I think they've done it again.

The fact that the problems are reported with high-wattage dimmers is consistent with the choke saturating at high currents in which case more turns on the same T-16 core won't solve the problem.

... Marc Marc_F_Hult

(some stuff snipped)

I can understand the inductor problem in their own device. But I'm confused by reports of other dimmers flickering during transmission of Insteon signals. That's what pointed me toward possible early detection of the zero crossing in the effected devices.

Do you think the Insteon dimmers emit enough ringing onto the line to cause other dimmers to misbehave? Why would that happen just during transmission of Insteon signals? Or are the reports of other dimmers being effected of questionable validity?

Jeff

| Do you think the Insteon dimmers emit enough ringing onto the line to cause | other dimmers to misbehave? Why would that happen just during transmission | of Insteon signals?

It's possible that when the MCU is busy handling an Insteon transmission it has timing problems controlling the triac (because of unanticipated code paths or even a deficiency in total processor cycles). Perhaps merely a jitter in the turn-on time could make the noise worse for some dimmers.

The issue of firmware-timed triac dimmers misbehaving when the MCU is doing something else is certainly not unheard of. Odd sensitivity in zero-crossing detectors in other devices isn't that uncommon either. I have a clock and a VCR (among other things) on an APC SmartUPS 1000XL. When on battery the clock in the VCR runs fast and the stand-alone digital clock runs slow. (Or maybe it was the other way around.) The UPS is supposedly pure sine wave...

Dan Lanciani ddl@danlan.*com

[ First let me correct a stupid misstatement on my part. The red wire is of course the _load_ not line input as I wrote -- or none of the devices I wired into my house would be working ... ;-) One of INSTEON's nice little features is excellent and durable labeling so they are not to blame for that gaffe.. ]

I glimpsed at the various threads and with the little time I invested wasn't able to separate the wheat from the chaff. My understanding from a summary from Mike from INSTEON is that INSTEON concluded that there were two device- (not protocol) related problems.

There is a second choke (actually marked L1) that is near the (presumed coupling) transformer. I'll try to untangle the schematic. This statement form Mike at INSTEON

" We have increased the value of the choke coil to attenuate the INSTEON signals that go into the triac"

can be interpreted to mean that at least one of the problems is related to the PLC signal strength at the TRIAC and it is this other choke that they are modifying.

Back to your question, one way to approach the analysis would be to construct a spice model with both the INSTEON and another TRIAC based dimmer in the circuit and explicitly model the AC line and neutral wires as interconnects. Some of the reported problems could be related to high impedance neutrals. The low inductance I measured for the INSTEON load filter/choke(`18uH compared to ~44uH for even the cheapest X10 wall dimmer) suggests that these will not be clean dimmers but I haven't scoped the output.

I'll look at the reports some more so as to be able to respond more usefully. I think that i understand your timing question and add the comment that when I looked at line noise created by generic and X-10 WS467 dimmers several years ago, I found that the highest peak voltages were measured at about the 1/4 the RMS output IIRC.

Recall that an inductor 'stretches' the duration of a pulse, so the delay caused by the L1 choke might be long enough to trigger gate triggering in a second TRIAC in a second dimmer when the delayed/stretched INSTEON PLC signal is _added_ to the TRIAC noise from the INSTEON TRIAC at some time significantly after zero crossing and that signal is not sufficiently attenuated (there are two issues here; timing and noise/signal strength.)

Later ... Marc Marc_F_Hult

Could be the case when a whole house full of them starts singing in a mesh network chorale.

We've seen other reports through the years of dimmers being affected by devices not directly connected to them.

Very, very coincidentally today, at my Dad's house, I noticed that the shop light begins to flicker when he plugs in his powerchair charger, which delivers a constant 4A at 24VDC. The strip lamp is a standard 48" HD special with energy saving bulbs behind an X-10 5A filter plugged into the same outlet (eventually) as the charger (which is actually plugged into the UPS's surge protected but not battery backed outlets. That UPS is plugged into a powerstrip with 4 others that are plugged into an ACT 15A filter.

