Re: I think they've done it again.

[nobody@xxxxxxxxxxxx (Dave Houston)]

Jeff,

I understood what you were describing. I just don't think that would happen.
Normally, I would expect that the earliest the triac is triggered (full
bright) would be just after the Insteon control signal ends at ZC+1023µS.

If it were switched off early, the electronics should still detect ZC (and
maybe detect 232 of them caused by the control signal before true ZC). I
think it likely the triac will be triggered on at the normal point after the
true ZC.

In most of the reports, the Insteon device is at about 20% dim level when
the flicker occurs. This would put the triac switch-on point well past the
ZC.

"Jeff Volp" <JeffVolp@xxxxxxx> wrote:

>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
>> >
>>
>