X10 signals can be TOO strong!

Sounds to me like you've duplicated the problem that Insteon was experiencing with flicker! Just plug in an unfiltered signal sucker. That should attenuate the signal back down to an acceptable level. (-:

FWIW, the Control Linc Maxi's have a status LED that can be set to blink in synch with any X-10 transmission. It's pretty useful.

-- Bobby G.

A signal sucker didn't attenuate the XTB-II output enough. What works is running that lamp module through a X10 5A plug-in filter. The XTB-II still punches enough signal through the filter so that the lamp module works fine.

This must be load related because the other modules on that same circuit do not exhibit any flicker. As I recall, the Insteon problem was only reported on wall switches with heavy loads.

Jeff

It has also been reported on non-Insteon dimmers - Lutron, Leviton and some that were not named.

snipped-for-privacy@yahoogroups.com

It looks like the 30Vpp signals that appear on the MT1 and MT2 pins of the triac are exceeding the triac's dV/dt spec. These signals capacitively couple to the triac's gate and turn it on. Sensitive gate triacs typically have higher dV/dt limits, but are probably not used in the modules because they are more expensive.

Alan

That makes sense. The inductor in series with the triac should limit the dV/dt, but perhaps not enough. I recall Insteon had to change an inductor to resolve their flicker problem. I don't understand why this seems to effect modules running near their maximum load. Of all the switches and modules in the house, only this one exhibits the effect.

Like you say, it may be that the least expensive triacs are used in these modules. We have an older Leviton 6343 "red line" X10 wall switch on the same circuit as the XTB-II, and much closer than the misbehaving X10 module. It has an even heavier load, but doesn't exhibit any flicker. However, that Leviton switch was not targeted at the low end market, and may have better grade components.

Jeff

Update - I had not dimmed the Leviton enough to see the flickering. It does it too.

There is a recent thread on the HomeSeer board about the Insteon flicker. One user reduced the load by unscrewing a few bulbs, and the problem went away. Another reported there was still some minimal flicker even with the modified Insteon switches.

The problem may be more evident in an Insteon system because every module is also a transmitter. So average signal levels are apt to be much stronger than a typical X10 system. Here the flicker occurs on two heavily loaded dimmers on the family room branch circuit with its very high signal levels. With the XTB-II in its normal location by the distribution panel, we never saw flicker anywhere.

Jeff

Jeff,

I previously posted to c.h.a. my experiments with a 12-lamp chandelier that allows me to create any load between 0 and 720 watts in 15 watt increments. The original-version V2 INSTEON dimmer powering the lamp could be made to flicker. I had not experienced it prior to the experiments because the load wasn't great enough in normal use/configuration/wattage. The replacement INSTEON V2's don't flicker..

In a different post to c.h.a., I speculated that the 'fix' that SmartLabs might institute would be to add more turns to the existing inductor. As best I can determine, that is exactly what they did -- leastwise the replacement units appear to be identical, with an identical inductor core, except for more turns.

This suggests that the 'fix" that I also suggested (and SmartLabs also apparently contemplated recommending but decided against) of adding inductance externally in series would also work to solve flicker issues. One could do this with an inductor salvaged out of an old dimmer (eg WS-467 or non-X-10) connected to stranded 16AWG wire and insulated with a single piece of ~3/4" heat-shrink tubing. There are also lotts toroid cores on the surplus market, but color codes of core composition and properties are not standardized so obtaining appropriate cores may require some sleuthing unless one is willing to pay full price.

It should be noted that the problem of unintended turn-on of TRIACs is as old as TRIACs themselves. This is why virtually all TRIAC dimmer circuits use some sort of snubber circuit to prevent self-triggering. I am skeptical of the conclusion that the problem has to do with the 'quality' ("least expensive") of the TRIACs used.

It may very well be that the folks at Pico what thunk up X-10 to begin with considered the issue when they chose the maximum voltage for the X-10 transmitters.

Comparisons of the output of the TW-523 and CM11a in this newsgroup (the CM11a has roughly 1/2 the voltage output of the TW-523 that it followed) have implied that there was something wrong/inferior with the CM11a. Lower voltage would further mitigate the flicker problem (if any).

It is also useful to note that when ACT designed the TI-103 series of transmitter/couplers, they beefed up the current available using a transformer so as to be able to drive low impedance loads, but spec 'd the output at 6 volts, presumably on purpose, and perhaps to avoid the flicker problem. T' would be useful to inquire, and they/ Uncle Phil might respond since they are (apparently?) gitting out of the X-10 arena.

... Marc Marc_F_Hult

Interesting. When dimmers first hit the market there was that BUZZ problem in radios. I thought the snubber circuit was to reduce RF radiation. In fact, Leviton says "RFI Filter - Suppresses radio frequency interference" on their rotary dimmers.