The lamp's flickered before under other circumstances but the charger is definitely new to the equation. I'm going to look for any voltage drop when the charger is switched on because that's probably the simplest explanation. But it sure surprised the both of us when we I hit the "On" button and the overheads flickered. There is an XTB in that room. I'll unplug that too, just to make sure it's not involved. I'm going to film my experiments with my new solid state pocketcam with only three moving parts lest my credibility be questioned! :-) We had some massive storms roll by in the last few days and the power's been flipping on and off like store lights at closing time. Anything could be wrong.

Say, Jeff - why aren't you locked away in your lab creating a followup to the XTB? There's a great line from (I think) _The Usual Suspects_ that goes something like this: "Sure you saved my last last week but what have you done for me lately?" :-)

-- Bobby G.

I conclude that as a an actual performance problem, this is a tempest in a teapot: a problem nobody here has actually experienced (not surprising since it seems most folks participating in this thread may not even have an INSTEON installation ;-)

An INSTEON rep wrote in the thread I cited previously that: "We saw this problem during the beta testing of the SwitchLinc dimmer in two units out of

800 beta samples." and goes on to give contact info for a person with a flickering dimmer to be able to contact Smarthome on a Sunday to arrange for a replacement dimmer. The same rep reports that INSTEON spent $40,000 troubleshooting and replacing possible off-spec components before shipping but apparently a few slipped through (or at least that is one explanation offered).

According to INSTEON, the dimmers with revised/QA'd TRIAsC/chokes will be shipping 4th Qtr which will presumably reduce problem frequency closer even to zero. I haven't experienced any problems myself nor apparently have the vast majority of other INSTEON users. So the solution to this apparently infrequent problem is at hand.

As to the challenge of trying to divine the cause, first step is problem definition which is problematic because reports are not consistent. I'd be more interested if there was a way of testing the various hypotheses posed. Absent an actual case of flickering on which to test causes and remedies, another way would be (eg Spice) modeling but that's more work than I'm inclined to put into this particular academic exercise. ... Marc Marc_F_Hult

Well, here is one guy who has the problem. Before the coversion was complete Insteon devices were making certain Leviton X10 switches flicker and now that I'm 98% Insteon I still get some flickering. I will changeout the offenders when a fix is availble.

Bruce,

I recall you also reported some problems when you tested UPB but cannot recall the details.

"bruceR" wrote:

I tested the UPB Starter kit for a few days but found that the signal would not make it througout the house. IOW, no better than X10 in MY application. I was going to play with it some more but then the desktop controller stopped working and I put it all aside.

As I understand it, a field fix that has been considered by SmartHome is to wrap the load wire several times through a external toroid choke core. In other words, add more inductance in series to the (measly) ~18uH provided by the T-16 toroid choke (labeled L3) they already have in the dimmers.

That's easy enough to do if you have enough volume in the switch box and is a conventional fix for filament buzz and other noise-induced problems. Commercial de-buzzer coils I am aware of are typically need an additional or very large switch box.

... Marc Marc_F_Hult

>

The latest post from Dave Walters to the Smarthome Insteon forum appears to refute the bad choke/bad triac theories. He has swapped 3-4 switches that worked OK in other locations with the one switch that is giving him a problem and 'all' of them exhibit the problem when in that location (and under the same load/dim conditions).

I would sure like to see a 'scope on that switch location.

Bruce hav>I'd be quite pleased if that were the fix. I spec'd deep boxes all through

> >

I'm not sure whether that's a reference to "Butch the Bulldog" or someone else. ;-)

A consensus seems to be forming among those seeing the flickering that it only occurs when a switch has more than ~250W (total) connected and is dimmed to 50% or less.

This puts the triac switching point near the peak of the line voltage and at the furthest point (in time) from the Insteon control signal. That the triac is being turned off at this point is the least likely explanation as the current, being at or near maximum, is almost certainly far above the triac's holding current.

