the test bench than they might in the real world. What else should I be measuring to try to eliminate variables? I want to know which devices present obstacles to X-10 signal propagation but I don't want to waste time recording worthless readings because I didn't think it through first.

Thanks!

-- Bobby G.

Reply to
Robert Green

It may be that the combination is creating a resonant circuit. That's why I suggested to the OP that he remove the powerstrip and test with just the filter. It's always best to start with the simplest possible setup.

Without knowing exactly what components are used in each filter, it's hard to say what interactions are possible.

Ground loops might cause erroneous results.

I didn't think the Lynx-10 PLC would be very useful as a test instrument. I also hate to see anyone spend so much money for the Monterey. The Monterey maxes out at 4.096V so, while being able to measure =might in the real world. What else should I be measuring to try to

I've found that plugging everything into one powerstrip makes for resonably reliable benchmarks. That's how I measured the outputs of the various transmitters at

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You need to be careful about having other transmitters between the test transmitter and whatever you use for a meter since transmitters will attenuate the signal.

The filter will provide further isolation but you probably don't need it unless there are signal suckers nearby. You can verify this by taking readings with and without the filter in place.

It really is a shame that the web site that had all those papers on powerline communications was taken down. There were some really informative studies there that, if nothing else, illuminated the complexity of using the powerline as a communications medium. The powerline acts like a transmission line with a characteristic impedance that varies from ~2-80 ohms. Like any transmission line, there can be reflections, nulls and peaks.

Reply to
Dave Houston

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