Jeff

I don't think so. While I had no way to calibrate things and have no idea how the ACT Scope-Test2 might affect them, the Insteon signals I observed on my 'scope were in the range one would expect from the Insteon spec (3.1Vpp). The "strength" of the Insteon approach is the ubiquity (with adequate modules spaced appropriately) of the signal rather than its magnitude. See the Insteon article on my web page for some 'scope shots with the vertical scale being 2V/div for the Insteon signal.

X-10 used ~10Vpp with the PL513, TW523, TM751, RR501 and almost everything else prior to the CM11A which has ~5Vpp but which falls off badly during the

1mS burst to just 3-4Vpp at the end (John Galvin published a couple of simple fixes). The CM15A and Leviton's HCPRF outputs are ~6Vpp. Europe limits PLC level to 5Vpp so that may be the reason X-10 reduced the output. Did you ever measure the CM14A output?

snipped-for-privacy@yahoogroups.com

in

RF is also a concern and reason for snubbers, but not the only one.

from

many other possible references):

" Application Note AN-3008 RC Snubber Networks for Thyristor Power Control and Transient Suppression

REV. 4.01 6/24/02 Introduction RC networks are used to control voltage transients that could falsely turn-on a thyristor. These networks are called snubbers. "

HTH ... Marc Marc_F_Hult

Perhaps the heavier the load the greater the amplitude of the carrier across the triac?

Dan Lanciani ddl@danlan.*com

Another possibility is saturation of the inductor core at high currents.

... Marc Marc_F_Hult

| >Perhaps the heavier the load the greater the amplitude of the carrier | >across the triac?

| Another possibility is saturation of the inductor core at high currents.

I like that even better. One thing I wasn't clear on: do the lights flicker even when the switch/module is supposedly totally off? With cold filaments that should give the highest carrier amplitude across the triac, and of course there is little/no current through the inductor.

Dan Lanciani ddl@danlan.*com

I considered that, but there should be virtually no current to saturate the core before the triac switches on. And even after the triac switches on, the inductor would take some time to saturate.

Jeff

No, I didn't have the ESM1 back then.

X10 systems normally have just a single transmission point. That can be

5Vpp, 10Vpp, or over 20Vpp in the case of a XTB. However, my measurements show signal levels fall off rapidly as they propagate through the network. Before the XTB, our "core" X10 circuit only had .1Vpp when driven by a TW523. That circuit has no electronic devices other than X10 switches and transmitters. Even with the XTB boosting the TW523 output, that circuit was still only 1Vpp.

I built a simulation of the AC distribution network in a typical home using inductance based on wire length. The numbers were from the audio guys whose high power speaker cables are similar in dimensions to Romex. I also added distributed capacitance and a few signal suckers. It is easy to see from that simulation why the signals fall off as they do. An AC distribution network is basically a very complex low-pass filter that has various peaks and nodes throughout the system. The nodes are the "black holes" where it is virtually impossible to get a decent signal without moving the transmitter.

Since Insteon is based on having multiple transmission points, signal strengths throughout the network should be more constant.

Jeff

Apparently I misunderstand the problem posed, which I thought included the observation you made in the first post, namely:

" All three lamp modules exhibit the same characteristic with that heavy load. None of the modules flicker at all with a dimmed 75W table-lamp load, even at the same receptacle. The lamp modules are from various eras. "

"heavy load" implies high currents.

... Marc Marc_F_Hult

Sensitive gate triacs would less likely be turned on by capacitively coupled pulses of the same amplitude that caused the problem seen by Jeff Volp. At higher DV/dts, they would still have a problem.

But aren't we talking about two different things here? The XTB-II is providing pulses that are turning the triac on. Doesn't the Insteon flicker problem only occur when the load is on? In other words, aren't the triacs inadvertently trying to turn off in this case?

Alan

Marc_F_Hult wrote:

Right. Apparently I misunderstood Jeff's problem. I understood "heavy loads" (which yo me implied large currents) and devices of "various eras" (which implies construction with earlier TRIAC designs) but apparently I captured the wrong circuit diagram in my noggin. I'll go back and re-read.

... Marc Marc_F_Hult

Yes, but core saturation is an instantaneous phenomenon. The triac turns off at each zero crossing, and current is virtually zero before the triac switches on early. I don't think core saturation can be an issue at that instant.

I thought it might be thermal due to the heavy load. There is some evidence to support this. After being on, and then ramped to max dim, the flicker is more evident for awhile. So the triac may be more sensitive to premature triggering from dV/dt when hot.

Jeff