This is also the area where triac switching noise will be at a maximum. An undersized choke could allow this noise to reach the PIC (in the subject switch or in other devices on the line) and this might cause the PIC to stutter and miss a half-cycle or more. (The PIC has to actively turn the triac on for each half-cycle.) Earlier Smarthome designs (e.g. 1132B and

2000STW) have been overly sensitive to disruption by out of band noise.

Butch Cassidy and the Sundance Kid . . . I think it was right after the famous knife fight scene with Harvey (the 7 foot Lurch, from the Addams Family). Butch uses creative thinking to win a potentially hopeless encounter:

Butch Cassidy: No, no, not yet. Not until me and Harvey get the rules straightened out. Harvey Logan: Rules? In a knife fight? No rules. [Butch immediately kicks Harvey in the groin] Butch Cassidy: Well, if there aint' going to be any rules, let's get the fight started. Someone count. 1,2,3 go. Sundance Kid: [quickly] 1,2,3, go. [Butch knocks Harvey out]

(If you've seen it, you'll never forget it!)

So, this is a state where the triac is passing a relatively high amount of current per cycle. Why would dimming below 50% be important? Is that when the triac is likely to put "spikes" out on the line? If electrical circuitry can be compared to water flow in pipes then quickly interrupting the flow of water, as in a shower massage, causes stress on all nearby joints and fittings. Is the analogy even slightly on target as to how triac noise can affect other components ???? :-)

When the triac is triggered does it keep conducting until the current passing though it drops below the holding current or can it be turned off before the zero crossing is reached?

(As an aside, IIRC, resistors change value when heated. Do the properties of inductors change if they get very hot? I'll bet those teensy little SwitchLincs get God-awful hot driving a large load with significant dimming.)

(Forgive me for breaking your message up like this, I know it's not your preferred style, but I need line-by-line guidance!)

Why would the switching noise be at maximum? Because the voltage is at its peak? Because there's more area under the curve at the peak for a given length of time and so there's more current? Is the noise created harmonic?

I believe Dan had also mentioned this unwanted PIC interaction as a possible cause for the flickering. FWIW, this seems to be the likely explanation because reports indicate the V2's are emitting EMI that's extending well beyond the local circuit. Something's leaking out of the V2's that's strong enough to fool nearby devices into behaving erratically. There's not much other than EMI and voltage fluctuations to explain flickering. I believe I read that the EMI placed on the line by a triac is 90 degrees out of phase with the original AC cycle. Is that what's causing nearby dimmers to flicker?

I also read that chokes are selected for dimmer circuits that limit the rate of rise of current to minimize EMI and that the choke by itself does not solve the noise problem. The self-capacitance of the inductor means they typically resonate below 200 kHz and look like capacitors to disturbances above the resonance frequency.

(BTW, the odd effect I saw with my dad's shoplite flickering was caused by a bulb that was on its last legs. Even the small voltage drop caused by the charger was enough to destabilize the lamp, which is electronically ballasted.)

It seem as if the flicker issue is pretty close to resolved. Now, what about the flashing/blinking reports? Would triac noise be able to trigger a very brief on/off cycle? It seems to get back to the issue of whether noise on the line can cause unwanted switch operation. IIRC, a while back you had discovered that a big enough spike will cause X-10 switches to cycle without valid input. Is that what we're seeing here?

One more stupid question: Are triacs and thyristors the same thing?

-- Bobby G.

First, I screwed something up in translation. The consensus seems to be that the total wattage connected to the switch needs to be about 300W or less and the dim level needs to be about 50%. (Why higher wattage doesn't exhibit the problem is a bit mysterious.)

Here's a very short Microchip App Note which discusses triacs, noise and PICs.

Here's another short app note from ST that discusses why IGBT dimmers do not need chokes.

