Re: I think they've done it again.

["Jeff Volp" <JeffVolp@xxxxxxx>]

Dave, what I was trying to describe was a scenario that could cause the
triac to be off for the entire next half cycle, or 8.3 mS.  We know that at
full intensity the triac is triggered just after the zero crossing, and it
continues to conduct until the end of that half cycle.  If the Insteon
signal causes the trigger circuitry to think the zero crossing has just
passed, it might trigger the triac before the actual zero crossing.  In that
case the triac would immediately turn off, and miss conduction for the
entire next half cycle.

While I am not saying this is the case, it is certainly a possibility to
consider.  If I could obtain one of the dimmers susceptible to this
phenomena, I may be able to simulate it here running a triggered 130KHz
burst from a Wavetek through the XTB.

Jeff

"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
news:449bd3c2.43406000@xxxxxxxxxxxxxxxx
> The reports of flickering go back at least a year. At that time someone
with
> Smarthome said it was caused by defective triacs. Now, someone from
> Smarthome is saying it is caused by a choke.
>
> To kick Jeff's idea around a bit. The Insteon signal starts 800µS before
ZC
> which is approximately 10% of the time it takes for 1/2 cycle. I'm not
sure
> of the maximum amplitude of the Insteon signal. The specs give a minimum
> figure (3.16Vpp). On my scope it appears to be about 3Vpp (but that may be
> distorted by the ACT ScopeTest-2 I was using). If it's symmetrical about
0V
> this means the negative peak is about 1.5V. I haven't done the trig but
the
> point where the line voltage drops below 1.5V is awfully close to ZC.
While
> the Insteon signal might cause a premature turn-off, I really doubt that
> anyone would perceive a flicker. It would just increase the off time
> slightly. The lamp would turn on again at the point past the ZC called for
> by the dim setting. I don't know how the Insteon electronics detect ZC but
> doubt whether a 1.5V amplitude would be detected.
>
> If non-Insteon devices are being affected by such a low amplitude signal
so
> near ZC (I've seen reports of Lutrom dimmers and Leviton X-10 dimmers
> flickering when Insteon signals are being sent) it would seem they would
> also react to triac noise from other dimmers which is much higher in
> amplitude. Even if their triacs are turning off in reaction to a false ZC,
> they would (by Jeff's reasoning) turn on either at the normal point or
turn
> on and off at twice the Insteon 131.65kHz rate.
>
> I think it takes some rather large voltage anomolies that last for more
than
> 1/2 cycle to cause a perceptible flicker and don't think the Insteon
control
> signal fits the bill (of indictment).
>
> "Jeff Volp" <JeffVolp@xxxxxxx> wrote:
>
> >Since Insteon starts sending data BEFORE the actual zero crossing, I
suspect
> >that dimmers using the zero crossing as a time reference may be confused
by
> >the Insteon signal.  That would cause the triac phase to be modulated by
how
> >early that erroneous zero crossing is detected.  At full intensity, the
> >triac should be triggered right after the real zero crossing.  If the
> >Insteon signal causes the triac to be turned on early, it would switch
off
> >at the real zero crossing, and miss conduction for the next half cycle.
> >Similarly, dimmed lights would change intensity in response to any
shifting
> >trigger phase delay.
> >
> >Since X10 sends its data after the zero crossing, dimmers that use zero
> >crossing as a time reference would be unaffected by X10 data.
> >
> >There are reports of dimmers made by other manufacturers being effected,
so
> >this may be a nasty problem to resolve.
> >
> >Jeff
> >
> >"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
> >news:4496d9fc.206904843@xxxxxxxxxxxxxxxx
> >> As for trying to reconcile the reports, that's what I was alluding to
when
> >I
> >> said some reports may be due to user inexperience or ineptitude.
However,
> >> there have been reports from someone who is neither inexperienced nor
> >inept
> >> that some X-10 dimmers are flickering during Insteon events. I think
the
> >> most likely culprit is excessive triac noise getting to the mains from
the
> >> Insteon dimmers. That could also explain the Lutron dimmer report.
> >>
> >> It really seems improbable that Insteon, X-10 & Lutron devices would
all
> >> flicker in some reaction to the low level Insteon control signals.
> >>
> >> Also, I'm not really losing confidence in Insteon. I still think the
> >concept
> >> is sound. I think the problem is one of too much haste in introducing
new
> >> devices and maybe cost cutting in component choices. The demand has
been
> >> high for new devices
> >
>