Once switched on by a pulse on its gate, a triac can only be turned off when the current through it drops below its holding current. This normally occurs just before ZC but can be triggered at other points by noise un the line. Here's another short ST App Note discussing this.

Yes, a triac is a thyristor. But not all thyristors are triacs.

Your plumbing analogy is not entirely inapt but things are reversed. Around

50%, the triac is being turned on at or near the point of maximum voltage. This creates a "ringing" noise on the line (roughly analogous to your pulsating shower head) very similar to the pulses that UPB generates by discharging a capacitor onto the line.

See pp8-10

PCS says the spectrum of their "data" pulse is in the 4-40kHz range. They indicate thay got the idea for this when they noticed how well triac noise pulses propagate through the "network".

Echelon says that the "ringing tail" of a triac noise pulse is in the 150kHz range.

While research>>

Yes, I think Dan Lanciani and I are saying something similar but I'm suggesting that the triac noise at mid-cycle is triggering a false reaction by the PIC (assuming it's a PIC) that then prevents it from turning on the PIC during the following half-cycle(s).

I have a NEC Multisync XV15 monitor which outputs noise of an unknown (to me) spectra. When connected to the same power circuit as the NEC monitor, the initial Powerlinc 1132B goes deaf to the powerline. With the 1132B powered by a different circuit it works OK.

I have 3 Lamplinc 2000STW modules. None work reliably on the power circuit with the NEC monitor - their LEDs flash randomly and they respond to PLC commands intermittently. All work normally when powered by a different circuit or when the NEC is powered down.

At the moment I have two Insteon Powerlinc 2414S PC interfaces and two LampLinc V2 2456 modules. The LEDs on all flash randomly when connected to the circuit with the NEC monitor but are rock steady when powered by a different circuit or when the NEC monitor is off.

Plugging the NEC monitor into a Leviton plug-in filter reduces the LED flicker on most of the devices and 2 of the 3 Lamplinc 2000STWs appear to work OK. Adding a John M. Jones homebrew filter (just the choke from an X-10 lamp module) in series with the plug-in filter eliminates the LED flickering on all of the Insteon modules and the 3rd Lamplinc 2000STW starts working.

No noise shows up on my 'scope using the ACT Scope-Test2 (tuned for X-10). Triac switching transients from my dimmers do show on the 'scope. All of my X-10 modules work with no problem in the circuit with the unfiltered NEC monitor.

I suspect they have a fundamental design flaw that causes their devices to be affected by out-of-band noise (or by very low level in-band noise) and that they have carried this flaw through all of their designs.

The published signal sensitivity spec for all of their modules is in the

10mV or lower range so this might also be a factor.

With the 1132B and the 2000STWs, it appears that they get >> An undersized choke could allow this noise to reach the PIC

That's pretty interesting. It does lend support to the theory that it's the Insteon signal itself getting through to the triac and causing it to trigger when it shouldn't.

Your comment is also a good reminder that the devil's always in the details. Flickering, at least in my mind, means dimming from a known brightness level and then a return to that level. I know that it really means "variations in light level" and was probably first used to describe candle light but when applied to electrical lights, it seems to imply "loss of light." All along, though, we've been seeing reports of "flashing, popping, brightening and, IIRC, even bulbs popping." That seems to me to be attempts to convey what you have described, not a dimming, but a brief brightening.

Those reports now make me think the "flickering" and the "flashing" problem may be more closely related than I first thought. Perhaps everyone's seeing what you're seeing but to different degrees.

One thing that I've learned from this thread is that house wiring is certainly not the passive transport platform I once thought it to be. I was disappointed to learn from your experience that more Insteon switches mean less reliability for co-existing X-10. The XTB will be a great aid should I decide I want to switch to Insteon but I don't believe I will go that way. I'm still leaning toward a hardwired automation system over an RF or PLC based one for the next house. It's a lot of work and expense in the beginning, but it's immune to the problems that afflict RF and PLC based solutions.

-- Bobby G.